Hominid cranium from Omo: Description and taxonomy of Omo-323-1976-896

Omo-323-1976-896, a partial hominid cranium dated to ca. 2.1 from the Member G, Unit G-8 of the Shungura Formation, lower Omo Basin of Ethiopia, is described. It is suggested that the specimen is an adult male based on the well-developed and completely fused sagittal crest; heavily worn teeth; relatively large canine; and size of the articular eminence. Omo-323 consists of fragments of the frontal, both temporals, occipital, parietals, and the right maxilla, and is attributed to Australopithecus boisei, making it the oldest known cranium of this species. The specimen shares features with Australopithecus aethiopicus (KNM-WT 17000), thus supporting the existence of an evolving East African robust lineage between ca. 2.6-1.2 Ma. The morphology of Omo-323 increases our knowledge of the intraspecific variability of A.boisei.     

The sixth skull cap of Pithecanthropus erectus

The sixth skull cap of Pithecanthropus erectus (or skull V, since the Modjokerto skull has not been given a number) was found in the upper layers of the Trinil beds of Sangiran (Central Java) in 1963, associated with fossils of the Sino-Malayan fauna. No stone tools were discovered in direct association with the find. The specimen consists of the occipital, both parietals, both temporals, sphenoid fragments, the frontal and the left zygomatic bone. We consider the skull to be a male in his early twenties. The occipital, parietal, frontal and temporal bones demonstrate definite pithecanthropine characteristics, and the cranial capacity is estimated to be 975 cm³. Of the superstructures, the supraorbital torus is extraodinarily thick, approaching the condition in Australopithecus boisei and Rhodesian man. And the sagittal torus is certainly higher than in skulls I and II, but lower than in skull IV. In addition, the angle between the occipital and nuchal planes is larger than in the previous finds. As revealed by various features, the gap between the robustness of skull IV on one hand, and skulls I, II and III on the other, is bridged by the present find. There is no reasonable taxonomic need to ascribe this specimen to a new species, because it seems to be merely an intrapopulational variant of the same species. Other skulls of P. erectus suggest that the bregmatic eminence, and hence the vertex, is invariably situated at bregma, but this new skull cap deviates from the pattern. Its pteric regions disclose the anthropoid X and I types. The middle meningeal groove pattern is similar to other Pithecanthropus skulls; however, it betrays a known anomaly in that the main stem is covered for a short distance by a bony plate. The mastoid process is fairly well developed, and is also well pneumatized as in P. pekinensis, with its air cells invading the pronounced supramastoid crest. The zygomatic bone, the first one recovered of P. erectus, does not show characters of particular importance. In fact, its thickness is in the range of modern man. We would like to stress that the absence of the cranial base does not necessarily indicate that the specimen must be a poor victim of cannibalism, since the morphology of the base renders it more susceptible to post-mortem natural traumata.     

The Belohdelie frontal: new evidence of early hominid cranial morphology from the Afar of Ethiopia

Study of the Belohdelie frontal has demonstrated that this four-million-year-old specimen belongs to a very generalized hominid that may be close to the divergence point of the hominid and African ape clades. Features associated with the temporalis muscle in the Belohdelie frontal and other new hominids from Hadar (AL 333-125) and West Turkana (KNM-ER 17000) suggest that the earliest hominids shared a large anterior component of this muscle relative to the extinct and extant apes. Results of this study support the phylogenetic hypothesis put forward by many workers that A. afarensis gave rise to the “robust” Australopithecus and A. africanus clades.     

南京1号直立人头骨与肯尼亚KNM-ER 3733人类头骨化石的形态比较

KNM-ER 3733人类头骨化石的年代为距今1.78百万年,1975年发现于肯尼亚。Walker和Leakey注意到这具头骨与周口店直立人的在脑颅形态上很相近,但二者在年代上相差大约1百万年,故认为直立人形态在这1百万年期间是稳定的。长期来此观点缺乏更多的人类化石证据来支持。1993年在中国发现了南京1号人类头骨化石。该头骨与KNM-ER 3733头骨一样兼具脑颅和面颅,且都属于成年女性个体,但南京1号人类头骨化石的年代比KNM-ER 3733人类头骨化石的要晚大约1百万年。因此,南京1号人类头骨是目前所知的可用来验证直立人头骨形态是否在1百万年期间保持稳定的唯一合适的人类头骨化石材料。形态比较表明,这两个人类头骨化石的脑颅虽然在眶上圆枕上沟的发育程度、眶后收缩的程度、额骨横向隆起的程度、角圆枕和乳后突的发育与否、顶骨形状以及骨壁厚度的表现上有所差异,但有更多的形态性状显示出相近。这些相近表现在脑颅的长、宽、高值上;颅容量上;脑颅的低矮性上;脑颅最大宽之位置上;额骨、顶骨、枕骨之矢弧值的比例上;眶上圆枕的纤细上;顶骨的大小和矢向扁平性上;颞线位置和颞鳞顶缘的形状上;枕鳞的低宽形状上;上枕鳞与下枕鳞之间的转折形状和比例上;枕骨圆枕和枕骨圆枕上沟的发育程度上等。这两具头骨的面颅虽然有同属突颌型的面角、皆发育有鼻骨间嵴、两鼻骨组成的上部宽度与下部宽度皆差别很大,但有更多的形态性状显示出差别。这些差别表现在面型上、颜面上部扁平度上、眶形和眶型上、上颌额突外侧面的朝向上、鼻骨横向隆起程度上、鼻梁外突程度上、鼻型上、颧骨下缘外展程度上、颊高上、颧上颌下缘的形状上、上颌颧突基部的位置上以及颧结节的位置上等。因此,南京1号头骨与KNM-ER 3733头骨之间在脑颅上显示出较多的相近性状,在面颅上则显示出较多的相异性状。脑颅方面的相近性状大多具有分类上的鉴别价值。这两个头骨脑颅形态的相近支持把KNM-ER 3733头骨鉴定为"直立人"的观点;也提示了南京1号头骨的脑颅似乎保持着1百多万年前的"祖先"形态。如果直立人的某些成员在至少1百万年期间保持着形态稳定的话,则这种形态上的稳定主要是表现在脑颅形态上。这两具头骨的面颅形态上较大差异的意义,目前尚不清楚。     

Variation among early Homo crania from Olduvai Gorge and the Koobi Fora region

Fossils recognized as early Homo were discovered first at Olduvai Gorge in 1959 and 1960. Teeth, skull parts and hand bones representing three individuals were found in Bed I, and more material followed from Bed I and lower Bed II. By 1964, L.S.B. Leakey, P.V. Tobias, and J.R. Napier were ready to name Homo habilis. But almost as soon as they had, there was confusion over the hypodigm of the new species. Tobias himself suggested that OH 13 resembles Homo erectus from Java, and he noted that OH 16 has teeth as large as those of Australopithecus. By the early 1970s, however, Tobias had put these thoughts behind him and returned to the opinion that all of the Olduvai remains are Homo habilis. At about this time, important discoveries began to flow from the Koobi Fora region in Kenya. To most observers, crania such as KNM-ER 1470 confirmed the presence of Homo in East Africa at an early date. Some of the other specimens were problematical. A.C. Walker and R.E. Leakey raised the possibility that larger skulls including KNM-ER 1470 differ significantly from smaller-brained, small-toothed individuals such as KNM-ER 1813. Other workers emphasized that there are differences of shape as well as size among the hominids from Koobi Fora. There is now substantial support for the view that in the Turkana and perhaps also in the Olduvai assemblages, there is more variation than would be expected among male and female conspecifics. One way to approach this question of sorting would be to compare all of the new fossils against the original material from Olduvai which was used to characterize Homo habilis in 1964. A problem is that the Olduvai remains are fragmentary, and none of them provides much information about vault form or facial structure. An alternative is to work first with the better crania, even if these are from other sites. I have elected to treat KNM-ER 1470 and KNM-ER 1813 as key individuals. Comparisons are based on discrete anatomy and measurements. Metric results are displayed with ratio diagrams, by which similarity in proportions for several skulls can be assessed in respect to a single specimen selected as a standard. Crania from Olduvai examined in this way are generally smaller than KNM-ER 1470, although OH 7 has a relatively long parietal. In the Koobi Fora assemblage, there is variation in brow thickness, frontal flattening and parietal shape relative to KNM-ER 1470. These comparisons are instructive, but vault proportions do not help much with the sorting process. Contrasts in the face are much more striking. Measurements treated in ratio diagrams show that both KNM-ER 1813 and OH 24 have relatively short faces with low cheek bones, small orbits and low nasal openings. Also, they display more projection of the midfacial region, just below the nose. This is not readily interpreted to be a female characteristic, since in most hominoid primates the females tend to have flatter lower faces than the males. The obvious size differences among these individuals have usually been interpreted as sex dimorphism, but, in fact, two taxa may be sampled at Olduvai and in the Turkana basin at the beginning of the Pleistocene. One large-brained group made up of KNM-ER 1470, several other Koobi Fora specimens, and probably OH 7, can be called Homo habilis. If these skulls go with femora such as KNM-ER 1481 and the KNM-ER3228 hip, then this species is close in postcranial anatomy to Homo erectus. The other taxon, including small-brained individuals such as KNM-ER 1813 and probably OH 13, seems also to be Homo rather than Australopithecus. If the OH 62 skeleton is part of this assemblage, then the small hominids have postcranial proportions unlike those of Homo erectus. However, it is too early to point unequivocally to one or the other of these groups as the ancestors of later humans. Both differ from Homo erectus in important ways, and both need to be better understood before we can map the earliest history of the Homo clade. © 1993 Wiley-Liss, Inc.     

Appearance of hyperostosis frontalis interna in some osteoarcheological series from Hungary

Hyperostosis frontalis interna (HFI) is a generalised pathological condition with an unknown etiology and variable clinical association. It is characterized by excess bone growth and manifested on the inner table of the frontal bone, occasionally extending onto the temporals, parietals and the occipital.The etiology of HFI is uncertain: it may be an unknown genetic predisposition, a common environmental exposure, or special metabolic diseases.The purpose of the present study is to report cases of HFI in some osteoarcheological series from Hungary and to emphasize the importance of the investigation of HFI in ancient populations.Twenty out of 803 adults with observable frontal bones exhibited HFI, ranging from early to mid-type, including 15 females and 5 males. Some overgrowths with edges were blending into the endocranial surface, and some were prominently protruding from the surface. Advanced cases of HFI (type C) were observed after age 40-60 years.     

Where are inion and endinion? Variations of the exo- and endocranial morphology of the occipital bone during hominin evolution

The occipital bone is frequently investigated in paleoanthropological studies because it has several features that help to differentiate various fossil hominin species. Among these features is the separation between inion and endinion, which has been proposed to be an autapomorphic trait in (Asian) Homo erectus. Methodologies are developed here to quantify for the first time the location of these anatomical points, and to interpret their variation due to the complex interactions between exocranial and endocranial size and shape of the occipital and nuchal planes, as well as the occipital lobes and cerebellum. On the basis of our analysis, neither ‘the separation between inion and endinion’ nor ‘endinion below inion’ can be considered as an autapomorphic trait in H. erectus, since this feature is a condition shared by extant African great apes and fossil hominins. Moreover, our results show that the exo- and endocranial anatomy of the occipital bone differs between hominins (except Paranthropus boisei specimens and KNM-ER 1805) and great apes. For example, chimpanzees and bonobos are characterized by a very high position of inion and their occipital bone shows an antero-posterior compression. However, these features are partly correlated with their small size when compared with hominins. Asian H. erectus specimens have a thick occipital torus, but do not differ from other robust specimens, neither in this feature nor in the analysed exo- and endocranial proportions of the occipital bone. Finally, the apparent brain size reduction during the Late Pleistocene and variation between the sexes in anatomically modern humans (AMH) reflect that specimens with smaller brains have a relatively larger posterior height of the cerebellum. However, this trend is not the sole explanation for the ‘vertical shift’ of endinion above inion that appears occasionally and exclusively in AMH.     

A Homo habilis maxilla and other newly-discovered hominid fossils from Olduvai Gorge, Tanzania

In 1995, a 1.8 million year old hominid maxilla with complete dentition (OH 65) was excavated from Bed I in the western part of Olduvai Gorge. The molar crowns are small relative to the long flaring roots, and the root of the canine is very long and straight. The broad maxilla with wide U-shaped palate and the form of the tooth roots closely match those of KNM-ER 1470 which, in its parietal size and morphology, matches the type specimen of Homo habilis, OH 7. Thus, OH 65 and KNM-ER 1470 group with OH 7 as representatives of H. habilis while some other Olduvai specimens, such as OH 13 and OH 24, have more in common in terms of morphology and brain size with Australopithecus africanus. Between 1995 and 2007, the OLAPP team has recovered teeth of eight other hominid individuals from various parts of Olduvai Gorge. These have been identified as belonging to H. habilis, Paranthropus boisei, and Australopithecus cf. africanus.     

Brain expansion and rotation during hominid evolution

The question of how an endocast (or brain) is oriented within a skull that is positioned in the Frankfurt plane is investigated for African great apes, early hominids STS 71, KNM-ER 1813 and KNM-ER 1470, and modern humans using a 3SPACE digitizer. Our results suggest that, rather than being positioned in the orientation in which isolated brains (endocasts) are conventionally illustrated, brains within skulls that are oriented in the Frankfurt plane tend to be inclined so that the frontal pole is higher than the occipital pole, especially inHomo. These preliminary findings have implications for interpreting early hominid endocasts such as that of AL 162-28.     

A new species of the genusAustralopithecus (primates: hominidae) from Plio/Pleistocene deposits west of Lake Turkana in Kenya

The cranium of a robust australopithecine, KNM WT 17000, was discovered from the Plio/Pleistocene deposits west of Lake Turkana in Kenya, and assigned to the speciesAustralopithecus boisei Leakey, 1959. A comparative morphological study shows that it does not conform with the diagnosis forA. boisei. It is characterized by having a much smaller brain, a low hyperprognathous facial skeleton, and a less developed masticatory apparatus. Its unique morphological pattern justifies its placement in a new taxon which is calledAustralopithecus walkeri n. sp.     

Taxonomic affinity of the early Homo cranium from Swartkrans,South Africa

A quantitative analysis that employs randomization methods and distance statistics has been undertaken in an attempt to clarify the taxonomic affinities of the partial Homo cranium (SK 847) from Member 1 of the Swartkrans Formation. Although SK 847 has been argued to represent early H. erectus, exact randomization tests reveal that the magnitude of differences between it and two crania that have been attributed to that taxon (KNM-ER 3733 and KNM-WT 15000) is highly unlikely to be encountered in a modern human sample drawn from eastern and southern Africa. Some of the variables that differentiate SK 847 from the two early H. erectus crania (e. g., nasal breadth, frontal breadth, mastoid process size) have been considered to be relevant characters in the definition of that taxon. Just as the significant differences between SK 847 and the two early H. erectus crania make attribution of the Swartkrans specimen to that taxon unlikely, the linkage of SK 847 to KNM-ER 1813, and especially Stw 53, suggests that the Swartkrans cranium may have its closest affinity with H. habilis sensu lato. Differences from KNM-ER 1813, however, hint that the South African fossils may represent a species of early Homo that has not been sampled in the Plio-Pleistocene of eastern Africa. The similarity of SK 847 and Stw 53 may support faunal evidence which suggests that Sterkfontein Member 5 and Swartkrans Member 1 are of similar geochronological age. © 1993 Wiley-Liss, Inc.     

A newHomo erectus cranium from Sangiran, Java

A newHomo erectus cranium was found on May 18, 1993 by Budi, a local farmer, at Sangiran. It dates from the Middle Pucangan Formation approximately 1.6–1.8 mya. The braincase is essentially complete and as is most of the face. The vault has the typicalH. erectus gable shape. There is a clear sagittal ridge beginning below the middle of the frontal squama and running to mid-parietal. Parasagittal ridges are rounded angulations halfway up the parietals, and coincide with poorly marked temporal lines. In all measurements, this skull is longer and consistently narrower than Trinil. It is chronologically and morphologically similar to the famousH. erectus skull from east Africa, KNMER-3733. Although existing much older, this new specimen is what one would expect a female counterpart to Sangiran 17 to look like.     

Cranium of a juvenile Australopithecus boisei from the lower Omo Basin,Ethiopia

A partial cranium of a juvenile Australopithecus boisei, recovered from the Shungura Formation in the lower Omo basin, southern Ethiopia, and dated at 2.1 m.y. B.P. , is described anatomically and compared to young and adult australopithecines, modern Homo sapiens, chimpanzees, and gorillas. A resemblance to the gracile Australopithecus is observed but is attributed mainly to the generalized appearance of the Omo specimen resulting from its young individual age. An attempt is made to reconstruct part of the ontogenetic process of A. boisei. This process is compared to the developmental changes exhibited by the African great apes and modern man and is found to combine characteristics of both.     

Brief communication: Possible third molar impactions in the hominid fossil record

Impacted third molars affect 15%–20% of modern Americans and Western Europeans. In contrast, third molar impactions have not been reported in the early hominid fossil record. It is uncertain whether the lack of reports reflects an absence of impactions or a failure to recognize them. This communication is intended to raise awareness of the possibility of impactions by describing the appearance of impacted teeth and by noting two possible instances of impaction in early hominids. Specifically, the mandibular third molars of the Sterkfontein specimen, STS52b (Australopithecus africanus), and the left maxillary third molar of the Lake Turkana specimen, KNM-WT17400 (Australopithecus boisei), are positioned in a manner which suggests that they would not have erupted normally. Both specimens also exhibit strong crowding of the anterior dentition, providing further support for the view that these individuals lacked sufficient space for normal eruption of the third molars. Other published reports of dental crowding in the hominid fossil record are noted, and it is suggested that more attention be paid to dental impaction and dental crowding in hominid evolution. © 1993 Wiley-Liss, Inc.     

Improved age control on early Homo fossils from the upper Burgi Member at Koobi Fora,Kenya

To address questions regarding the evolutionary origin, radiation and dispersal of the genus Homo, it is crucial to be able to place the occurrence of hominin fossils in a high-resolution chronological framework. The period around 2 Ma (millions of years ago) in eastern Africa is of particular interest as it is at this time that a more substantial fossil record of the genus Homo is first found. Here we combine magnetostratigraphy and strontium (Sr) isotope stratigraphy to improve age control on hominin-bearing upper Burgi (UBU) deposits in Areas 105 and 131 on the Karari Ridge in the eastern Turkana Basin (Kenya). We identify the base of the Olduvai subchron (bC2n) plus a short isolated interval of consistently normal polarity that we interpret to be the Pre-Olduvai event. Combined with precession-forced (∼20 kyr [thousands of years]) wet–dry climate cycles resolved by Sr isotope ratios, the magnetostratigraphic data allow us to construct an age model for the UBU deposits. We provide detailed age constraints for 15 hominin fossils from Area 131, showing that key specimens such as cranium KNM-ER 1470, partial face KNM-ER 62000 and mandibles KNM-ER 1482, KNM-ER 1801, and KNM-ER 1802 can be constrained between 1.945 ± 0.004 and 2.058 ± 0.034 Ma, and thus older than previously estimated. The new ages are consistent with a temporal overlap of two species of early Homo that can be distinguished by their facial morphology. Further, our results show that in this time interval, hominins occurred throughout the wet–dry climate cycles, supporting the hypothesis that the lacustrine Turkana Basin was a refugium during regionally dry periods. By establishing the observed first appearance datum of a marine-derived stingray in UBU deposits at 2.058 ± 0.034 Ma, we show that at this time the Turkana Basin was hydrographically connected to the Indian Ocean, facilitating dispersal of fauna between these areas. From a biogeographical perspective, we propose that the Indian Ocean coastal strip should be considered as a possible source area for one or more of the multiple Homo species in the Turkana Basin from over 2 Ma onwards.     

Evolutionary Relationships Among Robust and Gracile Australopiths: An “Evo-devo” Perspective

Hominin fossils of gracile and robust australopith groups were found both in East and in South Africa. It is unclear, however, whether all robusts belong to a monophyletic Paranthropus clade, as the craniofacial resemblance among robust australopiths might only be a superficial correlate of similar masticatory adaptations and not evidence of shared ancestry. It has been suggested that the East African Australopithecus/Paranthropus boisei and the South African A./P. robustus might be convergent allometric variants of their gracile geographical neighbors A. afarensis and A. africanus. Here we approach the phylogenetic questions about robust and gracile australopiths from an ??evo-devo?? perspective, examining how simple alterations of development could contribute to the shape differences among hominin species. Using geometric morphometrics we compare gracile and robust australopith crania in the context of the allometric scaling patterns of Pan troglodytes, P. paniscus, and Gorilla gorilla. We examine support for two alternative evolutionary scenarios based on predictions derived from quantitative genetics models: either (1) A./P. robustus evolved in South Africa from the gracile A. africanus, or (2) A./P. robustus is a local variant of the eastern African A./P. boisei. We use developmental simulations to demonstrate that some robust characteristics (wide faces, anteriorly placed zygomatics, and facial dishing) can be predicted by allometric scaling along the ontogenetic trajectory of the gracile A. africanus. We find, however, that the facial differences between A. africanus specimens (Taung, Sts 5, Sts 71, and Stw 505) and A./P. robustus specimen SK 48 cannot be explained by allometric scaling alone. Facial shape differences between A./P. robustus SK 48 and A./P. boisei (KNM-ER 732, KNM-ER 406, OH 5) and the A./P. aethiopicus specimen KNM-WT 17000, on the other hand, can largely be explained by allometric scaling. This is consistent with a close evolutionary relationship of these robust taxa.     

Nouvelles découvertes de dents d’hominidés dans le membre Kaitio de la formation de Nachukui (1,65–1,9 Ma), Ouest du lac Turkana (Kenya)

New hominid teeth from the Kaitio member (1.65–1.9 Myr) in West Turkana (Kenya). New hominid teeth have been recovered from the archaeological sites of Kokiselei 1 and Naiyena Engol 1. These two sites are located in the west side of the Turkana Basin and belong to the Kaitio member of the Nachukui Formation. They are dated between 1.65-1.79 and 1.7-1.8 Myr respectively. The four teeth (left maxillary canine and first molar, right maxillary third molar and left mandibular third molar) discovered in Kokiselei 1 are attributed to Australopithecus boisei. The right mandibular first premolar found in Naiyena Engol 1 is referred to Homo sp. aff. ergaster. To cite this article: S. Prat et al., C. R. Palevol 2 (2003).     

A new skeleton of Theropithecus brumpti (Primates: Cercopithecidae) from Lomekwi, West Turkana, Kenya

A relatively complete skeleton of the fossil papionin, Theropithecus brumpti, from the site of Lomekwi, west of Lake Turkana, Kenya, is here described. The specimen, KNM-WT 39368, was recovered at the site of LO 5 (3°51′N and 35°45′E), from sediments dated to approximately 3·3 Ma. The skeleton is that of an old adult male and preserves a number of articulated elements, including most of the forelimbs and tail. The cranial morphology is that of a large, early T. brumpti, exhibiting a deep mandible with a deeply excavated mandibular corpus fossa, and mandibular alveoli and cheek teeth arrayed in a reversed Curve of Spee. The forelimb skeleton exhibits a unique mixture of characteristics generally associated with a terrestrial locomotor habitus, such as a narrow scapula and a highly stable elbow joint, combined with those more representative of habitual arborealists, such as muscle attachments reflecting a large rotator cuff musculature and a flexible shoulder joint. The forelimb of KNM-WT 39368 also presents several features, unique toTheropithecus , which represent adaptations for manual grasping and fine manipulation. These features include a large, retroflexed medial humeral epicondyle (to which large pronator, and carpal and digital flexor muscles attached) and proportions of the digital rays that denote capabilities for precise opposition between the thumb and index finger. Taken together, these features indicate that one of the earliest recognized representatives of Theropithecus exhibited the food harvesting and processing anatomy that distinguished the genus through time and that contributed to its success throughout the later Pliocene and Pleistocene. Based on the anatomy of KNM-WT 39368 and the known habitat preference of T. brumpti, the species is reconstructed as being a generally terrestrial but highly dexterous, very large-bodied, sexually dimorphic, and possibly folivorous papionin. T. brumpti was adapted for propulsive quadrupedal locomotion over generally even ground, and yet was highly adept at manual foraging. The estimate of 43·8 kg body mass for KNM-WT 39368 renders unlikely the possibility that the species, or at least adult males of the species, were highly arboreal. T. brumpti, as represented by KNM-WT 39368, is seen as a large, colorfully decorated, and basically terrestrial papionin that was restricted to riverine forest habitats in the Lake Turkana Basin from the middle to latest Pliocene.     

The unusual cranial attributes of KNM-ER 1805 and their implication for studies of sexual dimorphism inHomo habilis

A principal components analysis (PCA) of basicranial measurements (Thompson 1991) isolated KNM-ER 1805 as having the highest Principal Component (PC) score on PCI of all the fossil hominids. Two measurements with high loadings on PCI were B12 and B13 and these two measurements indicate the relative positions of the foramina ovale (FO) and infratemporal crests (IT) to the tympanic bone (TP). The object of this study was to compare the two measurements of KNM-ER 1805 with those of other early fossil hominids as well as a sample of extant hominoids. The comparison involved the raw measurements, the index of the two measurements, the coefficient of variation, and a t-test. The results of this comparison showed that KNM-ER 1805 had more forwardly placed foramina ovale than any of the comparative specimens. KNM-ER 1805 possesses a number of other unique features which differentiate it from other hominids including a persistent metopic suture, the form of the premolar roots, and the form of the asterionic region. These apparent unique features mean that KNM-ER 1805 is unlikely to represent an “average” maleHomo habilis and so is an inappropriate model for the male morph of that species.