Feloidea - Evolution

Evolution

In the Middle Palaeocene (60 million years ago), Miacoidea appears. Miacoids were a group of paraphyletic taxa believed to be basal to Carnivora. They had Carnivora-like carnassials but lacked fully ossified auditory bullae. Miacids were small arboreal carnivorans and, based on their size (roughly that of mongooses), they probably fed on insects, small mammals and birds.

The miacoids are divided into two groups: the miacids, with a full complement of molars, and the viverravines with a reduced number of molars and more specialized carnassials. These dental differences resemble the difference between Caniforms (with more teeth) and Feliforms (with fewer teeth) but this may not mean evolutionary lineages. It was thought that Viverravidae was basal to the Feliforms. However, recent studies suggest this is not the case (Wesley-Hunt and John J. Flynn 2005).

In the Middle Eocene (about 42 mya) the miacids started to branch into two distinct groups of the order Carnivora: the Feliforms and Caniforms. The miacid precursors to the extant Feliforms remained forest-dwelling, arboreal or semi-arboreal ambush hunters, while the Caniform precursors were more mobile, opportunistic hunters. While it is clear the first Feliforms appeared at this time, there is no clear common ancestor of the Feliform families in the fossil records. As forest dwellers, the early Feliforms were subject to more rapid decomposition in the absence of sedimentary materials, resulting in large gaps in the fossil records.

For more discussion on feliform evolution and the divergence from the caniforms, together with additional external references on this subject, see the articles on Carnivora, Miacoidea and Carnivoramorpha.

The diagram below presents a contemporary (2010) view of feliform evolution and familial relationships (cladogram) overlaid onto the geological time scale. The information presented is based on fossil records and systematic classifications.