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Monday, 30 April 2012

Miocene Apes and the Large Yeti, Sasquatch and Gigantopithecus

This blog entry I hope to finish off the discussion of the Miocene apes by suggesting some relatives of Gigantopithecus and seeing if what we know about these other apes strengthens our case for Sasquatch to be the same as Gigantopithecus.
Above, full painting reconstruction for the gorilla-sized Late Miocene ape Ouranopithecus from Greece and Turkey. At left Ouranopithecus' reconstructed skull and an interpretation of it as fleshed out in life. (this is slightly altered from the original, chiefly by increasing the vertical height in both images correspondingly)
Fig. 1 Reconstructions and partial reconstructions of the craniums of fossil apes: (a) Proconsul, (b) Afropithecus, (c) Oreopithecus, (d) Ouranopithecus, (e) Sivapithecus, and (f) Ankarapithecus

Reconstruction of Ouranopithecus skull largely based on comparison to a gorilla's.
Am J Phys Anthropol. 1980 Nov;53(4):541-68.

Morphometric affinities of Gigantopithecus.


Multivariate analyses, supplemented by univariate statistical methods, of measurements from mandibular tooth crown dimensions and the mandible of Gigantopithecus blacki, G. bilaspurensis, Plio-Plelstocene hominids, Homo erectus, and seven Neogene ape species from the genera Proconsul, Sivapithecus, Ouranopithecus, and Dryopithecus were used to assess the morphometric affinities of Gigantopithecus. The results show that Gigantopithecus displays affinities to Ouranopithecus and to the hominids, particularly the Plio-Plelstocene hominids, rather than to the apes. Ouranopithecus demonstrated dental resemblances to G. bilaspurensis and the Plio-Pleistocene hominids but mandibular similarities to the apes. Results of analyses of tooth and mandibular shape indices, combined with multivariate distance and temporal relationships, suggest that Ouranopithecus is a more likely candidate for Gigantopithecus ancestry than is Silvapithecus indicus. Shape and allometric differences between G. bilaspurensis and the robust australopithecines weaken the argument for an ancestral-descendant relationship between these groups. The results support the hypothesis that Gigantopithecus is an extinct side branch of the Hominidae.[End of Abstract]

Above, Grover Krantz's reconstriction for the skull and lower jaw of Gigantopithecus. The lower jaws of Gigantopithecus are very similar to those of Ouranopithecus,' both the male and the females being parallel and both genera showing a similar pattern for sexual dimorphism. The comparison of the Ouranopithecus fossil facial material to the reconstruction for the facial skeleton of Gigantopithecus tends to vindicate Krantz's reconstruction.

Above, Ouranopithecus fossil material and below, comparison of Ouranopithecus to an orangutan.

Gigantopithecus' lower jaw compared to a human's for absolute size, and below left, an independant attempt. The end result still comes recognisably similar to Krantz's version.

Copy of an illustration of male and female Ouranopithecus jaws, both looking remarkably similar to the corresponding Gigantopithecus jaws. Unfortunately, this is the best copy of the illustration I can get at present.


Sun, 2005-01-23 23:27 -- John Hawks
Ouranopithecus macedoniensis (called by some Graecopithecus [Graecopithecus is a smaller and more primitive genus, its jaws and teeth are not that similar]) is from the Late Miocene of Greece, around 8 million years old. Based on its facial and dental anatomy, Ouranopithecus is clearly a dryopithecine, but it is not clear if it may be particularly related to either humans or some living ape lineage. The morphology of the male skull appears similar to living gorillas, with a large and broad face, prominent supraorbital torus, and square-shaped orbits. These similarities may reflect nothing more than a relatively large body size, though a close relationship with gorillas is a possibility.

Some of the features of Ouranopithecus are similar to hominids. Most notably, like some other Late Miocene remains, the canines are relatively smaller in size than in many apes, especially in females. With fairly thick molar enamel and low cusps, the molar teeth are not gorilla-like, but instead are more similar to later hominids. Sexual dimorphism is substantial between the teeth, however, and males have large canines and shearing lower premolars. 

Miocene ape review, in brief

Fri, 2010-01-29 19:58 -- John Hawks

Science has a short essay by Terry Harrison this week about Miocene ape evolution: "Apes among the tangled branches of human origins."
This is the sort of article that shows just how frustrating the Miocene apes can be. It's short, probably not even 1500 words, and it has more than 20 genus names stacked into it -- and he doesn't even list Proconsul and its Early Miocene ilk.
I've been trying to give a longer account of Miocene ape evolution here, by dribs and drabs. You can get most of the list under my "Miocene" category. Last fall's account of "Late Miocene apes from Africa" expands significantly on a topic that Harrison glosses -- what do we know about African apes during the time that chimpanzees, gorillas, and humans were diverging?
There are two phylogenetic issues related to Miocene apes that command a lot of attention. Where did hominins come from? -- that's one issue. The other is, how are Asian and African apes related?
This latter question is important because it helps to establish the timeline of orangutan divergence from us and subsequent evolution. It also determines the position of the European apes -- and thereby, whether their locomotor and dietary diversity is relevant to later ape evolution.
Harrison comes down in favor of the hypothesis that Dryopithecus and most other European apes were stem hominids -- that is, collaterals of all living great apes, not specially related to the African apes and humans. The main alternative to that view is that the European apes mostly represent the African side of an early Asia-Africa biogeographic split, such that chimpanzees, gorillas and humans (the hominines) descend from Dryopithecus or some similar lineage closely aligned with these European apes. Harrison is willing to admit the Late Miocene Greek ape Ouranopithecus to the African ape lineage, but in his view the earlier European apes belong to one or more side-branches of the great apes.
A question: If Harrison is correct here, does that affect the paleontological evidence for the human-orangutan divergence? That is, if Dryopithecus were a hominine, it is plausible that the Asian/African ape divergence actually happened in Eurasia not long before 12 million years ago. If Dryopithecus branched off before the African and Asian ape divergence, and Sivapithecus was derived from an African ape, does that make the divergence earlier or later?
I'll consider that over the weekend.

The mystery ape from Longgupo

Tue, 2009-06-23 09:29 -- John Hawks
In last week's Nature, Russell Ciochon has a remarkable essay:
For many years, I used Longgupo to promote this pre-erectus origin for H. erectus finds in Asia. But now, in light of new evidence from across southeast Asia and after a decade of my own field research in Java, I have changed my mind. Not everyone may agree; such classifications are always open to interpretation. But I am now convinced that the Longgupo fossil and others like it do not represent a pre-erectus human, but rather one or more mystery apes indigenous to southeast Asia's Pleistocene primal forest. In contrast, H. erectus arrived in Asia about 1.6 million years ago, but steered clear of the forest in pursuit of grassland game. There was no pre-erectus species in southeast Asia after all.
I think it's interesting how much speculation Nature is willing to publish about hominid evolution in Asia. The 2005 review article by Robin Dennell and Wil Roebroeks, "An Asian perspective on early human dispersal from Africa," speculated that the origin and early evolution of Homo may have been in Asia, not Africa. And of course, several papers on the hobbits have included speculations about the pattern of early Homo in Asia, in pursuit of ways to derive Homo floresiensis from early hominids not yet found in Asia.
Ciochon's essay is part of this new tradition, but it bucks the trend. Instead of arguing that Asia was the home to an undiscovered diversity of hominids, he instead argues that the hominids have been overestimated (in part by himself) and that some fossils represent an undiscovered diversity of apes.
Ancient orangutans (Pongo) and Gigantopithecus are already known from China. Ciochon proposes a third lineage of great ape, one that would be similar to the earlier Lufengpithecus from China and Thailand:
Later, we had to field a serious proposal that Longgupo belonged to Lufengpithecus (4, 5). Although the age disparity remained troubling, the dental similarities could not be denied. I began to imagine a mystery ape as a possible solution to the problem.
The "age disparity" Ciochon refers to is that Lufengpithecus is known from the Late Miocene and very earliest Pliocene, but not the Late Pliocene. Still, if the teeth look like Lufengpithecus, it seems probable that the "mystery ape" actually is a late-surviving Lufengpithecus, or at least a close relative. Reference 5 is a paper by Dennis Etler, Tracy Crummett and Milford Wolpoff, which is available (PDF) from Etler's excellent website. Wolpoff refers to this in his 1999 book, Paleoanthropology:
The Longgupo mandible is actually a fossil ape that is related to Lufengpithecus, the missing P3 was sectorial in shape. However the prestigious British Journal Nature hastily published it as a hominid, with a picture of the specimen on its cover, and subsequently refused to accept papers establishing its identity. The misidentifications actually started decades ago, when G.H.R. von Koenigswald identified an ancient australopithecine-like hominid from South China based on worn, isolated teeth, which he named “Hemianthropus.” These turned out to be worn postcanine teeth of a medium-sized Pongo species. The resemblances of the other materials to Australopithecus species were real enough, but they were not unique resemblances. A. Kramer and Zhang Yinyun have each shown there are no synapomorphies that support the hypothesis of Asian australopithecines.
So it's not a new idea that Longgupo represents an ape, or that the ape was different in size and morphology from Pongo or Gigantopithecus. It is probably natural that early paleontologists might associate these ape teeth with the hominids -- until 40 years ago, most paleontologists thought that hominids went back far into the Miocene. They were wrong, but a mistake like "Hemianthropus" was a natural one. The opposite mistake -- "Meganthropus" as an australopithecine-like hominid -- was also a natural consequence of the assumption that an unrecognized hominid diversity existed in Asia. That assumption has outlived Meganthropus, as we've seen.
Ciochon adds the idea that the ape may also be represented at other contemporary or later sites, and is apparently unwilling to attribute them to Lufengpithecus, at least not yet. He does not mention the isolated upper incisor from Longgupo, but he does appear to accept the claim that the two stone artifacts from the site are intrusive elements that are not contemporary with the jaw. The same is probably true of the incisor, which Etler and colleagues found morphologically most like living East Asians.
Ciochon suggests that some of the Hemianthropus collection may be his mystery ape:
Von Koenigswald viewed Hemanthropus as a distant relative of African Australopithecus. Later research revealed that these were worn or atypical orangutan teeth and Hemanthropus was quickly abandoned. But, had von Koenigswald actually discovered evidence of the mystery ape? In October 2005, I examined the original Hemanthropus collection. Among the many worn orangutan teeth I found several small ape teeth that very closely resembled the mystery ape teeth from Mohui. Perhaps von Koenigswald was the first to lay hands on the mystery ape.
It's not an easy task to sort through large samples of teeth trying to sort them into sets. Particularly not with these teeth -- sure, Gigantopithecus falls right out, but worn orangutan teeth aren't very easy to tell from hominids, much less "mystery apes." Ciochon ends his essay with a plan to revisit the existing samples of teeth, trying to document the variation in the mystery lineage. Sounds like a good topic for a TV show. There's a historical angle, lots of museums, a personal hook, reversal of fortune, the whole "mystery ape" thing....
Meanwhile, the introductory paragraph at the top of the post raised two issues, not one. The first is the focus of the rest of the essay: Longgupo represents a third ape in Pleistocene China; smaller than both Gigantopithecus and Pongo. The second idea is covered briefly near the end of the essay, but I think it deserves more consideration. Is it true that humans reached China 1.6 million years ago, and then "steered clear of the forest"?
Here's what Ciochon writes:
Homo erectus, it seems from this perspective, hunted grazing mammals on open grasslands, and did not or could not penetrate the dense subtropical forest. In fact, there is no record of early hominins living in tropical or subtropical forested environments in Africa or Asia.
In resolving the mystery, two other Asian sites come to mind: Jianshi (Hubei province, China) and Tham Khuyen (Lang Son province, Vietnam). At both sites, teeth labelled variously as Australopithecus, H. erectus and Meganthropus are most likely to be the mystery ape instead. Others have come to similar conclusions; a 2009 paper identifies a tooth from Sanhe Cave (Chongzuo, Guangxi province, China) as belonging to an unidentified ape.
The map accompanying the article is mysteriously depauperate of actual early hominid sites in China. Considering their locations relative to the proposed distribution of subtropical forest in Pleistocene China, I don't see an immediate objection to the hypothesis. The earliest Chinese archaeological sites, from the Nihewan basin near Beijing (Majuangou and Xiaochangliang) and also from around the Yellow River (Gongwangling and Xihoudu), are north of the Stegodon--Ailuropoda fauna. Yuanmou may have been forested at this time, but the hominid teeth there appear to be later (Hyodo et al. 2002), when the Ciochon's forest-plains biogeographic proposal may no longer hold. Josette Sarel and colleagues (2009) report on stone tools from Baerya Cave, which does preserve the Stegodon--Ailuropoda fauna, but these are so far undated and the stratigraphy has not been worked out. For all we know, the association is no clearer than at Longgupo, but that may change.
The other early Chinese sites with hominid teeth, Ciochon suggests are not hominids -- Mohui and Sanhe. Since he has examined the Mohui teeth (Wang et al. 2007), this isn't an idle speculation, and it would be odd for humans to drop their teeth around these sites without dropping a single stone tool. If he's right, that would make the earliest clear evidence of human occupation of South China into the Middle Pleistocene in age.
So, it's an interesting generalization. It remains to be seen how true it may be -- was early Homo really limited to a biogeographic strip of plains and savanna as it left Africa, or were the early humans more broadly adapted -- or adaptable?


Ciochon RL. 2009. The mystery ape of Pleistocene Asia. Nature 459:910:911. doi:10.1038/459910a
Ciochon R, Long VT, Larick R, González L, Grün R, de Vos J, Yonge C, Taylor L, Yoshida H, Reagan M. 1996. Dated co-occurrence of Homo erectus and Gigantopithecus from Tham Khuyen Cave, Vietnam. Proc Nat Acad Sci 93:3016-3020.
Etler DA, Crummett TL, Wolpoff MH. 2001. Longgupo: Early Homo colonizer or Late Pliocene Lufengpithecus survivor in South China? Hum Evol 16:1-12.
Hyodo M, Nakaya H, Urabe A, Sagua H, Xue S, Yin J, Ji X. 2002. Paleomagnetic dates of hominid remains from Yuanmou, China, and other Asian sites. J Hum Evol 43:27-41. doi:10.1006/jhev.2002.0555
Sarel J, Zhang P, Weng Z. 2009. Recent discoveries in Baerya Cave (Bijie District, Northern Province of Guizhou, China). Antiquity 83 (online).
Wang W, Potts R, Yuan B, Huang W, Cheng H, Edwards RL, Ditchfield P. 2007. Sequence of mammalian fossils, including hominoid teeth, from the Bubing Basin caves, South China. J Hum Evol 52: 370-379. doi:10.1016/j.jhevol.2006.10.003
Zhu RX, Potts R, Xie F, Hoffman KA, Deng CL, Shi CD, Pan YX, Wang HQ, Shi RP, Wang YC, Shi GH, Wu NQ. (2004). New evidence of the earliest human presence at high northern latitudes in Northeast Asia. Nature 431:559-562.

ca 15-14.5 Million years ago, dispersal of the Proconsuls and early apes Out Of Africa. early apes are most similar to macaque monkeys in size and appearance but they already have the standard types of molar teeth that apes and humans still have.

13 to 14  Million years ago approximately. Dryopithecine radiation.Sivapithecine apes make a first appearance in the Siliwak deposits of India

11 to 12.5 million years ago according to the stage indicated. Apes with more recognisably ape-shaped bodies and adaptations begin to spread, including Sivapithecus and its allies.

9 to 10.5 million years ago
This would represent Ouranopithecus' age except that it persisted longer than the indicated date. The majority of apelike creatures are dying out in Europe and the Near East, becoming established in tropical Asia and Africa instead. [Source for maps and information, in French]
Folia Primatol (Basel). 2007;78(5-6):328-43. Epub 2007 Sep 7.

Middle Miocene dispersals of apes.


Department of Palaeontology, Natural History Museum, London, UK. <>


The earliest record of fossil apes outside Africa is in the latest early Miocene of Turkey and eastern Europe. There were at least 2, and perhaps 4, species of ape, which were found associated with subtropical mixed environments of forest and more open woodland. Postcranial morphology is similar to that of early Miocene primates and indicates mainly generalized arboreal quadrupedal behaviours similar to those of less specialized New World monkeys such as Cebus. Robust jaws and thick enamelled teeth indicate a hard fruit diet. The 2 best known species of fossil ape are known from the site of Paşalar in Turkey. They have almost identical molar and jaw morphology. Molar morphology is also similar to that of specimens from Germany and Slovakia, but there are significant differences in the anterior teeth of the 2 Paşalar species. The more common species, Griphopithecus alpani, shares mainly primitive characters with early and middle Miocene apes in Africa, and it is most similar phenetically to Equatorius africanus from Maboko Island and Kipsaramon. The second species is assigned to a new species of Kenyapithecus, an African genus from Fort Ternan in Kenya, on the basis of a number of shared derived characters of the anterior dentition, and it is considered likely that there is a phylogenetic link between them. The African sites all date from the middle Miocene, similar in age to the Turkish and European ones, and the earliest emigration of apes from Africa coincides with the closure of the Tethys Sea preceding the Langhian transgression. Environments indicated for the African sites are mixtures of seasonal woodlands with some forest vegetation. The postcrania of both African taxa again indicate generalized arboreal adaptation but lacking specialized arboreal function. This middle Miocene radiation of both African and non-African apes was preceded by a radiation of arboreal catarrhine primates in the early Miocene, among which were the earliest apes. The earliest Miocene apes in the genus Proconsul and Rangwapithecus were arboreal, and because of their association with the fruits of evergreen rain forest plants at Mfwangano Island, it would appear that they were forest adapted, i.e. were living in multi-storied evergreen forest. The same or similar species of the same genera from Rusinga Island, together with other genera such as Nyanzapithecus and the small ape Limnopithecus, were associated with plants and animals indicating seasonal woodland environments, probably with gallery forest forming corridors alongside rivers. While the stem ancestors of the Hominoidea were almost certainly forest adapted, the evidence of environments associated with apes in the later part of the early Miocene and the middle Miocene of East Africa indicates more seasonal woodlands, similar to those reconstructed for the middle Miocene of Paşalar in Turkey. This environmental shift was probably a requisite for the successful emigration of apes out of Africa and made possible later movement between the continents for much of the middle Miocene, including possible re-entry of at least one ape lineage back into Africa.
Copyright 2007 S. Karger AG, Basel.

Above, Ouranopithecus fossils are compared to the more Orangutan-like Ankarapithecus. Ouranopithecus-like fossils evidently later re-entered Africa from the Middle Eastern area and were ation for the lines which later went to African apes and humans. Among them was Sahelanthropus (below, from the middle of the Sahara (then green), thought to have advanced features like the later Australopithecines and humans, but in fact these now seem to be residually primitive. Among these anatomical features were some which suggest an inclination to walking bipedally on the ground.

A new Late Miocene great ape from Kenya and its implications for the origins of African great apes and humans

  1. Yutaka Kunimatsua,b,
  2. Masato Nakatsukasac,
  3. Yoshihiro Sawadad,
  4. Tetsuya Sakaid,
  5. Masayuki Hyodoe,
  6. Hironobu Hyodof,
  7. Tetsumaru Itayaf,
  8. Hideo Nakayag,
  9. Haruo Saegusah,
  10. Arnaud Mazurieri,
  11. Mototaka Saneyoshij,
  12. Hiroshi Tsujikawak,
  13. Ayumi Yamamotoa, and
  14. Emma Mbual
Edited by Alan Walker, Pennsylvania State University, University Park, PA, and approved October 3, 2007 (received for review July 1, 2007)


Extant African great apes and humans are thought to have diverged from each other in the Late Miocene. However, few hominoid fossils are known from Africa during this period. Here we describe a new genus of great ape (Nakalipithecus nakayamai gen. et sp. nov.) recently discovered from the early Late Miocene of Nakali, Kenya. The new genus resembles Ouranopithecus macedoniensis (9.6–8.7 Ma, Greece) in size and some features but retains less specialized characters, such as less inflated cusps and better-developed cingula on cheek teeth, and it was recovered from a slightly older age (9.9–9.8 Ma). Although the affinity of Ouranopithecus to the extant African apes and humans has often been inferred, the former is known only from southeastern Europe. The discovery of N. nakayamai in East Africa, therefore, provides new evidence on the origins of African great apes and humans. N. nakayamai could be close to the last common ancestor of the extant African apes and humans. In addition, the associated primate fauna from Nakali shows that hominoids and other non-cercopithecoid catarrhines retained higher diversity into the early Late Miocene in East Africa than previously recognized.


  • bTo whom correspondence should be addressed. E-mail:
  • Author contributions: Y.K., M.N., Y.S., and E.M. designed research; Y.K., M.N., Y.S., T.S., M.H., H.H., T.I., H.N., A.M., M.S., H.T., and A.Y. performed research; Y.K., Y.S., T.S., M.H., H.H., T.I., H.N., H.S., A.M., M.S., H.T., and A.Y. analyzed data; and Y.K., M.N., Y.S., and H.N. wrote the paper.
  • The authors declare no conflict of interest.
  • This article is a PNAS Direct Submission.
  • This article contains supporting information online at

Lufengpithecus is a rather odd fossil genus and appears to have many priimitive features not related to the Orangutan line. It is thus in contrast to the contemporary Sivapithecus and there are some indications that there might be material ascribed to it which does not belong with the rest at all. This comparison shows the tooth row of Lufengpithecus to Ardipithecus, ateeth ascribed to possibly being "Lufengpithecus" are of a similar age to Ardipithecus in Africa. Other such teeth have otherwise been called Austalopithecine or proto-Australopithecine. One thing that was noticed fairly on is that the orbits (eye sockets) are not set closely together as in Sivapithecus, they are set more widely apart as in Ouranopithecus and the African great apes. At present the issue is  unresolved.  
It is rather important that Ouranopithecus, Lufengopithecus, and their allies are all generally thought to have some tendency to moving bipedally on the ground (suspected for Sahelanthropus and more definitely for Ardipithecus). From the Wikipedia entry on Gigantopithecus: "Gigantopithecus's method of locomotion is uncertain, as no pelvic or leg bones have been found. The dominant view is that it walked on all fours like modern gorillas and chimpanzees; however, a minority opinion favor bipedal locomotion, most notably championed by the late Grover Krantz, but this assumption is based only on the very few jawbone remains found, all of which are U-shaped and widen towards the rear. This allows room for the windpipe to be within the jaw, allowing the skull to sit squarely upon a fully erect spine like modern humans, rather than roughly in front of it, like the other great apes."
(then commonly used in reference to the other similar Miocene apes that were otherwise suspected of showing bipedal adaptations or at least a habitual asumption of an upright stance)

Gigantipithecus is commonly stared to be a candidate to have survived as the Sasquatch, Big Yeti or Western Bigfoot. This was Grover Krantz's view and he has made the case better than any of the other proponents of the theory. I have made a quick mockup-reconstruction of a Gigantopithecus female as Sas based on the reconstruction of a male robust australopithecine by Jat Maternes and published in the Time-Life book Early Man. I am not sure about the nose but most of the rest is probably a fairly good likeness.. 

As to the humanlike foot of the Sasquatch, fairly long ago I had a conception which one of my friwnds described as "Gorrilla toes arranged as if they were a human foot" and to this was added an additionall elongated heel; pointing backwards. I still think that is a good descrption and I still feel that Gigantopithecus feet route for more efficient bipedal walking. It is not exactly a human foot because the toes grip the earth differently than in a human foot and the toes have an inhuman range of motion (Typical gorilla foot on the far left, the elements of the foot rearranged as in Sasquatch on the right)

Sunday, 29 April 2012

Miocene Apes and The Smaller Yeti (Migu)

Reconstruction-portraits for the Scientific American article on Miocene apes, artwork by John Gurche on the left. The two reconstructions above represent forms of Sivapithecus, thought to have been directly ancestral to the Orangutans of Asia. Miocene apes in general seem to have gone through the three stages illustrated at left: the small and early Proconsuls which had apelike teeth but had be monkeys and lived much like them when they were in their heydays went more or less directly into the larger and more diversified Dryopithecines (best represented in Europe) and then on to the more fully apelike forms typified by Sivapithecus. John Gurche remarks that Sivapithecus took everything that made apes distinctive and then exaggerated the features as much as they could.l chart placing fossil apes and humans together and showing their assumed relationships.

Fig. 1 Reconstructions and partial reconstructions of the craniums of fossil apes: (a) Proconsul, (b) Afropithecus, (c) Oreopithecus, (d) Ouranopithecus, (e) Sivapithecus, and (f) Ankarapithecus.

Oreopithecus, one of the Miocene apes of which we have full skeletons, and its reconstruction below. It has bipedal adaptations and limb proportions about like a gorilla, and it evidently had an ecleclectic selection of locomotor modes including suspesnion by the arms ("Swinging through the Trees") Please note the widely opposed big toe of the foot in the painting below.
Ardipithecus feet, much more recent fossil form but evidently still the conservative form of the hands and feet, much like Oreopithecus (skeletons for Ardi hands and feet below)mal stance on the ground includes a widely-spread big toe. Ardipithecus survived until about four million years ago and is thought to have been directly ancestral to Australopithecus.

Hands of fossil apes. The two hands on the left are different specimens of Oreopithecus, which are smaller and more generalized than the later ape pictured on the right, with more obvious adaptations for brachiation and knuckle-walking.   are shown below, indicating how far out the opposed big toe could rotate.

Oreopithecus and the other conservative early apes, right up to Ardipithecus, had the same shorter toes and widely-separated big toe as shown in casts of the Orang Pendek feet. The orangutan and Chimpanzee ancestors both had feet of this type, it was the primitive pattern. More specializations related to climbing trees followed this stage, including having the fingers and toes grow longer and more curved, and the arms lengthened and legs shortened along with this (the primitive condition has all four legs at about the same length, and even in the conservative ape types this also tends to be true. Knuckle-walking developed at different times in all three lines of great apes (chimpanzees, gorillas and orangutans) and they all have different adaptations to it: the way that chimpanzees and orangutans hold the hands when they are on all fours are also quite distinctive from one another.

The Miocene apes began to radiate out into different ecological niches by exploring different modes of locomotion. The more conservative types of Miocene apes were upright on the ground on they had committed to climbing upright in the trees rather than running along branches on all fours like monkeys do. The pattern of locomotive flexibility survived up until the Australopithecines came along, and Bonobos still tend to be that way.The earlier types of apes such as Proconsul still had the limb proportions of a baboon and they walked flat on the soles and palms of the hands, like the monkeys still do.

Above, mural at the AMNH done by Jay Matternes showing Sivapithecus climbing upright and contrasted with Proconsuls running on all fours. At right, the skeleton for the primitive proconsuls and below, a reconstruction. A small proconsul would have been the size of a rhesus monkey and a big one the size of a big baboon: they rarely stood up on their hind legs alone.
Incidentally, NO species of Miocene or Pliocene apes known from fossils has been definitively identified as being a knuckle-walker like the modern great apes. NONE of them.
A variety of early apes at the Proconsul and Dryopithecus level. These early apes were ecologically replaced by Old World monkeys when it turned out the monkeys could breed faster. They are sometimes called "Dental apes" because about the only way you could tell they were apes was from their teeth. Gibbons also descended from them and developed arm-suspension tree-climbing and brachiation or "Swinging through the trees" independantly of the other apes. Some of thir early relatives also still had tails-and long tails at that

Above, some later African apes began to develop the adaptations typical of gorillas and chimpanzees. In Asia the descendants of Sivapithecus did also, but independantly with different adaptations.

Sivapithecus fossil and Orangutan skull.

Sivapithecus males and females were so dimporphic (differene from each other) that originally their fssils were put into distinct genera, the females being thought to be much more advanced. At the right, a very "Yeti"-like reconstruction portrait.
Above some more reconstructions showalking upright on the ground, and the skeleton of Ardipithecus which still showed adaptations for walking upright on the ground, in the conservative Miocene Ape pattern. The immediate ancestors of the orangutans were the descendants of Sivapithecus which lived in Southern Asia and were walking upright on the same primitive (Orang Pendek) pattern of feet, but they grew to about the same size as gorillas so we know they were NOT living in trees nor yet would they have any of the usual orangutan adaptations for living in the trees as a consequence. Paleontologists commonly call the remains "Fossil Pongo" in the absence of a better names no real agreement over the classification. The "Fossil Pongo" is undoubtedly the dirsct forerunner of the "Yetis", Yerens, Xing-xings and Hibagons. Below at left is Michel Raynal's depiction of "le Petit Yeti" of Heuvelmans, the smaller red-haired type of "Abominable Snowman" described by the Sherpas: educated Tibetans translate the meaning of its name as being  like "Chimpanzee". At the right is Dale Drinnon's reconstruction drawing of the same creature done as an illustration submitted to PURSUIT in the 1990s, ultimately never published. The two reconstructions shae many similarities and the fact that each one was made independantly and without any knowledge of the other is somsupport the idea tat the representations could be getting near to the truth of the matter.