Carl Zimmer wrote on evolution in jellyfish, with the fascinating conclusion that they bear greater molecular complexity than was previously thought. He cited a recent challenging review by Seipel and Schmid that discusses the evolution of triploblasty in the metazoa—it made me rethink some of my assumptions about germ layer phylogeny, anyway, so I thought I'd try to summarize it here. The story is clear, but I realized as I started to put it together that jeez, but we developmental biologists use a lot of jargon. If this is going to make any sense to anyone else, I'm going to have to step way back and explain a collection of concepts that we've been using since Lankester in the 19th century.
Continue reading "Diploblasts and triploblasts" (on Pharyngula)
Remarkable, and extraordinary. Any other reason to think, apart from this, that the common ancestor of protostomes and deuterostomes was itself a triploblast? I’m (evidently) completely out of my depth here and would appreciate a life-line.
Update