THURSDAY, 21 APRIL 2011L. hamatus was one of the first reptiles to live permanently on land. While its predecessors fed exclusively on insects, L. hamatus had an omnivorous diet, and its fossilized remains show a number of physical changes that made it better adapted to its new lifestyle. It had sturdy legs and an armour-like skin, and evolved a deeply anchored single row of teeth which were more able to withstand the pressure put on them when chewing the tough vegetation found on land. By contrast, the reptiles from which L. hamatus derived had a loose row of weak teeth that fell out regularly and were replaced by another row that came up from the inner jaw.
Whilst enhancing eating efficiency, the new development meant that bacteria living on the teeth were no longer frequently removed, leading to long-term infections and eventual tooth decay and loss. 275 million years later, this susceptibility is seen in humans and is the major cause of cavities .
Written by Sarah Gardner