Specialized Position of the Horns, and Frontal and Parietal Bones in Bos taurus (Bovini, Artiodactyla), and Notes on the Evolution of Bos

Abstract

We explored the unusual position, anatomy and evolutionary significance of the position of the horns in Bos taurus. In the genus Bos, the frontal bone, frontal sinus and parietal bones are shifted and repositioned. A new occipital (pseudo-occipital) crest forms at the edge of the calvaria. The true occipital crest has shifted to the back along with the parietal. The frontal sinus has overridden a parietal sinus. We compared this bone reorganization with the anatomy of deer (Dama and Odocoileus), a gazelle (Gazella dorcas) and a bovid (Eotragus clavatus) in which the bones are in the primitive positions. The fetal Bos has a fontanelle which is not seen in Gazella or Odocoileus. An evolutionary succession can be developed based on the backward shift of the frontal and horns in Bos taurus and other Bovini.