Talk:Terebratulida

Derivation
The article as it stands give Atrypida as the possible source for the Terebratulida. Although I've found nothing so far as to the ancestry of the terebratulids or what the Atrypida may have given rise to, I doubt it. Terebratulids have a looped brachidium, in atripids it's spiral. It seems to me that the Pentamerida is a more likely source, with some having looped brachidia. True, all three have narrow hinge lines, but as for the Atrypida that's about the only similarity, other than for being a brachiopod. J.H.McDonnell (talk) 21:51, 1 July 2010 (UTC)