Monday, 12 September 2011

A New Species Of Predatory Fish Once Roamed The Waterways Of Ancient North America

An artist's impression of Laccognathus embryi lurking behind a tree stump
The Devonian Period from 415 to 360 million years ago is often described as the 'Age of Fish.' A rich variety of aquatic forms populated the seas, rivers, lagoons, streams and lakes, each perfectly suited to hunt prey in their own unique habitat. There are a startling number of forms each with a different feeding strategy. Laccognathus embryi was a bottom dwelling, ambush predator that would rise from the silt and kill its prey with a powerful bite backed up with many strong, sharp teeth.

A fossil and diagram of the skull of Laccognathus embryi from the front
This 375 million year old sarcopterygian (lobe finned fish), whose closest living relative is the lungfish, was discovered by the same team of palaeontologists who discovered the world famous Tiktaalik roseae in the same place as Tiktaalik, on Ellesmere Island in the remote Nunavut territory of Arctic Canada. The 6 foot beast, named in honour of Dr Ashton Embry, whose work in the Arctic islands paved the way for the team's palaeontological exploration had a wide head, small eyes on top with strong, robust jaws.

'This study is the culmination of a lot of work in the field, in the fossil lab, and in the office,' said Downs, lead author of the study. Downs, an Academy of Natural Sciences research associate and a visiting professor at Swarthmore College, started studying fossils in high school as an Academy volunteer. 'Our team collected the first fossils of Laccognathus almost 10 years ago, and the collection has grown with each subsequent field season. The quality and quantity of this collection will continue to shed new light on these unusual animals.'

'I wouldn't want to be wading or swimming in waters where this animal lurked,' added Daeschler, co-author of the paper published in the current issue of the Journal of Vertebrate Palaeontology and the Academy's curator of vertebrate zoology. 'Clearly these Late Devonian ecosystems were vicious places, and Laccognathus filled the niche of a large, bottom-dwelling, sit-and-wait predator with a powerful bite.' A different species of Laccognathus was discovered in Eastern Europe prior to this study. 

This new species, whose name translates as 'pitted tooth,' extends the genus range all the way to North America and provides confirmation of a direct connection between North America and Europe during the Devonian period. The region during that time would have been subtropical, providing a perfect home for Laccognathus in the streams, rivers and lakes that would have dotted the landscape.