Limiting the costs of mutalism: multiple modes of interaction between yuccas and yucca moths

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Abstract
A new specimen from the base of the Beaufort Group, Upper Permian of South Africa, represents a new therapsid (‘mammal–like reptile’) which has been identified as the most basal (‘primitive’) member of the Anomodontia. Anomocephalus africanus gen. et sp. nov. is based upon a partial skull that exhibits several characteristic anomodont synapomorphies including the presence of isodont marginal teeth and a dorsally bowed zygoma, but is distinguished from other anomodonts by the possession of peg–like marginal dentition with oblique wear facets on the tips of the teeth. Anomocephalus is excluded from a clade comprised of all other anomodonts as (i) the snout is relatively long, (ii) the vertically aligned zygomatic process of the squamosal is blade–like, and (iii) the squamosal does not contact the ventral tip of the postorbital. The basal position of Anomocephalus, together with its South African occurrence, strongly supports the postulate that a Gondwanan distribution was ancestral for anomodonts.