Thursday, 23 September 2010

Lost and found

There's a story today about two new ceratopsian dinosaurs, Kosmoceratops richardsoni and Utahceratops gettyi, bring found in the rich Cretaceous deposits of Southern Utah. Kosmoceratops in particular is an oddball, with fifteen horns including a strange 'fringe' draped from the top of its crest. The site - the Grand Staircase-Escalante National Monument - is an important site in a state packed with dinosaur localities. During the Cretaceous, what's now Utah was part of Larimidia, separated from the bulk of the rest of North America (called Appalachia) by a shallow sea.

Most people are familiar with ceratopsians; Triceratops has always been among the dinosaur favourites. It's a large group, though, with a range of sizes and ornamentation. 'New' dinosaurs are found surprisingly frequently, adding to the pile. Sadly, though, earlier this year the ceratopsians lost one of their number. The mighty Torosaurus, which had an enormous skull and weighed in at around six tons, was identified in 1891, only a couple of years after Triceratops, and from the same Hell Creek deposits. The paper in July suggests Torosaurus is simply a large adult Triceratops, stripping it of genus status.

This happens from time to time, and it's easy to see why. When working from incomplete fossils - almost always the case with dinosaurs - an animal can be described and named from a part of the skeleton. Different parts can be accidentally given different names. In cases like these, the name used first gets seniority and the more recent gets consigned to history's dustbin. Since Linnaeus, natural sciences have had their lumpers and splitters. Splitters are those who would find some small anatomical difference - say, a seagull that had a larger head than its friends - and get all excited.

"A brand new type of seagull! Wow! I'm going to call it the Mekon Gull and publish a paper!"

The lumper tends to dismiss it as simply a gull with a big head.

"Ha ha, Look at that seagull. It's got a big head."

At times, the names allocated on evidence of slightly dubious strength have stuck. Later, these can collapse, the genus or species status retracted and old bighead gets to be a normal seagull again. In dinosaur terms, one of the biggest departures is that of Brontosaurus. Everybody loved Brontosaurus, the thunder lizard. Then one day it was discovered he had been an Apatosaurus all along. I think many of the other sauropods had had their suspicions for some time. Still - what happens in the Jurassic, stays in the Jurassic.

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