Friday, September 17, 2010

How Many Species of T. Rex?

As journalistic offenses against science go, this is pretty minor, I guess, but it still grates:
It's been a big year for a big dinosaur: Tyrannosaurs rex. Scientists have identified six new species of the animal, recently discovered T. rex feathers and maybe even the remains of some soft tissue.
Yes, you read that right: there are six new species of T. rex. Unsurprisingly, the scientists interviewed get it right without really thinking about how terribly confusing the binomial Genus-species nomenclature is to the average illiterate journalist.
"You know, we've really doubled the tyrannosaur diversity in the last 10 years," says Norell, who is among the world's leading fossil hunters. "And [we've] found ones that aren't just giant ones like Tyrannosaurus rex but smaller ones like raptorex, feathered ones like dilong. So it's really been this really big sort of renaissance, and tyrannosaurs are probably studied more than any other dinosaur that's ever been found."
Dispensing with snark, here's a quick overview: living things are grouped with similar living things in ever finer, more specific classifications ranging from Kingdom (most general) to species (most specific). The standard mnemonic is "Kings play chess on family grave stones." A student of mine came up with another that I quite like, and might be more likely to stick in the minds of younger learners: "Kids puke chunks on fat Grandma's skirt." Either way, the initial letters stand for kingdom, phylum, class, order, family, genus and species, and there can be different levels, (sub- or super-) of those. So Tyrannosaurus rex (by convention, the genus name is capitalized, the species name is not) is the genus and species of a particular type of dinosaur. It's "full name," or more accurately, classification, would be
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Dinosauria
Order: Saurischia
Suborder: Theropoda
(unranked): Coelurosauria
Superfamily: Tyrannosauroidea
Family: Tyrannosauridae
Subfamily: Tyrannosaurinae
Genus: Tyrannosaurus
Osborn, 1905
according to Wikipedia.

So how many "species" of T. rex are there? One. By definition. Though the NPR article doesn't explicitly say how many species of Tyrannsaurs there are, combining the two quotes, "six new species," and "doubled the diversity," suggests that the count is somewhere around a dozen- though the Wikipedia link lists T. rex as the only species. In this case, I'm inclined to take the word of the researchers interviewed over the wiki piece.

It's actually a decent and interesting article, but it irritates me when basic, simple, and elementary science is screwed up. It casts a dubious pall over the whole thing.

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