Date of this Version
The American Museum of Natural History no. 2930, 32 pp.
In studies of carnivoran phylogeny, the configuration and ontogenetic development of the auditory bulla enclosing the middle ear have been useful in tracing modern lineages to their first appearances in the mid-Cenozoic. Pre-Oligocene carnivorans, however, lack preserved bullae and have been difficult to relate to later Cenozoic groups. The carnivoran petrosal bone, because of its durability both in intact skulls and as an isolated element, can be tracked through Cenozoic time, and can supply new information on lineage continuity through its geometry and spatial relationships. Aeluroid carnivorans are united by a petrosal of characteristic shape, distinguished by a ventral promontorial process buttressing the lateral margin of the basioccipital. The configuration of the process is highly uniform in most living aeluroids (viverrids, herpestids, hyaenids) but has been suppressed in modem felids by encroachment of an inflated auditory bulla. Ancestral proailurine felids, however, retain the process. Among living aeluroids, the African palm civet Nandinia binotata is distinguished by a somewhat differently configured ventral promontorial process, which is more posteriorly situated and robust. Comparison with fossil aeluroid basicrania indicates that the form of Nandinia's petrosal closely approximates the petrosals of Oligocene stenoplesictine aeluroids from the Quercy fissues of France. Stenoplesictines are the oldest generally acknowledged aeluroids represented by basicranial remains. The strong anatomical correspondence shared by the Quercy stenoplesictine basicrania with the basicranium of Nandinia reflects the plesiomorphic auditory structure of these groups. However, relative to stenoplesictines, Nandinia's auditory region is more primitive in the structure of the auditory bulla and surrounding basicranium; its basicranium is arrested at a pre-Oligocene structural grade, and is representative of the projected ancestral aeluroid morphotype. Survey of the aeluroid fossil record suggests that the modem aeluroid basicranial and bulla patterns developed in the mid- to late Miocene, and were well established by the Plio-Pleistocene. Prior to the mid-Miocene, an array of archaic basicranial patterns characterized the aeluroid Carnivora.