E. L Simons

New Specimens of Oligopithecus savagei, Early Oligocene Primate from the Fayum, Egypt

New specimens of the early Oligocene anthropoidean, Oligopithecus savagei, from the Fayum, Egypt, include unworn specimens of lower teeth plus the first known upper molar, premolar, and incisor. These finds confirm the anthropoidean status of Oligopithecus. Comparisons with other Fayum taxa suggest that Oligopithecus is more closely related to Propliopithecidae than to Parapithecidae. Dental similarities between Oligopithecus and early platyrrhines are probably primitive retentions that do not support the hypothesis of an Oligocene trans-Atlantic crossing by primates. Among prosimians, the upper teeth of Oligopithecus very closely resemble those of Protoadapis and allied forms (Europolemur, Mahgarita, Periconodon, Hoanghonius), but differ substantially from other prosimian taxa. Most of the dental and osteological resemblances between Oligopithecus and the Protoadapis group are derived features, thus favoring the hypothesis that Oligopithecus and other Anthropoidea are descended from Adapidae.

Skeletal Remains of Propliopithecus chirobates from the Egyptian Oligocene

A distal humerus, a fragmentary ulna, a tibia and several partial calcanei from Oligocene sediments in the Fayum Province of Egypt are attributed to Propliopithecus chirobates. Comparison and analysis of this material indicates that this species was an arboreal quadruped. All of the skeletal elements are more similar to the same bones in the Miocene hominoid Pliopithecus vindobonensis than to any extant primate species. Like Pliopithecus and Aegyptopithecus zeuxis, Propliopithecus exhibits numerous primitive skeletal features and more closely resembles living ceboids than either extant hominoids or cercopithecoid monkeys.

New pedal remains of Megaladapis and their functional significance

New remains of Megaladapis from the caves within the Ankarana Range of northern Madagascar and the cave site of Ankilitelo near Toliara in southwestern Madagascar add considerably to the present sample of pedal remains for this genus. Here we describe and analyze the new pedal material and discuss the function of the Megaladapis foot in terms of positional behavior and substrate use. The northern specimens belong to the M. madagascariensis /M. grandidieri group in terms of size and morphology whereas the new southwestern fossils are assigned to M. madagascariensis. The new specimens demonstrate that the small and intermediate sized M. madagascariensis and M. grandidieri were very similar in anatomy and inferred locomotor function, findings that also support the prior suggestion that they belong to a single widespread subgenus (Megaladapis). The new fossils provide the first examples of many pedal elements and present the first opportunity to analyze the whole pedal complex from associated remains. The foot of Megaladapis is distinctive among primates in numerous features. Intrinsic proportions of the hindlimb indicate that the foot is relatively longer than that of any other primate. The first complete calcanei reveal a large and highly modified hindfoot. The calcaneus is reduced distally, indicating an emphasis on climbing over leaping or quadrupedal walking and running. Proximally, a large, medially directed calcaneal tuberosity suggests both a strong inversion component to plantarflexion and a well-developed abductor mechanism and recalls the calcaneal morphology of the larger lorisines in some respects. Talar shape is consistent with considerable tibial rotation during plantarflexion and dorsiflexion. The subtalar joint is designed to emphasize supination/pronation and medial/lateral rotation over proximodistal translation. The distal tarsals are extremely reduced in length, and they form a high transverse arch and a serial tarsus; this configuration promotes inversion/eversion at the transverse tarsal joint. The phalanges are long and moderately curved, and the hallux is very long, robust, and abducted. Pedal morphology suggests that Megaladapis (subgenus Megaladapis) was well adapted to exploit an arboreal environment.(ABSTRACT TRUNCATED)