Proconsul Africanus Research Articles

Wrist morphology reveals substantial locomotor diversity among early catarrhines: an analysis of capitates from the early Miocene of Tinderet (Kenya)

Considerable taxonomic diversity has been recognised among early Miocene catarrhines (apes, Old World monkeys, and their extinct relatives). However, locomotor diversity within this group has eluded characterization, bolstering a narrative that nearly all early catarrhines shared a primitive locomotor repertoire resembling that of the well-described arboreal quadruped Ekembo heseloni. Here we describe and analyse seven catarrhine capitates from the Tinderet Miocene sequence of Kenya, dated to ~20 Ma. 3D morphometrics derived from these specimens and a sample of extant and fossil capitates are subjected to a series of multivariate comparisons, with results suggesting a variety of locomotor repertoires were present in this early Miocene setting. One of the fossil specimens is uniquely derived among early and middle Miocene capitates, representing the earliest known instance of great ape-like wrist morphology and supporting the presence of a behaviourally advanced ape at Songhor. We suggest Rangwapithecus as this catarrhine’s identity, and posit expression of derived, ape-like features as a criterion for distinguishing this taxon from Proconsul africanus. We also introduce a procedure for quantitative estimation of locomotor diversity and find the Tinderet sample to equal or exceed large extant catarrhine groups in this metric, demonstrating greater functional diversity among early catarrhines than previously recognised.

A systematic revision of Proconsul with the description of a new genus of early Miocene hominoid

For more than 80 years, Proconsul has held a pivotal position in interpretations of catarrhine evolution and hominoid diversification in East Africa. The majority of what we ‘know’ about Proconsul, however, derives from abundant younger fossils found at the Kisingiri localities on Rusinga and Mfangano Islands rather than from the smaller samples found at Koru—the locality of the type species, Proconsul africanus—and other Tinderet deposits. One outcome of this is seen in recent attempts to expand the genus “Ugandapithecus” (considered here a junior subjective synonym of Proconsul), wherein much of the Tinderet sample was referred to that genus based primarily on differentiating it from the Kisingiri specimens rather than from the type species, P. africanus. This and other recent taxonomic revisions to Proconsul prompted us to undertake a systematic review of dentognathic specimens attributed to this taxon. Results of our study underscore and extend the substantive distinction of Tinderet and Ugandan Proconsul (i.e., Proconsul sensu stricto) from the Kisingiri fossils, the latter recognized here as a new genus. Specimens of the new genus are readily distinguished from Proconsul sensu stricto by morphology preserved in the P. africanus holotype, but also in I1s, lower incisors, upper and lower canines, and especially mandibular characteristics. A number of these differences are more advanced among Kisingiri specimens in the direction of crown hominoids. Proconsul sensu stricto is characterized by a suite of unique features that strongly unite the included species as a clade. There have been decades of contentious debate over the phylogenetic placement of Proconsul (sensu lato), due in part to there being a mixture of primitive and more advanced morphology within the single genus. By recognizing two distinct clades that, in large part, segregate these character states, we believe that better phylogenetic resolution can be achieved.

Distinctiveness of <i>Ugandapithecus</i> from <i>Proconsul</i>

The decision to create the genus Ugandapithecus by Senut et al., 2000 has been criticised, either directly and in detail by MacLatchy & Rossie (2005b) who argued that it is a junior synonym of Proconsul , or indirectly without providing reasons, firstly by Harrison (2001) who wrote that he did not retain it as a genus distinct from Proconsul , and then by Suwa et al., (2007) who employed the name “Ugandapithecus” with inverted commas, implying some degree of doubt about its validity as a genus, but without providing details. More recently Harrison & Andrews (2009) have recognised the Meswa sample as a separate species but they argue that it should be maintained within Proconsul , despite the morphological differences that it has from other species of the genus. We here re-examine the question by comparing, on the one hand, the holotype maxilla of Proconsul africanus , the type species of the genus, with the upper dentition of Ugandapithecus major , and, on the other hand, the holotype mandible of Ugandapithecus major with the lower dentition and mandibles previously attributed to Proconsul africanus . We conclude that the differences between the known upper and lower dentitions of P. africanus and U. major are of such a degree that the two taxa warrant generic separation, and that the differences are not related to sexual dimorphism. Where Proconsul africanus differs from Ugandapithecus major , it approaches Proconsul nyanzae and Proconsul heseloni from Rusinga. Furthermore, the range of morphometric variation within the fossil samples previously attributed to Ugandapithecus major is so great that it far surpasses variation in any other hominoid, fossil or extant. Previously this great amount of variation was interpreted to mean that U. major was extremely dimorphic, with huge males and small females, but if this is true, then U. major would be unique among hominoids in having females in which the cheek teeth fall completely outside the range of variation of male cheek teeth. All other known male and female hominoid species possess cheek teeth whose ranges of variation overlap strongly. Bivariate plots of the teeth attributed to Ugandapithecus reveal three consistent non-overlapping clusters of points among the Early Miocene specimens, which we interpret to represent three distinct species. A fourth species of the genus, U. gitongai , was previously defined at the Middle Miocene site of Kipsaraman, Kenya. We conclude that Ugandapithecus was a lineage of great ape distinct from Proconsul , and its main evolutionary trend was an increase in dimensions from basal Early Miocene Ugandapithecus meswae (21.5-19 Ma) to late Early Miocene species Ugandapithecus legetetensis nov. sp. (20-19 Ma) and Ugandapithecus major (19-18 Ma), and culminating in late Middle Miocene Ugandapithecus gitongai (ca. 14.5 Ma).

New proconsuloid postcranials from the early Miocene of Kenya

New early Miocene forelimb fossils have been recovered from the Songhor and Lower Kapurtay localities in southwestern Kenya. We describe four specimens that are similar in size and functional capabilities. Their specific allocation is problematic but these forelimb specimens must belong to either Rangwapithecus gordoni or Proconsul africanus. If these new postcranial specimens should belong to R. gordoni, on the basis of size and common dental specimens found at Songhor, they represent a new elbow complex. The morphology of these fossils is anatomically and functionally similar to that of Proconsul. The proconsuloid elbow complex allows extensive forelimb rotations and is capable of performing arboreal quadrupedalism and climbing activities. No suspensory adaptations are apparent. The proconsuloid elbow complex remains a good ancestral condition for hominoid primates.

Dental variation ofProconsulfrom the Tinderet region, Kenya

Abstract The morphology of mandibular molars of the two Proconsul species, Proconsul major and Proconsul africanus , from the Tinderet region, Kenya was analyzed. While the molar size variability within the Tinderet P. major was slightly greater than those of local African ape subspecies, the shape variability was comparable. Because the two Proconsul species show some differences in cusp areal proportions, P. major is not just a larger P. africanus in molar morphology. Napak specimens are generally similar to the Tinderet P. major .

A new species of Proconsul from the early Miocene of Rusinga/Mfangano Islands, Kenya

The species Proconsul africanus from the early Miocene of East Africa has long been recognized from Koru (the type locality), Songhor, Rusinga Island and Mfangano Island. Comparison of the type series from Koru with specimens from Rusinga and Mfangano indicates that this material does not belong to a single species. The material from Koru and from Songhor belongs to a single species that takes the name P. africanus and which is not represented at Rusinga or Mfangano. The Rusinga and Mfangano material exhibits levels of metric variation in the teeth and postcranial skeleton that are incompatible with its recognition as one species. The larger species at Rusinga and Mfangano takes the name Proconsul nyanzae. The smaller species does not have a name available for it and is described here as a new species, Proconsul heseloni.

Kinematics of the trapezium-1st metacarpal joint in extant anthropoids and Miocene hominoids

In his many papers on the functional morphology of the primate hand John Napier paid particular attention to the thumb and its kinematics. He suggested that in most New World monkeys the trapezium-1st metacarpal joint (t-lmcj) is almost cylindrical in form, allowing flexion-extension, limited abduction-adduction, and no rotation. He referred to this joint type as a modified hinge, allowing pseudo-opposition of the thumb. By contrast, the t-lmcj joint is sellar in catrrrhines, allowing all three of these movements to be combined in the movement of opposition. On the evidence of the trapezium, Napier & Davis (1959) considered Proconsul africanus to have a t-lmcj of the modified hinge type. These views were challenged by Lewis (1977), who pointed out that a sellariform t-lmcj is a primitive feature in mammals, although it is modified from this shape in some New World monkeys. Lewis (1977) also believed that the trapezium of P. africanus does in fact bear a sellar articular surface. Beard et al. (1986) observations on recently collected trapezia of P.africanus confirm Lewis' interpretation. Currently there is a considerably larger sample of fossil material than that available to Napier & Davis. A consideration of the functional morphology and kinematics of the t-lmcj in extant anthropoids, Proconsul spp. and Afropithecus turkanensis, suggests that the sellariform nature of the t-lmcj in these taxa is emphasized enough to result in abduction-adduction and rotatory movements as extensive as those typical of extant large hominoids. This contrasts with the more limited movements found at the t-lmcj of other extant anthropoids. This similarity of the t-lmcj and its kinematics in large hominoids, and the Miocene species is most likely to be a shared derived character.

New hominoid facial skeleton from the Early Miocene of Rusinga Island, Kenya, and its bearing on the relationship between Proconsul nyanzae and Proconsul africanus

Recent paleontological fieldwork has led to the discovery of a plate and partial face of a young adult male Proconsul on Rusinga Island, Kenya. Morphologically, it is most similar to Proconsul nyanzae. However, it is intermediate in size between Proconsul nyanzae and Proconsul africanus. Since the distinction between these two species, not to mention the relationship between Proconsul from Rusinga and other sites, is not as clear as it once was, this specimen will undoubtedly add further fuel to the fire of discussions and debates concerning early Miocene hominoid taxonomy. In particular, it shows that we have relied far too heavily on limited samples of cranio-dental material in making our taxonomic assignments and distinctions.

A hominoid proximal humerus from the Early Miocene of Rusinga Island, Kenya

Recently, an isolated proximal humerus of an early Miocene hominoid was discovered at Rusinga Island, Kenya. The precise taxonomic allocation of this specimen is currently problematic, but the fossil almost certainly belongs to either Dendropithecus macinnesi or Proconsul africanus. The humeral head is expanded above the greater tuberosity in the new fossil suggesting that this early Miocene hominoid possessed a relatively mobile shoulder joint for climbing as well as for postural and feeding activities, and that rapid protraction at the shoulder joint was not important. This proximal humeral morphology contrasts with that of Aegyptopithecus, but is quite similar to that of Pliopithecus. Among extant primates, a similar proximal humeral morphology occurs in several platyrrhines such as Alouatta, but living apes share several apparently derived features of the proximal humerus which are lacking in the Rusinga Island specimen.

Positional behavior of long-tailed macaques (Macaca fascicularis) in northern Sumatra.

Although the majority of extant primates are described as "quadrupedal," there is little information available from natural habitats on the locomotor and postural behavior of arboreal primate quadrupeds that are not specialized for leaping. To clarify varieties of quadrupedal movement, a quantitative field study of the positional behavior of a highly arboreal cercopithecine, Macaca fascicularis, was conducted in northern Sumatra. At least 70% of locomotion in travel, foraging, and feeding was movement along continuous substrates by quadrupedalism and vertical climbing. Another 14-25% of locomotion was across substrates by pronograde clambering and vertical clambering. The highest frequency of clambering occurred in foraging for insects, and on the average smaller substrates were used in clambering than during quadrupedal movement. All postural behavior during foraging and feeding was above-substrate, largely sitting. Locomotion across substrates requires grasping branches of diverse orientations, sometimes displaced away from the animal's body. The relatively low frequency of across-substrate locomotion appears consistent with published analyses of cercopithecoid postcranial morphology, indicating specialization for stability of limb joints and use of limbs in parasagittal movements, but confirmation of this association awaits interspecific comparisons that make the distinction between along- and across-substrate forms of locomotion. It is suggested that pronograde clambering as defined in this study was likely a positional mode of considerable importance in the repertoire of Proconsul africanus and is a plausible early stage in the evolution of later hominoid morphology and locomotor behavior.

Species recognition and sexual dimorphism in Proconsul and Rangwapithecus

The taxonomy of the early Miocene hominoid genera Proconsul and Rangwapithecus is re-examined. The recognition of sexual dimorphism and the identification of sex dimorphs among canine specimens is made an important element in the sorting of specimens into phena and the allocation of these to species hypodigms. I propose that specimens from Rusinga and Mfwangano previously identified as Proconsul africanus , including the well known 1948 skull, are actually females of P. nyanzae. P. africanus specimens from Songhor and the type site of Koru differ from Rusinga and Mfwangano specimens formerly placed in P. africanus . Accordingly, P. africanus sensu stricto is restricted to Koru and Songhor and Proconsul nyanzae is restricted to Rusinga and Mfwangano. Previous characterizations of P. africanus were based almost entirely upon specimens from Rusinga, and should therefore now be applied to female P. nyanzae instead; the paleobiology of P. africanus and P. nyanzae must now be reconsidered. As a result of the reassignment of the Rusinga Proconsul specimens, P. nyanzae exhibits degrees of postcanine metric variability exceeding those of living catarrhines. It is suggested that this reflects in part a true species characteristic, perhaps related to an exceptional amount of size dimorphism, and in part a preservational artifact relating to the time-accumulated nature of the fossil sample. These results have implications for the systematics of other Miocene hominoid species.

Encephalization in Proconsul africanus (reply)

Encephalization in Proconsul africanus (reply)

The skull of Proconsul africanus: reconstruction and cranial capacity

The distorted skull of a female Proconsul africanus was found by Dr M. Leakey in 1948 in early Miocene sediments at locality R106 on Rusinga Island, Kenya1,2. Le Gros Clark1 and Robinson3 both made graphic reconstructions of this skull showing significant prognathism. The occipital portion of the skull could not, however, be attached to the main specimen because large posterior parts of the skull were missing. Two pieces missing from this skull have now been found, and these make it possible to attach the main specimen to the occipital portion. The skull is now complete in the midline from the face to the foramen magnum. The skull is distorted, but arc measurements along the midline are still accurate. A regression analysis of these arcs and cranial capacities in recent catarrhines allows us to make an accurate cranial capacity estimate for P. africanus for the first time. It seems that P. africanus had a relatively larger brain than extant monkeys of similar body size. The new pieces also make possible a more complete reconstruction.

New hominoid skull material from the Miocene of Pakistan.

Neogene hominoid cranial material is regrettably scarce, especially from the middle and late Miocene. Between the 18-Myr-old virtually complete early Miocene Proconsul africanus skull from Rusinga1 and the 3–4-Myr-old Hadar hominoid cranial material2, the only significant large (non-hylobatid) hominoid facial or cranial specimens are those from the late Miocene Salonika in Greece3, Yassioren in Turkey4, Lufeng in China5, the possibly middle Miocene site of Moroto in Uganda6 and the new facial-mandibular piece from late Miocene deposits in Pakistan reported here. The specimen is a Sivapithecus indicus7 adult, probably male, and consists of most of the left side of the face including a small portion of the frontal bone, the zygomatic arch and temporo-mandibular joint, the maxilla, a virtually entire mandible and the complete dentition. The fossil, catalogued as GSP 15000, is the property of the Government of Pakistan and is at present on loan for study at Harvard University.

New specimens of Proconsul from Koru, Kenya

The morphological and metrical definitions of the three species of Proconsul: Proconsul africanus, Proconsul nyanzae and Proconsul major , are reviewed. New finds of large fossil primates from the Lower Miocene deposits at Koru, Kenya are described and assigned to two of these species; P. africanus and P. major . The large sample of P. major from Koru permits a more complete understanding of the morphology and variability of this species and necessitates a revised diagnosis. The increased range of variation for this species is discussed in the light of sexual dimorphism and species variability in extant African hominoids.

Restoration of the Holotype of Proconsul nyanzae

The crushed palate and lower face of the holotype of Proconsul nyanzae has been prepared using the acetic acid technique. The prepared and conserved fragments have been restored to their natural positions using a synthetic cement and polyethylene glycol wax (Carbowax 4000) to fill the gaps. Preparation revealed the inferior margin of the right orbit, the inferior border of the nasal bones, and a posterior divergence of the palate which has now been corrected. The restored face of P. nyanzae shows the orbits to have been wider apart than those of Proconsul major, both absolutely and relatively, and that it had a long narrow nose and palate. It differs from Proconsul africanus, which has the shortest and broadest face of all Proconsul species, and from P. major which has a much longer narrower face.

Correlation of tooth size and body size in living hominoid primates, with a note on relative brain size inAegyptopithecus andProconsul

Second molar length and body weight are used to test the correlation between tooth size and body size in living Hominoidea. These variates are highly correlated (r= 0.942, p less than 0.001), indicating that tooth size can be used in dentally unspecialized fossil hominoids as one method of predicting the average body weight of species. Based on tooth size, the average body weight of Aegyptopithecus zeuxis is estimated to have been beteen 4.5 and 7.5 kg, which is corroborated by known cranial and postcranial elements. Using Radinsky's estimates of brain size, the encephalization quotient (EQ) for Aegyptopithecus was between 0.65 and 1.04. A similar analysis for Proconsul africanus yields a body weight between 16 and 34 kg, and an EQ between 1.19 and 1.96.

A Reconstruction of the Skull of Proconsul Africanus (R.S.51)

A Reconstruction of the Skull of Proconsul Africanus (R.S.51)

FOSSIL EVIDENCE RELATING TO THE EARLY EVOLUTION OF PRIMATE BEHAVIOR

Annals of the New York Academy of SciencesVolume 102, Issue 2 p. 282-294 Free Access FOSSIL EVIDENCE RELATING TO THE EARLY EVOLUTION OF PRIMATE BEHAVIOR E. L. Simons, E. L. Simons Department of Geology and Yale Peabody Museum, New Haven, Conn.Search for more papers by this author E. L. Simons, E. L. Simons Department of Geology and Yale Peabody Museum, New Haven, Conn.Search for more papers by this author First published: December 1962 https://doi.org/10.1111/j.1749-6632.1962.tb13646.xCitations: 35AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL References Avis, V. 1961. The significance of the angle of the mandible: An experimental and comparative study. Amer. Joum. Phys. Anthrop. 19(1): 55. Buettner-Janusch, J. & R. J. Andrew. 1962. The use of the incisors by Primates in grooming. Amer. Journ. Phys. Anthrop. 20(2): 129. Gazin, C. L. 1958. A review of the Middle and Upper Eocene Primates of North America. Smiths. Misc. Coll. 126(1): 1. Gregory, W. K. 1920. On the structure and relationships of Notharctus, an American Eocene primate. Mem. Amer. Mus. Nat. Hist. 3(2): 49. Hill, W. O. C. 1953. Primates. Comparative anatomy and Taxonomy, I. Strepsirhini. Edinbuigh University Press, Edinburg , Scotland . LeGros Clark, W. E. 1956. A Miocene lemuroid skull from East Africa. Fossil Mammals of Africa, British Museum (Nat. Hist.) 9: 1. LeGros Clark, W. E. 1959. The Antecedents of Man. Quadrangle Books, Chicago , Ill. Napier, J. R. & P. R. Davis. 1959. The forelimb skeleton and associated remains of Proconsul africanus. Fossil mammals of Africa. 16: 1. Noback, C. R. 1959. The heritage of the human brain. James Arthur lecture. Amer. Mus. Nat. Hist.: 1. Polyak, S. 1957. The Vertebrate Visual System. Chicago University Press. Chicago , Ill. Polyak, S. 1957. The Vertebrate Visual System. University of Chicago Press. Chicago , Ill. Simons, E. L. 1962. A new Eocene primate genus, Cantius, and a revision of some allied European lemuroids. Bull. Brit. Mus. (Nat. Hist.) Geol. Ser. 7(1): 1. Simons, E. L. & D. E. Russell. 1960. Notes on the cranial anatomy of Necrolemur. Breviora Mus. Comp. Zool., Harvard. 127: 1. Stehlin, H. 1916. Die Saugetiere des schweizerischen Eocaens. Abh. Schweiz. Palaont. Ges., Zurich. 41: 1299. Strauss, W. L. & G. B. Wislocki. 1932. On certain similarities between sloths and slow lemurs. Bull. Mus. Comp. Zoology, Harvard. 74(3): 1. Walls, G. L. 1942. The Vertebrate Eye and Its Adaptive Radiation. Cransbrook Institute of Science. Bloomfield Hills , Mich. Citing Literature Volume102, Issue2The Relatives of Man: Modern Sudies of the Relation of the Evolution of Nonhuman Primates to Human EvolutionDecember 1962Pages 282-294 ReferencesRelatedInformation

Note on the skull of Proconsul africanus

American Journal of Physical AnthropologyVolume 10, Issue 1 p. 7-12 Article Note on the skull of Proconsul africanus J. T. Robinson, J. T. Robinson Transvaal Museum, Pretoria, South AfricaSearch for more papers by this author J. T. Robinson, J. T. Robinson Transvaal Museum, Pretoria, South AfricaSearch for more papers by this author First published: March 1952 https://doi.org/10.1002/ajpa.1330100114Citations: 4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume10, Issue1March 1952Pages 7-12 RelatedInformation