Tuesday, January 22, 2008

If you didn't know it before, you know it now

Dinosauria is defined as:

The most recent common ancestor of Triceratops horridus and Passer domesticus, and all its descendants.

Fun fact! Before birds were confirmed to be dinosaurs, Passer was replaced by Allosaurus!

This, of course, assumes that Ornithischia + Saurischia = monophyletic clade. I'm still iffy on that proposal, for reasons I've gone into before. Still, if you're ever on Jeopardy, and that's the answer, you can buzz in and say "Dinosauria!"

Thanks to Jerry for pointing out that sparrows are not the same as pigeons. :-)

1 comment:

Jerry said...

Dinosauria is defined as:

The most recent common ancestor of Triceratops and Columba, and all its descendants.


Uh...no. It's not Columba (though that'd be a good choice given its common-ness!), it's Passer. Specifically, a definition has to be anchored by species, not "genera" (because genera are clades, and things with more than one member can't anchor a clade because there's too much risk that one of the members might later be yanked out and put somewhere else, destabilizing the definition -- I seem to have learned that the hard way), so the definition can't be anchored by Triceratops and Passer (or Columba) -- it's properly anchored by Triceratops horridus and Passer domesticus.