Meeting Abstract

P1.80  Tuesday, Jan. 4  The Evolution of Cranial Vasculature in Ruminant Artiodactyls O’BRIEN, Haley D.*; DUFEAU, David; STEVENS, Nancy J; Ohio University; Ohio University; Ohio University Haley.D.OBrien@gmail.com

The carotid rete is a cranial vascular structure found within the cavernous venous sinus of most artiodactyls. It plays an important physiological role whereby it selectively maintains cooler cranial blood temperatures during periods of peak activity and environmental temperature, in spite of rising body temperature. Although the details of cranial vasculature have not been documented in all artiodactyls, the carotid rete is generally thought to be present in all extant artiodactyls, except for the genus Tragulus. This study explores the evolutionary history of this potentially advantageous structure in a selection of extant and fossil ruminants. The external carotid artery of a domestic goat (Capra hircus) was injected with a radio-opaque latex/barium solution and CT scanned. The 3D imaging program Amira 4.0 was used to visualize the arterial cranial vasculature and to calculate volume and area of the isolated carotid rete. The foramen orbitorotundum was identified as an osteological correlate for the carotid rete, providing baseline data to explore the prevalence of this structure in the fossil record of early ruminants. Preliminary investigation of this osteological correlate in the fossil taxa Leptomeryx and Hypisodus suggests that the carotid rete was secondarily lost in Tragulus, and may not be common to other small-bodied Artiodactyls.