{"paper_id":"1119f465-7beb-4654-95c2-13a38dc8308e","body_text":"1\n Guide to Australopithecus species\n These ancient human relatives include the first species with\nevidence of upright walking and running like humans. They\n represent more than a third of our evolutionary history.\n John Hawks\n Date: Sep 20, 2023\n URL: https://www.johnhawks.net/p/guide-to-australopithecus-species\n Five australopith skulls\nThe first fossil of Australopithecus became part of the science of human origins in 1925 when\nRaymond Dart described the fossil skull from Taung, South Africa. In the ninety-eight years\nsince then, anthropologists have recovered hundreds of fossils of these early hominins,\nspanning from more than four million years ago until just around two million. That's roughly\nthe middle third of the time since our ancestors first divided from the ancestors of chimpanzees\nand bonobos.\nThis post gives a quick overview of each species of Australopithecus that we know about today.\nMany scientists use a common name for these species: australopiths. In the human family tree,\nthese species are close relatives of our own genus, Homo, and some may have been our\nancestors. I'll include one species that is not Australopithecus but is a very close relative.\n\n\n2\nAt the end, I'll consider the question so many people ask me about early hominins: Why does it\nseem like their names keep changing?\nRelationships of Australopithecus\nAll australopiths shared the bipedal form of locomotion that today's humans rely upon. Their\nbodies had many features that reflect this adaptation to upright walking, from their feet, legs,\nand pelvis, to their spines and skulls. These features set them apart from early fossil relatives\nthat were not bipedal, like Ardipithecus. Australopiths differ from our own genus, Homo, in\nother ways. They had bigger molar and premolar teeth than living humans, with thicker\nenamel. All had smaller brain sizes than humans, with average endocranial volumes between\naround 400 and 600 milliliters.\n The pelvis of Australopithecus has a short and broad ilium that curves around the trunk. Their rounded\npelvic inlet is very much like humans and different from living great apes, which have tall ilia that are flat\n against the back of the trunk, a long sacrum, and elongated pelvic inlet.\nScientists think that some form of australopith was the ancestor of Homo. The best information\ntoday suggests that the ancestral population of our genus first separated from australopiths\nbefore 2.8 million years ago. Another form of hominins, which scientists classify as\nParanthropus, likewise separated from some australopith lineage before this time. These\nspecies, often known as “robust australopiths”, had bigger jaw muscles and mandibles as well\nas larger molar and premolar teeth than either Australopithecus or Homo.\n\n\n3\nAustralopiths lived across a wide range of time and geographic location. The earliest of these\nspecies, Australopithecus anamensis, is represented by fossils as early as 4.17 million years\nago. The latest, Australopithecus sediba, lived just under 2 million years ago. Anthropologists\nhave found australopith fossils in many parts of Africa. Some lived in very wooded landscapes\nand others in more grassland habitats.\nScientists know a lot more about two Australopithecus species than they know about the others.\nAustralopithecus africanus and Australopithecus afarensis are both represented by\nhundreds of fossils from multiple sites, in each case extending across a substantial period of\ntime. These fossil samples have biases. Teeth are more often preserved than bones, and\nscientists recognize parts of jaws and skulls more often than other parts of the body. Even so,\nscientists have found many postcranial remains of these species, including some partial\nskeletons that help show how different parts of their bodies evolved. Both adult and young\nindividuals have been found, providing valuable evidence about how each species grew and\ndeveloped.\nAbout other kinds of Australopithecus we have less evidence. For some, like Australopithecus\nsediba, fossil skeletons provide strong evidence about their anatomy, but from only a single\ntime and place. For others, like Australopithecus bahrelghazali or Australopithecus\ndeyiremeda, only a few fossils provide much evidence about them. These fossils help to add\nbreadth to our knowledge of the diversity of hominins, but we can't yet say as much about their\nadaptations or ways of life.\n\n\n4\n Map of fossil sites with evidence of Australopithecus or Kenyanthropus.\nAustralopithecus africanus\n• First appearance: As early as 3.7 million years, Sterkfontein, South Africa\n• Last appearance: Possibly less than 2.3 million years, Sterkfontein, South Africa\n• Holotype: Taung fossil cranium, Taung, South Africa\n• Named by: Raymond Dart, who described the Taung fossil skull in 1925. Other names were\nonce applied to some of the fossils that scientists now attribute to this species, most notably\nPlesianthropus transvaalensis as named by Robert Broom in 1936.\n• Etymology: Australis is Latin for “southern”, pithekos is Greek for “ape” or “monkey”. The full\nname Australopithecus africanus is “southern ape from Africa”.\n\n\n5\nAt the time the Taung skull was discovered, no fossil relatives of humans were known to be so\nmuch like living great apes in their brain size or facial anatomy. Further discoveries by Robert\nBroom started at Sterkfontein Caves in 1936, eventually revealing the anatomy of Au. africanus\nacross much of its body. The species combines a very apelike brain size with large molar and\npremolar teeth, and a humanlike pelvis, spine, and lower limb. By the 1950s, these discoveries\nhad established a basic scientific picture of Australopithecus.\nThe known sites of Au. africanus are all in South Africa: Sterkfontein Caves, Makapan\nLimeworks, and Taung. Sterkfontein has produced the largest number of fossils, more than 600\nover the years, and over the last decade scientists have developed two different ideas about the\nage of these fossils, diverging by more than a million years from each other. Remains of\nAustralopithecus mostly come from two geological units, the earlier Member 2 and later\nMember 4. The most recent work at the site suggests an age up to 3.7 million years for Member\n2 and 3.5 million for Member 4. Those are older than estimates from previous analyses of the\nsite, which had suggested that the Member 4 fossils are between 2.6 and 2.1 million years old.\nToday this is an open scientific question and both older and younger estimates have some\nevidence to support them. This uncertainty about the date of the fossils does not change their\nbiological relationship to humans or other hominin species, which scientists interpret from\ntheir anatomy and not their age. Still, an accurate knowledge of the date means a lot for\nunderstanding the initial dispersal of hominins into southern Africa.\n\n\n6\n Skeletons attributed to Au. africanus from Sterkfontein\nThe last decade has seen a resurgence of scientific work on Au. africanus. Researchers have\nuncovered some details about the early childhood development of this species, finding that\nmothers provided mostly breastmilk to their infants for the first year but not long afterward—a\ntiming that resembles some human societies but not living great apes. High-resolution scans of\nthe internal structure of bones has shown how Au. africanus hand bones may reflect their use\nof tools. Such studies are leveraging a century of knowledge and new technology to help us\nunderstand the lives of these early hominins.\nAustralopithecus afarensis\n• First appearance: 3.9 million years, Belohdelie, Ethiopia\n• Last appearance: 3.0 million years, Hadar, Ethiopia\n• Holotype: LH 4 fossil mandible, Laetoli, Tanzania\n• Named by: Donald Johanson and coworkers in 1978. The name they gave, Australopithecus\nafarensis, is still used by most anthropologists. However, some use the name Praeanthropus\nafarensis, which recognizes that the species cannot be on the same branch as Australopithecus\nafricanus without also including the genus Homo.\n• Etymology: The Afar region of Ethiopia is the homeland of the Afar people and language,\nafarensis means “from Afar”.\n\n\n7\n Cast of the AL 288-1 skeleton, popularly known as “Lucy”. Photo: 120 (Wikipedia) CC-BY 2.5x\nAustralopithecus afarensis is the first human relative that many people think of today, and the\nfame of the “Lucy” skeleton is a big reason why. This individual is widely known in Ethiopia as\n“Dinkenesh”, which in the Amharic language means “you are beautiful”. Anthropologists know\nthe skeleton by the number AL 288-1, and the individual lived around 3.18 million years ago.\nLike some other adult individuals of Au. afarensis, the AL 288-1 individual was quite small\ncompared to living people, only around 1.2 meters in height and 28 kg in mass. Some other\nadult individuals were closer to the average body size of recent humans. For example, the\nKSD-VP-1/1 skeleton from the Korsi Dora 1 locality, Ethiopia, represents an individual of around\n50 kg and 1.6 meters in height.\nAll of them walked bipedally. Their locomotion is attested abundantly by their skeletons and\nalso by the 3.6-million-year-old footprint trails at Laetoli, Tanzania.\nAustralopithecus afarensis includes some exceptional fossil samples. The AL 333 locality, part of\nthe Hadar field survey region in Ethiopia, is a place where anthropologists found more than 250\nfossil fragments from at least 17 individuals. Something happened to these individuals that\nlived around 3.2 million years ago, burying remains of young and old alike in one small area.\nAnother exceptional fossil is a child's skeleton from Dikika, Ethiopia, discovered by a team led\nby Zeresenay Alemseged. More fragmentary remains have been found at more than a dozen\nsites, including Laetoli in Tanzania, Kantis and Sinibo in Kenya, and Maka, Neferaytu, and\nLeado Dido'a in Ethiopia.\n\n\n8\nFor the first thirty years after its discovery, scientists tended to see Au. afarensis as a direct\nancestor of humans, and other species—like Au. africanus—as extinct side branches of the\nhominin tree. Today researchers pursue a greater diversity of approaches to these fossils.\nYohannes Haile-Selassie has emphasized that other species including Australopithecus\ndeyiremeda lived during the same time range in the region of Ethiopia where Au. afarensis is\nknown best. How such different populations may have interacted, or whether they represent\nrecurrent invasion of the region by hominins with more continuous habitation elsewhere, is\nnot yet clear.\nAustralopithecus anamensis\n• First appearance: 4.17 million years, Kanapoi, Kenya\n• Last appearance: 3.8 million years, Miro Dora, Ethiopia\n• Holotype: KNM-KP 29281 mandible from Kanapoi, Kenya\n• Named by: Meave Leakey and coworkers in 1995\n• Etymology: anam is a word from the Turkana language that means “lake”; anamensis means\n“from the lake”.\n\n\n9\nMost anthropologists agree that Au. anamensis is very much like Au. afarensis. The key\ndifferences between the two species are in the shape of the jaw and teeth: Au. anamensis had\nlong and more parallel alignments of the premolars and molars, with a more sloping symphysis\nand more procumbent incisors. The two overlap in the form and size of most teeth, although Au.\nafarensis more often had canine and premolar form that prevented cutting wear between the\ntwo. Both species lived in Ethiopia and Kenya, although the earlier Au. anamensis has not yet\nbeen found south of the Turkana Basin. For the first twenty-five years after the recognition of\nAu. anamensis, most researchers supported the idea that the two species are earlier and later\nparts of a single lineage.\nThat idea has shifted somewhat in the last few years. Yohannes Haile-Selassie and coworkers\ndescribed the MRD-VP-1/1 partial skull from Miro Dora, Ethiopia, in 2019. This established that\nAu. anamensis may have persisted a bit later than the first Au. afarensis. The known samples of\nthese two species differ in their carbon stable isotopes, with Au. afarensis depending more on\nwarm-season grasses, and they may have survived best in different habitats. The possibility that\nSouth African Au. africanus fossils may be earlier than once thought provokes the question of\nwhether Au. anamensis or early Au. afarensis may be the ancestor of this species.\nKenyanthropus platyops\n• First appearance: 3.50 million years, Lomekwi, Kenya.\n• Last appearance: 3.03 million years, Lomekwi, Kenya.\n• Holotype: KNM-WT 40000 partial skull, from Lomekwi, Kenya.\n\n\n10\n• Named by: Meave Leakey and coworkers in 2001\n• Etymology: Kenyanthropus honors the nation of Kenya; platyops is Greek for “flat face”.\nAll fossils so far attributed to Kenyanthropus platyops come from the western part of the\nTurkana Basin, in deposits that formed from 3.5 million to 3 million years ago. The\nmuch-better-known species that lived at this same time is Au. afarensis, which researchers have\nfound in Tanzania, southern Kenya, and Ethiopia. Australopithecus africanus may also have\nbeen a contemporary, much further to the south. In its skull and teeth, K. platyops does differ\nfrom these species in several ways. Its teeth are a bit smaller on average, the lower part of its\nface is flatter and less projecting, and it has a smaller ear opening, along with other slight\ndifferences.\nMeave Leakey and collaborators broke a longstanding trend by placing this fossil species into a\nnew genus instead of Australopithecus. Their analysis of K. platyops suggested that this species\nmight be a close relative of Homo. They especially noted similarities between the best-preserved\nK. platyops skull, KNM-WT 40000, and an early Homo fossil from around 2.1 million years ago,\nKNM-ER 1470.\nStill, the fossil record of K. platyops leaves open most questions about its relationships. The\nKNM-WT 40000 skull was crushed as it fossilized, impeding comparisons with known samples\nof Australopithecus. Also, researchers have not yet reported any postcranial fossils of this\nspecies. Some anthropologists think that K. platyops may have been a regional population of Au.\nafarensis.\nWhile anthropologists may have divergent opinions about the connection of the Lomekwi fossil\nsamples to other hominins, the Lomekwi region is very important to archaeologists also. Here,\naround 3.3 million years ago, someone made the first-known stone tools. At present, only K.\nplatyops fossils are known from this interval anywhere in the Turkana Basin. Understanding\nhow the populations of this region were connected to others across Africa is a high priority for\nfossil exploration.\nAustralopithecus bahrelghazali\n\n\n11\n• Only appearance: 3.58 ± 0.27 million years, Koro Toro, Chad.\n• Holotype: KT 12/H1 mandible, from Koro Toro locality 12, near the shore of the former\nmega-Lake Chad.\n• Named by: Michel Brunet and coworkers in 1995\n• Etymology: Bahr el Ghazal is the name of the region of Chad where the fossils were found.\nPaleontologists have worked hard to find Pliocene fossil deposits in the Rift Valley of eastern\nAfrica and the cave systems of South Africa. Another area with Pliocene fossils is central Chad,\nwhere the basin that now contains Lake Chad has fossil deposits on the ancient shorelines that\nmark its much larger Pliocene extent. The 3.5-million-year-old deposits near Koro Toro have\nproduced pieces of three fossil hominin individuals, which Michel Brunet and coworkers\nattributed to Australopithecus bahrelghazali.\nThe most substantial fossil is the KT 12/H1 mandibular fragment. Brunet and coworkers\nobserved some subtle differences between this fossil and those known for Au. afarensis at the\ntime, including the more vertical posterior surface of the symphysis and its three-rooted\npremolars. As in the case of K. platyops, some researchers have suggested that the Koro Toro\nfossils may represent a regional variation of Au. afarensis.\nAustralopithecus deyiremeda\n• First appearance: ~3.5 million years, Burtele collection area 3, Ethiopia\n• Last appearance: ~3.3 million years, Waytaleyta collection area 2, Ethiopia\n\n\n12\n• Holotype: BRT-VP-3/1 maxillary fragment\n• Named by: Yohannes Haile-Selassie and coworkers in 2015\n• Etymology: The name comes from the Afar language; deyi means “close” and remeda means\n“relative”.\n Comparison of Australopithecus deyiremeda face with Sts 52 Australopithecus africanus and Hadar\n Australopithecus afarensis\nThis species was identified by Yohannes Haile-Selassie and coworkers based on their work in\nthe Woranso-Mille area, around 40 km north of the Afar River and sites including Hadar and\nDikika. Both the upper and lower jaw of Au. deyiremeda are shaped in ways that would have\npositioned the masseter muscles of the jaw were further toward the front of the face, with the\nzygomatic process of the maxilla and mandibular ramus both further forward than in Au.\nafarensis. The sizes of the molar and premolar teeth are relatively small, and the upper canine\nis small and simple compared to Au. afarensis also. None of the rest of the skeleton of this\nspecies is known.\nThe Woranso-Mille region has several sites with Au. afarensis fossils, and if Au. deyiremeda had\na different evolutionary history from Au. afarensis, the two species would likely have been in\ncontact with each other. This may be the earliest evidence that two hominin species lived in the\nsame area at the same time. With so little information from Au. deyiremeda, it's not clear\nwhether the two species differed in diet or habitat preferences. One possibility is that one or\nboth species first evolved elsewhere and later came into contact. If this region was a contact\nzone between two hominin species, there may be signs that some fossils come from populations\nwith hybrid ancestry.\n\n\n13\nAustralopithecus prometheus\n• First appearance: 3.7 million years, Sterkfontein, South Africa\n• Last appearance: 2.6 million years, Makapan Limeworks, South Africa\n• Holotype: MLD 1 cranial fragment\n• Named by: Raymond Dart in 1948\n• Etymology: In Greek myth, Prometheus was a character who first brought knowledge of fire\nto humanity.\n MLD 1 and StW 573 fossil skulls attributed by some researchers to Australopithecus prometheus\nAnatomy students at the University of the Witwatersrand, including Phillip Tobias, prospected\nthe breccia dumps from the Makapan Limeworks after the Second World War, finding many\nfossils. Dart studied these fossils and came to the point of view that hominins had been\nresponsible for many broken and blackened animal bones, prompting the idea that these\nancient human relatives may have used fire. His name, Australopithecus prometheus, reflects\nthat hypothesis. Later scientists showed that the color of the fossils was caused by mineral\nstaining after they were deposited in the cave, and their breakage cannot be attributed to\nhominin activity.\nDart recognized many similarities between the Makapan fossils and those from Sterkfontein\nand Taung, but he judged that the MLD 1 cranial fragment represented a larger brain size, and\nso he separated it as Au. prometheus. John Robinson later argued that these three samples of\nhominin fossils all represent a single form, which he recognized as Au. africanus. Most\n\n\n14\nanthropologists since the late 1950s have followed this idea. However, not all scientists today\naccept that the Sterkfontein Australopithecus fossils all are one species. The analysis of the StW\n573 skeleton by Ronald Clarke and many coworkers led them to hypothesize that this individual\nis connected with MLD 1 and some other Makapan and Sterkfontein fossils as Australopithecus\nprometheus. In their description, the evidence for larger tooth size, larger jaw musculature, and\nlarger brain size, together with other features of the face and skull, really do set the Au.\nprometheus fossils apart from Au. africanus.\nI have written that I think Dart's definition of Au. prometheus no longer can stand up today.\nStill, the StW 573 skeleton provides a great deal of information that helps to put the Sterkfontein\nand Makapansgat variation into better context. I would not be surprised if some of the variation\nof these fossil samples represents closely related species, or mixture of populations. The\ncompeting ideas of geologists about the formation of the Sterkfontein deposits is a big challenge\nfor interpreting this variation. The earliest estimate of the geological age of the StW 573\nskeleton is 3.7 million years, but some scientists have proposed it may be less than 2.3 million.\nThat's a big uncertainty. Understanding whether the fossils actually come from widely\nseparated times makes a difference to interpreting their variation.\nAustralopithecus garhi\n• Only appearance: 2.5 million years, Bouri, Ethiopia.\n• Holotype: BOU-VP-12/130, a fragmentary cranium from Bouri, in the Middle Awash field\nsurvey region of Ethiopia.\n• Named by: Berhane Asfaw and coworkers in 1999\n• Etymology: In the Afar language, the word garhi means “surprise”.\n\n\n15\n A cast copy of a reconstruction of the partial BOU-VP-12/130 cranium. Photo: Sailko (Wikipedia) CC-BY 3.0\nIn the context of 1999, the BOU-VP-12/130 skull looked very different from other hominins\nknown in Ethiopia. The massive premolars of this skull compare to Paranthropus, while the\nlarge canine size stood out from all other Australopithecus species. From today's perspective,\nvery large Au. afarensis crania, especially the AL 444-2 skull, have a shape a lot like what is\npreserved in this skull. Some aspects of the skull's anatomy are similar to samples from other\nspecies, particularly Au. africanus which lived around the same time in South Africa.\nNo other parts of the individual represented by the BOU-VP-12/130 skull are known, which\nmakes it difficult to assess whether other hominin fossils also may belong to Au. garhi. A few\nhominin fossils from roughly the same time are known from other localities near Bouri,\nincluding a mandible and a partial skeleton.\nA number of animal bones with cutmarks were identified at the same fossil locality where the\nAu. garhi holotype skull was found. The association suggested that Au. garhi may have made\nstone tools and relied on meat and marrow. An early form of Homo may be present in the\nregion as much as 300,000 years earlier than the Au. garhi skull, and without more fossils to\nassess their distribution or possible relationship, it's hard to say where Au. garhi may fit in.\nAustralopithecus sediba\n• Only appearance: 1.98 million years, Malapa, South Africa.\n• Holotype: MH1 fossil skeleton, Malapa, South Africa.\n\n\n16\n• Named by: Lee Berger and coworkers in 2010\n• Etymology: The word sediba means “fountain” or “spring” in the Sesotho language commonly\nspoken in the region of South Africa that includes the Malapa site.\nAustralopithecus sediba is known from two partial skeletons and a few fossils attributable to\nother individuals, all from Malapa, South Africa. The MH1 skeleton belonged to a child of\nbetween seven and nine years of age, and MH2 was an adult with strongly worn teeth, inferred\nto be a female individual based on its small tooth dimensions and body size compared to the\nMH1 juvenile. The fossils are similar to earlier species of Australopithecus in many aspects of\ntheir anatomy. The MH1 individual had a small brain size, both skeletons came from\nindividuals similar in size to Au. africanus fossils, and both had relatively long arms and short\nlegs like Au. africanus.\nAt the same time Au. sediba differs from other fossils of Australopithecus in ways that align the\nspecies with early Homo fossils. The individuals have smaller molars and premolars than other\nAustralopithecus species and thinner mandibles. They have less flaring pelves, and the anatomy\nof the MH2 wrist and hand shows humanlike features that not evident in other known\nAustralopithecus fossils. These kinds of observations suggest that Au. sediba had common\nancestors with Homo more recently than other Australopithecus species.\n\n\n17\n Cast of the wrist and hand of Australopithecus sediba skeleton MH2. Photo: John Hawks\nNames of fossil species\nAnytime I discuss so many species names, it brings up the old debate about lumping versus\nsplitting in recognizing fossil species. How do scientists decide which fossils represent new\nspecies and which ones belong to already-known species?\nThe longer I study fossil hominins, the more I understand Charles Darwin's perspective on\nspecies. Darwin wrote:\n“In determining whether a form should be ranked as a species or a variety, the opinion of\nnaturalists having sound judgment and wide experience seems the only guide to\nfollow.”—Charles Darwin\nWhat marked the differences between species, for Darwin, was that they could be clearly\ndistinguished from each other; they don't grade continuously from one into another. Fossils\ndon't often give us the kind of evidence that lets us test whether they belonged to groups with\nboundaries between them. Some fossil samples cover a long period of time during which\nspecies evolved.\nIdeas about fossil species are subject to scientific testing. With more evidence, scientists change\ntheir ideas about fossil groups. Part of systematics is revising old definitions and sometimes\ndiscarding species names entirely. Some species names on this list may not last. Maybe we will\nfind that Australopithecus garhi really was a regional population of Au. africanus, or that\nKenyanthropus platyops and Au. deyiremeda were closer than we now think. Some may join the\n\n\n18\nlist of names that scientists don't use any more, like Plesianthropus transvaalensis.\nGenus names may change for another reason. For a long time from the 1960s to the 2000s, many\nanthropologists saw Australopithecus as a catch-all for every kind of early human relative that\nwas not part of our own genus, Homo. In that era, biologists defined a genus to be a group of\nspecies that are close relatives and share a similar pattern of adaptation to their environments.\nAll the hominins that were known at that time walked bipedally like humans, but early\nhominins had much smaller brains than humans today. Anthropologists saw two simple\ncategories: Later, larger-brained hominins were Homo and earlier hominins with smaller brain\nsize were Australopithecus.\nOver the past thirty years scientific ideas about classification have changed in a crucial way.\nToday biologists try to make sure that all the species that share a common ancestor are included\nwithin a group. Applied to the family level, this concept has made a big difference to the way we\nclassify living great apes. Before the 1980s, most systematists accepted living chimpanzees,\ngorillas, and orangutans as a single family, called Pongidae, and humans as a separate family,\nHominidae. This recognized the many differences in body form and behavior in humans\ncompared to those great apes. But we now recognize that humans are closer to chimpanzees\nand bonobos than to orangutans, and classify the great apes and humans as Hominidae. They\nare in the same family because they all share the same ancestor, despite their differences in\nbody and behavior.\nTaking this principle to the genus level in fossil hominins has consequences for\nAustralopithecus. Under our current best evidence, almost all researchers agree that some of\nthe species of Australopithecus are closer relatives of Homo than others. If we classify them by\ntheir place on the tree, and not just the size of their brain, then some of their names must\nchange. The name Australopithecus must stick with Au. africanus. Biologists may need different\n\n\n19\ngenus names for some others.\nThis has caused anthropologists to revive some older genus names for some species. Species of\n“robust australopiths”, in the 1970s commonly accepted as Australopithecus, are now usually\nclassified within their own genus, Paranthropus. Another name, Praeanthropus, is an earlier\ngenus name attributed to Australopithecus afarensis that has returned in some anthropologists'\nwork. And in 2001, Meave Leakey and collaborators recognized that new names may be\nnecessary when they defined Kenyanthropus. It is likely that scientists will continue to add new\nnames.\nNonetheless, our knowledge of relationships among fossil species is still shifting with each new\ndiscovery. With living primates we have whole genomes, but our knowledge of relationships of\nearly hominins depends on the quality of the fossils. For the time being, many anthropologists\nare content to clump many similar species within Australopithecus without worrying too much\nabout whether the names are a perfect fit to the branches of today's tree.\nNotes: I've given “first appearance” and “last appearance” dates where possible, and this raises a\npossible confusion since both may have ranges of error or uncertainty. I've generally chosen to\nmake these the modal date for the earliest or latest fossil attributed to the species, reported by the\nmost recent research study. But that date may be a long time away from the earliest possible or\nlatest possible dates. For Sterkfontein, where more than a million years of time are involved, I\ndiscuss this issue in some detail. For other sites, uncertainty of tens of thousands of years may\napply.\nThe 2023 work by Mongle and coworkers gives a current perspective on the phylogeny of these\nspecies and my tree diagram relies on this study. They did not include Au. bahrelghazali or Au.\ndeyiremeda due to the low representation of anatomy in these species. It seemed logical to include\nAu. bahrelghazali from a node that includes Au. afarensis, so I added it. The placement of Au.\ndeyiremeda is less intuitive to me, whether the features it shares with Homo are the same or\ndifferent as those found in Kenyanthropus or Au. sediba matters a lot, and more study will be\nrequired. So I didn't place this species in the tree.\nI've included references below that give the first diagnosis of each species. To a more limited\ndegree, I include references to current information about the age of key fossils, although this\nwould quickly become a very long list. Articles by Granger and coworkers and by Pickering and\nHerries provide alternative points of view regarding the age of Sterkfontein fossils. For readers\nwho would like more information about the names of fossil hominins, I can recommend the article\nby Denné Reed and coworkers, who have compiled a list of more than 200 names that scientists\nhave defined for hominins, and they provide information about how the rules of taxonomy apply\nto these.\nReferences:\nAsfaw, B., White, T., Lovejoy, O., Latimer, B., Simpson, S., & Suwa, G. (1999). Australopithecus\ngarhi: A New Species of Early Hominid from Ethiopia. Science, 284(5414), 629–635.\nhttps://doi.org/10.1126/science.284.5414.629\n\n\n20\nBerger, L. R., de Ruiter, D. J., Churchill, S. E., Schmid, P., Carlson, K. J., Dirks, P. H. G. M., & Kibii, J.\nM. (2010). Australopithecus sediba: A New Species of Homo-Like Australopith from South\nAfrica. Science, 328(5975), 195–204. https://doi.org/10.1126/science.1184944\nBroom, R. (1938). The Pleistocene Anthropoid Apes of South Africa. Nature, 142(3591), Article\n3591. https://doi.org/10.1038/142377a0\nBrunet, M., Beauvilain, A., Coppens, Y., Heintz, E., Moutaye, A. H. E., & Pilbeam, D. (1995). The\nfirst australopithecine 2,500 kilometres west of the Rift Valley (Chad). Nature, 378(6554), Article\n6554. https://doi.org/10.1038/378273a0\nBrunet, M., Beauvilain, A., Coppens, Y., Heintz, E., Moutaye, A. H. E., & Pilbeam, D. (1996).\nAustralopithecus bahrelghazali, une nouvelle espèce d’Hominidé ancien de la région de Koro\nToro (Tchad). Australopithecus Bahrelghazali, Une Nouvelle Espèce d’Hominidé Ancien de La\nRégion de Koro Toro (Tchad), 322(10), 907–913.\nClarke, R. J., & Kuman, K. (2019). The skull of StW 573, a 3.67 Ma Australopithecus prometheus\nskeleton from Sterkfontein Caves, South Africa. Journal of Human Evolution, 134, 102634.\nhttps://doi.org/10.1016/j.jhevol.2019.06.005\nDart, R. A. (1925). Australopithecus africanus the man-ape of South Africa. Nature, 115(2884),\nArticle 2884. https://doi.org/10.1038/115195a0\nDart, R. A. (1948). The Makapansgat proto-human Australopithecus prometheus. American\nJournal of Physical Anthropology, 6(3), 259–284. https://doi.org/10.1002/ajpa.1330060304\nGranger, D. E., Gibbon, R. J., Kuman, K., Clarke, R. J., Bruxelles, L., & Caffee, M. W. (2015). New\ncosmogenic burial ages for Sterkfontein Member 2 Australopithecus and Member 5 Oldowan.\nNature, 522(7554), Article 7554. https://doi.org/10.1038/nature14268\nGranger, D. E., Stratford, D., Bruxelles, L., Gibbon, R. J., Clarke, R. J., & Kuman, K. (2022).\nCosmogenic nuclide dating of Australopithecus at Sterkfontein, South Africa. Proceedings of the\nNational Academy of Sciences, 119(27), e2123516119. https://doi.org/10.1073/pnas.2123516119\nHaile-Selassie, Y. (2010). Phylogeny of early Australopithecus: New fossil evidence from the\nWoranso-Mille (central Afar, Ethiopia). Philosophical Transactions of the Royal Society B:\nBiological Sciences, 365(1556), 3323–3331. https://doi.org/10.1098/rstb.2010.0064\nHaile-Selassie, Y., Gibert, L., Melillo, S. M., Ryan, T. M., Alene, M., Deino, A., Levin, N. E., Scott, G.,\n& Saylor, B. Z. (2015). New species from Ethiopia further expands Middle Pliocene hominin\ndiversity. Nature, 521(7553), Article 7553. https://doi.org/10.1038/nature14448\nBerger, L. R., & Hawks, J. (2019). Australopithecus prometheus is a nomen nudum. American\nJournal of Physical Anthropology, 168(2), 383–387. https://doi.org/10.1002/ajpa.23743\n\n\n21\nJohanson, Donald C., White, Tim D., & Coppens, Yves. (1978). A new species of the genus\nAustralopithecus (Primates: Hominidae) from the Pliocene of eastern Africa. Kirtlandia, 28,\n1–14.Leakey, M. G., Feibel, C. S., McDougall, I., & Walker, A. (1995). New four-million-year-old\nhominid species from Kanapoi and Allia Bay, Kenya. Nature, 376(6541), Article 6541.\nhttps://doi.org/10.1038/376565a0\nLeakey, M. G., Feibel, C. S., McDougall, I., Ward, C., & Walker, A. (1998). New specimens and\nconfirmation of an early age for Australopithecus anamensis. Nature, 393(6680), Article 6680.\nhttps://doi.org/10.1038/29972\nLeakey, M. G., Spoor, F., Brown, F. H., Gathogo, P. N., Kiarie, C., Leakey, L. N., & McDougall, I.\n(2001). New hominin genus from eastern Africa shows diverse middle Pliocene lineages. Nature,\n410(6827), Article 6827. https://doi.org/10.1038/35068500\nLebatard, A.-E., Bourlès, D. L., Duringer, P., Jolivet, M., Braucher, R., Carcaillet, J., Schuster, M.,\nArnaud, N., Monié, P., Lihoreau, F., Likius, A., Mackaye, H. T., Vignaud, P., & Brunet, M. (2008).\nCosmogenic nuclide dating of Sahelanthropus tchadensis and Australopithecus bahrelghazali:\nMio-Pliocene hominids from Chad. Proceedings of the National Academy of Sciences, 105(9),\n3226–3231. https://doi.org/10.1073/pnas.0708015105\nMbua, E., Kusaka, S., Kunimatsu, Y., Geraads, D., Sawada, Y., Brown, F. H., Sakai, T., Boisserie,\nJ.-R., Saneyoshi, M., Omuombo, C., Muteti, S., Hirata, T., Hayashida, A., Iwano, H., Danhara, T.,\nBobe, R., Jicha, B., & Nakatsukasa, M. (2016). Kantis: A new Australopithecus site on the\nshoulders of the Rift Valley near Nairobi, Kenya. Journal of Human Evolution, 94, 28–44.\nhttps://doi.org/10.1016/j.jhevol.2016.01.006\nMongle, C. S., Strait, D. S., & Grine, F. E. (2023). An updated analysis of hominin phylogeny with\nan emphasis on re-evaluating the phylogenetic relationships of Australopithecus sediba. Journal\nof Human Evolution, 175, 103311. https://doi.org/10.1016/j.jhevol.2022.103311\nPickering, Robyn & Herries, Andy I. R. (n.d.). A new multidisciplinary age of 2.61–2.07 Ma for the\nSterkfontein Member 4 australopiths. In Zipfel, Bernhard, Richmond, Brian, & Ward, Carol V.\n(Eds.), Hominin Postcranial Remains from Sterkfontein, South Africa, 1936-1995 (pp. 21–32).\nOxford University Press.\nReed, D. N., Raney, E., Johnson, J., Jackson, H., Virabalin, N., & Mbonu, N. (2023). Hominin\nnomenclature and the importance of information systems for managing complexity in\npaleoanthropology. Journal of Human Evolution, 175, 103308.\nhttps://doi.org/10.1016/j.jhevol.2022.103308\nSpoor, F., Leakey, M. G., & O’Higgins, P. (2016). Middle Pliocene hominin diversity:\nAustralopithecus deyiremeda and Kenyanthropus platyops. Philosophical Transactions of the\nRoyal Society B: Biological Sciences, 371(1698), 20150231. https://doi.org/10.1098/rstb.2015.0231\nWhite, T. D., WoldeGabriel, G., Asfaw, B., Ambrose, S., Beyene, Y., Bernor, R. L., Boisserie, J.-R.,\nCurrie, B., Gilbert, H., Haile-Selassie, Y., Hart, W. K., Hlusko, L. J., Howell, F. C., Kono, R. T.,\n\n\n22\nLehmann, T., Louchart, A., Lovejoy, C. O., Renne, P. R., Saegusa, H., … Suwa, G. (2006). Asa Issie,\nAramis and the origin of Australopithecus. Nature, 440(7086), Article 7086.\nhttps://doi.org/10.1038/nature04629","source_license":"CC-BY-4.0","license_restricted":false}