Malerisaurus, A New Eosuchian Reptile from the Late Triassic of India

S. Chatterjee

Abstract

Two almost complete skeletons of a new eosuchian reptile, Malerisaurus robinsonae n.sp., were discovered as the presumable gastric contents of `twin' skeletons of Parasuchus hislopi. The specimens are from fluvial flood plain deposits of the late Triassic Maleri Formation of the Gondwana supergroup, India. The osteology of Malerisaurus is described in detail. Malerisaurus was a small, gracile, long-necked eosuchian, facultatively bipedal, and probably able to climb trees or to take to the water when alarmed. It is comparable to modern bipedal lizards in size, proportions and inferred activities. The skull, although showing some carnivorous adaptation, is relatively unspecialized and indicates an insectivorous diet. Because Malerisaurus shows such a combination of primitive and advanced features as a diapsid skull, unossified laterosphenoid, lack of antorbital and mandibular fenestrae, slender limbs, primitive girdles, distinctive elongated cervicals and lack of dermal armour, it is assigned to the suborder Prolacertiformes of the order Eosuchia. A classification of Prolacertiformes indicates four families within this suborder: Petrolacosauridae, Protorosauridae, Prolacertidae and Tanystropheidae. Malerisaurus is tentatively allied to Protorosaurus in the family Protorosauridae; in neither genus is the temporal region of the skull adequately known. Malerisaurus furnishes detailed information about the skeletal morphology of what may be a hitherto undocumented lineage of eosuchian reptiles.