Brain & behaviour of dinosaurs

Bones have been big news recently, following the publication of two papers which document remarkable fossil finds. First, a group of palaeontologists led by Phil Gingerich of the University of Michigan described Maiacetus inuus, a primitive whale which lived in the water but gave birth on land, and which marks the transition between modern whales and their terrestrial ancestors. This was quickly followed by the report, from Jason Head’s group at the University of Toronto, of Titanoboa cerrejonesis, a prehistoric snake which is estimated to have grown to 13 metres and to weigh more than a tonne.

Such spectacular discoveries always grab the headlines, and rightly so. There are, however, other recent developments in palaeontology, which have been largely overlooked, but are nevertheless equally interesting. The new findings come from Lawrence Witmer‘s lab at Ohio University’s College of Osteopathic Medicine, where the main focus of research is the structure, function and biomechanics of the heads of vertebrates, both living and extinct.

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Pea-brained primates

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From New Scientist:

The earliest ancestors of old-world monkeys, apes and humans had surprisingly small brains, a new study shows.

This finding – based on a newly described fossil skull – means that large brains evolved independently in new- and old-world primates. It also suggests that evolutionary anthropologists may have to rethink some cherished theories about why such big, powerful brains evolved.

The skull in question, which belongs to a roughly cat-sized primate called Aegyptopithecus zeuxis, is remarkable because it is so well preserved.

The brain turned out to be much smaller than they expected – in fact, no larger in proportion to the body than the brain of lower primates such as lemurs. This implies that higher primates, or anthropoids, must have still had small brains when Aegyptopithecus lived, about 29 million years ago – which is after old-world anthropoids diverged from their new-world cousins.

Update: The study has now been published in the Proceedings of the National Academy of Sciences.