A Review of Oreopithecus Bambolii

Michael HuffstutlerCreated for the Department of Anthropology

A Comprehensive Review of Oreopithecus bambolii: An Island Dwelling Anomaly

Written for the University of Minnesota Twin-Cities [2013]

Post-dating the original discovery of a jaw belonging to

Oreopithecus in 1872, and since the discovery of a rather complete

skeleton of the species in 1958 in the coal mines of what is

today Tuscany1, Oreopithecus bambolii has presented a complex idea of

what it might mean to be human, what it may mean to be ape, and

furthermore what how these anatomical differences help

paleoanthropologists better understand other lineages as well as

our own. Some claims describe Oreopithecus as having anatomically

similar features as to humans when looking at the pelvic

architecture, lumbo-sacral region, the femora, and the feet.

These features have in-turn been described as being closely

related to australopithecines as well as modern humans.2 However,

1 Among dozens of other fossils, the impressive, almost complete skeleton of Oreopithecus bambolii was discovered by Johannes Hürzeler. Due to the implications that it would have been able to walk on two legs, Hürzeler first thought that it may have been an extremely early human ancestor upon its discovery. Note that the original discovery of Oreopithecus was by Paul Gervais in 1872 on Monte Bamboli. See Wayman, E. (December, 2011). Human Evolution’s Cookie Monster, Oreopithecus. Smithsonian. 2 Wayman, E. (December, 2011). Human Evolution’s Cookie Monster, Oreopithecus.Smithsonian.

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Oreopithecus bambolii

a strong argument of opposition has been predicated on the

foundation that Oreopithecus in fact was an ape and not part of our

lineage.3 Understanding the origin of Oreopithecus and its

anthropological and phylogenetic meaning forces a new perspective

of what being ape, and what being human may actually mean, and

where the line is drawn.

Due to its unique island environment 6-7 million years ago

in the Miocene epoch, Oreopithecus likely became increasingly

specialized due to its environmental surroundings. Lacking any

natural predators, there would be less of a necessity to hone a

solely arboreal locomotive repertoire since moving in a

terrestrial manner would have proved quite safe for the species4.

A transition to incorporating bipedalism would have saved this

Miocene creature energy, adapting towards more efficient means of

movement. However, there were probably high levels of competition

for food and other natural resources due to the confined space of

3 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15). 4 Matson, S., Rook, L., Oms, O., Fox, D. (July, 2012). Carbon isotopic record of terrestrial ecosystems spanning the Late Miocene extinction of Oreopithecusbambolii, Baccinello Basin (Tuscany, Italy). Journal of Human Evolution (v63, i1).

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the Italian island and the limited amounts of available

resources, which may further explain why a broader repertoire

arose5. Paleobotanical data generally associated with Oreopithecus

would suggest that it inhabited mixed mesophytic forests with

scattered swamp and marshland incorporated6. However, evidence

from a study conducted on the eco-morphological features of

extinct endemic Muridae7. It can probably be assumed that there

were wetland like environments on part of the Tuscan-Sardinia

bioprovince, while other areas tended to be drier and open. Due

to the fact that all localities of Oreopithecus are insular in the

Late Miocene, typical fauna found and associated with this

species generally have unique adaptations and morphology based on5 Begun, D. (2007). Fossil Record of Miocene Hominoids. Pgs. 962-964. 6 Cassanovas-Vilar, I., Van Dam, J., Moya-Sola, S., Rook, L. (July, 2011). Late Miocene Insular Mice from the Tusco-Sardinian Palaeobioprovince Provide new insights on the Palaeoecology of the Oreopithecus Faunas. Journal of HumanEvolution (v61, i1). 7 An explanation of the overall results and conclusions found from the study of mice on an insular island: “Our results show that the successive species ofendemic insular murids (Huerzelerimys and Anthracomys) evolved a number of adaptations observed only in extant family members that include significant proportions of grass in their diet. While this fits the pattern exhibited by large mammals, it contrasts with the available palaeobotanical information, which indicates that grasses were minor components of the vegetation. This contradiction may be explained because these endemic murids may have been adapted to the consumption of particular food items such as hard parts of aquatic plants (as shown by some extant murid species).” Cassanovas-Vilar, I.,Van Dam, J., Moya-Sola, S., Rook, L. (July, 2011). Late Miocene Insular Mice from the Tusco-Sardinian Palaeobioprovince Provide new insights on the Palaeoecology of the Oreopithecus Faunas. Journal of Human Evolution (v61, i1).

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an isolated environment, making comparison difficult to any other

parts of the world8. Conflicting paleoenvironmental data such as

these results have fueled controversy and debate about what the

true environment of Oreopithecus may have been during a much warmer

epoch and a different climatological spectrum than the Holocene.

Although the 1958 cranium and mandible were crushed before

the date of its discovery, they are nearly complete9. The IGF

1177810 skull reconstruction along with other specimens of

maxillae and mandibles provide insight into the architecture and

morphological features present in the crania and dentition. For

instance, the orbits are positioned above the premolars11 and the

face has been described as “Relatively short, deep, and quite

broad.12” The supraorbital ridges are pronounced and clearly

8 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).9 Rook, L., Bondioli, L., Casali, F., Rossi, M., et. al. (2004). The Bony Labyrinth of Oreopithecus bambolii. Journal of Human Evolution (v46).10 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).11 L’Engle Williams, F. (2013). Enamel Microwear Texture Properties of IGF 11778 (Oreopithecus bambolii) From the Late Miocene of Baccinello, Italy. University of Georgia, GA. Journal of Anthropological Sciences (v91).12 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).

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thickened, and the nasal aperture is relatively high and

narrow13. Furthermore, the temporal lines are positioned high on

the cranial vault and at least in male fossils these lines

undergo a sharp convergence, forming a sagittal crest14. In these

respective instances, the cranium of Oreopithecus bambolii is

representative of a primitive catarrhine morphotype15. The set of

catarrhine-like features exhibited by Oreopithecus are not found in

any recent catarrhines, but instead suggests a resemblance close

to New World Monkeys and catarrhine families such as the

hylobatids and the sub-family colobinae16. In numerous ways as

well, the cranium also exhibits derived traits. For example, the

anterior origin of the zygomatic arch is forwardly oriented on

13 A further, detailed explanation goes on to assert: “The anterior margin of the temporal fossa behind the orbit is rounded and relatively robust in the region on the frontal, but becomes distinctly more angular in its malar component; the external orbital margin is smoothly rounded rather than angular; the nasal aperture is relatively high and narrow; the anterior root of the zygomatic arch is situated close to the alveolar margin of the cheek teeth; the neurocranium is globular, but relatively low.” Harrison, T. (1986).A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of Human Evolution (v15).14 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).15 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).16 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).

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the face. This anatomical characteristic is contrary to recent

catarrhines, in which the origin of the zygomatic is positioned

more posteriorly17. Australopithecine and other non-catarrhine

primates such as Cebus have also exhibited this feature.

Respectively, all of the above were specialized and adapted

towards a stronger chewing apparatus and increased jaw strength.

Essentially, this trait would have arisen to provide an increased

ability to chew. When the estimated body size of Oreopithecus is

taken into account, the brain size was relatively small.

One of the more prominent hypotheses about Oreopithecus is

that it may be ancestral to the great apes. As seen in

orangutans, a robust zygomatic arch with an upwards curvature is

evident18. Similar to Sivapithecus as well as other non-hominids, the

articular and temporal portions of the temporal bone remain

unfused; however, the subarcuate fossae are small, in likeness

17 In Oreopithecus, the anterior root of the zygomatic arch is positioned above P4-M1. In more recent catarrhine taxa, this initial point is located posteriorly. There have been suggestions that the primitive placement was likely above the M2 region (Harrison, 1982). Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of Human Evolution (v15).18 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).

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with hominids19. The maxilla has a substantially thick

architecture, while the mandible is short, with a high and

vertical ascending ramus and a pronounced gonial angle20.

Although these derived features shed comparative light to the

primitive features exhibited by the skull of Oreopithecus, they are

likely a functional set of autapomorphies adapted around a

specialized masticatory structure21. These specialized traits no

doubt have been influenced by the insular environmental

geographic landscape that this creature inhabited millions of

years ago.

It is generally well accepted that Oreopithecus was a

folivore, and maintained a diet that consisted mainly of leaves,

a variety of terrestrial vegetation, and insects22. This dietary

pattern is neontologically comparable to that of Gorilla. However,

small fauna may have also played a smaller role in diet, as seen

in Pan Because of the estimated large body size of IGF 11778, it 19 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).20 Rook, L., Bondioli, L., Casali, F., Rossi, M., et. al. (2004). The Bony Labyrinth of Oreopithecus bambolii. Journal of Human Evolution (v46).21 Begun, D. (2007). Fossil Record of Miocene Hominoids. Pgs. 962-964.22 L’Engle Williams, F. (2013). Enamel Microwear Texture Properties of IGF 11778 (Oreopithecus bambolii) From the Late Miocene of Baccinello, Italy. University of Georgia, GA. Journal of Anthropological Sciences (v91).

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is reasonable to conclude that Oreopithecus would have had to

consume large amounts of leaves to achieve the necessary protein

requirements. Similar to colobines, more prominent features in

the dentition of Oreopithecus include high-cusped molars and

relatively small incisors23. High-cusped molars would be useful

for shearing and shredding leaves, as well as tougher vegetation

such as roots and tubers. These adaptive features are consistent

with other primates whose diet was centered on folivory.

In a study conducted on the textual properties of enamel

microwear, Oreopithecus was found to have a relatively complex

surface enamel texture24. One major feature identified through

dental microwear is striations on the enamel of various

dimensions, yet only a mild amount of pitting was present25. 23 Cassanovas-Vilar, I., Van Dam, J., Moya-Sola, S., Rook, L. (July, 2011). Late Miocene Insular Mice from the Tusco-Sardinian Palaeobioprovince Provide new insights on the Palaeoecology of the Oreopithecus Faunas. Journal of HumanEvolution (v61, i1).24 L’Engle Williams, F. (2013). Enamel Microwear Texture Properties of IGF 11778 (Oreopithecus bambolii) From the Late Miocene of Baccinello, Italy. University of Georgia, GA. Journal of Anthropological Sciences (v91).25 The author briefly discusses the importance of the specialized morphological dentition present in Oreopithecus. Oreopithecus was most likely the last surviving taxon of broad radiation of western European Miocene hominoids.By approximately 9.6mya during the “Vallesian Crisis,” all of these hominoids except Oreopithecus seem to have gone extinct. During this, time, deciduous species began to dominate the tropical landscape, indicating a more seasonal climate shift (Rook et. al, 2000). Oreopithecus most likely survived this crisisbecause it lived in an insular environment, and because of its morphological adaptations. However, by about 7mya when the Tusco-Sardinian Island

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Heavy chewing is evident and indicated by the ectocranial

superstructures. The study goes on to assert that “ The forward

projection of the zygomatic arch and the presence of a sagittal

crest suggest masticatory functional affinities with

Australopithecus perhaps indicative of a rather coarse fiber-rich

diet26.”

While Oreopithecus does follow a catarrhine dental formula of

2.1.2.3., many morphological characteristics and specialized

traits set it apart from the rest. For instance, the crown of the

upper molars is not as broad as it is long and to some degree

display bucco-lingual waisting27. Moving from M1 to M3, the upper

molars, with distinct crests, continue to increase in size. The

upper premolars are also very distinctive, and derived in

numerous ways. The crown is long and narrow, and the two cusps

are elevated, and evident in both P3 and P4, the cusps are

reconnected with Europe, Oreopithecus went extinct. L’Engle Williams, F. (2013). Enamel Microwear Texture Properties of IGF 11778 (Oreopithecus bambolii) From the Late Miocene of Baccinello, Italy. University of Georgia, GA. Journal of Anthropological Sciences (v91).26 L’Engle Williams, F. (2013). Enamel Microwear Texture Properties of IGF 11778 (Oreopithecus bambolii) From the Late Miocene of Baccinello, Italy. University of Georgia, GA. Journal of Anthropological Sciences (v91).27 L’Engle Williams, F. (2013). Enamel Microwear Texture Properties of IGF 11778 (Oreopithecus bambolii) From the Late Miocene of Baccinello, Italy. University of Georgia, GA. Journal of Anthropological Sciences (v91).

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essentially subequal in height28. Furthermore, the transverse

crest that links the cusps together is poorly-developed and is

subdivided by a rigidly defined sulcus29. The lower molars have

sharply-defined crests paired with a specialized occlusal

morphology. The upper molars have been described as

“Cristodont30,” which closely mirror the resemblance of the lower

molars. This specialized dentition draws close parallels with,

and could reasonably be suggested to be the precursor to

bilophodont molars, as seen in Old World monkeys. The lack of a

diastema suggests the canines were roughly the same size as the

rest of its small and gracile dentition31. From this it would be

logical to assert that there was probably a reduced amount of

sexual dimorphism, and that inter-male mating competition was

low. This same trend has been and continues to be exhibited by

many primate species. While the rather thin enamel allows for

similarity compared to Dryopithecus and the African apes32, the

28 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).29 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).30 Begun, D. (2007). Fossil Record of Miocene Hominoids. Pgs. 962-964.31 Begun, D. (2007). Fossil Record of Miocene Hominoids. Pgs. 962-964.32 Begun, D. (2007). Fossil Record of Miocene Hominoids. Pgs. 962-964.

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uniquely robust lingual cingulum and lingual pillar33 further

extends the list of derived dental features that distinguishes

Oreopithecus from other catarrhines.

Although the preservation of the post-cranial skeleton of

Oreopithecus is rather complete, its combination of various

primitive and derived hominoid features make it very difficult to

establish a phylogenetic position for with great certainty. The

forelimbs are much longer than the hind limbs, giving Oreopithecus

the highest intermembral index out of all the extant apes besides

Gorilla and the Asian apes. The measured range has been measured

from 118-6 to 121-434 (See figure/fn 35).

33 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).34 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).

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35

This pronounced limb elongation can be functionally

associated with adaptations towards arboreal behavior and a

suspensory mode of locomotion. The high intermembral index found

in Oreopithecus suggests a phylogenetic link to the Hominoidea36.

Some features such as the radius, the distal ulna, the lunate,

and the head and shaft of the proximal humerus could have

provided valuable insight into unique morphological

characteristics and phylogenetic affinities of Oreopithecus37;

35 Photo courtesy of: Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York.Journal of Human Evolution (v15).36 Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of HumanEvolution (v15).37 All of the above mentioned characteristics were badly crushed by natural causes. Reconstructions would not have been reliable. Harrison, T. (1986). A Reassessment of the Phylogenetic Relationships of Oreopithecus bambolii Gervais. New York University, New York. Journal of Human Evolution (v15).

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however, the degree of diagenetic alteration present in each

feature is too severe to make form any conclusive statements.

One lingering controversial aspect of Oreopithecus’ post-

cranial functionality is whether or not habitual terrestrial

bipedalism was part of its locomotive repertoire. Evaluating the

lumbosacral region has been a formidable point of defense for

those who conclude that habitual terrestrial bipedalism is not

exhibited in the skeletal-lumbar adaptations that are found. The

medio-laterally broad thorax and short lumbar region present

evidence for a locomotive repertoire of arboreal climbing and

suspensory behavior38. The shortened lumbar spine comprised of

five vertebrae is more like that of living hominoids. With regard

to the sacrum, the rectangular shape of the S1 the ventral face

of S1 in Oreopithecus39 draws similarities to that of the living

38 Obtained from (Schultz, 1960, 1961; Straus, 1963; Hürzeler, 1968) as used in Russo, G.A., Shapiro, J.L. (2013). Reevaluation of the lumbosacral region of Oreopithecus bambolii. University of Texas at Austin, Texas. Journal of Human Evolution. 39 In this portion of the sacral region discussion, BA #72 is the specimen in regard.

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apes40 (See figure below/fn 41).

40 Obtained from (Schultz, 1960) as used in Russo, G.A., Shapiro, J.L. (2013).Reevaluation of the lumbosacral region of Oreopithecus bambolii. University ofTexas at Austin, Texas. Journal of Human Evolution.41 Photo courtesy of: (Schultz, 1960) as used in Russo, G.A., Shapiro, J.L. (2013). Reevaluation of the lumbosacral region of Oreopithecus bambolii. University of Texas at Austin, Texas. Journal of Human Evolution.

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This exhibits good evidence that there were probably more than

three vertebrae that made up the sacrum. In comparison, the

ventral face of S1 in monkeys which possessed only three sacral

vertebrae takes on a trapezoidal shape rather than rectangular42.

The examination of a partial sacral specimen43 was able to

indicate that Oreopithecus actually had six sacral vertebrae.

Even though the specimen examined is missing most of the first

sacral vertebra, the fact that it would have had six sacral

vertebrae is indicative that Oreopithecus morphologically aligns

with living non-human great apes44. The counter-argument that

Oreopithecus would have been a habitual and facultative biped cites

evidence that the specimen they examined to produce their results

(IGF 11778; the same used for the arboreal argumentation) had a

“Well-developed sacropubic and ilioischial trabecular bundles

like those found in modern humans, indicating that Oreopithecus and

42 Obtained from (Schultz, 1960) as used in Russo, G.A., Shapiro, J.L. (2013).Reevaluation of the lumbosacral region of Oreopithecus bambolii. University ofTexas at Austin, Texas. Journal of Human Evolution.43 The specimen being compared next to BA #72 now is BA #50. 44 Obtained from (Harrison, 1987; Lovejoy and McCollum, 2010; Williams, 2011) as used in Russo, G.A., Shapiro, J.L. (2013). Reevaluation of the lumbosacral region of Oreopithecus bambolii. University of Texas at Austin. Journal of Human Evolution.

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humans share similar patterns of pelvic weight transmission45.”

There has also been debate over whether the skeletal architecture

of the hand and phalanges promotes the argument for habitual

bipedalism or arborealism. Proponents46 for the bipedalism

hypothesis argue that the hand features a derived, human-like

precision grip. They explain that the inferior border of the

ischiopubic border possesses coarse and rough crests for the

attachment of perineal musculature47. A reappraisal of the

skeletal hand material for IGF 11778 found that Oreopithecus had

curved manual phalanges and an ape like power grasp. These

characteristics are commonly found and associated with forelimb

suspensory and vertical climbing locomotion48. A re-evaluation of

specimen BA# 71 argues that many postcranial features cited as 45 Rook, L., Bondioli, L., Köhler, L. et. al (March, 1999). Oreopithecus Was aBipedal Ape After All: Evidence From the Iliac Cancellous Architecture. National Academy of Science (v96). University of California, Berkeley, CA.46 Originally from (Moya-Sola et. al., 1995, 2000). The argument was based on IGF 11778 and BA# 140. (Harrison, 1987; Lovejoy and McCollum, 2010; Williams, 2011) as used in Russo, G.A., Shapiro, J.L. (2013). Reevaluation of the lumbosacral region of Oreopithecus bambolii. University of Texas at Austin. Journal of Human Evolution.47 (Harrison, 1987; Lovejoy and McCollum, 2010; Williams, 2011) as used in Russo, G.A., Shapiro, J.L. (2013). Reevaluation of the lumbosacral region of Oreopithecus bambolii. University of Texas at Austin. Journal of Human Evolution.48 Originally from (Sussman, 1984, 2004, 2005) Also see (Deane & Begun, 2008).(Harrison, 1987; Lovejoy and McCollum, 2010; Williams, 2011) as used in Russo,G.A., Shapiro, J.L. (2013). Reevaluation of the lumbosacral region of Oreopithecus bambolii. University of Texas at Austin. Journal of Human Evolution.

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adaptations for bipedalism in Oreopithecus are commonly found in

highly suspensory extinct and extant mammals as well. Included

features are a well-developed ischial spine (sloths, suspensory

sub-fossil lemurs), and the length and robusticity of the

metatarsals49.

While evidence from the lumbosacral region and analysis of

the skeletal hand architecture seem to point towards Oreopithecus

having a more arboreal and climbing like locomotive repertoire,

evidence from the architecture of the iliac cancellous network

supports the theory that there was in fact a significant

component of bipedalism in Oreopithecus’ locomotion50.

49 Originally from (Wunderlich et. al, 1999). (Harrison, 1987; Lovejoy and McCollum, 2010; Williams, 2011) as used in Russo, G.A., Shapiro, J.L. (2013). Reevaluation of the lumbosacral region of Oreopithecus bambolii. University ofTexas at Austin. Journal of Human Evolution.50 Rook, L., Bondioli, L., Köhler, L. et. al (March, 1999). Oreopithecus Was aBipedal Ape After All: Evidence From the Iliac Cancellous Architecture. National Academy of Science (v96). University of California, Berkeley, CA.

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51

51 This photo illustrates the similarities in architectural structure between Oreopithecus and Homo. Photo courtesy of: Rook, L., Bondioli, L., Köhler, L. et. al (March, 1999). Oreopithecus Was a Bipedal Ape After All: Evidence From the Iliac Cancellous Architecture. National Academy of Science (v96). University of California, Berkeley, CA.

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Because cancellous bone architecture and bone mechanics are

intricately related, the variation that occurs within the

patterning, structure, and degree of anisotropy are able to

produce specific locomotion related architectural patterns. In

the humans, trabecular bundles, which cross over the acetabulum

absorb and distribute loads of weight (See figure above/fn 51 for

comparison)52.

This process begins in early childhood when walking first

occurs. As biomechanical strain and magnitude increase over time,

the trabeculae thicken and develop a distinct pattern. As a

result, the general degree of anisotropy increases. The

trabecular bundles in Oreopithecus are well pronounced and set

apart from the trabecular frame in a manner similar to humans and

fossil hominids53. This differs from monkeys in apes, where the

52 The authors explain why it is useful discussing the architecture of the iliac cancellous network: “. On the whole, more than 80% of the variance in cancellous bone biomechanical behavior can be explained by measures of site specific density and textural orientation.” Rook, L., Bondioli, L., Köhler, L.et. al (March, 1999). Oreopithecus Was a Bipedal Ape After All: Evidence From the Iliac Cancellous Architecture. National Academy of Science (v96). University of California, Berkeley, CA.53 The authors further illustrate here precisely where thickening and patterning is evident: “Especially along the sacropubic bundle running from the auricular surface and the posterior superior and inferior iliac spines toward the trabecular chiasma.” Rook, L., Bondioli, L., Köhler, L. et. al (March, 1999). Oreopithecus Was a Bipedal Ape After All: Evidence From the Iliac Cancellous Architecture. National Academy of Science (v96). University

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distinction fades. The superior and posterior marginal bundles

appear to be much thicker than those of any extant apes, and

patterning in the sacropubic bundles in distinctly traceable from

the posterosuperior portion of the blade toward the iliac body

and the upper acetabular rim54. Overall, features such as the

density of the cancellous network, anisotropy of the cancellous

network, long ischial spine, a short pubic symphysis, a short

ischium, and the position of peak locomotive strain have been

observed to be different than any nonhuman primate, and

illustrate that the skeletal architecture of Oreopithecus would

have been compatible with a form of bipedal locomotion55.

Since its discovery, Oreopithecus has puzzled anthropologists

and archaeologists for years. Some have phylogentically placed it

as a stem in close relationship to Dryopithecus, while others have

of California, Berkeley, CA.54 Rook, L., Bondioli, L., Köhler, L. et. al (March, 1999). Oreopithecus Was a Bipedal Ape After All: Evidence From the Iliac Cancellous Architecture. National Academy of Science (v96). University of California, Berkeley, CA.55 For their analysis, the authors discuss two hip bones of Oreopithecus bambolii that were qualified for a structural analysis of the iliac cancellous region. A fragmentary blade and corpus from the right ilium was used from BAC 76, and an incomplete left and right ilia, left ischium, pubis, and sacrum were analyzed for the fossil specimen IGF 11778. Rook, L., Bondioli, L., Köhler, L.et. al (March, 1999). Oreopithecus Was a Bipedal Ape After All: Evidence From the Iliac Cancellous Architecture. National Academy of Science (v96). University of California, Berkeley, CA.

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offered interpretations where both Oreopithecus and Dryopithecus are

stem pongines56. The cranio-dental features can be most closely

associated with recent hominoid primates57. The morphology of

both the cranium and the dentition appear to be very specialized

and probably formed around its robust masticatory complex, giving

it significantly high bite force. These features include a

smaller brain size and its robust mandibles58. Out of any

hominid, the molars of Oreopithecus demonstrate the highest

shearing quotient, indicative of a high fiber diet59. However,

many specialized post-cranial features such as an increased

rotation in the forelimb, increased flexibility localized at the

wrist joint, and a differential use and functioning of the

forelimbs versus the hindlimbs are all similar to those of extant

apes60. Overall, the post-cranial skeleton of Oreopithecus most

56 Begun, D. (2007). Fossil Record of Miocene Hominoids. Pgs. 962-964.57 Begun, D. (2007). Fossil Record of Miocene Hominoids. Pgs. 962-964.58 Primitive features unique to Oreopithecus and not and not present in Late Miocene or extant hominids described by Begun include: “a short, gracile premaxilla, large incisive foramen, low position of the zygomatic root, small brain, a number of features of the basicranium and several postcranial characters (gracile phalanges, transversely small carpals, short, relatively gracile tarsal).” Begun, D. (2007). Fossil Record of Miocene Hominoids. Pgs. 962-964.59 L’Engle Williams, F. (2013). Enamel Microwear Texture Properties of IGF 11778 (Oreopithecus bambolii) From the Late Miocene of Baccinello, Italy. University of Georgia, GA. Journal of Anthropological Sciences (v91).60 Begun, D. (2007). Fossil Record of Miocene Hominoids. Pgs. 962-964.

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reasonably demonstrates synapomorphies with extant apes in its

prominent forelimb suspensory and arboreal climbing

adaptations61. Oreopithecus bambolii is a complex mixture of derived

and primitive traits, and has made it challenging to place

phylogenetically without great debate. Due to its insular island

environment, it likely evolved specialized adaptations and

morphological features, which could likely explain the anomalies

that are still debated. Today, Oreopithecus is well-accepted as a

hominoid that belongs into the clade of humans and great apes62

61 Begun, D. (2007). Fossil Record of Miocene Hominoids. Pgs. 962-964.62 Rook, L., Bondioli, L., Casali, F., Rossi, M., et. al. (2004). The Bony Labyrinth of Oreopithecus bambolii. Journal of Human Evolution (v46).

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A Review of Oreopithecus Bambolii

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