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Re: Sweet cynodont Thursday

Ah, I knew I had seen that e-mail onlist...

You know the oldest cynodonts are things like /Procynosuchus/ and /Dvinia/?
A couple of families bursting onto the stages of South Africa and Russia at
about the same time? [...] This beat's been belted
out by a more basal cynodont from the /Tropidostoma/ Assemblage Zone, and
it's several million years earlier than the first record of procynosuchids.

Except that Botha et al. don't mention why they put *Dvinia* deep into the Late Permian. According to the Geological Time Scale 2004, there is no Late Permian in Russia; *Dvinia* must come from the Capitanian, the last of the three stages of the Middle Permian. Now the question becomes how old the *Tropidostoma* zone of South Africa is. If it is as young as Botha et al. claim (the paper they cite for their correlation chart contains several mutually contradicting charts, but not that one, and isn't concerned with correlation across continents in the first place), *Charassognathus* is considerably younger than *Dvinia*. It goes without saying that at least one other correlation chart has been published recently. Let's just be glad there are no dinosaurs in the Permian. B-)