FOSSILIZED DINOSAUR BRAIN TISSUE IDENTIFIED FOR THE FIRST TIME

Researchers have identified the first known example of fossilized brain tissue in a dinosaur from Sussex. The tissues resemble those seen in modern crocodiles and birds.

An unassuming brown pebble, found more than a decade ago by a fossil hunter in Sussex, has been confirmed as the first example of fossilized brain tissue from a dinosaur.

The fossil, most likely from a species closely related to Iguanodon, a large herbivorous dinosaur that lived during the Early Cretaceous Period, about 133 million years ago displays distinct similarities to the brains of modern-day crocodiles and birds.

Finding fossilized soft tissue, especially brain tissue, is very rare, which makes understanding the evolutionary history of such tissue difficult. According to the researchers, the reason this particular piece of brain tissue has been so well-preserved is that the dinosaur's brain was essentially 'pickled' in a highly acidic and low-oxygen body of water shortly after its death. This allowed the soft tissues to become mineralized before they decayed away completely, so that they could be preserved.

In typical reptiles, the brain has the shape of a sausage, surrounded by a dense region of blood vessels and thin-walled vascular chambers (sinuses) that serve as a blood drainage system. The brain itself only takes up about half of the space within the cranial cavity.

In contrast, the tissue in the fossilized brain appears to have been pressed directly against the skull, raising the possibility that some dinosaurs had large brains which filled much more of the cranial cavity. However, the researchers caution against drawing any conclusions about the intelligence of dinosaurs from this particular fossil, and say that it is most likely that during death and burial the head of this dinosaur became overturned, so that as the brain decayed, gravity caused it to collapse and become pressed against the bony roof of the cavity.

Thanks to: sciencedaily.com