Posted on July 13, 2009 by Oldcola
This is a pre-cteappv Oops and I start wondering how Fleury manage to find journals with so poor review process as to let go to press such mistakes.
This one is from An Elasto-Plastic Model of Avian Gastrulation, Vincent Fleury, Organogenesis 2:1, 6-16, 2005.
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Posted on July 12, 2009 by Oldcola
There is not as much paleontology as one would expect by the title of the chapter. Mostly paleontology is an excuse to further discuss developmental biology, except for subsection 4.1
4.1 Tetrapod origin
If we turn to paleontology, we ﬁnd a description of tetrapods appearance into three main steps. Appearance of chordates, segmentation of lateral fins, appearance of tetrapods.
That’s the shortest version one can get except “pouf they appeared”. Interesting nevertheless the second step, the “segmentation of lateral fins“. This is one of three hypothetical, not exclusive, working models. Not to be used as a granted fact (see below).
Good news, bad news.
Good news are that Fleury abandonned the idea it appeared in one of his conferences announcement, and promoted in fora, that the tetrapods may have appeared suddenly, with all there attributes, specifying suddenly as “in a single generation“.
But he still think that:
These early tetrapods have well formed complex limbs apparently almost “right away”.
Almost right away being an estimate of the time-lapse between Haikouichthys ercaicunensis, presenting a single median fin-fold and tail, to the tetrapodomorph Tiktaalik roseae; almost right-away corresponds to 100 millions years. At least we are not anymore at the “single generation“level.
Progressive modifications are problematic for a model which is based on a suddenly appearing bauplan.
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Posted on July 11, 2009 by Oldcola
I’m greek and during my young years I was feed a lot of geometry. You know how it is, national pride for the ancestors, especially under a military junta. So, I’m quite sensible when one presents geometrical problems incorrectly.
My very first objection concerning Fleury’s model1 was that he described the epiblast cells as contained between two extracellular membranes. When I pointed that his only response was that if there is a single basal membrane that doesn’t affect his model, the flow would be just faster. From that point on you can’t trust the guy with any description.
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Posted on July 1, 2009 by Oldcola
This is an old question which never received an answer. And certainly an answer wasn’t required before the publication of cteappv. As everything in the paper is about clarification and one more particular point remain unclear, I’ll post my question here and maybe Vincent Fleury will be kind enough to provide an answer.
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