The Hyaenidae: taxonomy, systematics and evolution

Today the Hyaenidae is a small carnivore family. In the fossil record, however, hyaenids are both diverse and abundant, and nearly 100 species have been named. Hyaenids have an expanded ectotympanic and semi-recumbent to recumbent septum bullae, and all fossil taxa likely to display this morphology are reviewed herein. Taxonomic and nomenclatural problems have hampered the study of this group. The taxa are treated in two groups: the core taxa, including the 18 (3 Recent and 15 fossil) best known taxa, and the remaining taxa, which for the most part are poorly known. In the phylogenetic analysis of the extant taxa it is found that Proteles cristatus is sister group to the other three species, which form an unresolved trichotomy. Next, P. cristatus is removed and the fossil core taxa added. The resulting cladogram topology is (Ancestor (P. orbignyi, (T. spocki (I. viverrinum (H. wongü (H. hyaenoides (((L. dubia (C. borissiaki, C. lunensis)) (P. reperta (I. abronia (B. beaumonti (L. lycyaenoides (H. hyaena (P. brunnea (P. perrieri (P. brevirostris (A. eximia (C. crocuta)))))))))))))))))). The remaining taxa are placed with reference to this cladogram, and a cladistic classification of the Hyaenidae is presented on this basis. The interrelationships of Feloidea are discussed on the basis of several recent publications. The fossil record of hyaenids negates many current ideas, and the feloid cladogram is at present unresolved. The key taxon Herpestides antiquus is reviewed and found to share no synapomorphies with hyaenids. The age of the Hyaenidae is suggested to be some 25 million years. This is compatible with biochemical dates. Macroevolutionary patterns in the Hyaenidae are examined on the basis of the established cladogram and are found to be overwhelmingly gradual. Taxic patterns show that the Hyaenidae were most diverse in the late Miocene (Turolian). The family is divided into 'hyaenid' and 'non-hyaenid' forms. The diversity patterns of these two groups differ. The 'non-hyaenid' forms show a decrease in diversity which is strongly correlated with the invasion of Eurasia by dogs (family Canidae) in the late Miocene-early Pliocene. Biogeographic patterns within the Hyaenidae are generally uninformative.