ABOUT THE SKULLSSahelanthropus tchadensis6-7 MYA. The Sahelanthropus tchadensis skull was discovered by Michael Brunet's team in Chad in 2001 and described in Nature in 2002. Some suggest that S. tchadensis existed near the time that hominids and apes separated on their evolutionary paths. It could be that this specimen is a representative of an early hominid, predating A. afarensis aferensis by 3 to 4 million years; on the other hand, it might be an ancestor of the gorilla. The characteristics of the cranium are a mosaic of hominid-like (short face, the size and shape of the canines), and ape-like (very large browridges and small brain case) features.

Ardipithecus ramidus “ARDI” female4.4 MYA. Ardipithecus ramidus was discovered by Tim White and associates in 1994 in the Afar region of Ethiopia. The partial skeleton ARA-VP-6/500 is now considered by many to be the oldest skeleton of a supposed human ancestor. The discovery team's examination of the pelvis indicates that this species was able to walk upright, not with the same fluidity of later humans or even 'Lucy' but with much more efficiency than chimpanzees. However, the lower part of the pelvis offers evidence that the species possessed the musculature required for tree-climbing. The bones of the wrist indicate, according to the discovery team, that while moving quadrupedally, weight was placed on the palms of the hands rather than on the knuckles. White and associates hypothesize that Australopithecus is a descendant of Ardipithecus, while others hypothesize that Ardipithecus might be an extinct sister species to Lucy's genus.Australopithecus afarensis “Lucy” female3.2 MYA. The Australopithecus afarensis Skull "Lucy" was discovered by D. Johanson in 1974 in Hadar, Ethiopia. Several branches of the hominid evolutionary tree that began between 2 and 3 MYA stemmed from "Lucy's" species. Although the short stature of this female, only 1.2 meters, suggests that she was immature, eruption of the third molar provides evidence that this specimen was mature, and was simply a female representative of a sexually dimorphic species. The jaw shares features with both apes and other early hominids, with the shape showing some similarities to apes, with relatively large front teeth and parallel-sided tooth rows, and the size of the canine teeth being intermediate between apes and hominids who lived later. The cheek teeth are intermediate in size between hominids who lived earlier and those who lived later. The brain of "Lucy" was relatively small and overlapped in size with living apes; however, the shape of the pelvis, along with other characteristics of the postcranial skeleton, indicates that "Lucy" walked upright. At the same time, other characteristics of the limb skeleton indicate that members of this species spent time in the trees. This combination of an ape-sized brain in a hominid adapted to upright walking adds to the evidence that bipedalism occurred before the development of a relatively large brain.Australopithecus afarensis male2.9 to 3.6 MYA. Australopithecus afarensis Skull. The australopithecines are only known from Africa and are believed to be the earliest known true hominids. None has ever been found in Europe or Asia. They had ape-sized brains; their cranial capacity ranged from 375 to 530 cc. The cranial capacity of Australopithecus afarensis had a similar range. They had strong jaws with large teeth. Like modern gorillas the adult males were much larger than the females. The babies probably took approximately the same length of time to grow up as a modern chimpanzee or gorilla.

Kenyanthropus platyops3.5 MYA. The Kenyanthropus platyops Skull KNM-WT-40000 was discovered in 1999 by J. Erus, a member of Meave Leakey's team, west of Lake Turkana, Kenya. In 2001 Leakey, et al. described the specimen in Nature. Leakey and colleagues viewed the finds as being distinct enough from Australopithecus, particularly in the marked flatness of the face, that it justifies giving them a new genus and species, Kenyanthropus platyops (meaning "flat faced hominid from Kenya"). Providing a second hominid species in the period from 3 to 3.5 MYA, the discovery of this specimen challenges A. afarensis "Lucy" as the direct ancestor of modern human. The classification of this specimen as a separate genus is not uncontroversial, especially given the damaged condition (1,100 face pieces) in which the skull was found. Some authorities emphasize that the skull was so deformed that it is difficult to interpret its position in hominid evolution.

Australopithecus africanus2.5 MYA, the Australopithecus africanus Skull Sts 5 "Mrs. Ples" was discovered in 1947 by R. Broom and J. Robinson in Sterkfontein, Transvaal, South Africa. The discovery of this nearly complete cranium of a mature specimen led to a much more positive reception of South African australopithecines as hominids. Twenty years earlier Raymond Dart labeled a skull found at Taung "Australopithecus africanus." The dentition of that skull indicates that it was a juvenile, which led to much criticism and broad dismissal of Dart's contention that the skull was a hominid; instead, critics considered it an ape. Like other early hominids, it had an ape-sized brain. The Sts 5 cranial capacity is about 485 cc. Compared to Australopithecus afarensis, it has a more rounded skull, a less projecting face, absence of cranial crests, and smaller front teeth. However, the front teeth are larger than in robust australopithecines. The cheek teeth are larger than in Australopithecus afarensis but smaller than in the robust australopithecines. The discovery of Sts 5 two decades later provided support for Dart's earlier claim. Originally thought by Broom to be a middle-aged female, Sts 5 is now considered by most to be a male.Paranthropus aethiopicus2.5 MYA. The Paranthropus aethiopicus Skull KNM-WT 17000 was discovered by A. Walker in 1985 on the west shore of Lake Turkana in northern Kenya. It was described by Walker, Leakey, Harris and Brown in Nature in 1986. The skull is commonly referred to as the "Black Skull" due to its blue-black color. Although not considered on a direct line to humans, it gives insights into early hominid evolution. Although it shares many primitive features with A. afarensis (e.g., projecting face, small cranial capacity (410 cc)), it also has features typical of australopithecine species (e.g., projecting face, large sagittal crest and jaws, and expanded cheek teeth). Given that it seems to fall between A. afarensis and A. boisei, it was given its own species name.

Paranthropus robustus1.5 to 2 MYA. The Paranthropus robustus Skull SK-48 was discovered by Fourie in Swartkrans, South Africa in 1950 and described by R. Broom in 1952. SK-48, formerly called Paranthropus crassidens, greatly increased what is known about australopithecines. The Transvaal cave site where it was found was blasted by explosives but, remarkably, the skull survived. The skull was found with the right canine, the first premolar and all three molars intact. On the basis of the adult teeth and small sagittal crest, Broom determined the specimen to be an adult female.

Homo habilis1.9 MYA. The Homo habilis Skull KNM-ER 1813 was discovered by K. Kimeu in 1973 at Koobi, Kenya, and described by R. Leakey in Nature in 1973. There is still controversy about this specimen's classification, with some scientists opting to classify it as an australopithecine and others believing it is a species of Homo. Some paleoanthropologists have raised the possibility that KNM-ER 1813 is the female counterpart to the Homo rudolfensis KNM-ER 1470. While dated to the same time period and sharing some characteristics, KNM-ER 1813 has a much smaller face, brain and teeth than 1470. Other paleoanthropologists argue that its brain size of 510 cc (in contrast to 1470's 750 cc) indicates a size difference too great to be due to sexual dimorphism and represents a separate species. It's also not the case that this specimen is simply an immature version of H. rudolfensis, as the third molar appears to have been worn down. Instead, it has been suggested that it belongs in a category of Homo habilis, with which it shares similarities in tooth size and shape, cranium size, and face shape. It is found with tools that have been made from stones so this species is known as “Handy Man”.Homo rudolfensis1.8 to 1.9 MYA. The Homo rudolfensis Skull KNM-ER 1470 was discovered by B. Ngeneo in 1972 at Koobi Fora in Kenya and described by R. Leakey in Nature in 1973. The classification of this specimen has been a matter of debate since its discovery, with some scientists arguing in favor of Australopithecus, and some in favor of a species of Homo. Originally dated (incorrectly) a million years before habilis, the most current theory holds that though contemporaneous and geographically concurrent with habilis, this specimen is in fact a different species of Homo. 1470 features a 750 cc braincase, too large for australopithecines, and perhaps even for habilis, and lacks the crests and heavy muscle markings that characterize australopithecine skulls, as well as lacking the brow ridges associated with Homo erectus. Several features differ from other habilis specimens (a longer face, squared upper jaw and short, shallow palate), leading some scientists to conclude that there is too great a range of characteristics within the specimens for them to be a single species. In 1986 Valerii Alexeev proposed another species within Homo, giving 1470 the scientific name Homo rudolfensis.Paranthropus boisei male (OH 5)1.8 MYA. The Paranthropus boisei Skull, “Nutcracker Man”, is the most famous fossil from Olduvai Gorge, Tanzania. OH 5 was discovered by Mary Leakey in 1959 and originally classified as Zinjanthropus boisei by L. Leakey in Nature later that year. The accepted genus name has since changed to Australopithecus. This discovery spurred paleoanthropology toward a modern, multidisciplinary approach, and focused paleoanthropologists' attention on East Africa. Unique in hominid evolution, A. boisei's massive skull features a wide, concave face, enormous, flat molars (about 4 times as big as modern H. sapiens) and cranial adaptations for powerful chewing, hence its nickname, Nutcracker Man. Note the sagittal crest and extremely large area for muscle attachments on the zygomatic arch. The thick jaw allowed for the species' exceptional chewing capabilities. Cranial capacity of this individual is 530 cc.Homo habilis1.8 MYA. The Homo habilis Skull OH 24 (KNM) was discovered by P. Nzube in 1968 and first described by M. Leakey, Clark, & L. Leakey in Nature in 1971. This nearly complete but very badly crushed specimen constituted the oldest hominid found in Olduvai Gorge, Tanzania, and supported the designation of the then controversial species of Homo habilis. Originally, some scientists had resisted classification of Homo habilis as a new species, preferring instead to separate specimens into either A. africanus or H. erectus. Though OH 24 features characteristics of both species, there are marked differences. Its estimated cranial capacity of 600 cc is the minimum for classification as Homo, but the difficulties of reconstruction may have contributed to the smallish estimation. The species possessed a larger brain than A. africanus or A. boisei, though smaller than Homo erectus from Java and China. The cranial bones are thinner than typical for australopithecines, and the braincase is wider and shorter. The width of the face approaches A. boisei in breadth, but is not similarly flat. The facial profile of H. habilis slopes forward but projects less than in A. africanus. Some scientists believe that the range of variation of specimens once attributed to Homo habilis is too great to represent a single species; consequently, more than one species of early Homo may have lived at the same time in East Africa.Homo ergaster/erectus1.75 -2.0 MYA. The Dmanisi Homo erectus (ergaster) was discovered in 1999 by Abesalom Vekua, et al. in Dmanisi, Georgia. The cast comprises the D2700 cranium and D2735 jaw. This small-brained specimen, found alongside Oldowan-like choppers and scrapers, undercuts the theory that hominids did not leave Africa until about one million years ago and only after becoming large-brained bipeds with well-developed tool-making abilities. The small capacity of the cranium D2700 (600 cc) is similar to that of the African H. habilis specimens. Despite their small cranial capacity, characteristics of the crania and mandibles show greater similarity to early African H. erectus/ergaster than to H. habilis. The skull is small and rounded at the back.

Homo ergaster1.75 MYA. Female The Homo ergaster Skull KNM-ER 3733 with dentition was discovered by B. Ngeneo in 1975 in Koobi Fora, Kenya, and described by R. Leakey in Nature in 1976. Several teeth are intact, but no mandible was ever found. Of great significance is the fact that this skull was found in the same sediment layer that A. boisei KNM-ER 406 had been six years earlier, adding to the evidence against the single species hypothesis, the notion that only one hominid species existed at any time in history. Also known as Homo erectus, KNM-ER 3733 is said to be very similar in appearance to the H. erectus finds of Peking, China, including a cranial capacity of 850 cc, keeling of the cranium and the presence of an occipital torus. Due to its features (including wear on teeth and closure of cranial sutures) and compared to KNW-WT 15000, this specimen is considered to be a mature female.

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Paranthropus boisei male (KNM-ER 406 BH006)1.7 MYA. Male. The Paranthropus boisei Skull KNM-ER 406 was discovered by R. Leakey at Koobi Fora, Kenya, in 1969. This discovery helped to shed light on the controversial hypothesis that all australopithecines were of the same species, and tended to support the classification of boisei as a separate species of Australopithecus. A comparison of KNM-ER 406 and KNM-ER 732 revealed that australopithecines were sexually dimorphic. Some of the features possessed by this skull are sagittal and nuchal crests (missing in KNM-ER 732), massive cheek teeth, and widely flaring cheekbones, giving the face a dish shape. An interesting feature of this specimen is a little hole on the frontal bone, which may be rare evidence in early hominids of bone disease. The cranium is virtually complete and has a capacity of 510 cc.Paranthropus boisei female1.7 MYA. Female. The Paranthropus boisei Skull KNM ER 732 was discovered in 1970 at Koobi Fora, Kenya by R. Leakey and H. Mutua and described in Nature in 1971. A comparative analysis of KNM ER 732 and KNM ER 406 revealed a host of similarities with the only differences (e.g., smaller size, lack of sagittal and nuchal crests in KNM ER 732) being typical of the sexual dimorphism found in great ape skulls. Consequently, KNM ER 732 is considered to be a female and KNM ER 406 a male of the species, Paranthropus boisei. Using the sexual dimorphism found in this pair as a guide, researchers suggested that P. robustus and A. africanus, which had been hypothesized by some to be male and female specimens of the same species, were, in fact, far more different than one would expect from simple sexual dimorphism. They proposed instead that P. robustus and A. africanus were separate species.Homo ergaster1.6 MYA. Male. The Homo ergaster Skull KNM-WT 15000 "Nariokotome Boy" or "Turkana Boy" was discovered by K. Kimeu in 1984 in Nariokotome, Kenya. It was first described by Brown, Harris, R. Leakey and Walker in Nature in 1985 as H. erectus. The completeness of this skull allowed scientists to get accurate measurements of brain size. Many other skeletal parts were also recovered, giving anthropologists a great deal of information regarding body size, limb proportions, age of death (probably 12 or 13 years) and whether or not language was possible. The pelvis reveals a greater ability to run than modern humans, and some reveal a closer affinity to australopithecines.

Homo erectus240,000 to 500,000 YA. The Homo erectus Skull Peking Man is also known as Pithecanthropus pekinensis (Sinathropus). The original reconstruction was prepared by Dr. F. Weidenreich and Mrs. Lucille Swan in 1937 from the fossil remains of several different individuals found in the caves at Zhoukoudian, China. The skull is somewhat unique in that a rare metopic suture is present along the mid-line of the frontal bone. The re-creation offered here is based on a more recent reconstruction by Sawyer and Tattersall of the American Museum of Natural History. In Sawyer's and Tattersall's reconstruction, the jaw is more massive based on males, while the original was based on females. Cranial capacity averages about 1050 cc. The skull has a large brow ridge and a ridge of bone on the back of the skull.Homo heidelbergensis Bodo600,000 YA. This Homo heidelbergensis skull was discovered by Asfaw, Whitehead and Wood in 1976 in Bodo D'ar, Ethiopia. The designation of Homo heidelbergensis as a separate species is not without controversy. Its estimated age places it as a contemporary of Homo erectus; however, its combination of features positions it as a transitional fossil. With Homo erectus it shares a broad massive face (its face is the largest among all fossil hominids) and heavy browridge. The more modern features that it exhibits include a brain capacity (estimated at 1250 cc) that falls within the range of Homo sapiens, the shape of the nasal bones, and a browridge that, while heavy, is composed of separate supraorbital tori, Acheulean hand axes and cleavers, along with animal bones, were found at the site, suggesting that Bodo butchered animals. Interestingly, the Bodo cranium has cut marks on it indicating that stone tools were used to take the flesh off the skull shortly after the death of this individual.Homo sapiens idaltu BOU-VP-16/1 Herto Skull160,000 YA. BOU-VP-16/1 was discovered in Herto, Middle Awash, Ethiopia, by the United States and Ethiopian team including Tim White in 1997. The Herto skull is a large, nearly complete, slightly distorted adult cranium with an estimated brain capacity of 1450 cc. Its features include a high cranial vault, projecting mastoids and a notably angular occipital. The discoverers attribute it to a new subspecies, idaltu ('elder') because of its differences from modern humans: greater cranial capacity, differences in palate breadth, mastoid height and occipital angle. But it does have features associated with modern humans, even though it predates the Neanderthals. So, some argue that Herto lends support to the "Out of Africa" hypothesis. It suggests, they argue, that that modern Homo sapiens arose from Africa and that this early Homo sapiens replaced such groups as Neanderthals rather than being their direct ancestors.

Homo heidelbergensis125,000 to possibly 400,000 YA. The Homo heidelbergensis Skull Broken Hill 1 (Rhodesian Man) was discovered in Kabwe, Zambia (formerly Rhodesia), by miner T. Zwigelaar and originally described by A. Woodward in 1921 in Nature as Rhodesian Man (H. rhodesiensis). This is the first human ancestor to be found in Africa. Once considered to be only 40,000 years old, which would make it a contemporary of Homo sapiens in Europe, the skull was pointed to by some as evidence of the "primitiveness" of Africans. Subsequent evidence led to the more correct dating of at least 125,000 YA. The skull shares features of both Homo erectus (heavy browridge) and Homo sapiens (flatter face, large brain (1300 cc).

Homo sapiens Skhul 5 BH-032100,000 YA. The Homo sapiens Skull Skhul 5 was discovered by T. McCown near Mount Carmel, Israel in 1932. The remains of 10 individuals were excavated from Skhul cave in 1932.. The Skhul skulls show much variation in the expression of modern traits. With a cranial capacity of 1520 cc, features common to modern skulls are the high forehead, expanded frontal portion of the braincase, and rounded back of the skull. Differences from modern skulls include its more pronounced brow ridges, and prognathic lower face. Skhul 5 has been suggested as providing evidence of hybridization between humans and Neanderthals. Current evidence, indicates that Neanderthals and early modern Homo sapiens alternately occupied the Near East during cold and warm periods, respectively, for thousands of years.

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Homo neanderthalensis 70,000 YA. The Homo neanderthalensis (Child) Skull Teshik-Tash was discovered by A. Okladnikov in Uzbekistan in 1938. This skull helped establish the easternmost range of Neanderthals. It has been suggested that this skeleton was buried in a ritual fashion. With an estimated age of 9 years, this young boy had matured enough physically to exhibit distinctive Neanderthal characteristics, such as a large face and nasal area, a long, low cranium, a mandible without a chin, and a maturing browridge.

Homo neanderthalensis45,000 – 70,000 YA. The Homo neanderthalensis female skull was discovered in 1848 at Forbes' Quarry in Gibraltar. Interestingly, the discovery of this female skull occurred eight years before skeletal elements were found in the Neander Valley, Germany, the study of which is said to mark the beginning of paleoanthropology (and which predates Darwin's On the Origin of Species). It was this later find in Neander Valley that provided the fossil that serves as the type specimen for Homo neanderthalensis. The significance of the Gibraltar fossil went unrealized for years. Finally, a zoologist named George Busk, who had translated into English the description of the Neander Valley discoveries, was sent the Gibraltar Skull in 1861. He recognized its similarities to the Neandertal, including the projecting face and expanded maxillary sinuses. Neandertals are thought to have lived between 200,000 and 30,000 years ago.

Homo neanderthalensis50,000 YA. The Homo neanderthalensis Skull was discovered by A. and J. Bouyssomie and J. Bonneval in 1908 in La Chapelle-aux-Saints, France. It was the most complete Neandertal skull found at the time. Called the "old man," this individual clearly lived a long time, having much pathology, such as the declined tooth sockets in the molar region and severe arthritis in the neck. Despite his very large brain capacity (over 1,600 cc), early descriptions by Boule declared him to be primitive, leading to the term "Neanderthal" to be synonymous with brutality for decades. More recently, however, many consider Neandertal to have been a highly successful and social species with many of its physical features, such as low cranial vault and project face, due to adaptations to cold weather. This cranium is representative of many fossil remains of Neandertals found throughout present-day Europe

Homo floresiensis18,000 YA. The Homo floresiensis Skull (Flores Skull LB1) was discovered by P. Brown and his team on the island of Flores, Indonesia, in 2003 and reported in Nature in 2004. A skeleton of this species, which has been designated as female because of characteristics of the pelvis, shows that in maturity she was only about 3.3 feet tall. That such a specimen (which had an unusually small brain capacity -- 380 cc -- for its body size) was in existence only 18,000 YA could be one of the most important discoveries in decades. Stone tools were also found at this site. H. floresiensis is the subject of much debate centering around whether it is a new human species or a microcephalic human. P. Brown et al. originally proposed that the Flores hominid was the result of a long term process of isolation on an island known as "insular dwarfism.

Homo sapiens (Cro-Magnon) 10,000-30,000 YA. This Cro-Magnon Skull was discovered in 1998 in the Rhine River deposits in Southwest Germany near Mainz. Since it was dredged from a gravel pit, the stratum can only be assumed. However, the association with Mammuthus, Megaceros and Equis, as well as the state of mineralization, suggests an age of at least 10,000 to 30,000 years. It also matches the description of other Cro-Magnon type hominid fossils from the area.

Homo sapiens (“modern”)160,000 YA-present. Oldest fossils of modern humans have been found in the Middle Awash (Herto people) and Omo regions of Ethiopia.

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