Xenothrix AMNHM

Phee, R. D. E. M & Meldrum, Jeff, 2006, Postcranial Remains of the Extinct Monkeys of the Greater Antilles, with Evidence for Semiterrestriality in Paralouatta, American Museum Novitates 3516, pp. 1-66 : 37-38

Xenothrix AMNHM 268003

The highly distinctive femur of Xenothrix was originally described on the basis of AMNHM 259900, a relatively intact specimen from Long Mile Cave ( MacPhee and Fleagle, 1991; fig. 18; table 10). This specimen presents an odd combination of features: some are primatelike, such as large greater and lesser trochanters, but others are rare or absent in other members of the order, such as the ‘‘fourth’’ trochanter or adductor process on the posterior aspect of the bone. As with the os coxae, functionally significant features of the femur suggests that Xenothrix was a slow, quadrupedal climber with no obvious adaptations for more energetic forms of locomotion such as leaping.

The Somerville specimen (AMNHM 268003; fig. 19) is much less complete, although for the parts represented it is actually in a better state of preservation. The femur was found in a small pile of bones on the surface of an exposed ledge on the north side of the large pit fall that represents the entrance to the cave (for a plan, see Fincham, 1997). It is thus possibly very recent in age. No additional primate elements were found among these other bones, which seem to have fallen or weathered out of openings (?owl roosts) situated about a meter above the ledge.

The shaft of the new specimen is somewhat more gracile than that of AMNHM 259900. This feature tends to emphasize the relative bulk of the condyles ( fig. 19), which are essentially intact. As noted by MacPhee and Fleagle (1991) on the basis of the less complete Long Mile specimen, the femoral condyles of Xenothrix are large, mediolaterally compressed, and define between them a broad, rather flat patellar surface. The area giving rise to the adductor process seen in AMNHM 259900 is not preserved.

For completeness, it may be briefly noted that no additional examples of femora resembling those from Coco Ree Cave (UF 40097) and Sheep Pen (UF 58350) in central hypodigm, but no progress has been made in finding a better attribution for them.

and northern Jamaica have been found in recent years (see Ford and Morgan, 1986; Ford 1990; see also MacPhee and Fleagle, 1991: their fig. 2). These specimens—both poorly preserved proximal femora—are of considerable interest because Ford described them as possessing primatelike features. MacPhee and Fleagle (1991) concluded that they differed too greatly from AMNHM 259900 to warrant their placement in the same