Twilight of the Reptiles

Making use of the new world of free information, I trucked over to Wikipedia to see whether, in the final analysis, dinosaurs were classified as reptiles. I was happy to see that, no, they're not reptiles. I've been gunning for the nonreptile angle since the 70s, when I saw the Nova episode about hot-blooded dinosaurs. I was a bit disoriented, however, to find out, further, that reptiles aren't reptiles either. The "Age of Reptiles" was supposed to have ended 65 million years ago in the shadow of a massive meteorite strike, but reptiles actually have gone defunct very recently.


It turns out that the category “reptile” doesn't match the new, evolution-oriented way to understand taxonomy: cladistics. Back before Darwin invented the theory of evolution, Linnaeus, et al, defined groups of organisms according to their traits. Birds have feathers, etc., so they weren't reptiles. Now that Darwin has changed everything, biologists define groups according to lines of descent. In this new evolutionary way of thinking, the category “reptile” does not make the grade. It can't be a clade because it does not represent “all organisms, living and dead, that are descended from a particular population.” “Reptile” is not a clade because it excludes birds. Whether it also excludes dinosaurs is irrelevant. The only ancestor that all “reptiles” share, they also share with all birds and dinosaurs, so any taxonomic group that includes all “reptiles” also includes birds and dinosaurs. Like birds and “reptiles,” dinosaurs are dry-egg vertebrates, that is: sauropsids. The category "reptile" isn't a natural phenomenon, merely a linguistic one.


Here scientific classification, which is objective, contradicts common linguistic classification, which is relative. There's no common-language term for “all organisms descended from the ancestor of reptiles, dinosaurs, and birds” because that's a technical category based on a prehistoric scientific fact (common ancenstry) rather than a workaday category based on the human perspective. For us, it's easy and useful to distinguish all those scaly dry-egg vertebrates from the feathery ones.


On this point, creationists have it right. The category "reptile" is a man-made category, not representing ultimate reality. The Bible only mentions one level for categorizing organisms, the "kind" or "baramin." All grosser or finer categories are arbitrary.


September 2007, September 2013



man, burning