Tuesday, April 19, 2011

World's Oldest Toothache

Osteomyelitis in a Paleozoic reptile: ancient evidence for bacterial infection and its evolutionary significance. 2011. R. Reisz, et al. Naturwissenschaften, published on-line, April 16, 2011

A reptile that lived in what is now Oklahoma is giving paleontologists a glimpse of the oldest known toothache.
Scientists have found evidence of bone damage due to oral infection in a 275 million years ago Paleozoic reptile, Labidosaurus hamatus. Their findings predate the previous record for oral and dental disease in a terrestrial vertebrate by nearly 200 million years.

As the ancestors of advanced reptiles adapted to life on land, many evolved dental and cranial specializations to feed more efficiently on other animals and to incorporate high-fiber plant leaves and stems into their diet. The primitive dental pattern in which teeth were loosely attached to the jaws and continuously replaced, changed in some animals. Teeth became strongly attached to the jaw, with little or no tooth replacement. This was clearly advantageous to some early reptiles, allowing them to chew their food and thus improve nutrient absorption. The abundance and global distribution of Labidosauris and its kin suggest that it was an evolutionary success.

However, as this reptile lost the ability to replace teeth, the likelihood of infections of the jaw, resulting from damage to the teeth, increased substantially. This is because prolonged exposure of the dental pulp cavity of heavily worn or damaged teeth to oral bacteria was much greater than in other animals that quickly replaced their teeth. link