A Scansorial Varanopid Eupelycosaur from the Pennsylvanian of New Mexico

ABSTRACT An incomplete skeleton of a small tetrapod from the Upper Pennsylvanian of New Mexico represents a new genus and species of varanopid eupelycosaur named Eoscansor cobrensis. This skeleton is from the Cobrean (Virgilian) interval of the El Cobre Canyon Formation in the Cañon del Cobre of Rio Arriba County, New Mexico. Eoscansor is a small varanopid distinguished from other varanopids primarily by the unique structure of its manus and pes metapodials and phalanges. Diverse aspects of its anatomy indicate that Eoscansor was a climber, and possibly arboreal, the oldest such tetrapod now known. These features include: claw, phalangeal, and metapodial adaptations indicative of grasping, clinging, and climbing ability; equivalence of high claw curvature and limb length between the fore- and hind limbs; body mass per SVL within the range of extant climbing lizards; very low tibia length/femur length ratio; and a low center of gravity to facilitate an inclined surface-hugging posture.