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To: forsnax5
"These results suggest that the barbs form first and later fuse to form a rachis, much like downy feathers are formed before flight feathers when a chicken grows up. Under the general rule of ontogeny repeating phylogeny, downy feather made only of barbs probably appeared before the evolution of feathers with rachides and capable of flight," Chuong says.

Ontogeny recapitulating phylogeny is one of those mistaken ideas like that went out like Lamarkism.

Strange comment.

The Nature article has very little about the "evo" part of the "evo-devo" study.

35 posted on 10/31/2002 9:09:35 AM PST by tallhappy
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To: tallhappy
Ontogeny recapitulating phylogeny is one of those mistaken ideas like that went out like Lamarkism.

I noticed that, too. This is one of those things that people like to toss off as conversational "snow."

Kind of odd to see it in this context...

37 posted on 10/31/2002 9:16:49 AM PST by forsnax5
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To: tallhappy
Ontogeny recapitulating phylogeny is one of those mistaken ideas like that went out like Lamarkism.

Any idea of strict, predictable recapitulation is gone, yes. Still, Evo-Devo lives in the parallelisms of ontogeny and phylogeny.

Amphibians are thought to have arisen come from fish. (In fact, there's a lot of fossil evidence for this.) Baby frogs look like little fish.

Arthropods are thought to have arisen from worms. (There's some scattered fossil evidence for this.) There are many cases of hatchling arthropods (most insects, for instance) resembling worms.

Hatchling horsehoe crabs look like trilobites. Hatchling lampreys look like primitive cephalochordates. Mammalian embryos start out with what looks like a four-part jawbone, but three bones migrate to the ear. That looks an awful lot like a recapitulation of a funny thing in the fossil record where reptilian cynodont therapsid jaws developed a double-joint and the function of the bones beyond the first part seem to have been increasingly coopted for hearing rather than jaw operation. Perhaps you recall that from an earlier thread.

52 posted on 10/31/2002 10:38:50 AM PST by VadeRetro
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To: tallhappy
Ontogeny recapitulating phylogeny is one of those mistaken ideas like that went out like Lamarkism.

Strange comment.

Agreed. I don't know the proper terminology, but I suppose the (more correct) relevant principle would be that the order of events in developmental pathways tends to be conserved.

175 posted on 11/02/2002 6:07:14 PM PST by Stultis
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