Saturday, 1 October 2011

Incredible New Insights Into The Heads Of Armoured Dinosaurs

A Euoplocephalus skull (top left) and a model of the
scans (bottom right). The green tube is the  nasal passage
All armoured dinosaurs are part of the reptile group Ankylosauria. These large herbivorous, low lying creatures are depicted, in popular culture, as a biological version of a tank. Creatures such as Ankylosaurus even had armoured eyelids as well as a spine shattering club composed of solid bone on its tail which could inflict terrible damage on any creature that came too close. What we know less about are the cognitive and sensory functions of these incredible beasts. This has now changed.

It was well known that the ankylosaurids had small brains. Some could fit into a coffee mug, others were not much bigger than this. Yet the inside of the skull remained a  mystery. The dense armour meant that scans were not reliable; and no curator would allow palaeontologists to crack open a skull, take casts and perform more sophisticated scans. Now palaeontologists have discovered an ankylosaurid skull, not in the badlands of Nevada or the like, but in the storage rooms of the University of Alberta.

Lead researcher Tetsuto Miyashita found a 72 million year old Euoplocephalus cranium. It was damaged, allowing Miyashita a unique view of the nasal passages, blood vessels and brain case. While it again showed that these creatures had very small brains in relation to body size, there was another feature that was far more surprising. Its nasal passage was not a relatively straight and short airway, but was made up instead of loops, twists and turns inside the armoured head. A 2008 study led by Dr Ryan Ridgely of the American Natural History Museum showed similar results.

The question is why. The various research teams believe that it used its extraordinary nasal passages to generate low frequency sounds to communicate with other members of its species. A study of its ear shows that it was built to register such frequencies. Its brain size shows that, as well as a good sense of smell, it had also had very well developed auditory capacities. Euoplocephalus is very similar to many of ankylosaurids, so the results of this study can be re-applied, giving us a greater insight into the lives of this animal group.