Carnivorous dinocephalian from the Middle Permian of Brazil and tetrapod dispersal in Pangaea

Abstract

The medial Permian (~270-260 Ma: Guadalupian) was a time of important tetrapod faunal changes, in particular reflecting a turnover from pelycosaurian- to therapsid-grade synapsids. Until now, most knowledge on tetrapod distribution during the medial Permian has come from fossils found in the South African Karoo and the Russian Platform, whereas other areas of Pangaea are still poorly known. We present evidence for the presence of a terrestrial carnivorous vertebrate from the Middle Permian of South America based on a complete skull. Pampaphoneus biccai gen. et sp. nov. was a dinocephalian "mammal-like reptile" member of the Anteosauridae, an early therapsid predator clade known only from the Middle Permian of Russia, Kazakhstan, China, and South Africa. The genus is characterized, among other features, by postorbital bosses, short, bulbous postcanines, and strongly recurved canines. Phylogenetic analysis indicates that the Brazilian dinocephalian occupies a middle position within the Anteosauridae, reinforcing the model of a global distribution for therapsids as early as the Guadalupian. The close phylogenetic relationship of the Brazilian species to dinocephalians from South Africa and the Russian Platform suggests a closer faunistic relationship between South America and eastern Europe than previously thought, lending support to a Pangaea B-type continental reconstruction.

Fig. 1.

P. biccai from the Middle Permian of Brazil. Photographs of the cranium UFRGS PV386P (holotype) in (A) dorsal, (B) ventral, and (C) lateral view. Reconstruction (D) of holotype in lateral view.

Fig. 2.

Strict consensus of anteosaurid relationships, after pruning of Microsyodon (see SI Text for the four most parsimonious trees including all taxa). BR, Brazil; CN, China; KZ, Kazakhstan; RU, Russia, SA, South Africa. Decay index and symmetric resampling values (above and below, respectively) are provided as measures of support before each node. Decay index calculated from 422 trees. Resampling calculated from 3,000 replicates.

Fig. 3.

Reconstruction of Pangaea B showing anteosaurid dinocephalians and platyoposaurid temnospondyles during the Middle Permian. Probable dispersal routes are indicated by red arrows. 1, Russian Platform; 2, southern fore-Urals, Kazakhstan; 3, Ordos Basin, China; 4, Parnaíba Basin, Brazil; 5, Paraná Basin, Brazil; 6, Karoo Basin, South Africa. The map is considerably modified from ref. after new geological data.

Fig. 4.

Life reconstruction of the dinocephalian P. biccai from the Middle Permian of Brazil.