CANINAE

Lyras, George A. & Van Der Geer, Alexandra A. E., 2003, External brain anatomy in relation to the phylogeny of Caninae (Carnivora: Canidae), Zoological Journal of the Linnean Society 138 (4), pp. 505-522 : 508

THE CANINAE CEREBRUM

GENERAL FEATURES

In general, the basic sulcal pattern of the cerebrum of members of the subfamily Caninae does not appear to be affected by brain size, since it is the same from the smallest ( Vulpes zerda ) to the largest ( Canis lupus ) species ( Radinsky, 1973a). The only differences of an allometric nature are that the sulci of the cerebral cortex of the larger brained Caninae tend to be more wavy, and that there are more secondary sulci in the larger brains. These differences are due to the nature of the neocortex, which is organized as a thin sheet that can only increase by areal expansion, while the underlying subcortical matter expands as a volume (see reviews by Sacher, 1970; Jerison, 1973). As in living mammals, the brain’s information-processing capacity is closely related to the surface area of the cortex ( Jerison, 1991), it is obvious that the more wavy the sulcal pattern is and the more secondary sulci there are, the higher this capacity is. Though this is generally true, such an analysis is beyond the scope of the present study. Besides, the present study focuses on a relatively uniform group as regards external brain anatomy ( Atkins, 1978; see above), so that such differences in capacity are not likely to be of great taxonomic value.

In spite of the uniformity, two clearly discriminative features are recognized in the brains of modern Caninae , on the basis of which some groups can be distinguished. These features consist of the sulcal pattern of the cortex between the coronal sulci, and the shape and relative size of the proreal gyrus of the frontal pole. Differences in these features can be traced back in the ancestral canids as far as the Miocene.