Two endocranial casts of cetaceans from the Oligocene of New Zealand

Abstract

"Two natural endocranial casts of cetaceans from the Oligocene of New Zealand are described. No skeletal remains are associated with either of them. The larger closely resembles published figures of endocranial casts of Archaeocetes except in that its cerebellum is small and normal instead of being of immense size. The cerebral hemispheres are small, especially anteriorly, and apparently had an olfactory region. The smaller specimen more closely approaches the condition seen in Recent specimens. The cerebral hemispheres have no olfactory region and are rounded anteriorly, but they are far less swollen. The two specimens afford intermediate stages between the brain of the primitive mammal and that of the Recent Odontocete. It is suggested that the immense and unique cerebellum described previously in the brain of Archaeocetes might conceivably be a misinterpretation of a large vascular plexus."