Taphonomy of Quaternary Pectinidae and a Comparison With Early Permian Shells

Taphonomy of Quaternary Pectinidae and a Comparison With Early Permian Shells | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Taphonomy of Quaternary Pectinidae and a Comparison With Early Permian Shells Hugo Schmidt Neto, Rodrigo Scalise Horodyski This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3764580/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Actuopaleontology has been widely developed to improve the interpretations of the fossil record. In the Paraná Basin, a pectinid-dominated fossil record marks the Late Paleozoic strata (Upper Carboniferous, Lower Permian), an opportunity to compare their taphonomic signatures with Quaternary valves through actualistic research. This research aims to improve the biostratinomic knowledge of pectinid fossil concentrations, leading to better environmental and ecological interpretations of the fossil record. Thus, the present study is based on the taphonomy of 173 valves of Aequipecten tehuelchus . The Quaternary valves were collected on the foreshore of the coastal plain of the Rio Grande do Sul state. Fragmentation degree, flat/convex valve rate, dissolution, bioerosion ( i.e ., borings and drill holes), and incrustation were quantified. Following, Quaternary pectinid data were compared with available information on the Lower Permian pectinids from the Rio Bonito Formation (Paraná Basin). Not all signatures imprinted in the Quaternary material were observed in Permian molds. However, physical and biological damages were preferentially observed in both Quaternary and Permian samples. Quaternary pectinids on the modern beach suggest the high transportability and durability of their hard skeletons. These taphonomical and sedimentary processes increase the time-averaging and spatial-averaging since Lower Permian pectinids storm-assemblage was registered in the estuarine setting. Furthermore, both deposits studied here were generated during an icehouse/greenhouse transition, and the spatial averaging may have been increased due to the sea-level oscillation and consequent erosion/reworking in marginal marine environments. icehouse-greenhouse mollusk physical damage time average marine deposits Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. INTRODUCTION Several paleontologists have executed studies using recent shells to improve the scientific biostratinomy knowledge as a key to understanding the fossil record (Agostini et al., 2017 ; Allen, 1984 ; Best and Kidwell, 2000a , 2000b ; Brenchley and Newall, 1970 ; Cadée, 2002 , 1992 ; Carthew and Bosence, 1986 ; De Francesco and Hassan, 2008; Dent and Uhen, 1993 ; Flessa and Fürsich, 1991 ; Fürsich and Flessa, 1987 ; Kosnik and Kowalewski, 2016 ; Kowalewski, 1995 ; Kowalewski et al., 2003 , 2000 , 1994 ; Lever, 1958 ; Lever et al., 1964 , 1961 ; Meldahl and Flessa, 1990 ; Messina and Labarbera, 2004 ; Powell et al., 2011 ). However, despite the number of actualistic projects using recent mollusk shells as subjects for paleontological studies (references herein), taphonomic research with pectinids remains scarce (Aguirre et al., 1996 ; Hayami, 1991 ; Mandic and Piller, 2001 ; Rocha-Campos, 1966 ; Schmidt-Neto et al., 2018a , 2014 ). The Pectinidae family has occurred since Devonian until today (Waller, 2006 ), and they are one of the most famous taxa due to their charismatic fan shape, which is even used as a logo by a fuel company. Currently, pectinids are distributed worldwide, inhabiting shallow to deep bathymetric zones, and exhibit various behaviors such as swimming, byssally attached, or reclining on the floor (Brand, 2006 ). Morphological adaptations to variations in the bathymetric gradient and its sediments are observed (Aguirre et al., 1996 ; Stanley, 1972 , 1970 ). Such characteristics of pectinids give them a singular quality that allows us to improve our biostratinomic knowledge about this group. Pectinid-dominated fossil assemblages are described in the Late Paleozoic sedimentary strata of the Paraná Basin (Beurlen, 1954 ; Neves et al., 2014a ; Rocha-Campos, 1970 ; Schmidt-Neto et al., 2018a , 2014 ), opening us a valuable window to study the potential preservation of taphonomic signatures on Paleozoic pectinid fossils. Therefore, it presents the taphonomic signatures observed in the Aequipecten tehuelchus d’Orbigny, 1842 (Pectinida) collected in the death assemblages from the Coastal Plain of the Rio Grande do Sul (CPRS) and a comparison with Lower Permian fossils of the Rio Bonito Formation. This effort aims to improve the knowledge of pectinid biostratinomy by comparing the taphonomy of Quaternary and Permian pectinid valves. The results reached with this study improve the environmental and paleoecological interpretations of the fossil record. Additionally, our observations will contribute to future studies on pectinid-dominated fossil assemblages. 2. MATERIAL AND METHODS This study is based on an analysis of 173 Quaternary pectinid valves collected during six field campaigns realized between 2019 and 2022. Two CPRS sites were established for collection. Five field campaigns took place in the south (Chuí) and one in the north (Nova Tramandaí) (Fig. 1 A-C). All valves were collected manually along a 3 km long by 10 m wide transect drawn along the foreshore (Fig. 1 D). This sampling methodology was applied to all six field campaigns. To the south, the field campaigns occurred in April (autumn season) and November (spring season). We opted for these two months due to the graduation activities carried out in the region during this same period. The collection in the north of CPRS was carried out in October (Spring season). During the sampling, the valves were wrapped in cotton to avoid fragmentation due to their fragility in handling. In the lab, a 5x magnifying glass was used to observe the taphonomic signatures, epibionts, and macro-bioerosion on the valves. All valves were housed in the Laboratório da Vida e da Terra at the Unisinos University (São Leopoldo, RS). Fragmentation degree, corrosion, abrasion, left-right valve ratio, bioerosion, and incrustation were considered in the analyses. Valves were qualified as whole when ≥ 90% were preserved while the others were signed as fragments. Corrosion was qualified as light (stains and incomplete pitting), moderate (discolored, margin dissolved), and severe (full pitting resulting in holes in the surface, valve translucid, and most accentuated dissolution between ribs). Abrasion was qualified as mild (peeling of the umbo), moderate (wear of the ribs and auricles), and severe (rounding of fragments and severe wear of the ribs). Quaternary pectinids were taxonomically identified following the WORMS platform (World Register of Marine Species, https://www.marinespecies.org/ ) and the revision presented by Clavijo et al. ( 2005 ). Bioerosion traces were identified at the genus level, while epibionts were identified as common names. Sample values were grouped to calculate the abundance and frequency of the taphonomic variants (described above). The following equation f = c*100/n was used to compute the frequency. In this equation, “ c* ” is the value of the variant ( i.e ., fragmentation, corrosion, bioerosion), and n is the total sampling value. Whole valves were measured and their geometric mean was computed considering their height and length (see Kosnik et al., 2006 ). Permian pectinid data used in this study are available in previous publications (Rocha-Campos, 1970 ; Schmidt-Neto et al., 2018b , 2018a , 2014 ), giving an essential framework to reach the aims of this study. In this sense, a standardization of the analysis was adopted to compare the data from Permian pectinids with the Quaternary ones (Table 1 ). Table 1 Taphonomic signatures can be observed in both Permian and Quaternary pectinid valves. Abbreviations: W = whole; F = fragmented; Dis. = disarticulated; L-R = left-right; Bioer. = bioerosion; Incrust. = incrustation; Cor. = corrasion ( i.e ., abrasion and dissolution); pres. = preservation; Obs. = observed; f = frequency; Hcs = storm deposits; F-w = fair-weather deposits. From Fragmentation Articulation L-R ratio Bioer. Incrust. Cor. Kind of pres. Source W F Close Open Dis. Taió (Early Permian) f = 43% f = 57% Obs. ( f = < 0.5%) Obs. ( f = < 0.5%) f = 99% L: f = 99% R: f = 1% Obs. ( f = ~ 10%) Not obs. Not obs. Mold & cast Schmidt-Neto et al. 2014 , 2018b Cambaí Grande (Early Permian) Hcs : f = 26% F-w : f = 48% Hcs : f = 7 4% F-w : f = 52% f = 0% f = 0.5% f = 99% L: f = 99% R: f = 1% Obs. ( f = ~ 10%) Not obs. Not obs. Mold & cast Schmidt-Neto et al. 2018a PCRS (Quaternary) f = 17% f = 83% f = 0% f = 0% f = 100% L: f = 80% R: f = 8% Obs. ( f = 30%) Obs. ( f = 6%) Obs. ( f = 58%) Original shell Present research 3. STUDY AREA 3.1 Quaternary samples Considered the most extensive coastal plain in Brazil, the CPRS is 620 km long and up to 100 km wide at places (Fig. 1 A), covering ca. 33,000 km 2 (Tomazelli and Villwock, 2000 ). Classified as a dissipative beach ( i.e ., smooth-sloping, vast, and unprotected beach composed of fine-grained sands, sensu Masselink and Short, 1993 ; Wright et al., 1979 ), the CPRS is an exposed and open coastal zone usually subjected to high kinetic wind and wave energy. The depositional dynamic on CPRS is ruled mainly by wind regimes that influence the morphodynamic processes of coastal dune fields and long-shore currents and waves (Tomazelli and Villwock, 2000 ). The wind regime follows a bimodal seasonal pattern, which shows a predominance of Polar Mobile anticyclone regime during the autumn and winter (Tomazelli, 1993 ) when a most significative reworking of sediments and consequent transport of bioclasts is expected. As a result, fossiliferous strata exposed in outcrops near the coast (i.e., on the stream Arroio Chuí, see Lopes et al., 2001 ) and on the seafloor are reworking by hydrodynamic processes (fair-weather waves, storm surges, currents, and tides) resulting in death assemblages composed by recent and fossil bioclasts (Bettinelli et al., 2018 ; Cruz and Buchmann, 2010 ; Lopes and Buchmann, 2008 ; Villwock and Tomazelli, 1995 ). 3.2 Lower Permian samples The Late Paleozoic was marked by a transgression triggered by the glaciation demise. During this time, incised valleys were drowned, leading to the establishment of wave-dominated estuaries (Saldanha et al., 2023 ; Tedesco et al., 2016 ) and barrier-lagoon system (Elias et al., 1999 ; Lavina and Lopes, 1987 ). Besides influencing the ecology of benthic communities, the transgression also imprints taphonomic signatures as the mixing of better and worse preserved bioclasts (Schmidt-Neto et al., 2018a , 2014 ). According to Schmidt-Neto et al. ( 2014 , 2018a ), the taphonomic signatures observed on the fossil assemblages from the Rio Bonito Fm. correspond to the pattern described by Brett ( 1998 , 1995 ) for transgressive fossiliferous lags. One of the most evident features of Late Paleozoic deposits from the Paraná Basin is the heteropectinid-dominated fossil assemblages in the Upper Carboniferous and Lower Permian strata (Beurlen, 1954 ; Neves et al., 2014b ; Schmidt-Neto et al., 2018a , 2014 ; Simões et al., 1997 ). From the Early Permian (Rio Bonito Formation), two fossil assemblages (Taió Sandstones and Cambaí Grande) with fossils of the Family Heteropectinidae Beurlen, 1954 are described. The first fossil assemblage is characterized by the abundant occurrence of Heteropecten catharinae Rocha-Campos, 1970 , found in the central-eastern region of the Santa Catarina state. This fossil record has been interpreted as lower shoreface deposits influenced by storm events (Schmidt-Neto et al., 2014 ). The second fossil assemblage, characterized by an abundant record of Aviculopecten cambahyensis Martins, 1951 occurs in the central-western region of the Rio Grande do Sul state. The fossil assemblages from Cambaí Grande are interpreted as fair-weather and storm deposits in an estuarine environment (Schmidt-Neto et al., 2018a ). 4. RESULTS 4.1 Quaternary taphonomy Of the 173 Quaternary pectinid valves collected in the CPRS, 16.8% are classified as whole (n = 29), and 83.2% as fragmented (n = 144) (Fig. 2 ). 80% of the valves are convex (n = 138), while 8% are flat (n = 14) (Fig. 2 ), and the other 12% (n = 21) are so fragmented that it is not possible to identify if they are convex or flat. All category levels of corrosion were observed. Light corrosion level was observed in 54.9% of the valves (n = 95), moderate level at 2.3% (n = 4), and severe at 0.6% (n = 1) (Fig. 2 ). No corroded valves sum 42.2% of the total (n = 73). A total of 72.3% (n = 125) of the valves show any sign of abrasion, of which 68.2% (n = 118) are qualified as light, 3.5% (n = 6) as moderate, and 0.6% (n = 1) as severe (Fig. 2 ). Borings were observed in 29% (n = 50) of valves and are represented by cf. Caulostrepsis ( f = 16%, n = 28), cf. Gastrochaenolites ( f = 6.9%, n = 12), cf. Pennatichnus ( f = 4.6%, n = 8), and cf. Entobia ( f = 1.2, n = 2). A total of 23.7% of the valves were drilled. The traces correspond to cf. Oichnus simplex ( f = 40%, n = 21), O. ovalis ( f = 23%, n = 12), and O. paraboloides ( f = 2%, n = 1). Incomplete perforations sum 19 occurrences ( f = 36%). Eight valves were drilled more than one time. Epibionts were identified in 5.8% (n = 10) of valves. They were identified as bivalves ( f = 2.3%, n = 4), balanids ( f = 1.7, n = 3), bryozoans ( f = 1.2, n = 2), and corals (f = 1.2, n = 2). Valves with colors varying from black to gray, white, yellowish, and brown were observed (Fig. 3 ). Other differences in the morphological characteristics were the occurrence of round or flat ribs and variation in the number of them varying from 11 to 16. However, all specimens were identified as Aequipecten tehuelcus d’Orbigny, 1842. Among the valves collected on the foreshore of Chuí Beach, two samples correspond to fossilized specimens (Fig. 4 A and B). The first one is a whole valve with fragments nested in its concavity (Fig. 4 A). They are light gray-colored, bioeroded but not drilled, and have sediment lithified on their surfaces. The second sample is a single gray valve with sand lithified on its surface (Fig. 4 B). 5. DISCUSSION Comparing modern and fossil pectinids allowed us to understand that some taphonomic signatures observed in recent specimens are not preserved in the fossil specimens. Although microbial mats lead to the preservation of structures that otherwise would not be preserved (Iniesto et al., 2016 ), the dissolution of the original valves during fossil diagenesis leads to the loss of some taphonomic signatures imprinted in the original shell. Despite the higher quality preservation and detailing of delicate structures like ribs, lamellae, and adductor scar muscle in molds of the heteropectinids from Early Permian deposits of the Rio Bonito Fm. (Fig. 4 C and D), dissolution signs are not recognizable in these fossils. Determining if these molds show signs of abrasion also requires caution. How is the better manner to distinguish between the abrasion of the original valve preserved as a mold and the erosion of the rock that copies the valve as a mold? In this sense, we opted to discuss first the taphonomic signatures present in original valves and after a comparison with fossil heteropectinids. 5.1 Left-right valves ratio Despite the relative abundance of pectinid valves in the CPRS, only the convex (left) valves are numerous, while the flat (right) ones are scarce (n = 14 of the 173) (Fig. 2 ), which leads us to consider that the left-right valves ratio is conditioned to winnowing by transport. Likewise, a low rate of flat valves was recorded in the fossil assemblages of the Lower Permian Rio Bonito Formation (Beurlen, 1954 ; Reed, 1930 ; Rocha-Campos, 1970 ; Schmidt-Neto et al., 2018a , 2014 ), suggesting that winnowing by currents may be involved in the deposition of both Quaternary and Permian pectinids. Pectinids (including the fossil family Aviculopectinidae) are disk-shaped bivalves with one flat valve and another convex. For this reason, their valves present different hydrodynamic behavior when subjected to the same flow (Hayami, 1991 ). On the flat valves, a broad surface keeps in contact with water, increasing its floatage and influencing its terminal fall, while the convex valves tend to turn the convex dorsal portion of the valve downward (Allen, 1984 ; Hayami, 1991 ). Previous works with right and left valves have demonstrated that different morphologies show different answers to wind and hydraulic transports (Brenchley and Newall, 1970 ; Cadée, 1992 ; Lever, 1958 ; Lever et al., 1964 ). Thus, due to the features of pectinid valves (i.e., flat and convex shapes), we may expect a sorting effect on these. Moreover, the sorting observed between convex (left) and flat (right) valves of pectinids also represents a clear example of the “L-R Effect” (left-right effect) tested by Lever ( 1958 ). On the other hand, such disproportionate occurrence may also result from differences in preservation potential. A less calcifying condition of the margin of flat valves of pectinids is another factor to consider in interpreting the flat/convex ratio. Some authors considered the difference in calcification between both valves a result of the behavior of reclining on the floor (Johnson, 1984 ; Stanley, 1970 ). In this case, the valve in contact with the floor would be less calcified than its upward-facing pair. The small size of flat (right) valves of Heteropecten catharinae in comparison to their counterpart convex (left) valves has been attributed to the lower calcium concentration in the margin of the valve (Kegel and Costa, 1951 ; Rocha-Campos, 1970 ) which led to the faster dissolution of them. In this sense, a more accentuated dissolution on flat valves than convex one could bias the final left-right ratio values. 5.2 Fragmentation A higher frequency of fragmented valves ( f = 83.2%) was recorded, with the fragmentation attributed to mechanical factors. The shore of the CPRS is constantly affected by winds, resulting in a higher transport of sediments (e.g., sand grains and lightweight bioclasts) (Tomazelli, 1993 ). In the swash zone, the reworking by waves is constant, and bioclasts can be moved up and down on the shore, becoming subject to mechanical damages such as shocks and abrasion. Comparing the results presented by this research with those showed by Schmidt-Neto et al. ( 2014 ; 2018a , b ) for Permian pectinid deposits, two trends are noted: i) higher occurrence of highly-fragmented valves associated with high-energy environments, and ii) higher occurrence of whole valves in quiet environments or under higher sedimentation rates. Within the taphofacies model for epeiric seas presented by Speyer and Brett (1988), higher frequencies of fragmentation are expected in high-energy environments with a low sedimentation rate. Therefore, the fragmentation of pectinid valves is an advantageous signature to infer the energy environment, sedimentation rate, and the reworking suffered by valves. 5.3 Abrasion and corrosion A similar frequency for the same levels of abrasion and corrosion was observed (Fig. 2 ). Such results suggest the exposition of the valves on the taphonomic active zone. As a result of this exposition, wearing of the valve surfaces is expected (Meldahl and Flessa, 1990 ; Salamon et al., 2020 ). In this sense, the results showed in this research suggest the burial and exhumation of the valves several times. 5.4 Bioerosion (borings and drill holes) Traces attributed to the bioerosion activity of polychaetes (cf. Caulostrepsis ), sponges (cf. Entobia ), bivalves (cf. Gastrochaenolites ), bryozoans (cf. Pennatichnus ), and drill holes Oichnus simplex , O. paraboloides , and O. ovalis were observed. These bioerosions represent three ethology traces classified as Domichnia (cf. Caulostrepsis and cf. Gastrochaenolites ), Fixichnia (cf. Pennatichnus and cf. Entobia ), and Praedichnia ( Oichnus simplex, O. paraboloides , and O. ovalis ) (Fig. 5 ). The occurrence of traces if cf. Pennatichnus and cf. Entobia suggests the shells were available below the fair-weather wave base where the probability of the valves being turned or buried is low (Meldahl and Flessa, 1990 ). Furthermore, the transport of bioclasts from the lower shoreface to the foreshore by storm has already been documented by previous research (Cruz and Buchmann, 2010 ; Lopes, 2011 ; Lopes and Buchmann, 2008 ). Opposite to CPRS, only sponge traces ( Entobia and Clionolithes ) were recorded on the shells from Rio Bonito Fm. (Schmidt-Neto et al., 2018b ). Drilling valves correspond to at least 23% of all valves (n = 39, 173), with many valves showing more than one complete perforation. These multiple perforations are uncommon and led us to raise the question: was the mollusk attacked by two predators, or was the valve perforated after the mollusk had already been previously attacked? In any case, the presence of multiple complete perforations evidences the value of pectinids as a food resource for predators such as gastropods ( Oichnus simplex and O. paraboloides , Fig. 5 A and F) and octopods ( O. ovalis , Fig. 5 C). 5.5 Incrustation Despite the low number of encrusted valves (5%, n = 9 of 173), we can observe the occurrence of bivalves, barnacles, bryozoans, and corals as components of the epibiont assemblages (Fig. 6 ). Epibionts were observed both in the outer and inner surfaces of the valves. Regarding the epibionts on the outer side of the valve, it is impossible to determine whether they occurred during the life of the bivalve or after its death. The low abundance (n = 11) and low frequency ( f = 6%) of epibionts on pectinid valves suggest these are not the most suitable bioclast for attachments. Considering that barnacles need a few weeks to months to colonize hard ground (Meldahl and Flessa, 1990 ), the encrustation rate observed in this survey suggests that pectinid valves remained on the sediment for a short period. 5.6 Comparison between Quaternary and Permian pectinid valves Permian pectinid fossils from Paraná Basin are represented by two fossiliferous deposits known as Taió Sandstones (Rocha-Campos, 1970 ; Schmidt-Neto et al., 2014 ) and Cambaí Grande outcrop (Schmidt-Neto et al., 2018a ). According to Schmidt-Neto et al. ( 2014 ), the shell beds from Taió Sandstones are related to two depositional environments. The first, here called the Taió shell bed 1, corresponds to concentrations of shells deposited in an estuarine environment influenced by storm waves. Valves from Taio shell bed 1 were preserved preferentially whole and showed a narrow size range characterized by small valves (varying from 1 to 5 mm in height). The second is called the Taió shell bed 2 and is represented by shell beds formed in the lower shoreface during storm events. Such shell beds are characterized by a broad size range with a predominance of large pectinids (reaching 80 mm in height) and a greater abundance of fragments than whole valves. Comparing Quaternary and Permian pectinids, it was possible to recognize that left-right ratio, sorting size, fragmentation, and bioerosion are the commonest signatures among them. Although uncommon, it was possible to observe the muscle scars and lamellae in Permian molds (Fig. 4 C and D). Lamellae and ribs are fundamental for the taxonomic differentiation of fossil pectinid genera (Kegel and Costa, 1951 ; Neves et al., 2014; Rocha-Campos, 1970 ; Waterhouse, 1969 ). Other alterations, such as dissolution and abrasion, are hard to recognize in casts and molds and weren’t observed in the Permian fossils. As previously discussed, the fragmentation is directly proportional to the reworking grade suffered by the valves. Comparing CPRS fragmentation values with those recorded for the Cambaí Grande outcrop and Taió sandstones (i.e., Taió shell bed 1 and Taió shell bed 2), the influence of high and low energy processes on the genesis of these deposits is implied. The valves from Taió shell bed 1, deposited under moderate energy events (i.e., distal tempestites), show a predominance of whole valves (Fig. 7 ). On the other hand, the Quaternary valves from CPRS and the fossils from Taió shell bed 2 and Cambaí Grande outcrop show a predominance of fragmented valves (Fig. 7 ). The higher frequency of fragmented pectinid valves in the CPRS is attributed to their exposition to constant wave action in the upper shoreface and swash zone, where the wave currents may be considerate moderate to high energy, including in fair-weather periods. Well-sorted sizes may also be linked to differences in the kinetic gradient of the environment. The fossil deposits from Taió shell bed 1 show a well-sorted sized population, while a broad size range is observed for Quaternary pectinids from CPRS and fossils from Taió shell bed 2 and Cambaí Grande outcrop (Fig. 8 ). Such differences seem to show the capacity of transport of pectinid valves by current and waves. Another sorting observed is related to the left-right valve ratio. A low number of flat (right) valves is a well-marked characteristic observed in the current foreshore than in the three fossil assemblages used in this study (Fig. 7 ), highlighting how this morphological feature is significant to infer about transport and sorting of the valves by currents and waves. Regarding the presence of molds and casts of borings, chambers, and channels in the valves of Heteropecten catharinae (Schmidt-Neto et al., 2018b ), such paleontological records show that bioerosion traces have a better potential for preservation. However, we understand that it is necessary to carry out a more accurate search for bioerosion traces in the Permian heteropectinid valves from the Rio Bonito Formation to improve our understanding of the presence of these signatures in both Quaternary and Permian pectinids. Therefore, any comparison and discussion would be premature at this moment. Quaternary pectinids on the beach suggest the high transportability and durability of their hard skeletons. These taphonomical and sedimentary processes increase the time-averaging and spatial-averaging since Lower Permian pectinids storm assemblage was registered in an estuarine setting by Schmidt-Neto et al. ( 2018a ). Furthermore, both deposits studied here were generated during an icehouse/greenhouse transition, and the spatial averaging may have been increased due to the sea-level oscillation and consequent erosion/reworking in marginal marine environments. 6. CONCLUSION Conducting this research, we conclude that physical and biological damages on the pectinid valves, such as fragmentation, bioerosion, and incrustation, show high potential for preservation and can be easily identified in molds and casts from the fossil record. A relationship between the taphonomic characteristics (fragmentation, disarticulation, orientation), intrinsic features of the valves (robustness, flatness, convexity, and resistance), and sedimentological characteristics (winnowing) are similar to both Quaternary and Permian pectinids. The signatures described on pectinid valves in this study, when associated with the kinetic energy degree of the environment (fair-weather waves, storm surges, quiet environment), allow us to improve our paleoenvironmental and paleoecological inferences. The comparison between Quaternary and Permian pectinids demonstrated that actualistic taphonomic studies improve our paleontological knowledge about pectinid fossil assemblages. Declarations ACKNOWLEDGMENT The authors are thankful to Rômulo Cenci for the photographs. H.S.N. is thanks to CAPES/CNPq for the post-doctoral grant. R.S.H. is thanks to CNPq PQ 310970/2022-9 and CNPq 420748/2018-0. 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Marine Geology , 32 , 105–140. https://doi.org/10.1016/0025-3227(79)90149-X . Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 16 Jan, 2024 Reviewers invited by journal 16 Jan, 2024 Editor assigned by journal 20 Dec, 2023 First submitted to journal 15 Dec, 2023 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3764580","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":267472916,"identity":"d3a50983-0200-4480-a28d-a5073c8411ef","order_by":0,"name":"Hugo Schmidt Neto","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3klEQVRIiWNgGAWjYFAC5gYY4wCQkJAhQgsjWIsEDwNbAoQmQQuPAYhBWIs5+8HGBx932NTZs/d8fnWjxoKHgf3w0Q34tFj2JDYbzjyTJsHDc3abdc4xkG1paTfwaTE4kNgmzdt2WIJHInebcQ4bUIsEjxl+Lecftv/mbfsP1JLzzDjnHzFabiS2MfO2HQBpYX6c20aEFssZD5slZ7YlS/acOWbGnNsnwcNGyC/m/MkHP3xss+Nnb29+/DnnW50cP/vhY/gdhsRmkwCT+JSja2H+QEj1KBgFo2AUjEwAAPJnRLIzNZ9LAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0003-4472-9066","institution":"Unisinos: Universidade do Vale do Rio dos Sinos","correspondingAuthor":true,"prefix":"","firstName":"Hugo","middleName":"Schmidt","lastName":"Neto","suffix":""},{"id":267472917,"identity":"09a856f6-58f9-4daf-a19a-5d457696b12f","order_by":1,"name":"Rodrigo Scalise Horodyski","email":"","orcid":"","institution":"Unisinos: Universidade do Vale do Rio dos Sinos","correspondingAuthor":false,"prefix":"","firstName":"Rodrigo","middleName":"Scalise","lastName":"Horodyski","suffix":""}],"badges":[],"createdAt":"2023-12-16 19:44:50","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3764580/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3764580/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":49806700,"identity":"5c470880-b216-4f6c-839c-fb0364d9897d","added_by":"auto","created_at":"2024-01-18 10:35:45","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":654349,"visible":true,"origin":"","legend":"\u003cp\u003eMap of location and characterization of the study area. A) Map showing the two sampling localities on the Coastal Plain of the Rio Grande do Sul state. B) Shell concentration on the foreshore of the Chuí beach. C) Foreshore on the Nova Tramandaí beach. D) Schematic illustration of the transect (dot line) method used for sampling. The vertical line shows the width of the foraging area (5 meters on each side of the transect).\u003c/p\u003e","description":"","filename":"figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3764580/v1/ba75ec8b143b16ae37ffde9a.jpg"},{"id":49806303,"identity":"9710a96d-8f3c-418d-80ae-a5e4a3be0375","added_by":"auto","created_at":"2024-01-18 10:27:45","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":149433,"visible":true,"origin":"","legend":"\u003cp\u003eFrequency of taphonomic signatures observed in the modern pectinid valves.\u003c/p\u003e","description":"","filename":"figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3764580/v1/45850a6a89c15fc92ba11ebb.jpg"},{"id":49806304,"identity":"f74809b3-8e38-4144-ade7-1425e14a5849","added_by":"auto","created_at":"2024-01-18 10:27:45","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":693292,"visible":true,"origin":"","legend":"\u003cp\u003eDifferent colors observed for modern pectinid valves of \u003cem\u003eAequipecten tehuelcus\u003c/em\u003e.\u003c/p\u003e","description":"","filename":"figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3764580/v1/fede3bf34ad971d0b75a34c2.jpg"},{"id":49806307,"identity":"7b1cafb2-a628-4f96-9355-c413d1cb94cd","added_by":"auto","created_at":"2024-01-18 10:27:45","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":501483,"visible":true,"origin":"","legend":"\u003cp\u003eFossil specimens of pectinid forms. A and B) Fossilized valves of Aequipecten tehuelcus collected in the CPRS. C) Mold of Permian \u003cem\u003eHeteropecten catharinae\u003c/em\u003e with the record of lamellae (black arrows). D) Mold of Permian \u003cem\u003eHeteropecten paranaensis\u003c/em\u003e showing the adductor muscle scar on the right valve. Scale bars: A and B = 10 mm; C and D = 0.5 mm.\u003c/p\u003e","description":"","filename":"figure4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3764580/v1/9f6e7a3700860e8a5a8ea5ee.jpg"},{"id":49806310,"identity":"791f06e1-282d-4d58-a119-dc4246f978cd","added_by":"auto","created_at":"2024-01-18 10:27:45","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":921736,"visible":true,"origin":"","legend":"\u003cp\u003eBioerosion traces observed in the modern pectinids. A)\u003cem\u003eOichnus simplex \u003c/em\u003e(\u003cem\u003eOi\u003c/em\u003e), cf. \u003cem\u003eGastrochaenolites\u003c/em\u003e (\u003cem\u003eGa\u003c/em\u003e), and one incomplete perforation (\u003cem\u003eIp\u003c/em\u003e). B) cf. \u003cem\u003eCaulostrepsis\u003c/em\u003e. C) cf. \u003cem\u003eGastrochaenolites\u003c/em\u003e (\u003cem\u003eGa\u003c/em\u003e), \u003cem\u003eOichnus ovalis\u003c/em\u003e (\u003cem\u003eOo\u003c/em\u003e), and cf. \u003cem\u003eCaulostrepsis \u003c/em\u003e(\u003cem\u003eCa\u003c/em\u003e). D) cf. \u003cem\u003ePennatichnus\u003c/em\u003e. E) \u003cem\u003eOichnus simplex\u003c/em\u003e. F\u003cem\u003e Oichnus paraboloides \u003c/em\u003e(\u003cem\u003eOp\u003c/em\u003e), and cf. \u003cem\u003eCaulostrepsis \u003c/em\u003e(\u003cem\u003eCa\u003c/em\u003e).\u003c/p\u003e","description":"","filename":"figure5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3764580/v1/3e6f3d2e5f4f6a04a4bdf4b4.jpg"},{"id":49806309,"identity":"d85e982a-3cd7-49ac-8e22-6cc7a15aae97","added_by":"auto","created_at":"2024-01-18 10:27:45","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1159391,"visible":true,"origin":"","legend":"\u003cp\u003eSclerobionts observed in Quaternary pectinids. A) Bivalves inside of the left valve. B) Bryozoan (Bryo). C) Bivalves (Biv), and balanids (Bal) inside of the left valve. D) Fragmented base of coral on the auricle of the left valve. E) Fragmented base of balanids (Bal), and bryozoans (Bryo) on the left valve. F) A magnified image of the fragmented base of balanids shown in the figure E.\u003c/p\u003e","description":"","filename":"figure6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3764580/v1/519fc08ef24d6ea915c768d7.jpg"},{"id":49806701,"identity":"9ccdf734-3aac-4978-abcb-802b503305b5","added_by":"auto","created_at":"2024-01-18 10:35:45","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":213620,"visible":true,"origin":"","legend":"\u003cp\u003eFrequency of taphonomic signatures observed in both modern (CPRS) and fossil pectinid forms. Abbreviations: Taio sb 1 = Taió shell bed 1; Taió sb 2 = Taió shell bed 2.\u003c/p\u003e","description":"","filename":"figure7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3764580/v1/dcc6350d2ad1d64ebd636ab8.jpg"},{"id":49806305,"identity":"a31f5210-2245-4a7a-b3f3-722dda1c7fdb","added_by":"auto","created_at":"2024-01-18 10:27:45","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":164310,"visible":true,"origin":"","legend":"\u003cp\u003eGeometric mean comparison among Permian pectinids and the Quaternary \u003cem\u003eAequipecten tehuelcus\u003c/em\u003ecollected in the CPRS (Coastal Plain of the Rio Grande do Sul). Abbreviations: Tsb 1 = Taió shell bed 1; Tsb 2 = Taió shell bed 2; CG = Cambaí Grande; CPRS = Coastal Plain of the Rio Grande do Sul.\u003c/p\u003e","description":"","filename":"figure8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3764580/v1/8809b951f9959f87f22e1148.jpg"},{"id":49806987,"identity":"bff49603-ea14-4792-a3cb-bdff58bf42fe","added_by":"auto","created_at":"2024-01-18 10:43:45","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1012903,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3764580/v1/2fecc43c-d781-40e9-bf56-092b88868543.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003eTaphonomy of Quaternary Pectinidae and a Comparison With Early Permian Shells\u003c/p\u003e","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003eSeveral paleontologists have executed studies using recent shells to improve the scientific biostratinomy knowledge as a key to understanding the fossil record (Agostini et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Allen, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1984\u003c/span\u003e; Best and Kidwell, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2000a\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2000b\u003c/span\u003e; Brenchley and Newall, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1970\u003c/span\u003e; Cad\u0026eacute;e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2002\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Carthew and Bosence, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1986\u003c/span\u003e; De Francesco and Hassan, 2008; Dent and Uhen, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1993\u003c/span\u003e; Flessa and F\u0026uuml;rsich, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e1991\u003c/span\u003e; F\u0026uuml;rsich and Flessa, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e1987\u003c/span\u003e; Kosnik and Kowalewski, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Kowalewski, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e1995\u003c/span\u003e; Kowalewski et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2003\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2000\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e1994\u003c/span\u003e; Lever, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e1958\u003c/span\u003e; Lever et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1964\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e1961\u003c/span\u003e; Meldahl and Flessa, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e1990\u003c/span\u003e; Messina and Labarbera, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Powell et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). However, despite the number of actualistic projects using recent mollusk shells as subjects for paleontological studies (references herein), taphonomic research with pectinids remains scarce (Aguirre et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1996\u003c/span\u003e; Hayami, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e1991\u003c/span\u003e; Mandic and Piller, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Rocha-Campos, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e1966\u003c/span\u003e; Schmidt-Neto et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe Pectinidae family has occurred since Devonian until today (Waller, \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2006\u003c/span\u003e), and they are one of the most famous taxa due to their charismatic fan shape, which is even used as a logo by a fuel company. Currently, pectinids are distributed worldwide, inhabiting shallow to deep bathymetric zones, and exhibit various behaviors such as swimming, byssally attached, or reclining on the floor (Brand, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Morphological adaptations to variations in the bathymetric gradient and its sediments are observed (Aguirre et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1996\u003c/span\u003e; Stanley, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e1972\u003c/span\u003e, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e1970\u003c/span\u003e). Such characteristics of pectinids give them a singular quality that allows us to improve our biostratinomic knowledge about this group.\u003c/p\u003e \u003cp\u003ePectinid-dominated fossil assemblages are described in the Late Paleozoic sedimentary strata of the Paran\u0026aacute; Basin (Beurlen, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e1954\u003c/span\u003e; Neves et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2014a\u003c/span\u003e; Rocha-Campos, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1970\u003c/span\u003e; Schmidt-Neto et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), opening us a valuable window to study the potential preservation of taphonomic signatures on Paleozoic pectinid fossils. Therefore, it presents the taphonomic signatures observed in the \u003cem\u003eAequipecten tehuelchus\u003c/em\u003e d\u0026rsquo;Orbigny, 1842 (Pectinida) collected in the death assemblages from the Coastal Plain of the Rio Grande do Sul (CPRS) and a comparison with Lower Permian fossils of the Rio Bonito Formation. This effort aims to improve the knowledge of pectinid biostratinomy by comparing the taphonomy of Quaternary and Permian pectinid valves.\u003c/p\u003e \u003cp\u003eThe results reached with this study improve the environmental and paleoecological interpretations of the fossil record. Additionally, our observations will contribute to future studies on pectinid-dominated fossil assemblages.\u003c/p\u003e"},{"header":"2. MATERIAL AND METHODS","content":"\u003cp\u003eThis study is based on an analysis of 173 Quaternary pectinid valves collected during six field campaigns realized between 2019 and 2022. Two CPRS sites were established for collection. Five field campaigns took place in the south (Chu\u0026iacute;) and one in the north (Nova Tramanda\u0026iacute;) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA-C). All valves were collected manually along a 3 km long by 10 m wide transect drawn along the foreshore (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eD). This sampling methodology was applied to all six field campaigns.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo the south, the field campaigns occurred in April (autumn season) and November (spring season). We opted for these two months due to the graduation activities carried out in the region during this same period. The collection in the north of CPRS was carried out in October (Spring season).\u003c/p\u003e \u003cp\u003eDuring the sampling, the valves were wrapped in cotton to avoid fragmentation due to their fragility in handling. In the lab, a 5x magnifying glass was used to observe the taphonomic signatures, epibionts, and macro-bioerosion on the valves. All valves were housed in the Laborat\u0026oacute;rio da Vida e da Terra at the Unisinos University (S\u0026atilde;o Leopoldo, RS).\u003c/p\u003e \u003cp\u003eFragmentation degree, corrosion, abrasion, left-right valve ratio, bioerosion, and incrustation were considered in the analyses. Valves were qualified as whole when \u0026ge;\u0026thinsp;90% were preserved while the others were signed as fragments. Corrosion was qualified as light (stains and incomplete pitting), moderate (discolored, margin dissolved), and severe (full pitting resulting in holes in the surface, valve translucid, and most accentuated dissolution between ribs). Abrasion was qualified as mild (peeling of the umbo), moderate (wear of the ribs and auricles), and severe (rounding of fragments and severe wear of the ribs).\u003c/p\u003e \u003cp\u003eQuaternary pectinids were taxonomically identified following the WORMS platform (World Register of Marine Species, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.marinespecies.org/\u003c/span\u003e\u003cspan address=\"https://www.marinespecies.org/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) and the revision presented by Clavijo et al. (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). Bioerosion traces were identified at the genus level, while epibionts were identified as common names.\u003c/p\u003e \u003cp\u003eSample values were grouped to calculate the abundance and frequency of the taphonomic variants (described above). The following equation \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003ec*100/n\u003c/em\u003e was used to compute the frequency. In this equation, \u0026ldquo;\u003cem\u003ec*\u003c/em\u003e\u0026rdquo; is the value of the variant (\u003cem\u003ei.e\u003c/em\u003e., fragmentation, corrosion, bioerosion), and \u003cem\u003en\u003c/em\u003e is the total sampling value.\u003c/p\u003e \u003cp\u003eWhole valves were measured and their geometric mean was computed considering their height and length (see Kosnik et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2006\u003c/span\u003e).\u003c/p\u003e \u003cp\u003ePermian pectinid data used in this study are available in previous publications (Rocha-Campos, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1970\u003c/span\u003e; Schmidt-Neto et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2018b\u003c/span\u003e, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), giving an essential framework to reach the aims of this study. In this sense, a standardization of the analysis was adopted to compare the data from Permian pectinids with the Quaternary ones (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTaphonomic signatures can be observed in both Permian and Quaternary pectinid valves. Abbreviations: W\u0026thinsp;=\u0026thinsp;whole; F\u0026thinsp;=\u0026thinsp;fragmented; Dis. = disarticulated; L-R\u0026thinsp;=\u0026thinsp;left-right; Bioer. = bioerosion; Incrust. = incrustation; Cor. = corrasion (\u003cem\u003ei.e\u003c/em\u003e., abrasion and dissolution); pres. = preservation; Obs. = observed; \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;frequency; \u003cem\u003eHcs\u003c/em\u003e\u0026thinsp;=\u0026thinsp;storm deposits; \u003cem\u003eF-w\u0026thinsp;=\u003c/em\u003e\u0026thinsp;fair-weather deposits.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"12\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eFrom\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eFragmentation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c6\" namest=\"c4\"\u003e \u003cp\u003eArticulation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eL-R ratio\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eBioer.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eIncrust.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCor.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eKind of pres.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSource\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eW\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eClose\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOpen\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eDis.\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTai\u0026oacute; (Early Permian)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;43%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;57%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eObs. (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026lt;\u0026thinsp;0.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eObs. (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u0026lt;\u0026thinsp;0.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;99%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eL: \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;99%\u003c/p\u003e \u003cp\u003eR: \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eObs. (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;~\u0026thinsp;10%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eNot obs.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eNot obs.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eMold \u0026amp; cast\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003eSchmidt-Neto et al. \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2018b\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCamba\u0026iacute; Grande (Early Permian)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eHcs\u003c/em\u003e:\u003c/p\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003e26%\u003c/em\u003e\u003c/p\u003e \u003cp\u003e\u003cem\u003eF-w\u003c/em\u003e:\u003c/p\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003e48%\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eHcs\u003c/em\u003e:\u003c/p\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7\u003cem\u003e4%\u003c/em\u003e\u003c/p\u003e \u003cp\u003e\u003cem\u003eF-w\u003c/em\u003e:\u003c/p\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003e52%\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;99%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eL: \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;99%\u003c/p\u003e \u003cp\u003eR: \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eObs. (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;~\u0026thinsp;10%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eNot obs.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eNot obs.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eMold \u0026amp; cast\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003eSchmidt-Neto et al. \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePCRS (Quaternary)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;17%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;83%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eL: \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;80%\u003c/p\u003e \u003cp\u003eR: \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eObs. (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;30%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eObs. (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eObs. (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;58%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eOriginal shell\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003ePresent research\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"3. STUDY AREA","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Quaternary samples\u003c/h2\u003e \u003cp\u003eConsidered the most extensive coastal plain in Brazil, the CPRS is 620 km long and up to 100 km wide at places (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA), covering ca. 33,000 km\u003csup\u003e2\u003c/sup\u003e (Tomazelli and Villwock, \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Classified as a dissipative beach (\u003cem\u003ei.e\u003c/em\u003e., smooth-sloping, vast, and unprotected beach composed of fine-grained sands, \u003cem\u003esensu\u003c/em\u003e Masselink and Short, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1993\u003c/span\u003e; Wright et al., \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e1979\u003c/span\u003e), the CPRS is an exposed and open coastal zone usually subjected to high kinetic wind and wave energy.\u003c/p\u003e \u003cp\u003eThe depositional dynamic on CPRS is ruled mainly by wind regimes that influence the morphodynamic processes of coastal dune fields and long-shore currents and waves (Tomazelli and Villwock, \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). The wind regime follows a bimodal seasonal pattern, which shows a predominance of Polar Mobile anticyclone regime during the autumn and winter (Tomazelli, \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e1993\u003c/span\u003e) when a most significative reworking of sediments and consequent transport of bioclasts is expected. As a result, fossiliferous strata exposed in outcrops near the coast (i.e., on the stream Arroio Chu\u0026iacute;, see Lopes et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2001\u003c/span\u003e) and on the seafloor are reworking by hydrodynamic processes (fair-weather waves, storm surges, currents, and tides) resulting in death assemblages composed by recent and fossil bioclasts (Bettinelli et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Cruz and Buchmann, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Lopes and Buchmann, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Villwock and Tomazelli, \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e1995\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Lower Permian samples\u003c/h2\u003e \u003cp\u003eThe Late Paleozoic was marked by a transgression triggered by the glaciation demise. During this time, incised valleys were drowned, leading to the establishment of wave-dominated estuaries (Saldanha et al., \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Tedesco et al., \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) and barrier-lagoon system (Elias et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Lavina and Lopes, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1987\u003c/span\u003e). Besides influencing the ecology of benthic communities, the transgression also imprints taphonomic signatures as the mixing of better and worse preserved bioclasts (Schmidt-Neto et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). According to Schmidt-Neto et al. (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e), the taphonomic signatures observed on the fossil assemblages from the Rio Bonito Fm. correspond to the pattern described by Brett (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1998\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1995\u003c/span\u003e) for transgressive fossiliferous lags.\u003c/p\u003e \u003cp\u003eOne of the most evident features of Late Paleozoic deposits from the Paran\u0026aacute; Basin is the heteropectinid-dominated fossil assemblages in the Upper Carboniferous and Lower Permian strata (Beurlen, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e1954\u003c/span\u003e; Neves et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2014b\u003c/span\u003e; Schmidt-Neto et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Sim\u0026otilde;es et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e1997\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFrom the Early Permian (Rio Bonito Formation), two fossil assemblages (Tai\u0026oacute; Sandstones and Camba\u0026iacute; Grande) with fossils of the Family Heteropectinidae Beurlen, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e1954\u003c/span\u003e are described. The first fossil assemblage is characterized by the abundant occurrence of \u003cem\u003eHeteropecten catharinae\u003c/em\u003e Rocha-Campos, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1970\u003c/span\u003e, found in the central-eastern region of the Santa Catarina state. This fossil record has been interpreted as lower shoreface deposits influenced by storm events (Schmidt-Neto et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe second fossil assemblage, characterized by an abundant record of \u003cem\u003eAviculopecten cambahyensis\u003c/em\u003e Martins, 1951 occurs in the central-western region of the Rio Grande do Sul state. The fossil assemblages from Camba\u0026iacute; Grande are interpreted as fair-weather and storm deposits in an estuarine environment (Schmidt-Neto et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"4. RESULTS","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e4.1 Quaternary taphonomy\u003c/h2\u003e \u003cp\u003eOf the 173 Quaternary pectinid valves collected in the CPRS, 16.8% are classified as whole (n\u0026thinsp;=\u0026thinsp;29), and 83.2% as fragmented (n\u0026thinsp;=\u0026thinsp;144) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). 80% of the valves are convex (n\u0026thinsp;=\u0026thinsp;138), while 8% are flat (n\u0026thinsp;=\u0026thinsp;14) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), and the other 12% (n\u0026thinsp;=\u0026thinsp;21) are so fragmented that it is not possible to identify if they are convex or flat. All category levels of corrosion were observed. Light corrosion level was observed in 54.9% of the valves (n\u0026thinsp;=\u0026thinsp;95), moderate level at 2.3% (n\u0026thinsp;=\u0026thinsp;4), and severe at 0.6% (n\u0026thinsp;=\u0026thinsp;1) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). No corroded valves sum 42.2% of the total (n\u0026thinsp;=\u0026thinsp;73). A total of 72.3% (n\u0026thinsp;=\u0026thinsp;125) of the valves show any sign of abrasion, of which 68.2% (n\u0026thinsp;=\u0026thinsp;118) are qualified as light, 3.5% (n\u0026thinsp;=\u0026thinsp;6) as moderate, and 0.6% (n\u0026thinsp;=\u0026thinsp;1) as severe (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eBorings were observed in 29% (n\u0026thinsp;=\u0026thinsp;50) of valves and are represented by cf. \u003cem\u003eCaulostrepsis\u003c/em\u003e (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;16%, n\u0026thinsp;=\u0026thinsp;28), cf. \u003cem\u003eGastrochaenolites\u003c/em\u003e (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6.9%, n\u0026thinsp;=\u0026thinsp;12), cf. \u003cem\u003ePennatichnus\u003c/em\u003e (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.6%, n\u0026thinsp;=\u0026thinsp;8), and cf. \u003cem\u003eEntobia\u003c/em\u003e (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.2, n\u0026thinsp;=\u0026thinsp;2). A total of 23.7% of the valves were drilled. The traces correspond to cf. \u003cem\u003eOichnus simplex\u003c/em\u003e (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;40%, n\u0026thinsp;=\u0026thinsp;21), \u003cem\u003eO. ovalis\u003c/em\u003e (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;23%, n\u0026thinsp;=\u0026thinsp;12), and \u003cem\u003eO. paraboloides\u003c/em\u003e (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2%, n\u0026thinsp;=\u0026thinsp;1). Incomplete perforations sum 19 occurrences (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;36%). Eight valves were drilled more than one time. Epibionts were identified in 5.8% (n\u0026thinsp;=\u0026thinsp;10) of valves. They were identified as bivalves (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;2.3%, n\u0026thinsp;=\u0026thinsp;4), balanids (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.7, n\u0026thinsp;=\u0026thinsp;3), bryozoans (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.2, n\u0026thinsp;=\u0026thinsp;2), and corals (f\u0026thinsp;=\u0026thinsp;1.2, n\u0026thinsp;=\u0026thinsp;2).\u003c/p\u003e \u003cp\u003eValves with colors varying from black to gray, white, yellowish, and brown were observed (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Other differences in the morphological characteristics were the occurrence of round or flat ribs and variation in the number of them varying from 11 to 16. However, all specimens were identified as \u003cem\u003eAequipecten tehuelcus\u003c/em\u003e d\u0026rsquo;Orbigny, 1842.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAmong the valves collected on the foreshore of Chu\u0026iacute; Beach, two samples correspond to fossilized specimens (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA and B). The first one is a whole valve with fragments nested in its concavity (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA). They are light gray-colored, bioeroded but not drilled, and have sediment lithified on their surfaces. The second sample is a single gray valve with sand lithified on its surface (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"5. DISCUSSION","content":"\u003cp\u003eComparing modern and fossil pectinids allowed us to understand that some taphonomic signatures observed in recent specimens are not preserved in the fossil specimens. Although microbial mats lead to the preservation of structures that otherwise would not be preserved (Iniesto et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), the dissolution of the original valves during fossil diagenesis leads to the loss of some taphonomic signatures imprinted in the original shell. Despite the higher quality preservation and detailing of delicate structures like ribs, lamellae, and adductor scar muscle in molds of the heteropectinids from Early Permian deposits of the Rio Bonito Fm. (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC and D), dissolution signs are not recognizable in these fossils. Determining if these molds show signs of abrasion also requires caution. How is the better manner to distinguish between the abrasion of the original valve preserved as a mold and the erosion of the rock that copies the valve as a mold? In this sense, we opted to discuss first the taphonomic signatures present in original valves and after a comparison with fossil heteropectinids.\u003c/p\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e5.1 Left-right valves ratio\u003c/h2\u003e \u003cp\u003eDespite the relative abundance of pectinid valves in the CPRS, only the convex (left) valves are numerous, while the flat (right) ones are scarce (n\u0026thinsp;=\u0026thinsp;14 of the 173) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), which leads us to consider that the left-right valves ratio is conditioned to winnowing by transport. Likewise, a low rate of flat valves was recorded in the fossil assemblages of the Lower Permian Rio Bonito Formation (Beurlen, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e1954\u003c/span\u003e; Reed, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e1930\u003c/span\u003e; Rocha-Campos, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1970\u003c/span\u003e; Schmidt-Neto et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), suggesting that winnowing by currents may be involved in the deposition of both Quaternary and Permian pectinids.\u003c/p\u003e \u003cp\u003ePectinids (including the fossil family Aviculopectinidae) are disk-shaped bivalves with one flat valve and another convex. For this reason, their valves present different hydrodynamic behavior when subjected to the same flow (Hayami, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e1991\u003c/span\u003e). On the flat valves, a broad surface keeps in contact with water, increasing its floatage and influencing its terminal fall, while the convex valves tend to turn the convex dorsal portion of the valve downward (Allen, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1984\u003c/span\u003e; Hayami, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e1991\u003c/span\u003e).\u003c/p\u003e \u003cp\u003ePrevious works with right and left valves have demonstrated that different morphologies show different answers to wind and hydraulic transports (Brenchley and Newall, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1970\u003c/span\u003e; Cad\u0026eacute;e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Lever, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e1958\u003c/span\u003e; Lever et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1964\u003c/span\u003e). Thus, due to the features of pectinid valves (i.e., flat and convex shapes), we may expect a sorting effect on these. Moreover, the sorting observed between convex (left) and flat (right) valves of pectinids also represents a clear example of the \u0026ldquo;L-R Effect\u0026rdquo; (left-right effect) tested by Lever (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e1958\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOn the other hand, such disproportionate occurrence may also result from differences in preservation potential. A less calcifying condition of the margin of flat valves of pectinids is another factor to consider in interpreting the flat/convex ratio. Some authors considered the difference in calcification between both valves a result of the behavior of reclining on the floor (Johnson, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1984\u003c/span\u003e; Stanley, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e1970\u003c/span\u003e). In this case, the valve in contact with the floor would be less calcified than its upward-facing pair. The small size of flat (right) valves of \u003cem\u003eHeteropecten catharinae\u003c/em\u003e in comparison to their counterpart convex (left) valves has been attributed to the lower calcium concentration in the margin of the valve (Kegel and Costa, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1951\u003c/span\u003e; Rocha-Campos, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1970\u003c/span\u003e) which led to the faster dissolution of them. In this sense, a more accentuated dissolution on flat valves than convex one could bias the final left-right ratio values.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e5.2 Fragmentation\u003c/h2\u003e \u003cp\u003eA higher frequency of fragmented valves (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;83.2%) was recorded, with the fragmentation attributed to mechanical factors. The shore of the CPRS is constantly affected by winds, resulting in a higher transport of sediments (e.g., sand grains and lightweight bioclasts) (Tomazelli, \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e1993\u003c/span\u003e). In the swash zone, the reworking by waves is constant, and bioclasts can be moved up and down on the shore, becoming subject to mechanical damages such as shocks and abrasion.\u003c/p\u003e \u003cp\u003eComparing the results presented by this research with those showed by Schmidt-Neto et al. (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003eb\u003c/span\u003e) for Permian pectinid deposits, two trends are noted: i) higher occurrence of highly-fragmented valves associated with high-energy environments, and ii) higher occurrence of whole valves in quiet environments or under higher sedimentation rates. Within the taphofacies model for epeiric seas presented by Speyer and Brett (1988), higher frequencies of fragmentation are expected in high-energy environments with a low sedimentation rate. Therefore, the fragmentation of pectinid valves is an advantageous signature to infer the energy environment, sedimentation rate, and the reworking suffered by valves.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e5.3 Abrasion and corrosion\u003c/h2\u003e \u003cp\u003eA similar frequency for the same levels of abrasion and corrosion was observed (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Such results suggest the exposition of the valves on the taphonomic active zone. As a result of this exposition, wearing of the valve surfaces is expected (Meldahl and Flessa, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e1990\u003c/span\u003e; Salamon et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). In this sense, the results showed in this research suggest the burial and exhumation of the valves several times.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e5.4 Bioerosion (borings and drill holes)\u003c/h2\u003e \u003cp\u003eTraces attributed to the bioerosion activity of polychaetes (cf. \u003cem\u003eCaulostrepsis\u003c/em\u003e), sponges (cf. \u003cem\u003eEntobia\u003c/em\u003e), bivalves (cf. \u003cem\u003eGastrochaenolites\u003c/em\u003e), bryozoans (cf. \u003cem\u003ePennatichnus\u003c/em\u003e), and drill holes \u003cem\u003eOichnus simplex\u003c/em\u003e, \u003cem\u003eO. paraboloides\u003c/em\u003e, and \u003cem\u003eO. ovalis\u003c/em\u003e were observed. These bioerosions represent three ethology traces classified as Domichnia (cf. \u003cem\u003eCaulostrepsis\u003c/em\u003e and cf. \u003cem\u003eGastrochaenolites\u003c/em\u003e), Fixichnia (cf. \u003cem\u003ePennatichnus\u003c/em\u003e and cf. \u003cem\u003eEntobia\u003c/em\u003e), and Praedichnia (\u003cem\u003eOichnus simplex, O. paraboloides\u003c/em\u003e, and \u003cem\u003eO. ovalis\u003c/em\u003e) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe occurrence of traces if cf. \u003cem\u003ePennatichnus\u003c/em\u003e and cf. \u003cem\u003eEntobia\u003c/em\u003e suggests the shells were available below the fair-weather wave base where the probability of the valves being turned or buried is low (Meldahl and Flessa, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e1990\u003c/span\u003e). Furthermore, the transport of bioclasts from the lower shoreface to the foreshore by storm has already been documented by previous research (Cruz and Buchmann, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Lopes, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Lopes and Buchmann, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). Opposite to CPRS, only sponge traces (\u003cem\u003eEntobia\u003c/em\u003e and \u003cem\u003eClionolithes\u003c/em\u003e) were recorded on the shells from Rio Bonito Fm. (Schmidt-Neto et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2018b\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDrilling valves correspond to at least 23% of all valves (n\u0026thinsp;=\u0026thinsp;39, 173), with many valves showing more than one complete perforation. These multiple perforations are uncommon and led us to raise the question: was the mollusk attacked by two predators, or was the valve perforated after the mollusk had already been previously attacked? In any case, the presence of multiple complete perforations evidences the value of pectinids as a food resource for predators such as gastropods (\u003cem\u003eOichnus simplex\u003c/em\u003e and \u003cem\u003eO. paraboloides\u003c/em\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA and F) and octopods (\u003cem\u003eO. ovalis\u003c/em\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eC).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e5.5 Incrustation\u003c/h2\u003e \u003cp\u003eDespite the low number of encrusted valves (5%, n\u0026thinsp;=\u0026thinsp;9 of 173), we can observe the occurrence of bivalves, barnacles, bryozoans, and corals as components of the epibiont assemblages (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Epibionts were observed both in the outer and inner surfaces of the valves. Regarding the epibionts on the outer side of the valve, it is impossible to determine whether they occurred during the life of the bivalve or after its death.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe low abundance (n\u0026thinsp;=\u0026thinsp;11) and low frequency (\u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6%) of epibionts on pectinid valves suggest these are not the most suitable bioclast for attachments. Considering that barnacles need a few weeks to months to colonize hard ground (Meldahl and Flessa, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e1990\u003c/span\u003e), the encrustation rate observed in this survey suggests that pectinid valves remained on the sediment for a short period.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e5.6 Comparison between Quaternary and Permian pectinid valves\u003c/h2\u003e \u003cp\u003ePermian pectinid fossils from Paran\u0026aacute; Basin are represented by two fossiliferous deposits known as Tai\u0026oacute; Sandstones (Rocha-Campos, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1970\u003c/span\u003e; Schmidt-Neto et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) and Camba\u0026iacute; Grande outcrop (Schmidt-Neto et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e). According to Schmidt-Neto et al. (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), the shell beds from Tai\u0026oacute; Sandstones are related to two depositional environments. The first, here called the Tai\u0026oacute; shell bed 1, corresponds to concentrations of shells deposited in an estuarine environment influenced by storm waves. Valves from Taio shell bed 1 were preserved preferentially whole and showed a narrow size range characterized by small valves (varying from 1 to 5 mm in height). The second is called the Tai\u0026oacute; shell bed 2 and is represented by shell beds formed in the lower shoreface during storm events. Such shell beds are characterized by a broad size range with a predominance of large pectinids (reaching 80 mm in height) and a greater abundance of fragments than whole valves.\u003c/p\u003e \u003cp\u003eComparing Quaternary and Permian pectinids, it was possible to recognize that left-right ratio, sorting size, fragmentation, and bioerosion are the commonest signatures among them. Although uncommon, it was possible to observe the muscle scars and lamellae in Permian molds (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC and D). Lamellae and ribs are fundamental for the taxonomic differentiation of fossil pectinid genera (Kegel and Costa, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1951\u003c/span\u003e; Neves et al., 2014; Rocha-Campos, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e1970\u003c/span\u003e; Waterhouse, \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e1969\u003c/span\u003e). Other alterations, such as dissolution and abrasion, are hard to recognize in casts and molds and weren\u0026rsquo;t observed in the Permian fossils.\u003c/p\u003e \u003cp\u003eAs previously discussed, the fragmentation is directly proportional to the reworking grade suffered by the valves. Comparing CPRS fragmentation values with those recorded for the Camba\u0026iacute; Grande outcrop and Tai\u0026oacute; sandstones (i.e., Tai\u0026oacute; shell bed 1 and Tai\u0026oacute; shell bed 2), the influence of high and low energy processes on the genesis of these deposits is implied. The valves from Tai\u0026oacute; shell bed 1, deposited under moderate energy events (i.e., distal tempestites), show a predominance of whole valves (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). On the other hand, the Quaternary valves from CPRS and the fossils from Tai\u0026oacute; shell bed 2 and Camba\u0026iacute; Grande outcrop show a predominance of fragmented valves (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). The higher frequency of fragmented pectinid valves in the CPRS is attributed to their exposition to constant wave action in the upper shoreface and swash zone, where the wave currents may be considerate moderate to high energy, including in fair-weather periods.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWell-sorted sizes may also be linked to differences in the kinetic gradient of the environment. The fossil deposits from Tai\u0026oacute; shell bed 1 show a well-sorted sized population, while a broad size range is observed for Quaternary pectinids from CPRS and fossils from Tai\u0026oacute; shell bed 2 and Camba\u0026iacute; Grande outcrop (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e). Such differences seem to show the capacity of transport of pectinid valves by current and waves. Another sorting observed is related to the left-right valve ratio. A low number of flat (right) valves is a well-marked characteristic observed in the current foreshore than in the three fossil assemblages used in this study (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e), highlighting how this morphological feature is significant to infer about transport and sorting of the valves by currents and waves.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eRegarding the presence of molds and casts of borings, chambers, and channels in the valves of \u003cem\u003eHeteropecten catharinae\u003c/em\u003e (Schmidt-Neto et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2018b\u003c/span\u003e), such paleontological records show that bioerosion traces have a better potential for preservation. However, we understand that it is necessary to carry out a more accurate search for bioerosion traces in the Permian heteropectinid valves from the Rio Bonito Formation to improve our understanding of the presence of these signatures in both Quaternary and Permian pectinids. Therefore, any comparison and discussion would be premature at this moment.\u003c/p\u003e \u003cp\u003eQuaternary pectinids on the beach suggest the high transportability and durability of their hard skeletons. These taphonomical and sedimentary processes increase the time-averaging and spatial-averaging since Lower Permian pectinids storm assemblage was registered in an estuarine setting by Schmidt-Neto et al. (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2018a\u003c/span\u003e). Furthermore, both deposits studied here were generated during an icehouse/greenhouse transition, and the spatial averaging may have been increased due to the sea-level oscillation and consequent erosion/reworking in marginal marine environments.\u003c/p\u003e \u003c/div\u003e"},{"header":"6. CONCLUSION","content":"\u003cp\u003eConducting this research, we conclude that physical and biological damages on the pectinid valves, such as fragmentation, bioerosion, and incrustation, show high potential for preservation and can be easily identified in molds and casts from the fossil record. A relationship between the taphonomic characteristics (fragmentation, disarticulation, orientation), intrinsic features of the valves (robustness, flatness, convexity, and resistance), and sedimentological characteristics (winnowing) are similar to both Quaternary and Permian pectinids.\u003c/p\u003e \u003cp\u003eThe signatures described on pectinid valves in this study, when associated with the kinetic energy degree of the environment (fair-weather waves, storm surges, quiet environment), allow us to improve our paleoenvironmental and paleoecological inferences.\u003c/p\u003e \u003cp\u003eThe comparison between Quaternary and Permian pectinids demonstrated that actualistic taphonomic studies improve our paleontological knowledge about pectinid fossil assemblages.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eACKNOWLEDGMENT\u003c/h2\u003e \u003cp\u003eThe authors are thankful to R\u0026ocirc;mulo Cenci for the photographs. H.S.N. is thanks to CAPES/CNPq for the post-doctoral grant. R.S.H. is thanks to CNPq PQ 310970/2022-9 and CNPq 420748/2018-0.\u003c/p\u003e\n\u003cp\u003eSTATEMENTS AND DECLARATIONS\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003eDECLARATION OF COMPETING INTEREST\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could appear to influence the work reported in this paper.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAgostini, V. O., Ritter, N., Jose, A., Muxagata, E., \u0026amp; Erthal, F. (2017). 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Source: Journal of Paleontology 43, 1179\u0026ndash;1183.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWright, L. D., Chappell, J., Thom, B. G., Bradshaw, M. P., \u0026amp; Cowell, P. (1979). Morphodynamics of reflective and dissipative beach and inshore systems: Southeastern Australia. \u003cem\u003eMarine Geology\u003c/em\u003e, \u003cem\u003e32\u003c/em\u003e, 105\u0026ndash;140. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0025-3227(79)90149-X\u003c/span\u003e\u003cspan address=\"10.1016/0025-3227(79)90149-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"palaeobiodiversity-and-palaeoenvironments","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pbpe","sideBox":"Learn more about [Palaeobiodiversity and Palaeoenvironments](https://www.springer.com/journal/12549)","snPcode":"12549","submissionUrl":"https://www.editorialmanager.com/pbpe/default2.aspx","title":"Palaeobiodiversity and Palaeoenvironments","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"icehouse-greenhouse, mollusk, physical damage, time average, marine deposits","lastPublishedDoi":"10.21203/rs.3.rs-3764580/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3764580/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eActuopaleontology has been widely developed to improve the interpretations of the fossil record. In the Paran\u0026aacute; Basin, a pectinid-dominated fossil record marks the Late Paleozoic strata (Upper Carboniferous, Lower Permian), an opportunity to compare their taphonomic signatures with Quaternary valves through actualistic research. This research aims to improve the biostratinomic knowledge of pectinid fossil concentrations, leading to better environmental and ecological interpretations of the fossil record. Thus, the present study is based on the taphonomy of 173 valves of \u003cem\u003eAequipecten tehuelchus\u003c/em\u003e. The Quaternary valves were collected on the foreshore of the coastal plain of the Rio Grande do Sul state. Fragmentation degree, flat/convex valve rate, dissolution, bioerosion (\u003cem\u003ei.e\u003c/em\u003e., borings and drill holes), and incrustation were quantified. Following, Quaternary pectinid data were compared with available information on the Lower Permian pectinids from the Rio Bonito Formation (Paran\u0026aacute; Basin). Not all signatures imprinted in the Quaternary material were observed in Permian molds. However, physical and biological damages were preferentially observed in both Quaternary and Permian samples. Quaternary pectinids on the modern beach suggest the high transportability and durability of their hard skeletons. These taphonomical and sedimentary processes increase the time-averaging and spatial-averaging since Lower Permian pectinids storm-assemblage was registered in the estuarine setting. Furthermore, both deposits studied here were generated during an icehouse/greenhouse transition, and the spatial averaging may have been increased due to the sea-level oscillation and consequent erosion/reworking in marginal marine environments.\u003c/p\u003e","manuscriptTitle":"Taphonomy of Quaternary Pectinidae and a Comparison With Early Permian Shells","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-18 10:27:40","doi":"10.21203/rs.3.rs-3764580/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2024-01-17T04:02:09+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-01-16T08:02:01+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2023-12-20T11:43:38+00:00","index":"","fulltext":""},{"type":"submitted","content":"Palaeobiodiversity and Palaeoenvironments","date":"2023-12-15T10:08:50+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"palaeobiodiversity-and-palaeoenvironments","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pbpe","sideBox":"Learn more about [Palaeobiodiversity and Palaeoenvironments](https://www.springer.com/journal/12549)","snPcode":"12549","submissionUrl":"https://www.editorialmanager.com/pbpe/default2.aspx","title":"Palaeobiodiversity and Palaeoenvironments","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"905505e0-5019-4c97-a6b0-b4c9e25fcb86","owner":[],"postedDate":"January 18th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2024-01-18T10:27:40+00:00","versionOfRecord":[],"versionCreatedAt":"2024-01-18 10:27:40","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3764580","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3764580","identity":"rs-3764580","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}