Miocene Hominoids Research Articles

A Middle Miocene hominoid from Thailand and orangutan origins.

The origin of orangutans has long been debated. Sivapithecus is considered to be the closest ancestor of orangutans because of its facial-palatal similarities, but its dental characteristics and postcranial skeleton do not confirm this phylogenetic position. Here we report a new Middle Miocene hominoid, cf. Lufengpithecus chiangmuanensis n. sp. from northern Thailand. Its dental morphology relates it to the Pongo clade, which includes Lufengpithecus, Sivapithecus, Gigantopithecus, Ankarapithecus and possibly Griphopithecus. Our new species displays striking dental resemblances with living orangutans and appears as a more likely candidate to represent an ancestor of this ape. In addition, it originates from the geographic area of Pleistocene orangutans. But surprisingly, the associated flora shows strong African affinities, demonstrating the existence of a temporary floral and faunal dispersal corridor between southeast Asia and Africa during the Middle Miocene, which may have played a critical role in hominoid dispersion.

Morphology of the hallucial phalanges in extant anthropoids and fossil hominoids

Pedal phalanges of living anthropoids and several Miocene fossil hominoid taxa were studied to reveal functional adaptations of living anthropoid feet and to infer positional behavior of fossil hominoids. Among the examined living anthropoids, Pan has a very developed (long and robust) hallux. Proconsul and Nacholapithecus, a large hominoid from Nachola, northern Kenya, display a moderately long hallux like Alouatta and Cebus, suggesting the well-developed capability of a hallux-assisted power grip. Allometric analyses revealed that the Miocene hominoids examined (mainly from East Africa) as a whole displayed a different scaling pattern about the width of the proximal articular surface of the hallucial terminal phalanx from that of living anthropoids. Larger-sized hominoids display a wider articular surface than comparable-sized living anthropoids while smaller-sized fossil hominoids do the reverse. Such a difference was less marked for the height of the articular surface. These results may suggest that positional adaptations of Miocene hominoids are not merely resultants of a common body size function that is observed in living anthropods. The wide articular surface of fossil hominoid hallucial terminal phalanges suggests an adaptation for vertical climbing and clinging, in which the hallux is kept perpendicularly to the long axis of the vertical support.

Reconstructing the mechanics of quadrupedalism in an extinct hominoid

Traditionally, analogising comparative anatomical approaches, working on features of individual bony elements, have led to the Miocene hominoids Proconsul heseloni and P. nyanzae being described as arboreal, with a variety of possible locomotion modes. Whilst most researchers seemingly agree that quadrupedal was one of the most frequently adopted modes, any deeper knowledge about the kinematical characteristics of such quadrupedalism is very limited. Based on the previous studies and a computer simulation technique developed in our laboratory, a set of alternative models for Proconsul quadrupedalism was created. The body measurements and initial properties for the different models were held constant, using data from published literature if available, or otherwise estimated from data for Pan. Judged by the power output of joints, the results of computer simulation indicate that the style of quadrupedal locomotion typical of living macaques fits the body proportions of Proconsul better than that of Canis domesticus, Varecia variegata, Cebus albifrons or Pan troglodytes. It may reasonably be assumed that Proconsul's quadrupedal mode was similar to that of living macaques.

The Diet of the Yuanmou Hominoid, Yunnan Province, China: An Analysis from Tooth Size and Morphology.

In the past decades numerous late Miocene hominoid fossils have been discovered in Eurasia but the relationships among them and to the later hominids are still in debate. Yunnan Province of China is one of the key places of hominoid fossil discoveries. Till now, four sites have yielded Miocene hominoid fossils. Among them, Lufeng and Yuanmou rank with Siwalik as the richest fossil sites in Eurasia. Here, we report the results of a dietary analysis of the Yuanmou hominoid. Our analyses of tooth size proportions. M2 shearing crest development, tooth enamel thickness and body weight of Yuanmou and other Miocene hominoids indicate that, compared with other samples, the Yuanmou hominoid had relatively bigger front teeth and weakly developed molar shearing crests (lower SQ). So, the Yuanmou hominoid is considered to have mainly fed on a harder or frugivorous diet. Among the other Miocene hominoids considered in present study, the SQs of Proconsul nyanzae, Ouranopithecus macedoniensis, Dendropithecus macinnesis and Lufengpithecus lufengensis is close to that of Yuanmou indicating that they had similarly developed molar shearing crests with a likely preference for hard fruits. On the other hand, there are some differences between the Yuanmou hominoid and Lufengpithecus in all the four aspects of evidence studied here. Among them, Lufengpithecus had relatively smaller front teeth, relatively smaller M1, higher SQ, indicating that more folivorous and soft dietary items like leaves and berries were consumed. The preferred paleoenvironments of the Yuanmou hominoid and Lufengpithecus might also have been different.

人類進化と新生代後期の環境変化 ヒト科の出現 中新世におけるヒト上科の展開

The human lineage is a branch of the huge evolutionary tree of the Hominoidea, which today includes ourselves, chimpanzees, gorillas, orangutans, and gibbons. All extant hominoids, except for the single world-wide species Homo sapiens, are now endangered and restricted in their distribution to tropical/subtropical forests of Africa and Southeast Asia. However, hominoids were once a more flourishing group millions of years ago. In the Miocene, there were various kinds of hominoid primates, and their distribution was much wider than today, from the southern tip of Africa through Arabia, to Europe in the west and through India to China in the east. It is from this great diversity of Miocene hominoids that the earliest human ancestors emerged, probably during the Late Miocene. The first part of this article provides readers with general information about extant hominoids. The second part is devoted to Miocene fossil hominoids with emphasis on African fossils. Although the main subject of this article is fossil hominoids, some recent findings of early hominids are also mentioned to at the end.

Morphometric analysis of hominoid lower molars from Yuanmou of Yunnan Province, China

Shape analyses of cross-sectional mandibular molar morphology, using Euclidean Distance Matrix Analysis, were performed on 79 late Miocene hominoid lower molars from Yuanmou of Yunnan Province, China. These molars were compared to samples of chimpanzee, gorilla, orangutan,Lufengpithecus lufengensis, Sivapithecus, Australopithecus afarensis, and human mandibular molars. Our results indicate that the cross-sectional shape of Yuanmou hominoid lower molars is more similar to the great apes that to humans. There are few differences between the Yuanmou,L. lufengensis, andSivapithecus molars in cross-sectional morphology, demonstrating strong affinities between these three late Miocene hominoids. All three of the fossil samples show strong similarities to orangutans. From this, we conclude that these late Miocene hominoids are more closely related to orangutants than to either the African great apes or humans.

Postcranial functional morphology of Morotopithecus bishopi, with implications for the evolution of modern ape locomotion

The large-bodied hominoid from Moroto, Uganda has until recently been known only from proconsulid like craniodental remains and some vertebrae with modern ape like features. The discovery of two partial femora and the glenoid portion of a scapula demonstrates that the functional anatomy of Morotopithecus differed markedly from other early and middle Miocene hominoids. Previous studies have consistently associated the vertebral remains with a short, stiff back and with orthograde postures. Although the proximal femur more closely resembles the femora of monkeys than of apes and suggests a moderate degree of hip abduction, the distal femur resembles those of extant large bodied apes and suggests a varied loading regime and an arboreal repertoire that may have included substantial vertical climbing. The femoral shaft displays uniformly thick cortical bone, beyond the range of thickness seen in extant primates, and signifies higher axial loading than is typical of most extant primates. The glenoid fossa is broad and uniformly curved as in extant suspensory primates. Overall, Morotopithecus is reconstructed as an arboreal species that probably relied on forelimb-dominated, deliberate and vertical climbing, suspension and quadrupedalism.Morotopithecus thus marks the first appearance of certain aspects of the modern hominoid body plan by at least 20Ma. If the suspensory and orthograde adaptations linking Morotopithecus to extant apes are synapomorphies,Morotopithecus may be the only well-documented African Miocene hominoid with a close relationship to living apes and humans.

Middle Miocene Hominoid Origins

Middle Miocene Hominoid Origins

Middle Miocene Hominoid Origins

Ward et al . ([1][1]) ably show that samples of thickly enameled Middle Miocene hominoids that they attribute to a new genus, Equatorius , are distinct from Kenyapithecus . They fail to show, however, how Equatorius differs from Griphopithecus . In so doing, they may have missed the hominoid

Equatorius: a new hominoid genus from the Middle Miocene of Kenya.

A partial hominoid skeleton just older than 15 million years from sediments in the Tugen Hills of north central Kenya mandates a revision of the hominoid genus Kenyapithecus, a possible early member of the great ape-human clade. The Tugen Hills specimen represents a new genus, which also incorporates all material previously referable to Kenyapithecus africanus. The new taxon is derived with respect to earlier Miocene hominoids but is primitive with respect to the younger species Kenyapithecus wickeri and therefore is a late member of the stem hominoid radiation in the East African Miocene.

Planet of the apes: Function, Phylogeny, and Fossils: Miocene Hominoid Evolution and Adaptations.

Planet of the apes: Function, Phylogeny, and Fossils: Miocene Hominoid Evolution and Adaptations.

A simulation test of hominoid species number at Lufeng, China: implications for the use of the coefficient of variation in paleotaxonomy

High dental metric variation in the large hominoid sample from the late Miocene site of Lufeng, China has been interpreted in two ways: (1) there are two morphologically similar species that broadly overlap in size, and (2) there is one species that is more highly sexually dimorphic in dental size, and perhaps in body size, than any extant primate. It has been claimed that the high levels of dental metric variation falsify the single-species hypothesis, which has been viewed implicitly as corroboration of the two-species hypothesis. However, the two-species hypothesis has not been subjected to testing. Here we test the two-species hypothesis using computer simulations to attempt to reproduce the unusual pattern of intrasexual and intersexual dental metric variation observed in the Lufeng postcanine dentition. Conditions of the simulation experiments were optimized to favor the two-species hypothesis. It was found that, although the Lufeng pattern of metric variation could be reproduced by sampling two species, the likelihood of this occurrence was very low even when the conditions were optimized to the point of improbability. We conclude that the likelihood is very high that the Lufeng sample is composed of one species that is more highly sexually dimorphic in the postcanine dentition than any extent primate species. If so, then the high levels of sexual dimorphism and intraspecific dental metric variation in this species violate the central assumption of methods that employ the coefficient of variation (CV) for paleotaxonomy, namely, that neither can lie outside the ranges observed among extant species. Thus, we further conclude that the CV must be used with caution when evaluating the taxonomic composition of fossil samples and, further, that it cannot be used to falsify a single-species hypothesis in any meaningful way. Other fossil hominoid samples with high measures of dental variation may indicate that considerable sexual size dimorphism typified many Eurasian middle–late Miocene hominoids.

Function, phylogeny, and fossils: Miocene hominoid evolution and adaptations

Function and Phylogeny in Miocene Hominoids C.V. Ward, et al. Comments on the Last Decades of Research on Miocene Hominoids and Hominid Origins D. Pilbeam. Inter-Relationships Between Functional Morphology and Paleoenvironments in Miocene Hominoids P. Andrews, et al. The Early Evolution of the Hominoid Face T.C. Rae. Functional and Phylogenetic Features of the Forelimb in Miocene M.D. Rose. Functional Anatomy and Phyletic Implications of the Hominoid Trunk and Hindlimb C.V. Ward. Dental Evidence for Diets in Some Miocene Catarrhines with Comments on the Effects of Phylogeny on the Interpretation of Adaptation R.F. Kay, P.S. Ungar. Miocene Hominoid Mandibles: Functional and Phylogenetic Perspectives B. Brown. Paleobiological and Phylogenetic Significance of Life History in Miocene Hominoids J. Kelley. Proconsul - Function and Phylogeny A. Walker. Afrophitecus - Function and Phylogeny M. Leakey, A. Walker. On the Relationships and Africa M.L. McCrossi, B.R. Benefit. The Taxonomy and Phylogeny of Sivapithecus Revisited S. Ward. Phyletic Affinities and Functional Convergence in Dryopithecus and Other Miocene and Living Hominids D. Begun, L. Kordo. 4 Additional Articles. Index.

A newly discovered Kenyapithecus skeleton and its implications for the evolution of positional behavior in Miocene East African hominoids.

The middle Miocene stem kenyapithecine Nacholapithecus kerioi (16–15 Ma; Nachola, Kenya) is represented by a large number of isolated fossil remains and one of the most complete skeletons in the hominoid fossil record (KNM-BG 35250). Multiple fieldwork seasons performed by Japanese–Kenyan teams during the last part of the 20th century resulted in the discovery of a large sample of Nacholapithecus fossils. Here, we describe the new femoral remains of Nacholapithecus. In well-preserved specimens, we evaluate sex differences and within-species variation using both qualitative and quantitative traits. We use these data to determine whether these specimens are morphologically similar to the species holotype KNM-BG 35250 (which shows some plastic deformation) and to compare Nacholapithecus with other Miocene hominoids and extant anthropoids to evaluate the distinctiveness of its femur. The new fossil evidence reaffirms previously reported descriptions of some distal femoral traits, namely the morphology of the patellar groove. However, results also show that relative femoral head size in Nacholapithecus is smaller, relative neck length is longer, and neck–shaft angle is lower than previously reported for KNM-BG 35250. These traits have a strong functional signal related to the hip joint kinematics, suggesting that the morphology of the proximal femur in Nacholapithecus might be functionally related to quadrupedal-like behaviors instead of more derived antipronograde locomotor modes. Results further demonstrate that other African Miocene apes (with the exception of Turkanapithecus kalakolensis) generally fall within the Nacholapithecus range of variation, whose overall femoral shape resembles that of Ekembo spp. and Equatorius africanus. Our results accord with the previously inferred locomotor repertoire of Nacholapithecus, indicating a combination of generalized arboreal quadrupedalism combined with other antipronograde behaviors (e.g., vertical climbing).

Interpretation of Samburupithecus, an upper Miocene hominoid from Kenya

Samburupithecus, an extinct great ape from upper Miocene (9.5 Ma) deposits in Kenya, is compared with other fossil and extant hominoids. It possesses features which are derived in comparison with Proconsul and other Lower and Middle Miocene hominoids, but it has none of the derived features which characterize the Eurasian large apes. It possesses characters which indicate that its closest relationships lie with the AAH clade (extant African apes and man). Within this clade it is closest dentally to primitive hominids such as Praeanthropus.

Design of the Mandibular Molar in the Extant Great Apes and Miocene Fossil Hominoids.

The relative size of the cusps of the first mandibular molars of extant great apes and the Miocene hominoids, Proconsul and Sivapithecus were compared. As previously shown, molar morphology can differ between populations of the same species. Although the differences in crown size and shape are not as great as expected, each extant great ape species has a different overall design of the cusp base, probably reflecting its evolutionary history. The relative sizes of the cusps in Proconsul and Sivapithecus are different from those of any extant great apes.

Panafrican distribution of Lower Miocene Hominoidea

Palaeontological survey of the Neogene littoral deposits of the Namaqualand coastal strip, Northern Cape Province, South Africa, has resulted in the collection of the first Lower Miocene faunas from South Africa. Among the mammals from Ryskop and Hondeklip Bay is a gorilla-sized hominoid. This discovery greatly increases the geographic range of early Miocene hominoids and suggests that even at this remote epoch, the superfamily had a Panafrican distribution.

A new reconstruction of RUD 77, a partial cranium of Dryopithecus brancoi from Rudabánya, Hungary.

A newly reconstructed cranium (RUD 77) of the Miocene fossil hominoid Dryopithecus, formerly Rudapithecus (Kretzoi [1969] Symp. Biol. Hung. 9:3-11; Begun and Kordos [1993] J. Hum. Evol. 25:271-286) is presented here. This specimen, from the late Miocene locality of Rudabánya, in northeastern Hungary, consists of portions of the neurocranium, face, and postcanine dentition. Newly recovered portions of the parietal, occipital, temporal, zygomatic, and premaxillary bones, which are described here for the first time, in association with previously described portions of this specimen (Kordos [1987] Ann. Hist. Nat. Mus. Natl. Hung. 79:77-88) make RUD 77 among the most complete and well preserved neurocrania of any Miocene hominoid. Detailed anatomical descriptions and measurements are provided here, along with comparisons to other relatively complete Miocene hominoid cranial remains, and to living hominoids. While a more complete phylogenetic analysis is in preparation based on the sample as a whole, it is suggested here that RUD 77 provides some additional evidence in support of a previous hypothesis that Dryopithecus is more closely related to the African apes and humans than is Sivapithecus.

Book Review Function, Phylogeny, and Fossils: Miocene Hominoid Evolution and Adaptations. Edited by David R. Begun, Carol V. Ward, and Michael D. Rose. Plenum Press, New York and London, 1997, xii + 424 pp., $120.00 (hardback)

Book Review Function, Phylogeny, and Fossils: Miocene Hominoid Evolution and Adaptations. Edited by David R. Begun, Carol V. Ward, and Michael D. Rose. Plenum Press, New York and London, 1997, xii + 424 pp., $120.00 (hardback)

An analysis of the articular surface distribution of the femoral head and acetabulum in anthropoids, with implications for hip function in Miocene hominoids

Abstract Use of linear techniques to represent complex shapes has constrained morphological studies of the hip joint, with the result that functionally significant features have remained unquantified. This study uses a linear least squares sphere fit to the femoral head and acetabular subchondral bone as a framework for mapping the distribution of articular surface on the joint components of several extant anthropoids. The distribution of acetabular articular surface is believed to be related to mobility and the loading environment of the joint. Low dorsal and caudal lunate surfaces inPongopermit a wide range of abduction, while an extensive cranial lunate surface implies substantial cranial loading. The acetabula of pronograde monkeys has a uniform distribution of articular surface, presumably because the hip socket is loaded from cranial, dorsal and caudal directions.Panhas neither as much cranial lunate surface asPongo, nor as much dorsal lunate surface as the monkeys, suggesting a heterogeneous loading environment that may be a consequence of frequently using both orthograde and pronograde postures. The monkeys have a preponderance of articular surface on the anterior aspect of the femoral head, reflecting a greater emphasis on adducted, medially oriented postures and excursions than inPan.Evidence from the femur, and in the case ofProconsul, the acetabulum, was integrated with other data to reconstruct hip mobility and relate it to suspensory behavior in Miocene hominoids. Femoral articular configurations suggest that most Miocene hominoids had mobile hip joints, which would have facilitated climbing and hindlimb suspension, however, available humeral material does not support a similar mobility in the shoulder. The exception to this pattern are the fossil remains from Moroto, which combine a monkey-like hip, compatible with quadrupedal hip use, with a back that suggests orthograde adaptations.