An African Radiation of ‘Dryolestoidea’ (Donodontidae, Cladotheria) and its Significance for Mammalian Evolution

Abstract

The Ksar Metlili Formation, from the Jurassic – Cretaceous transition (Tithonian – Berriasian) of eastern High Atlas Mountains, Morocco, has yielded one of the richest microvertebrate assemblages from the Mesozoic of Gondwana. With at least 19 species, mammaliaforms are particularly diverse. ‘Dryolestoidea’ are the most abundant and the most diverse; nevertheless, only one species, Donodon perscriptoris Sigogneau-Russell, 1991a, of the monotypic Donodontidae, had been described so far. Here, we describe four new species and three new genera of ‘dryolestoids’ from the Ksar Metlili deposits: Donodon minor sp. nov., Stylodens amerrukensis gen. et sp. nov., Anoualestes incidens gen. et sp. nov., and Amazighodon orbis gen. et sp. nov, all of which are included in the Donodontidae based on their dental morphology. We present the first phylogenetic analysis that incorporates the five donodontid species from the Ksar Metlili site into the cladotherian phylogeny. Our new analysis provides evidence for the paraphyly of the ‘Dryolestoidea’: Dryolestidae, ‘Paurodontidae’, Donodontidae, and Zatheria form a clade to the exclusion of the South American Meridiolestida. Donodontids are found to be closer to prototribosphenidans and zatherians than to any other ‘dryolestoid’ family and are more derived than meridiolestidans. This topology refutes a previous hypothesis that meridiolestidans are phylogenetically rooted among donodontids. Our phylogenetic analysis also supports Donodontidae as an endemic African monophyletic group. The close relationships of the donodontids and zatherians suggest that zatherians had a geographical origin possibly from Africa or Gondwana instead of Laurasia.