Why thank you.
It’s interesting that Bechly starts his response with the complaint that:
Well, what I do count on is an average reading comprehension.
yet goes on to write:
Commenter Roy suggested that otters and ferrets should meet the challenge because they diverged “just over 10mya.” According to TimeTree.org , otters (genus Lutra ) and ferrets (genus Mustela ) diverged an estimated 17.5 million years ago.
Unfortunately for Bechly, I didn’t say otters and ferrets, I said “Sea otters and ferrets”. Sea otters are not of the genus Lutra, but the genus Enhydra. This doesn’t make any difference to the divergence time, but it does show that Bechly has no business commenting on the reading comprehension of others. It also nullifies his comment that “they are not different enough”. He’s comparing the wrong species.
Even more unfortunately for Bechly, timetree.org says that both Lutra and Enhydra diverged from Mustela about 11.0 or 12.3 mya, not the 17.5mya he claimed.
Here’s a screenshot:
Once more Bechly must be counting on no-one checking his references.
Now for his comments on trilobites. He writes:
Of course, Rusophycus traces show evidence of legs! That’s the whole point. Contrary to most trace fossils, which are paleontological problematica and cannot be attributed to a specific organism as trace maker, every undergraduate paleontology student learns that Rusophycus traces are the resting traces of trilobites and trilobite-like arthropods. So, by these traces we have evidence for crown group arthropods like trilobites for 537 million years ago.
But his original claim was for “the origin of trilobites from worm-like ancestors in less than 13 million years”. That’s trilobites, not “crown group arthropods like trilobites”. If Bechly had said something like ‘the origin of trilobite-like arthropods that left trace fossils’, I’d not have objected. But he wrote “trilobites”.
Now Bechly has clarified that he meant 13my from Ediacarian deposits lacking animals (550mya) to the earliest arthropod trace fossils (537mya), and not the 16my from the earliest trace fossils to the earliest trilobite fossils, there is another problem with his argument.[1]
Bechly writes:
… it would mean that the arthropod body plan with exoskeleton, articulated legs, mouth parts, compound eyes, central nervous system, and gut system evolved within 13 million years from such assumed jelly- or worm-like ancestors. The 13 million years represent the time span from the Ediacaran BST-localities 550 million years ago to the oldest Rusophycus traces 537 million years ago.
Rusophycus is a trace fossil. It shows the shape of the creatures underside, and the number and position of its feet.
It does not give any indication of the creature’s eye, mouth, nervous system or gut. It doesn’t even indicate an exoskeleton, since it could be made by a soft-bodied creature (and possibly was, given the lack of trilobite exoskeleton fossils at that time). There is absolutely no indication that trilobites’ compound eyes and mouth parts evolved in that 13my period before the earliest trace fossils. They could have evolved during the 16my period after the first trace fossils, but before the first body fossils. Or gradually across both periods. Or have started evolving even earlier. Bechly is drawing conclusions about eyes and mouths from footprints.
The previous problem remains, since he’s admitted his reference doesn’t say trilobites originated in less that 13my, only that trilobite-like arthropods did - with another 16my before there were trilobites. ↩︎