On the Paleontology of Animal Cognition: Using the Brain Dimensions of Modern Birds to Characterize Maniraptor Cognition

Abstract

Drawing inferences on the characteristics, including behavior, of extinct species using comparisons with extant species has a long tradition in paleontology. Departing from the observation that extinct maniraptors possessed brains with a relatively long and narrow telencephalon, we used digital endocasts taken from 11 species of modern birds to determine if any of the sampled modern bird species displayed a similar telencephalic shape, and by inference, similar cognitive ability. The analysis revealed that the telencephalon of the double-crested cormorant (Phalacrocorax auritus) is extraordinarily narrow (large length-to-width ratio) and strikingly similar to Archaeopteryx and even some non-avian, maniraptoran dinosaurs. The relatively narrow brain in turn suggests a relatively small nidopallium subdivision of the telencephalon and associated impoverished general cognitive ability. This first-order brain-anatomical observation, together with the relatively ancient origins of a cormorant fossil record, suggest that cormorants could be used as a model for the general cognitive abilities of extinct maniraptors.