Gunter Bechly: Darwin's gap problem (Introduction)

by David Turell @, Friday, September 15, 2023, 16:52 (19 days ago) @ David Turell

Flying dinosaurs have no predecessors:

"In a recent Fossil Friday article for Evolution News (Bechly 2023), I discussed the abrupt origin of gliding and flying reptiles in the Triassic period. This includes the origin of pterosaurs, of which we find the earliest fossil record mainly from the Triassic of the Alps in central Europe (Barrett et al. 2008) such as the famous Eudimorphodon.

"Out of Thin Air?
So, where did these pterosaurs come from? It looks like they appear out of thin air. Paleobiologists searched for potential terrestrial precursors and often suspected the enigmatic small bipedal reptile Scleromochlus from the early Triassic of Scotland as a likely candidate.


"...but how did flying pterosaurs with large winged forelegs originate from such bipedal terrestrial reptiles with smaller forelegs?


"Dalla Vecchia (2013) had reviewed the early fossil record of pterosaurs and found that “a ‘Big Bang’ model for their early history fits better with the fossil record: the earliest unequivocal pterosaurs show a sudden and geographically limited appearance in the fossil record, as well as a relatively high burst of diversity and considerable morphologic disparity.” Such an abrupt origin of pterosaurs, with the correlated very fast re-engineering of the body plan in terms of adaptation towards powered flight, or course also implies a significant waiting time problem (Bechly 2022), because the origin and fixation of the required genetic changes cannot be accommodated within the available window of time with an unguided evolutionary process. Thus, the fossil record of pterosaurs rather supports the predictions of intelligent design theorists.


"Consequently, we still lack any fossil intermediate form (missing link) documenting an evolutionary transition of walking terrestrial ancestors to actively flying pterosaurs with wings, in spite of highly misleading claims that “enigmatic dinosaur precursors bridge the gap to the origin of Pterosauria” (Ezcurra et al. 2020).


"...but honestly I don’t hold my breath given the total failure to find any transitional pterosaur ancestor in centuries of fervent search by vertebrate paleontologists around the globe.


"This means that there is a large morphological gap and a very short window of time to close it. Not exactly what would have been predicted by Darwin, who quite likely would have been more willing than his modern successors to acknowledge that such conflicting evidence presents a formidable problem for his theory. In fact that’s exactly what he said in his Origin of Species about the fossil record. He still hoped that the gaps are just artefacts of our incomplete knowledge of the fossil record and therefore would be closed with future research. Even almost 165 years after Darwin with an exponential growth of knowledge about the fossil record this did not happen and the persisting gaps still bug Darwin’s successors until this day.


"Long story short: Forget all the pop science ballyhoo, and if you should not trust my word, just check the provided primary sources to see that there is much ado about nothing concerning the alleged recent breakthrough in our knowledge on the evolutionary origin of pterosaurs. It’s still a complete mystery and defies Darwinian expectations."

Comment: a very long technical article, quoting many sources in the literature, but clearly showing a persistent gap between terrestrial and flying dinosaurs, equal to the Cambrian gap.
Just as Gould warned.

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