Perfect Permian Fruits

Perfect Permian Fruits | 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Share Download PDF Article Perfect Permian Fruits Weijia Huang, Xin Wang, Qiang Fu, yan Fang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8310107/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Although an increasing number of angiosperms are found in the Permian, they remain sparse among the flourishing Permian fossil flora. Apparently, the earlier history of angiosperms in the Permian requires further evidence to consolidate. To elucidate the early history of this important plant group (angiosperms), which is closely related to the well-being of humans, here we document a new angiosperm, Baipingfructus wuii gen. et sp. nov., from the Upper Permian of Henan province, China. The fossils of Baipingfructus reveal the existence of seven seeds/ovules of various maturities within a single fruit. For the first time, the anatomies of the pericarp and seed coat of this Permian angiosperm is documented: the sclerenchymatic framework in the mesotesta demonstrates unusual stratification and intercellular spaces, whereas the pericarp has a skewed distribution of the sclerenchymatic framework. Anatomic details and the general configuration of Baipingfructus eliminate all alternative interpretations and corroborate the occurrence of angiosperms in the Late Permian (>245 Ma). Biological sciences/Evolution/Palaeontology Biological sciences/Plant sciences/Plant evolution angiosperm Permian anatomy pericarp mesotesta fruit China Baipingfructus Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction The origin of angiosperms has long been a focus of botanical concern 1-28 . When the term “angiosperm” was coined in 1690 29 , it designated the plants that enclosed their seeds. A later refined concept of angiosperms designates plants that have “ovules enclosed before pollination” 30 . The original definition has been applied, both explicitly and implicitly, in botany 31,32 . Following these definitions and criteria, we recognize a Permian fruit, Baipingfructus gen. et sp., from the Xiaofengkou Formation of Dengfeng city, Henan province, China. Among the few reported Permian angiosperms, Baipingfructus is unique in its characteristic anatomy of mesotesta and mesocarp. This preservation allows us to pin down the existence of angiosperms in the Permian once again. This determination not only is compatible with recent progress in palaeobotany 32,33 but also favours the latest recent progress in molecular estimates 2,12,28 and fossil insects 34-37 . All this progress suggests that the current understanding and teaching of angiosperm history in textbooks are far from the reality of angiosperms, which can be dated back to the Permian. According to previous works, the fossils studied here belong to the Xiaofengkou Formation, and the flora includes abundant fossils of Sphenophytes, Cordaitales, Pteridophytes, Cycads, and Gigantopteridales 38 . Stratigraphic correlation indicates that the age is probably equivalent to that of the Makou stage 38 , which is dated to 245–260 Ma via U–Pb chronology in the Sichuan Basin, China 39 . The palaeolatitude of the fossil locality was 11 ֠ N 38 . The isotopic age of the flora is >245 Ma 40 . The specimens were two flattened fruit compressions embedded in dark gray and yellowish white siltstones collected from an outcrop of the Xiaofengkou Formation (Upper Permian) in Baiping town, Dengfeng city, Henan province, China (E113.0809°, N34.3145°; Fig. 1). The general morphology of the specimens was photographed using a Nikon D300S digital camera and a Nikon SMZ1500 stereomicroscope equipped with a Digital Sight DS-Fi1 camera, Details of the fossils were observed and photographed via a TESCAN Maia3 scanning electron microscope (SEM) housed at the Nanjing Institute of Geology and Palaeontology. All figures were saved in TIFF/JPEG format. The contrast and brightness of the figures were adjusted in whole. All the figures were organized together for publication in Photoshop CS6. Baipingfructus gen. nov Diagnosis : Fruit oval shaped, enclosing multiple ovules/seeds. Fruit tip fully secluded. Pericarp three-layered, mesocarp with a sclerenchymatic framework, endocarp of elongated cells. Seeds round, of various developmental stages. Seed coat four-layered. Mesotesta with osteosclereids and spacious intercellular spaces. Remarks : In the Cathayasian Flora 38 , a more or less similar plant organ called Carpolithus mitriformis was previously documented from the Late Permian (Page 174, 330, Plate 20, Figs. 6, 6a) 38 . Careful comparison indicates that Carpolithus mitriformis does not have the details comparable to those of Baipingfructus (for details see the discussion). Therefore, we prefer to propose a new genus, Baipingfructus gen. nov., for our specimens. Etymology: Baiping- for the fossil locality within Baiping town, Dengfeng city, Henan province, China, - fructus Latin for fruit. Type species: Baipingfructus wuii gen. et sp. nov. Type locality: Baiping town,Dengfeng city, Henan province, China (E113.0809°, N34.3145°). Horizon : the 4th Member of the Xiaofengkou Formation (Upper Shihhotse Formation), Upper Permian. Age: Kazanian, Kungurian,Cisuralian, Late Permian, >245 Ma. Baipingfructus wuii gen. et sp. nov (Figure 2–5) Species diagnosis : Fruit 8–11 mm long and 5–8 mm wide. Mesocarp with a sclerenchymatic framework. Multiple seeds in fruit. Seed approximately 1 mm in diameter. Seed coat approximately 0.2 mm thick, including neatly arranged macrosclereids, osteosclereids, and spacious intercellular spaces. Description : The fossils documented here include two compressions, preserved in slightly different statuses, embedded in dark gray and yellowish white siltstones (Figs. 2a-c). Both fruits are round or oval in shape (Figs. 2a-c), 8–11 mm long and 5–8 mm wide (Figs. 2a-c). Each fruit includes a pericarp and up to seven ovules/seeds inside a spacious ovary cavity (Figs. 2a-b). Each fruit has an occluded tip (Figs. 2a-c, 3a-b, 5a). The pericarp is 0.6–1 mm thick, three-layered, with a sclerenchymatic framework (Figs. 2a-c, 3a, 4a). The exocarp is approximately 0.1 mm thick, the mesocarp is approximately 0.5 mm thick, partially with a well-developed sclerenchymatic framework of variable thicknesses and branches, whereas the endocarp is approximately 0.1 mm thick (Figs. 4a, d). The sclerenchymatic frameworks of the mesocarp interconnect with each other and form a network composed of wall-like structures that range from nil to 0.5 mm in thickness, with frequent lateral branches (Figs. 3b, g, 4a-c, 5a-c). The wall-like structures are composed of two appressing layers of neatly arranged macrosclereids (Fig. 4c). In the lumina framed by the wall-like structures are some crystalline outgrowths (Figs. 5c-f). The endocarp is composed of elongated cells that are approximately 20 μm wide and up to 250 μm long (Figs. 2a, 3a, 4d). Up to seven seeds of different maturities and preservations are observed inside the fruit (Figs. 2a-c). Seeds are round or spheroidal in form and are 1–1.3 mm in diameter (Figs. 2a-c, 3a, c-d). One of the seeds has a well-developed seed coat (Fig. 3d), which may be lacking in other seeds (Fig. 3c). The fully developed seed coat includes four layers: the outermost cuticle layer is approximately 8 μm thick, inside it is the approximately 20–30 μm thick palisade layer, then is the approximately 120 μm thick hypodermal layer hypodermal layer, and the innermost is the approximately 60 μm thick endotesta (Figs. 3d-f). The cuticle layer has a smooth surface (Figs. 3e-f). The palisade layer is composed of neatly arranged macrosclereids (Figs. 3d-f). The hypodermal layer is composed of conspicuous spacious intercellular spaces (120 μm high and 140 μm wide) and vertical wall-like structures in between, the latter are up to 30 μm thick and include two appressing layers of neatly arranged macrosclereids (Figs. 3d-f). The endotesta is composed of amorphous crushed parenchyma (Figs. 3d-f). The seed content is poorly preserved and shows few cellular details (Figs. 3c-d). Remarks : Notably, the development of a sclerenchymatic framework in the seed coat may be inferred on the basis of observations of its developmental status in different seeds/ovules in a single fruit and in a single seed. The seed coat is apparently well developed in the lower left but poorly developed in the upper right of Figs. 2a, 3a. The difference in development of the pericarp was observed by comparing its statuses in two fruits: in the holotype, the good organization of the sclerenchymatic framework is restricted to the lower left in Figs. 2a and 3a, whereas such uneven development is only barely observed in the pericarp of the paratype specimen (Fig. 2c). Holotype : PB209247. Paratype : PB209248. Depository: Nanjing Institute of Geology and Palaeontology, Nanjing, China. Etymology: wuii is dedicated to the fossil collector, Mr. Jinbo Wu. Alternative interpretations Considering the size and overall morphology, the organs of Baipingfructus might be interpreted as ovules, seeds, sporangia, or fruits. However, alternatives other than fruit can be easily eliminated. The presence of millimetre-sized bodies within make ovules, seeds, and sporangia out-of-the-question, leaving only one alternative for Baipingfructus : fruits, as among these alternatives, fruit is the only one that allows the existence of multiple millimetre-sized bodies inside. As a then new species, Carpolithus mitriformis was given clear diagnosis and description by Dr. Yang. Its description is “seed flat, bell-shaped, 9 mm long by 8 mm wide, with the widest portion near seed base; base arcuate, with two lateral angles slightly apically oriented. Apex 5 mm wide, obtuse rounded. Small verrucae of irregular size (0.5–1 mm) present in the middle of the seed.” (Page 330) 38 . Although its general configuration and size are similar to our specimens, but the key difference between these two taxa lies in the interpretation of so-called “verrucae”: Yang 38 showed no anatomic details to support her determination of “verrucae”. Such a crude treatment of a “seed” is understandable: Dr. Yang faced hundreds of specimens in her fossil floral study, it was impossible for her to pay close attention to all the details in all specimens. However, now the information in Figure 2-3 of the seed coat of Baipingfructus ’ in situ seeds prevents us from conflating these seeds with Yang’s “verrucae”. Apparently, the systematics of previously documented Carpolithus mitriformis 38 require further careful study. Criteria of angiosperms As stated at the beginning, initially, the term “angiosperm” referred to the plants that enclosed their seeds. This definition contrasts with “gymnosperm”, which refers to plants whose seeds are exposed to the exterior space 29 . Although it was later modified in various ways to meet the needs of different authors 41 , the original definition of angiosperms has long been applied in palaeobotany 31,41,42 . A stricter definition of angiosperms was proposed by Tomlinson and Takaso 30 : plants in which pollination occurs after ovule enclosure are angiosperms. This definition apparently is most ideal (especially when the rarity of valuable specimens is ignored), as all plants meeting this criterion are unexceptionally angiosperms. Our observations indicate that the ovary tip of Baipingfructus is occluded and that the seeds within the fruit are at various developmental stages (Figs. 2a-b, 3a-d), implying that at least ovule enclosure is very likely to occur before pollination. The lack of well-developed seed coat in most seeds/ovules in Baipingfructus implies that these seeds/ovules are probably still their ovule stages (at most immature seed stage) (Figs. 3a, c). Therefore, Baipingfructus appears to have met the stricter criterion of angiosperms proposed by Tomlinson and Takaso 30 . Although the pollination process requires further study in Baipingfructus , the enclosed seeds (angiospermy), a feature that singled angiosperms from (at least most) gymnosperms according to the original concept of angiosperms 29 , are secured in Baipingfructus (Figs. 2a-b, 3a). Since Archaefructus was determined to be an angiosperm on the basis of this feature (angiospermy) alone (there is no evidence showing that there were ovules in Archaefructus thus far), we can also assume that our identifying Baipingfructus as an angiosperm is well-grounded, although Baipingfructus is from the Late Permian. The bottom line is that angiospermy (enclosed seeds) that used to be a feature idiosyncratic to angiosperms has now been achieved by a Permian fossil plant, being an angiosperm or not. Development of seeds Notably, the development of seeds in Baipingfructus is not synchronized within a fruit (Figs. 3a, c-d). The well-developed sclerenchymatic framework in the seed coat (Figs. 3d-f) is not observed in all seeds within the same fruit. For example, no well-developed sclerenchymatic framework, which is a seed within the same fruit, is shown in Fig. 3c. The occurrence of a well-developed sclerenchymatic framework suggests that the seed is close to mature, whereas its lack implies that the seed is still further from mature. While the former confirms the presence of angiospermy in Baipingfructus , the latter implies that the immature seed (probably ovule) is also enclosed (angio-ovuly) in Baipingfructus , strengthening the angiospermous affinity for Baipingfructus even according to the stricter definition proposed by Tomlinson and Takaso 30 . For the first time, the maturing order of seeds in the same fruit of Baipingfructus suggests that the ovules/seeds mature neither in an acropetal nor in a basipetal order in this Late Permian angiosperm. This new conclusion is apparently unexpected. Unusual sclerenchyma and its ecological implications Sclerenchyma is a type of tissuethat is usually related to the toughening, cushioning, rigidity and mechanical support of plants. In addition to its occurrence in vegetative organs, sclerenchyma is frequently observed in the seed coat and pericarp of reproductive organs. Apparently, Baipingfructus is not a vegetative organ (Figs. 2a-c). The occurrence of indurated sclerenchyma in the seed coat is more likely to be fossilized, and its occurrence is a symbol of seed identity. This implication is further strengthened by the occurrence of sclerenchyma in the pericarp of Baipingfructus . Notably, the sclerenchyma in Baipingfructus has unusual characteristics. Unlike in most seeds, the seed coat in Baipingfructus has unusual intercellular spaces in its hypodermal layer (Figs. 3d-f). A similar structure, although not as well developed as that in Baipingfructus , has been previously documented for the seed coat of soybean 43-46 . The typical soybean seed coat includes four layers: a cuticle + epidermal layer, palisade layer, hypodermal layer, and endotesta layer (Figs. 1 and 2 in 43 ; Figs. 2 and 3a in 44 ; Figs. 4a-b in 45 ; Fig. 1a in 46 ). This stratification corresponds to that observed in Baipingfructus (Figs. 3d-f). This unusual feature may be related to seed dispersal by water, as the large intercellular spaces in the hypodermal layer can provide buoyance in water that otherwise would be inconceivable. If confirmed by future studies, this would be the first and earliest evidence of hydrochory in the history of angiosperms. The sclerenchyma in the pericarp of coconut is well known for its cushioning function, mechanical toughness, elasticity, and mechanical protection during its descent onto the ground 47-49 . A similar situation also occurs in luffa, which has abundant sclerenchyma in its pericarp 50 . The occurrence of a three-dimensional sclerenchymatic framework in the pericarp of Baipingfructus (Figs. 2a-b, 3a, 4a, c) implies that its fruit needs to cope with mechanical impact when it hits the ground. This conclusion implies that the fruit is very likely borne by a tree of a certain height. Notably, the spatial distribution of sclerenchyma is not even in the pericarp of Baipingfructus (Figs. 2a-b, 3a, 4a, c). Such a skewed deployment of sclerenchyma within the pericarp seems to suggest that the fruit underwent certain oriented stresses, e.g. , gravity and sunshine. Apparently, this anatomic hint on ecology requires further testing before it is confirmed. There are only five types of sclerenchyma tissue in textbooks: brachyosclereids, macrosclereids, osteosclereids, asterosclereids, and trichosclereids. All these types are different than the wall-like sclerenchymatic tissue observed in Baipingfructus (Figs. 5a-c), implying a possible new type of sclerenchyma that has disappeared in extant plants. This may be one of the consequences of long-term evolution in plants. The diversity of Permian angiosperms Previously reported Permian angiosperms include Taiyuanostachya 32 , Yuzhoua 33 , and Dengfengfructus 51 , and the application of Baipingfructus to the list highlights the diversity of angiosperms in the Permian (Table 1). Notably, the distinctions in dimensions, general morphologies, and anatomies among these taxa suggest that they cannot be derived from the same common ancestor. Instead, such diverse taxa in the Permian imply that, if derived from a common ancestor, there must have been long-term evolution before the occurrence of these diverse taxa. Although this view of angiosperm history is apparently at odds with teaching in botanical textbooks, it is noteworthy that molecular estimates based on numerous genes and even genomes point to a pre-Cretaceous origin of angiosperms 2,12,28 . Moreover, studies on fossil insects have revealed that numerous Permian insects might have played a certain role in the pollination of plants during the Permian 34-37 . Instead, the former traditional perspective on angiosperm evolution should be updated. Conclusion Baipingfructus is a new fossil angiosperm fruit uncovered from the Xiaofengkou Formation (Upper Permian, >245 Ma) of Dengfeng city, Henan province, China. The seeds of various developmental stages in the same fruit suggest that Baipingfructus may have both enclosed ovules and enclosed seeds, satisfying both the stricter and original definitions of angiosperms. Baipingfructus corroborates the truthful occurrence of angiosperms in the Permian. This conclusion agrees with the conclusions of studies on fossil insects and molecular estimates. Together with previously reported angiosperms, Baipingfructus underscores the diversity of angiosperms in the Permian. Declarations Author Contributions XW designed the research project and drafted the manuscript. WH collected the specimen, YF carried out the SEM observation. XW, WH, QF, and YF analyzed the data. All the authors have finalized and approved the manuscript. Funding The research is supported by the National Key Research and Development Program of China (2024YFF0807601). Institutional Review Board Statement Not applicable. Informed Consent Statement Not applicable. Data availability statement All the data are reported in this paper. The type specimens are deposited in Nanjing Institute of Geology and Palaeontology, and are available for academic observations. 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Plants 11 , 3293 (2022). https://doi.org/https://doi.org/10.3390/plants11233293 Jiang, Y., Yan, D., Wang, J., Shao, L.-H. & Sharma, P. The giant flexoelectric effect in a luffa plant- based sponge for green devices and energy harvesters. Proc Natl Acad Sci USA 120 , e2311755120 (2023). Xin Wang, W. H., Qiang Fu et al. , 08 September 2025, PREPRINT (Version 1) available at Research Square []. (ed Academia Sinica Nanjing Institute of Geology and Palaeontology) (Research Square, 2025). Tables Table 1 Comparison between Baipingfructus gen. nov. and contemporaneous angiosperm genera. Taxa Organ Pollination canal Style #ovules per fruit Length(mm) Ovule-enclosing Seed-enclosing Location (in China) Age Baipingfructus fruit lacking lacking 7 8–11 present (?) present Henan Permian Taiyuanostachya infructescence present lacking 1 33–43 present present Shanxi Permian Yuzhoua ovary lacking present 3 23.5–40 present ? Henan Permian Additional Declarations There is NO Competing Interest. 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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-8310107","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":560935617,"identity":"ac09f22b-b46b-4b6a-98a3-8caae6983bfe","order_by":0,"name":"Weijia Huang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3UlEQVRIiWNgGAWjYLCCDwYScvzszQcOfCBWB+OMAgtjyZ5jiQdnEKuFmedDReKGGznGh3mIUc53I/nYBx4DCWOGM8cSDtuUWTPwt3cn4NUieSMteYYE0C+M7c0HDuecS2eQOHN2A14tBrdzjBkMgLYw8wBtyW07zGAgkUtIS/5nhgQDicQ2iRyDw5bEaclhZjgA1NID0sJIjBbJ+8+MGRuADpMAOuxgz7l0HoJ+4Ttz+DHznz91cvbHmw9/+FFmLcff3otfC8MBFB4bMxFRg66FsI5RMApGwSgYcQAAGbhN+B+jwHkAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-5112-8931","institution":"Blue Miracle Museum Science Research Studio","correspondingAuthor":true,"prefix":"","firstName":"Weijia","middleName":"","lastName":"Huang","suffix":""},{"id":560935618,"identity":"377c2fff-2bbd-420f-8410-d3d94300ff18","order_by":1,"name":"Xin Wang","email":"","orcid":"https://orcid.org/0000-0002-4053-5515","institution":"Chinese Academy of Sciences Nanjing Institute of Geology and Palaeontology","correspondingAuthor":false,"prefix":"","firstName":"Xin","middleName":"","lastName":"Wang","suffix":""},{"id":560935619,"identity":"8d777ae2-551b-47da-b9ee-2c7398ca489f","order_by":2,"name":"Qiang Fu","email":"","orcid":"https://orcid.org/0000-0002-6948-3747","institution":"Nanjing Institute of Geology and Paleontology","correspondingAuthor":false,"prefix":"","firstName":"Qiang","middleName":"","lastName":"Fu","suffix":""},{"id":560935620,"identity":"4273a77c-b001-44eb-b9a5-101ef3e2007a","order_by":3,"name":"yan Fang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"yan","middleName":"","lastName":"Fang","suffix":""}],"badges":[],"createdAt":"2025-12-08 17:30:53","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-8310107/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8310107/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":98434978,"identity":"c7b46ad1-6e22-4818-b9c9-ef3528a80f02","added_by":"auto","created_at":"2025-12-17 16:52:52","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":562732,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGeographicl information of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eBaipingfructus wuii\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e’s fossil locality.\u003c/strong\u003e \u003cstrong\u003ea. \u003c/strong\u003eFossil locality in suburb of Dengfeng city, Henan province, China (E113.0809°, N34.3145°). \u003cstrong\u003eb\u003c/strong\u003e. Fossil locality (red dot) in China. \u003cstrong\u003ec\u003c/strong\u003e. Outcrop of the fossiliferous strata. \u003cstrong\u003ed. \u003c/strong\u003eThe horizon of the fossiliferous stratum in the stratigraphical column of the Early Permian.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-8310107/v1/6e5fb42b4f61e5a6e47a9ebc.png"},{"id":98287111,"identity":"60a8e337-1248-4524-a2de-5b81784f6e5d","added_by":"auto","created_at":"2025-12-16 07:22:58","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1892600,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe holotype (a, b, d) and paratype (c) specimens of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eBaipingfructus wuii\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e.\u003c/strong\u003e \u003cstrong\u003ea-b. \u003c/strong\u003eFruit with seven \u003cem\u003ein situ \u003c/em\u003eseeds/ovules of various maturities. PB209247. Scale bar = 1 mm.\u003cstrong\u003e c\u003c/strong\u003e. A fruit showing a sclerenchymatic framework in the pericarp. Scale bar = 1 mm. PB209248. \u003cstrong\u003ed\u003c/strong\u003e. An \u003cem\u003ein situ \u003c/em\u003erelatively\u003cem\u003e \u003c/em\u003emature seed split through the middle, enlarged from Fig. 2a. Scale bar = 0.1 mm.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-8310107/v1/ffb84fa423780ac4a64d81d7.png"},{"id":98287106,"identity":"82cfb4b4-2237-40b4-b8a8-3c8c1ae6827c","added_by":"auto","created_at":"2025-12-16 07:22:58","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":652372,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of the holotype sample. PB209247. \u003cstrong\u003ea\u003c/strong\u003e. Whole fruit with a secluded fruit tip (upper), seven \u003cem\u003ein situ\u003c/em\u003e seeds/ovules of various maturities (central), and a partially preserved pericarp (right). Scale bar = 1 mm. \u003cstrong\u003eb.\u003c/strong\u003e Secluded fruit tip. Note the weakly developed sclerenchymatic framework in the inner portion of the pericarp. Scale bar = 0.5 mm. \u003cstrong\u003ec. \u003c/strong\u003eAn immature seed enlarged from Fig. 3a. Note its relatively poorly developed seed coat compared with the one shown in Fig. 3d. Scale bar = 0.2 mm. \u003cstrong\u003ed. \u003c/strong\u003eA mature seed enlarged from Fig. 3a. Note its relatively better developed seed coat than the one shown in Fig. 3c. Scale bar = 0.2 mm. \u003cstrong\u003ee.\u003c/strong\u003e Detailed view of the seed coat in Fig. 3d, showing intercellular spaces in the sclerenchymatic framework. Scale bar = 0.1 mm.\u003cstrong\u003e f.\u003c/strong\u003e Detailed view of the seed coat shown in Fig. 3e, showing the cuticle (1), palisade layer (2), hypodermal layer (3), and endotesta (4). Note the neatly arranged macrosclereids in the palisade layer. Scale bar = 50 µm. \u003cstrong\u003eg.\u003c/strong\u003e Detailed view of the right basal portion of the fruit in Fig. 3a, showing a poorly developed sclerenchymatic framework (arrows) in the mesocarp overlapping the endocarp (e). Scale bar = 0.2 mm\u003c/p\u003e","description":"","filename":"image3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8310107/v1/4a43e7453c4c7210a98b95bb.jpeg"},{"id":98434305,"identity":"6b1134ea-d510-475c-8a55-2f8b75d7b389","added_by":"auto","created_at":"2025-12-17 16:51:51","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1653182,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSEM images of a fruit. \u003c/strong\u003ePB209247.\u003cstrong\u003e A\u003c/strong\u003e. Three layers (1, 2, 3) of the pericarp, enlarged from the lower-left portion of Fig. 3a. Note the three-dimensional sclerenchymatic framework in the mesocarp. Scale bar = 0.2 mm. \u003cstrong\u003eB\u003c/strong\u003e. Detailed view of the pericarp, enlarged from the upper rectangle in Fig. 4a, showing details of the exocarp (1) and mesocarp (2). Scale bar = 0.1 mm. \u003cstrong\u003eC\u003c/strong\u003e. Detailed view of the mesocarp, enlarged from the lower rectangle in Fig. 4a, showing the neatly arranged macrosclereids. Scale bar = 0.1 mm. \u003cstrong\u003eD\u003c/strong\u003e. Detailed view of the pericarp in the upper right portion of the fruit in Fig. 3a (rotated 90 degrees), showing the exocarp (1), mesocarp (2), and endocarp (3) with elongated rectangular cells. Note that the sclerenchymatic framework (arrow) is only poorly developed in this portion of the mesocarp. Scale bar = 0.5 mm.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-8310107/v1/76a1401d6ef8725211d7b8f5.png"},{"id":98436362,"identity":"eabef690-09f4-407d-bb53-a1cff203bff3","added_by":"auto","created_at":"2025-12-17 16:55:30","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1476512,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSEM images of the paratype specimen. \u003c/strong\u003ePB209248.\u003cstrong\u003e a\u003c/strong\u003e. Detailed view of the fruit shown in Fig. 2c, showing the secluded fruit tip and sclerenchymatic framework in the pericarp. Scale bars = 1 mm.\u003cstrong\u003e b\u003c/strong\u003e. Detailed view of the sclerenchymatic framework. Note the sclerenchymatic wall with branches (arrows) and neatly deployed macrosclereids. Scale bars = 0.2 mm. \u003cstrong\u003ec. \u003c/strong\u003ePlanar view of the pericarp, showing sclerenchymatic frameworks (triangles) of the mesocarp tapering to the left. Scale bar = 50 μm. \u003cstrong\u003ed. \u003c/strong\u003eDetailed view of the rectangle in Fig. 5c, showing a growing ergastic crystal with a spiny margin. Scale bar = 10 μm.\u003cstrong\u003e e. \u003c/strong\u003eA well-developed ergastic crystal with spiny margins. Scale bar = 50 μm. \u003cstrong\u003ef. \u003c/strong\u003eDetailed view of the rectangle in Fig. 5e, showing the crystalline spines. Scale bar = 10 μm.\u003cstrong\u003e g. \u003c/strong\u003eNeatly deployed macrosclereids in the pericarp. Scale bar = 20 μm.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-8310107/v1/d56d84370b0543f9c14e87c7.png"},{"id":98774738,"identity":"18e462c3-1e03-4267-8791-13b950ace201","added_by":"auto","created_at":"2025-12-22 12:13:03","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6771571,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8310107/v1/eb3040ba-3aeb-4c3f-a485-bed9d08bf10f.pdf"},{"id":98434851,"identity":"002b1a1b-a3c9-46ce-ac43-fce8a1337d68","added_by":"auto","created_at":"2025-12-17 16:52:41","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2222943,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementary.docx","url":"https://assets-eu.researchsquare.com/files/rs-8310107/v1/576fdb1599a61d43c7762ffd.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Perfect Permian Fruits","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe origin of angiosperms has long been a focus of botanical concern \u003csup\u003e1-28\u003c/sup\u003e. When the term \u0026ldquo;angiosperm\u0026rdquo; was coined in 1690 \u003csup\u003e29\u003c/sup\u003e, it designated the plants that enclosed their seeds. A later refined concept of angiosperms designates plants that have \u0026ldquo;ovules enclosed before pollination\u0026rdquo;\u003csup\u003e30\u003c/sup\u003e. The original definition has been applied, both explicitly and implicitly, in botany\u003csup\u003e31,32\u003c/sup\u003e. Following these definitions and criteria, we recognize a Permian fruit, \u003cem\u003eBaipingfructus\u003c/em\u003e gen. et sp., from the Xiaofengkou Formation of Dengfeng city, Henan province, China. Among the few reported Permian angiosperms, \u003cem\u003eBaipingfructus\u003c/em\u003e is unique in its characteristic anatomy of mesotesta and mesocarp. This preservation allows us to pin down the existence of angiosperms in the Permian once again. This determination not only is compatible with recent progress in palaeobotany \u003csup\u003e32,33\u003c/sup\u003e but also favours the latest recent progress in molecular estimates \u003csup\u003e2,12,28\u003c/sup\u003e and fossil insects \u003csup\u003e34-37\u003c/sup\u003e. All this progress suggests that the current understanding and teaching of angiosperm history in textbooks are far from the reality of angiosperms, which can be dated back to the Permian.\u003c/p\u003e\n\u003cp\u003eAccording to previous works, the fossils studied here belong to the Xiaofengkou Formation, and the flora includes abundant fossils of Sphenophytes, Cordaitales, Pteridophytes, Cycads, and Gigantopteridales\u003csup\u003e38\u003c/sup\u003e. Stratigraphic correlation indicates that the age is probably equivalent to that of the Makou stage \u003csup\u003e38\u003c/sup\u003e, which is dated to 245\u0026ndash;260 Ma via U\u0026ndash;Pb chronology in the Sichuan Basin, China \u003csup\u003e39\u003c/sup\u003e. The palaeolatitude of the fossil locality was 11\u003cem\u003e֠\u003c/em\u003e N\u0026nbsp;\u003csup\u003e38\u003c/sup\u003e.\u0026nbsp;The\u0026nbsp;isotopic\u0026nbsp;age\u0026nbsp;of\u0026nbsp;the flora is\u0026nbsp;\u0026gt;245\u0026nbsp;Ma\u003csup\u003e40\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eThe specimens were two flattened fruit compressions embedded in dark gray and yellowish white siltstones collected from an outcrop of the Xiaofengkou Formation (Upper Permian) in\u0026nbsp;Baiping\u0026nbsp;town, Dengfeng city, Henan province, China (E113.0809\u0026deg;, N34.3145\u0026deg;; Fig. 1). The general morphology of the specimens was photographed using a Nikon D300S digital camera and a Nikon SMZ1500 stereomicroscope equipped with a Digital Sight DS-Fi1 camera, Details of the fossils\u0026nbsp;were observed and photographed via a TESCAN Maia3 scanning electron microscope (SEM) housed at the Nanjing Institute of Geology and Palaeontology. All figures were saved in TIFF/JPEG format. The contrast and brightness of the figures were adjusted in whole. All\u0026nbsp;the figures were organized together for publication in Photoshop CS6.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eBaipingfructus\u0026nbsp;\u003c/em\u003egen. nov\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDiagnosis\u003c/strong\u003e: Fruit\u0026nbsp;oval shaped, enclosing multiple ovules/seeds. Fruit tip fully secluded. Pericarp three-layered, mesocarp with\u0026nbsp;a\u0026nbsp;sclerenchymatic framework, endocarp of elongated cells. Seeds round, of various developmental stages. Seed coat four-layered. Mesotesta with osteosclereids and spacious intercellular spaces.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRemarks\u003c/strong\u003e: In the Cathayasian Flora \u003csup\u003e38\u003c/sup\u003e, a more or less similar plant organ called \u003cem\u003eCarpolithus mitriformis\u003c/em\u003e was previously documented from the Late Permian (Page 174, 330, Plate 20, Figs. 6, 6a)\u003csup\u003e38\u003c/sup\u003e. Careful comparison indicates that \u003cem\u003eCarpolithus mitriformis\u003c/em\u003e does not have the details comparable to those of\u0026nbsp;\u003cem\u003eBaipingfructus\u003c/em\u003e (for details see the discussion). Therefore, we prefer to propose a new genus, \u003cem\u003eBaipingfructus\u003c/em\u003e gen. nov., for our specimens.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEtymology:\u0026nbsp;\u003c/strong\u003e\u003cem\u003eBaiping-\u003c/em\u003e for the fossil locality within Baiping town, Dengfeng city, Henan province, China, -\u003cem\u003efructus\u0026nbsp;\u003c/em\u003eLatin for fruit.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eType species:\u0026nbsp;\u003c/strong\u003e\u003cem\u003eBaipingfructus wuii\u0026nbsp;\u003c/em\u003egen. et sp. nov.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eType locality:\u0026nbsp;\u003c/strong\u003eBaiping town,Dengfeng city, Henan province, China (E113.0809\u0026deg;, N34.3145\u0026deg;).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eHorizon\u003c/strong\u003e: the 4th Member of the Xiaofengkou Formation (Upper Shihhotse Formation),\u0026nbsp;Upper Permian.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAge:\u0026nbsp;\u003c/strong\u003eKazanian, Kungurian,Cisuralian, Late Permian, \u0026gt;245 Ma.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eBaipingfructus wuii\u0026nbsp;\u003c/em\u003egen. et sp. nov\u003c/p\u003e\n\u003cp\u003e(Figure 2\u0026ndash;5)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSpecies diagnosis\u003c/strong\u003e: Fruit 8\u0026ndash;11 mm long and 5\u0026ndash;8 mm wide. Mesocarp with a sclerenchymatic framework. Multiple seeds in fruit. Seed approximately 1 mm in diameter. Seed coat approximately 0.2 mm thick, including neatly arranged macrosclereids, osteosclereids, and spacious intercellular spaces.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDescription\u003c/strong\u003e: The fossils documented here include two compressions, preserved in slightly different statuses, embedded in dark gray and yellowish white siltstones (Figs. 2a-c). Both fruits are round or oval in shape (Figs. 2a-c), 8\u0026ndash;11 mm long and 5\u0026ndash;8 mm wide (Figs. 2a-c). Each fruit includes a pericarp and up to seven ovules/seeds inside a\u0026nbsp;spacious ovary cavity (Figs. 2a-b). Each fruit has an occluded tip (Figs. 2a-c, 3a-b, 5a). The pericarp is 0.6\u0026ndash;1\u0026nbsp;mm thick, three-layered, with\u0026nbsp;a\u0026nbsp;sclerenchymatic framework (Figs. 2a-c, 3a, 4a). The exocarp is approximately 0.1 mm thick, the mesocarp is approximately 0.5 mm thick, partially with\u0026nbsp;a\u0026nbsp;well-developed sclerenchymatic framework of variable thicknesses and branches,\u0026nbsp;whereas the\u0026nbsp;endocarp is approximately 0.1 mm thick (Figs. 4a, d). The sclerenchymatic\u0026nbsp;frameworks of the\u0026nbsp;mesocarp interconnect\u0026nbsp;with\u0026nbsp;each other and form\u0026nbsp;a\u0026nbsp;network composed of wall-like structures that range from nil to 0.5 mm in thickness, with frequent lateral branches (Figs. 3b, g, 4a-c, 5a-c). The wall-like structures are composed of two appressing layers of neatly arranged macrosclereids (Fig. 4c).\u0026nbsp;In the lumina framed by the wall-like structures are some crystalline outgrowths (Figs. 5c-f). The endocarp is composed of elongated cells that\u0026nbsp;are\u0026nbsp;approximately 20 \u0026mu;m wide and up to 250 \u0026mu;m long (Figs. 2a, 3a, 4d). Up to seven seeds of different maturities and preservations are\u0026nbsp;observed\u0026nbsp;inside the fruit (Figs. 2a-c). Seeds are round or\u0026nbsp;spheroidal\u0026nbsp;in form\u0026nbsp;and are 1\u0026ndash;1.3 mm in diameter (Figs. 2a-c, 3a, c-d). One of the seeds has a well-developed seed coat (Fig. 3d), which may be lacking in other seeds (Fig. 3c). The fully developed seed coat includes four layers: the outermost\u0026nbsp;cuticle layer\u0026nbsp;is approximately 8 \u0026mu;m thick, inside it is the\u0026nbsp;approximately\u0026nbsp;20\u0026ndash;30\u0026nbsp;\u0026mu;m thick\u0026nbsp;palisade\u0026nbsp;layer, then is the\u0026nbsp;approximately 120 \u0026mu;m thick\u0026nbsp;hypodermal\u0026nbsp;layer hypodermal layer, and the innermost is\u0026nbsp;the\u0026nbsp;approximately 60 \u0026mu;m thick\u0026nbsp;endotesta\u0026nbsp;(Figs. 3d-f). The cuticle layer has a smooth surface (Figs. 3e-f). The palisade layer is composed of neatly arranged macrosclereids (Figs. 3d-f). The hypodermal layer is composed of conspicuous spacious intercellular spaces (120 \u0026mu;m high and 140 \u0026mu;m wide) and vertical wall-like structures in between,\u0026nbsp;the latter are up to 30 \u0026mu;m thick and\u0026nbsp;include\u0026nbsp;two appressing layers of neatly arranged macrosclereids (Figs. 3d-f). The endotesta is composed of amorphous crushed parenchyma (Figs. 3d-f). The seed content is poorly preserved and shows\u0026nbsp;few\u0026nbsp;cellular details (Figs. 3c-d).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRemarks\u003c/strong\u003e: Notably, the development of a sclerenchymatic framework in the seed coat may be inferred on the basis of observations of its developmental status in different seeds/ovules in a single fruit and in a single seed. The seed coat is apparently well developed in the lower left but poorly developed in the upper right of Figs. 2a, 3a. The difference in development of the pericarp was observed by comparing its statuses in two fruits: in the holotype, the good organization of the sclerenchymatic framework is restricted to the lower left in Figs. 2a and 3a, whereas such uneven development is only barely observed in the pericarp of the paratype specimen (Fig. 2c).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eHolotype\u003c/strong\u003e: PB209247.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eParatype\u003c/strong\u003e: PB209248.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDepository:\u0026nbsp;\u003c/strong\u003eNanjing Institute of Geology and Palaeontology, Nanjing, China.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEtymology:\u0026nbsp;\u003c/strong\u003e\u003cem\u003ewuii\u0026nbsp;\u003c/em\u003eis dedicated to the fossil collector, Mr. Jinbo Wu.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAlternative interpretations\u003c/strong\u003e Considering the size and overall morphology, the organs of \u003cem\u003eBaipingfructus\u003c/em\u003e might be interpreted as ovules, seeds, sporangia, or fruits. However, alternatives other than fruit can be easily eliminated. The presence of millimetre-sized bodies within make ovules, seeds, and sporangia out-of-the-question, leaving only one alternative for \u003cem\u003eBaipingfructus\u003c/em\u003e: fruits, as among these alternatives, fruit is the only one that allows the existence of multiple millimetre-sized bodies inside.\u003c/p\u003e\n\u003cp\u003eAs a then new species, \u003cem\u003eCarpolithus mitriformis\u003c/em\u003e was given clear diagnosis and description by Dr. Yang. Its description is \u0026ldquo;seed flat, bell-shaped, 9 mm long by 8 mm wide, with the widest portion near seed base; base arcuate, with two lateral angles slightly apically oriented. Apex 5 mm wide, obtuse rounded. Small verrucae of irregular size (0.5\u0026ndash;1 mm) present in the middle of the seed.\u0026rdquo; (Page 330)\u003csup\u003e38\u003c/sup\u003e. Although its general configuration and size are similar to our specimens, but the key difference between these two taxa lies in the interpretation of so-called \u0026ldquo;verrucae\u0026rdquo;: Yang\u003csup\u003e38\u003c/sup\u003e showed no anatomic details to support her determination of \u0026ldquo;verrucae\u0026rdquo;. Such a crude treatment of a \u0026ldquo;seed\u0026rdquo; is understandable: Dr. Yang faced hundreds of specimens in her fossil floral study, it was impossible for her to pay close attention to all the details in all specimens. However, now the information in Figure 2-3 of the seed coat of \u003cem\u003eBaipingfructus\u003c/em\u003e\u0026rsquo; \u003cem\u003ein situ\u0026nbsp;\u003c/em\u003eseeds prevents us from conflating these seeds with Yang\u0026rsquo;s \u0026ldquo;verrucae\u0026rdquo;. Apparently, the systematics of previously documented \u003cem\u003eCarpolithus mitriformis\u0026nbsp;\u003c/em\u003e\u003csup\u003e38\u003c/sup\u003e require further careful study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCriteria\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;of angiosperms\u003c/strong\u003e As stated at the beginning, initially, the term \u0026ldquo;angiosperm\u0026rdquo; referred to the plants that enclosed their seeds. This definition contrasts with \u0026ldquo;gymnosperm\u0026rdquo;, which refers to plants whose seeds are exposed to the exterior space\u003csup\u003e29\u003c/sup\u003e. Although it was later modified in various ways to meet the needs of different authors \u003csup\u003e41\u003c/sup\u003e, the original definition of angiosperms has long been applied in palaeobotany\u003csup\u003e31,41,42\u003c/sup\u003e. A stricter definition of angiosperms was proposed by Tomlinson and Takaso \u003csup\u003e30\u003c/sup\u003e: plants in which pollination occurs after ovule enclosure are angiosperms. This definition apparently is most ideal (especially when the rarity of valuable specimens is ignored), as all plants meeting this criterion are unexceptionally angiosperms.\u003c/p\u003e\n\u003cp\u003eOur observations indicate that the ovary tip of \u003cem\u003eBaipingfructus\u0026nbsp;\u003c/em\u003eis occluded and that the seeds within the fruit are at various developmental stages (Figs. 2a-b, 3a-d), implying that at least ovule enclosure is very likely to occur before pollination. The lack of well-developed seed coat in most seeds/ovules in \u003cem\u003eBaipingfructus\u003c/em\u003e implies that these seeds/ovules are probably still their ovule stages (at most immature seed stage) (Figs. 3a, c). Therefore, \u003cem\u003eBaipingfructus\u0026nbsp;\u003c/em\u003eappears to have met the stricter criterion of angiosperms proposed by Tomlinson and Takaso\u003csup\u003e30\u003c/sup\u003e. Although\u0026nbsp;the pollination process requires further\u0026nbsp;study\u0026nbsp;in \u003cem\u003eBaipingfructus\u003c/em\u003e, the\u0026nbsp;enclosed seeds (angiospermy), a feature that singled angiosperms from (at least most) gymnosperms according to the original concept of\u0026nbsp;angiosperms\u0026nbsp;\u003csup\u003e29\u003c/sup\u003e, are secured in \u003cem\u003eBaipingfructus\u003c/em\u003e (Figs. 2a-b, 3a). Since \u003cem\u003eArchaefructus\u0026nbsp;\u003c/em\u003ewas determined\u0026nbsp;to\u0026nbsp;be\u0026nbsp;an angiosperm on\u0026nbsp;the basis of\u0026nbsp;this feature (angiospermy) alone (there is no evidence showing\u0026nbsp;that\u0026nbsp;there were ovules in \u003cem\u003eArchaefructus\u003c/em\u003e thus far), we can also\u0026nbsp;assume that our identifying\u0026nbsp;\u003cem\u003eBaipingfructus\u003c/em\u003e as an angiosperm is well-grounded, although \u003cem\u003eBaipingfructus\u003c/em\u003e is from the Late Permian. The bottom line is that angiospermy (enclosed seeds) that used to be a feature idiosyncratic to angiosperms has now\u0026nbsp;been\u0026nbsp;achieved by a Permian fossil plant, being an angiosperm or not.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDevelopment of seeds\u0026nbsp;\u003c/strong\u003eNotably, the development of seeds in \u003cem\u003eBaipingfructus\u0026nbsp;\u003c/em\u003eis not synchronized within a fruit (Figs. 3a, c-d). The well-developed sclerenchymatic framework in the seed coat (Figs. 3d-f) is not observed in all seeds within the same fruit. For example, no well-developed sclerenchymatic framework, which is a seed within the same fruit, is shown in Fig. 3c. The occurrence of a well-developed sclerenchymatic framework suggests that the seed is close to mature, whereas its lack implies that the seed is still further from mature. While the former confirms the presence of angiospermy in \u003cem\u003eBaipingfructus\u003c/em\u003e, the latter implies that the immature seed (probably ovule) is also enclosed (angio-ovuly) in \u003cem\u003eBaipingfructus\u003c/em\u003e, strengthening the angiospermous affinity for \u003cem\u003eBaipingfructus\u003c/em\u003e even according to the stricter definition proposed by Tomlinson and Takaso\u0026nbsp;\u003csup\u003e30\u003c/sup\u003e.\u0026nbsp;For the first time, the\u0026nbsp;maturing order of seeds in the same fruit of \u003cem\u003eBaipingfructus\u003c/em\u003e suggests that the ovules/seeds mature neither in an acropetal nor in a basipetal order in this\u0026nbsp;Late\u0026nbsp;Permian angiosperm. This new conclusion is apparently unexpected.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eUnusual\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003esclerenchyma\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;and its\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eecological implications\u003c/strong\u003eSclerenchyma is a type of tissuethat is usually related to the toughening, cushioning, rigidity and mechanical support of plants. In addition to its occurrence in vegetative organs, sclerenchyma is frequently observed in the seed coat and pericarp of reproductive organs. Apparently, \u003cem\u003eBaipingfructus\u003c/em\u003e is not a vegetative organ (Figs. 2a-c). The occurrence of indurated sclerenchyma in the seed coat is more likely to be fossilized, and its occurrence is a symbol of seed identity. This implication is further strengthened by the occurrence of sclerenchyma in the pericarp of \u003cem\u003eBaipingfructus\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003eNotably, the sclerenchyma in \u003cem\u003eBaipingfructus\u003c/em\u003e has unusual characteristics. Unlike in most seeds, the seed coat in \u003cem\u003eBaipingfructus\u003c/em\u003e has unusual intercellular spaces in its hypodermal layer (Figs. 3d-f). A similar structure, although not as well developed as that in \u003cem\u003eBaipingfructus\u003c/em\u003e, has been previously documented for the seed coat of soybean \u003csup\u003e43-46\u003c/sup\u003e. The typical soybean seed coat includes four layers: a cuticle + epidermal layer, palisade layer, hypodermal layer, and endotesta layer (Figs. 1 and 2 in \u003csup\u003e43\u003c/sup\u003e; Figs. 2 and 3a in \u003csup\u003e44\u003c/sup\u003e; Figs. 4a-b in \u003csup\u003e45\u003c/sup\u003e; Fig. 1a in \u003csup\u003e46\u003c/sup\u003e). This stratification corresponds to that observed in \u003cem\u003eBaipingfructus\u003c/em\u003e (Figs. 3d-f). This unusual feature may be related to seed dispersal by water, as the large intercellular spaces in the hypodermal layer can provide buoyance in water that otherwise would be inconceivable. If confirmed by future studies, this would be the first and earliest evidence of hydrochory in the history of angiosperms.\u003c/p\u003e\n\u003cp\u003eThe sclerenchyma in the pericarp of coconut is well known for its cushioning function, mechanical toughness, elasticity, and mechanical protection during its descent onto the ground \u003csup\u003e47-49\u003c/sup\u003e. A similar situation also occurs in luffa, which has abundant sclerenchyma in its pericarp \u003csup\u003e50\u003c/sup\u003e. The occurrence of a three-dimensional sclerenchymatic framework in the pericarp of \u003cem\u003eBaipingfructus\u003c/em\u003e (Figs. 2a-b, 3a, 4a, c) implies that its fruit needs to cope with mechanical impact when it hits the ground. This conclusion implies that the fruit is very likely borne by a tree of a certain height. Notably, the spatial distribution of sclerenchyma is not even in the pericarp of \u003cem\u003eBaipingfructus\u003c/em\u003e (Figs. 2a-b, 3a, 4a, c). Such a skewed deployment of sclerenchyma within the pericarp seems to suggest that the fruit underwent certain oriented stresses, \u003cem\u003ee.g.\u003c/em\u003e\u003cem\u003e,\u003c/em\u003egravity\u0026nbsp;and sunshine. Apparently, this anatomic hint on ecology requires further testing before it is confirmed.\u003c/p\u003e\n\u003cp\u003eThere are only five types of sclerenchyma tissue in textbooks: brachyosclereids, macrosclereids, osteosclereids, asterosclereids, and trichosclereids. All these types are different than the wall-like sclerenchymatic tissue observed in \u003cem\u003eBaipingfructus\u003c/em\u003e (Figs. 5a-c), implying a possible new type of sclerenchyma that has disappeared in extant plants. This may be one of the consequences of long-term evolution in plants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe diversity\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;of\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003ePermian angiosperms\u0026nbsp;\u003c/strong\u003ePreviously reported Permian angiosperms include\u0026nbsp;\u003cem\u003eTaiyuanostachya\u003c/em\u003e \u003csup\u003e32\u003c/sup\u003e, \u003cem\u003eYuzhoua\u0026nbsp;\u003c/em\u003e\u003csup\u003e33\u003c/sup\u003e, and \u003cem\u003eDengfengfructus\u003c/em\u003e \u003csup\u003e51\u003c/sup\u003e, and the application of \u003cem\u003eBaipingfructus\u003c/em\u003e to the list highlights the diversity of angiosperms in the Permian (Table 1). Notably, the distinctions in dimensions, general morphologies, and anatomies among these taxa suggest that they cannot be derived from the same common ancestor. Instead, such diverse taxa in the Permian imply that, if derived from a common ancestor, there must have been long-term evolution before the occurrence of these diverse taxa. Although this view of angiosperm history is apparently at odds with teaching in botanical textbooks, it is noteworthy that molecular estimates based on numerous genes and even genomes point to a pre-Cretaceous origin of angiosperms \u003csup\u003e2,12,28\u003c/sup\u003e. Moreover, studies on fossil insects have revealed that numerous Permian insects might have played a certain role in the pollination of plants during the Permian\u003csup\u003e34-37\u003c/sup\u003e. Instead, the former traditional perspective on angiosperm evolution should be updated.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003e\u003cem\u003eBaipingfructus\u003c/em\u003e is a new fossil angiosperm fruit uncovered from the Xiaofengkou Formation (Upper Permian, \u0026gt;245 Ma) of Dengfeng city, Henan province, China. The seeds of various developmental stages in the same fruit suggest that \u003cem\u003eBaipingfructus\u003c/em\u003e may have both enclosed ovules and enclosed seeds, satisfying both the stricter and original definitions of angiosperms. \u003cem\u003eBaipingfructus\u003c/em\u003e corroborates the truthful occurrence of angiosperms in the Permian. This conclusion agrees with the conclusions of studies on fossil insects and molecular estimates. Together with previously reported angiosperms, \u003cem\u003eBaipingfructus\u003c/em\u003e underscores the diversity of angiosperms in the Permian.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contributions\u0026nbsp;\u003c/h2\u003e\n\u003cp\u003eXW designed the research project and drafted the manuscript. WH collected the specimen, YF carried out the SEM observation. XW, WH, QF, and YF analyzed the data. All the authors have finalized and approved the manuscript.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThe research is supported by the National Key Research and Development Program of China (2024YFF0807601).\u003c/p\u003e\n\u003ch2\u003eInstitutional Review Board Statement\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eInformed Consent Statement\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eData availability statement\u003c/h2\u003e\n\u003cp\u003eAll the data are reported in this paper. The type specimens are deposited in Nanjing Institute of Geology and Palaeontology, and are available for academic observations.\u003c/p\u003e\n\u003ch2\u003eAcknowledgements\u003c/h2\u003e\n\u003cp\u003eWe thank Mr. Jinbo Wu for assisting with the collection of invaluable specimens and Ms. Jingjing Tang for assisting with the photography.\u003c/p\u003e\n\u003ch2\u003eConflicts of interest\u003c/h2\u003e\n\u003cp\u003eThe authors declare that they have no conflicts of interest.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eWang, X. Origin of angiosperms: problems, challenges, and solutions. \u003cem\u003eLife\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, 2029 (2023). https://doi.org/https://doi.org/10.3390/life13102029\u003c/li\u003e\n\u003cli\u003eZuntini, A. 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Fruit biology of coconut (\u003cem\u003eCocos nucifera\u003c/em\u003e L.). \u003cem\u003ePlants\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, 3293 (2022). https://doi.org/https://doi.org/10.3390/plants11233293\u003c/li\u003e\n\u003cli\u003eJiang, Y., Yan, D., Wang, J., Shao, L.-H. \u0026amp; Sharma, P. The giant flexoelectric effect in a luffa plant- based sponge for green devices and energy harvesters. \u003cem\u003eProc Natl Acad Sci USA\u003c/em\u003e \u003cstrong\u003e120\u003c/strong\u003e, e2311755120 (2023). \u003c/li\u003e\n\u003cli\u003eXin Wang, W. H., Qiang Fu et al. , 08 September 2025, PREPRINT (Version 1) available at Research Square []. (ed Academia Sinica Nanjing Institute of Geology and Palaeontology) (Research Square, 2025).\u003cstrong\u003e\u003cbr\u003e\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1 Comparison between \u003cem\u003eBaipingfructus\u003c/em\u003e gen. nov. and contemporaneous angiosperm genera.\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"567\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 11.6402%;\"\u003e\n \u003cp\u003eTaxa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.9912%;\"\u003e\n \u003cp\u003eOrgan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003ePollination canal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003eStyle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003e#ovules per fruit\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003eLength(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003eOvule-enclosing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003eSeed-enclosing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003eLocation\u003c/p\u003e\n \u003cp\u003e(in China)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003eAge\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 11.6402%;\"\u003e\n \u003cp\u003e\u003cem\u003eBaipingfructus\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.9912%;\"\u003e\n \u003cp\u003efruit\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003elacking\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003elacking\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003e8\u0026ndash;11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003epresent (?)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003epresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003eHenan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003ePermian\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 11.6402%;\"\u003e\n \u003cp\u003e\u003cem\u003eTaiyuanostachya\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.9912%;\"\u003e\n \u003cp\u003einfructescence\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003epresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003elacking\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003e33\u0026ndash;43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003epresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003epresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003eShanxi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003ePermian\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 11.6402%;\"\u003e\n \u003cp\u003e\u003cem\u003eYuzhoua\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.9912%;\"\u003e\n \u003cp\u003eovary\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003elacking\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003epresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 8.28924%;\"\u003e\n \u003cp\u003e23.5\u0026ndash;40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003epresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003e?\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003eHenan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 10.0529%;\"\u003e\n \u003cp\u003ePermian\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"angiosperm, Permian, anatomy, pericarp, mesotesta, fruit, China, Baipingfructus","lastPublishedDoi":"10.21203/rs.3.rs-8310107/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8310107/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Although an increasing number of angiosperms are found in the Permian, they remain sparse among the flourishing Permian fossil flora. Apparently, the earlier history of angiosperms in the Permian requires further evidence to consolidate. To elucidate the early history of this important plant group (angiosperms), which is closely related to the well-being of humans, here we document a new angiosperm, Baipingfructus wuii gen. et sp. nov., from the Upper Permian of Henan province, China. The fossils of Baipingfructus reveal the existence of seven seeds/ovules of various maturities within a single fruit. For the first time, the anatomies of the pericarp and seed coat of this Permian angiosperm is documented: the sclerenchymatic framework in the mesotesta demonstrates unusual stratification and intercellular spaces, whereas the pericarp has a skewed distribution of the sclerenchymatic framework. Anatomic details and the general configuration of Baipingfructus eliminate all alternative interpretations and corroborate the occurrence of angiosperms in the Late Permian (\u003e245 Ma).","manuscriptTitle":"Perfect Permian Fruits","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-16 07:22:47","doi":"10.21203/rs.3.rs-8310107/v1","editorialEvents":[{"type":"communityComments","content":1}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a5a7fa78-693e-4b6c-8e95-e0b45d1763c2","owner":[],"postedDate":"December 16th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":59719338,"name":"Biological sciences/Evolution/Palaeontology"},{"id":59719339,"name":"Biological sciences/Plant sciences/Plant evolution"}],"tags":[],"updatedAt":"2026-02-13T12:08:07+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-16 07:22:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8310107","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8310107","identity":"rs-8310107","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}