Guillermo W. Rougier

Reconstruction of the cranial vessels in the Early Cretaceous mammal Vincelestes neuquenianus: implications for the evolution of the mammalian cranial vascular system

ABSTRACT Vincelestes neuquenianus from the Early Cretaceous of Argentina is the earliest therian mammal known from nearly complete crania. Described here is the structure of the petrosal bone and other cranial elements inferred to be associated with the vascular system. From comparisons with Recent amniotes, the major basicranial arteries and veins that we reconstruct for Vincelestes represent a composite of the vascular patterns in monotremes and some placentals (e.g., lipotyphlan insectivorans). Vincelestes had a well-developed stapedial system that was supplied principally via the arteria diploetica magna, a transpromontorial internal carotid artery, and a well-developed lateral head vein that drained the prootic sinus via a prootic canal. As in monotremes and extinct “non-therian” mammals, Vincelestes had an enlarged anterior lamina of the petrosal (=lamina obturans), through the base of which (lateral flange) ran the ramus superior of the stapedial artery. Reconstruction of the major basicranial arte...