Oreopithecus bambolii
The Late Miocene northern Tyrrhenian palaeogeographic setting in which Oreopithecus lived was a stable, insular system forming the Tusco-Sardinian archipelago, and granting temporary isolation from the mainland within a peculiar endemic ecosystem. Surviving in isolation until 7.0-6.5 myr ago, Oreopithecus was the last European ape-like primate to become extinct. In this biogeographic context, Oreopithecus developed a number of hominin-like adaptations (homoplasies), together with peculiar cranial and dental morphological characteristics that have been considered similar to the ancestral catarrhine cercopithecoid or hominid condition. Most of the Oreopithecus craniodental anatomy has recently been interpreted as a derived structural adaptation to selective pressures favouring neoteny by heterochrony. Nonetheless, integrated into a large-bodied ape-like ch�ssis the fossil displays a wide thorax, short trunk and legs, high intermembral index, extensive elbow mobility, and widely abductable hallux. These constitute a unique mosaic of hominid-, hominin-, and cercopithecid-like features which legitimize its characterization as an "enigmatic anthropoid". from: http://www.geo.unifi.it/ricerca/bambolii.html
Oreopithecus bambolii
From Wikipedia, the free encyclopedia
| Swamp Ape Fossil range: Miocene | ||||||||||||||
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 Oreopithecus bambolii fossil | ||||||||||||||
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| †Oreopithecus bambolii Gervais, 1872 |
The Swamp Ape (Oreopithecus bambolii) is a prehistoric primate species from the Miocene epoch whose fossils have been found in Italy (Tuscany and Sardinia) and in East Africa. To date, over 50 individuals have been discovered from the Tuscan mines of Monte Bamboli, Baccinello, Montemassi, Casteani, and Ribolla, making Oreopithecus one of the best-represented fossil apes.
Etymology
The scientific name Oreopithecus quickly inspired the commonly used though unofficial name for the species among paleontologists, Cookie Monster. The true etymology, however, is rather more mundane: it comes from the Greek "oros" and "pithekos" meaning "hill-ape".
Evolutionary history
Oreopithecus bambolii evolved in isolation from other animals for at least two million years on an island in the Mediterranean where Tuscany in Italy is found today. A cooling phase around 9 million years ago transformed a tropical island into a temperate one characteristic of middle European biomes at the time. There were no large predators on the island and the apes didn't have any natural enemies. Later, probably during the ice age when the sea level dropped all over the world, a land bridge emerged and connected the island with the mainland. New species, among them large predators, were then free to invade this isolated environment where animals like the Swamp Ape were easy prey. Soon this strange primate, as well as other creatures on the island, was gone forever; a parallel to what happened when the land bridge between North America and South America joined the two continents.
Physical characteristics
Oreopithecus bambolii is estimated to have weighed 30–35 kg. It possessed a relatively short snout, elevated nasal bones, small and globular neurocranium, vertical orbital plane, and gracile facial bones. The shearing crests on its molars suggest a diet specializing in plant leaves. The very robust lower face, with a large attachment surface for the masseter muscle and a sagittal crest for attachment of the temporal muscle, indicates a heavy masticatory apparatus. Its teeth were small relative to body size. The lack of a diastema (gap) between the second incisor and first premolar of the mandible indicates that Oreopithecus had canines of size comparable to the rest of its dentition. In many primates, small canines correlate with reduced inter-male competition for access to mates and less sexual dimorphism.
Its habitat appears to have been swampy, and not savanna or forest. The postcranial anatomy of Oreopithecus features adaptations to both suspensory arborealism and bipedalism. Functional traits related to suspensory locomotion include its broad thorax, short trunk, high intermembral index, long and slender digits, and extensive mobility in virtually all joints. At the same time, it also features adaptations to upright walking such as the presence of a lumbar curve, in distinction to otherwise similar species known from the same period. Since the fossils have been dated to about 8 million years ago, this represents an unusually early appearance of upright posture. How adapted it was for bipedal walking is not known, but its fingers and arms also seems to show adaptations for climbing and swinging.
Another piece of evidence lies in the semicircular canals of the inner ear. The semicircular canal serves as a sense organ for balance and controls the reflex for gaze stabilization. The inner ear has three canals on each side of the head, and each of the six canals encloses a membranous duct that forms an endolymph-filled circuit. Hair cells in the duct’s ampulla pick up endolymph disturbances caused by movement, which register as rotatory head movement. They respond to body sway of frequencies greater than 0.1 Hz and trigger the vestibulocollic (neck) reflex and vestibuloocular (eye) reflex to recover balance and gaze stability. The bony semicircular canals allow estimates of duct arc length and orientation with respect to the sagittal plane.
During upright walking, human head rotation frequencies range between 2–8 Hz along the sagittal and coronal planes and between 1–3 Hz along the horizontal plane. Across species, the semicircular canals of agile animals have larger arcs than those of slower ones. For example, the rapid leaper Tarsius bancamus has semicircular canals much bigger than the slow-climbing Nycticebus coucang. The semicircular canals of brachiating gibbons are bigger than those of arboreal and terrestrial quadrupedal great apes. As a rule of thumb, arc size of the ducts decreases with body mass and consequently slower angular head motions. Arc size increases with greater agility and thus more rapid head motions. Modern humans have bigger arcs on their anterior and posterior canals, which reflect greater angular motion along the sagittal plane. The lateral canal has a smaller arc size, corresponding to reduced head movement from side to side.
