Date of this Version
THE AMERICAN MUSEUM OF NATURAL HISTORY Number 3030, 25 pp.
Among the mammalian fossils discovered in were crania and mandibles of rare carnivorans, 1930 by the Central Asiatic Expedition of the including the first complete skulls of several Asian American Museum of Natural History (New York) mid-Miocene lineages. Most of these fossils came in the Tung Gur Formation of Inner Mongolia from a single locality termed Wolf Camp Quarry that produced, among other striking finds, a small fox-sized cranium referred to a new genus and species Tungurictis spocki Colbert 1939. Today this remains the only known cranium of Tungurictis yet discovered. Preparation and reinterpretation of the auditory region demonstrate that Tungurictis belongs to an early lineage of Hyaenidae, although it has long been regarded as a viverrid. The WolfCamp Quarry cranium of Tungurictis combines a hyaenid auditory bulla structure with incipient hyaenid specializations of the cheek teeth, indicating that the typical bulla pattern evolved prior to the robust, bone-crushing dentitions that characterize living species of Crocuta and Hyaena. Previously undescribed remains of left and right hindfeet found in Wolf Camp Quarry near the skull are attributed to the same species, if not the same individual, and indicate that a digitigrade paraxonic stance characterized this small Asian carnivore. Tungurictis has been identified only in the Tung Gur Formation of Mongolia, with the exception of a doubtfully referred upper jaw fragment from north Africa. However, a survey of dentitions of small mid-Miocene European hyaenids indicates that the cheek teeth of Tungurictis spocki are comparable to the holotype dentition of Protictitherium gaillardi (Forsyth-Major, 1903) from the mid- Miocene of La Grive, France. So similar is the dental morphology that hyaenid basicranial structure can be reasonably inferred for P. gaillardi, and for Protictitherium for which no basicranium was known. Thus, at least three lineages of small hyaenids with plesiomorphic dentitions (lacking durophagous specializations of the premolars and carnassials) lived in Eurasia during the Miocene: (1) a Protictitherium (Tungurictis) lineage, with hypercarnivorous dentition and hyaenid auditory region; (2) a Protictitherium (Protictitherium) lineage, known chiefly from dentitions in which the ml entoconid is emphasized-an intact auditory region is not yet identified; (3) a Plioviverrops lineage, with hypocarnivorous dentition and hyaenid auditory region. Two additional early hyaenid lineages (Miohyaena, Percrocuta) of the mid-Miocene cannot be confused with Protictitherium or Plioviverrops because they show a precocious development of durophagous dental specializations, heralding the large bone-crushing species of the later Cenozoic of Eurasia. Old World Miocene hyaenids parallel New World Miocene canids in body size, skull form, dental specialization, and diversity. Small, intermediate, and large-sized digitigrade canid and hyaenid ecomorphs are known during the Neogene, some with plesiomorphic skull form and dentition, others with derived "hyaenoid" cranium and teeth, including durophagous animals of large body size within both Hyaenidae (Dinocrocuta, Pachycrocuta, Adcrocuta) and Canidae (Epicyon, Borophagus, Osteoborus).