Sunday, 16 December 2012

A New Species Of Reptile With An Unusual Name

In 2008, an international conference between geologists and palaeontologists concluded once and for all that the K-T extinction event, which wiped out the dinosaurs some 65 million years ago, was caused, at least partially, by a collision with an asteroid. The impact site lay over the junction between three of the Earth's tectonic plates. As a result, the damage caused by the collision was not restricted to this impact site alone.

A artist's impression of the impact event
The tectonic shock wave would have rippled through the mantle and crust. Coastlines crumbed into the sea as they became battered by the fury of massive, cataclysmic earthquakes and tsunamis. While overhead, the skies were darkened by a thick, choking layer of gas and ash belched forth by countless, simultaneous volcanic eruptions. The Earth was plunged into vicious winter, canopied by a night sky which lasted for over 3 years.

The dinosaurs perished in this. Diverse forms of predator and herbivore simply vanished from the face of the planet. While some managed to survive until 200,000 years after the cataclysm, yet eventually died out. And the ammonites, having survived the greatest mass extinction in the planet's history over 140 million years previously, breathed their last. The giant marine reptiles lost their dominance in the oceans, surrendering to the sharks. On land innumerable species of mammal, bird and arthropod were lost.

Now, palaeontologists working in North America have found another name to add to the casualty list. From a series of reptile specimens collected over a wide geographical range from Alberta in southern Canada to the state of New Mexico in the States, a team of researchers identified a number of species known to science, and 9 which were not.

The carnivorous lizard Palaeosaniwa stalks a pair of hatchling Edmontosaurus
as the snake Cerberophis and the lizard Obamadon look on
One of these, collected from 65.5 million year old rocks, was dubbed Obamadon gracilis. 'It is a small polyglyphanodontian distinguished by tall, slender teeth with large central cusps separated from small accessory cusps by lingual grooves.' The creature is known primarily from the jaw bones of 2 specimens.

Obamadon gracilis, named for the toothy grin of
the current President of the United States
The creature measured less than one foot long and probably ate insects. It was named, of course, after President Obama. The odon suffix is Greek for tooth and species name is 'slender,' giving the entire ensemble a translation of 'Obama's slender toothed one.' Odd in my opinion, but the researchers have said that no one should impute any political significance to the decision to name the extinct lizard after the recently re-elected U.S. president: 'We're just having fun with taxonomy.'

The researchers were able to compare jaws to try and reconstruct Obamadon as it would have been in life. This technique of cross-referencing has been possible because of the distinctive physiology of mammal jaws.

While the dinosaurs and their cousins the marine reptiles were the most spectacular losses after the K-T extinction, with massive ecological repercussions, we often forget that they were only one part of a wider picture, encompassing the deaths of 75% of all species on the planet. Yet facts and effects are two distinct fields. This holds true for every other extinction in the Earth's history - and those that are still to come.