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.