Different kinds of brain shapes in a variety of reptiles (from top) - a crocodile, the oldest known bird Archaeopteryx (145 million years old), the new Russian fossil (80 million years old) and a pigeon
New avian brain fossil research suggests that brain enlargement in early avians did not correlate with the evolution of powered flight.
The evolution of the avian brain and sense organs remains poorly understood since fossils are usually bones or shells and not soft tissue fossils like brains, eyes or muscles. Up to now it was thought that a large part of the avian brain was devoted to powered flight, but a new 90 million-year-old exceptionally well-preserved fossil brain from the Cretaceous of Russia shows that this was not the case. This new research forces a re-interpretation of the famous London Archaeopteryx endocast - the oldest fossil bird brain.
This new fossil is from the brain of the Melovatka bird from the Volgrograd region of European Russia and it has allowed researchers to piece together the sensory development of birds. Most importantly, it documents a new stage in avian sensory evolution – acute nocturnal vision coupled with well-developed hearing and smell, developed by the Late Cretaceous (who lived 90 million years ago). It also suggests that brain enlargement in early avians did not correlate with the evolution of powered flight.
A paper describing this unique fossil preservation has just been published on the Royal Society press site, entitled A fossil brain from the Cretaceous of European Russia and avian sensory evolution. One of the author’s* is Dr Gareth Dyke of the UCD School of Biology and Environmental Science. “It has always been assumed that the evolution of flight in birds drove the re-modelling of their brains; after all, flapping flight is such an important adaptation for birds”, says Dr Dyke.
It is important to view this work in light of the fact that fossils preserving traces of soft anatomy are rare in the fossil record, with the exception of a few carefully preserved three-dimensionally preserved specimens.
Part of this project was undertaken in Moscow, while Dr Dyke did the anatomical research at UCD. ”Based on the new Russian brain we now know that changes always linked to evolution of bird flight occurred much later in avian evolution. Perhaps flight was not so important to bird evolution after all?” adds Dr Dyke.
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