Friday 14 November 2014

Are we losing Dimetrodon?

Another installment in the great taxonomical debate that is rocking palaeontology, or at least, gently shaking it. Bathygnathus borealis is the name given to the very limited remains of an animal discovered on Prince Edward Island in 1854. It was lauded as being the first dinosaur found in Canada, before being passed around the 19th century zoological community and re-identified as a pelycosaur in 1905. The pelycosauria has since been abandoned as an order, although it is used informally to describe the sail-backed creatures of the Permian period. Nowadays, Bathygnathus is considered a sphenacodont, like the very popular genus Dimetrodon. Dimetrodon is also erroneously called a dinosaur all over popular culture - it turns up in cheapy plastic toy dinosaur sets all the time - and is one the beasts that people tend to think of if asked to visualise a prehistoric animal.

In 1940, it was suggested by Romer and Price that Bathygnathus and Dimetrodon were one and the same. Given that all that remains of Bathygnathus is one upper jaw, and that Dimetrodon is known from dozens of fossils and has numerous species, no one was really worried about Bathygnathus. However, recent reviews of the 1940 materials suggest that Romer and Price were correct, and that the two genera are synonymous. Which is a bugger, because Dimetrodon wasn't described until 1878, twenty-four years after Bathygnathus. If it is concluded that they are the same animal, Bathygnathus has naming priority. If this comes to pass, I suspect the ICZN will be petitioned to keep Dimetrodon as the name, much like they were for Tyrannosaurus, which was identified as synonymous with the earlier Manospondylus. As in that case, prevailing usage is clearly with the newer name, it has distinct cultural clout, and the earlier sample is so fragmentary as to be somewhat useless in the face of the later finds.

No comments:

Post a Comment