Analysis endocrinol extinct and living birds and related dinosaurs theropods revealed features of evolution of the brain size of the members of this group, reported in Current Biology. Among the early birds, relative brain size was not greater than that of the theropods, but it has become faster to increase after the Cretaceous-Paleogene extinction, which released new ecological niches. Really big relative to the body, the brain of birds was relatively recent, from an evolutionary young groups — parrots, corvids, hummingbirds and Swifts, and they came to this in different ways.
Although the absolute mass of the brain and its relation to body weight are not a direct measure of intelligence, some information about its General level and the possibilities of the nervous system they can give. Therefore, changes size during the evolution is given much attention. It may depend on other characteristics, which are themselves subject to selection, for example of the body weight. Birds in General, in the course of evolution has become a smaller: lighter body is easier to lift into the air.
A group of biologists led by Daniel Xepcoh (Daniel Ksepka) from the Museum named Bruce used the data on endocrine (casts of the inside of the skull) 284 types of modern birds, 22 species of extinct birds and 12 species of theropods, not related to the birds to determine the ratio of the volume of their brain and the entire body. They also used data from the work of other authors, where he studied the skulls around 1900 modern types of birds. Data used process Ornstein-Uhlenbeck (need to model how changing the structure of organisms over time) and covariance analysis (to confirm the findings obtained as a result of the previous operation).