Re: [dinosaur] Archosaur trackway from Triassci of Morocco + dicynodont extinction in Triassic

[William Parker <saurian55@gmail.com>]

Yes, and the Parasuchus specimen from the Adamanian of Arizona has long been shown not to be diagnostic. Regardless as I mention in my recent paper all of these correlations are made using plesiomorphies and should be disregarded. Unfortunately most work by other authors after 1993 gets ignored because the new data are inconvenient. Somehow these keep making it through peer review mistakingly implying that these data still have credence.

On Sun, Sep 2, 2018 at 10:54 AM David Marjanovic <david.marjanovic@gmx.at> wrote:

Gesendet:ÂDonnerstag, 30. August 2018 um 23:35 Uhr
Von:Â"William Parker" <saurian55@gmail.com>
An:Â"David Marjanovic" <david.marjanovic@gmx.at>
Cc:Âdinosaur-l@usc.edu
Betreff:ÂRe: [dinosaur] Archosaur trackway from Triassci of Morocco + dicynodont extinction in Triassic

Spencer Lucas has long disagreed with the Long Norian hypothesis for the Late Triassic and this paper reflects that thinking. He also distrusts U-Pb dating and also tends to think that many taxa are oversplit. He also now maintains that large vertebrates are generally the best tool for vertebrate biostratigraphy. Through this process he has discounted or ignored a very large body of recent work and continues to use identifications and hypotheses from his early 1990s work. [...] There is a large consensus now that has shown pretty conclusively that his global biostratigraphy hypotheses for the Late Triassic are untenable. Despite that these papers still get through peer review.

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I have now read a paper by Lucas from 2015 that talks about this disagreement with the Long Norian on almost half of p. 633. Even that discussion ends with:

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Nevertheless, the âlong Norian,â if accepted, cross correlates the Adamanian to the Norian, which would make the KrasiejÃw level Norian, as Szulc et al. (2015b [in the same issue]) conclude. Furthermore, the possibility that the CarnianâNorian boundary correlates to a level within the Adamanian, and that the KrasiejÃw level is younger than the Norian base should be considered. In these ways, a Norian age for the KrasiejÃw level is possible. However, my analysis of the available data suggests this is unlikely, so I regard the KrasiejÃw level as late Carnian.

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These "available data" are mentioned in the abstract: "The tetrapod assemblage of the KrasiejÃw level is assigned to the early Adamanian LVF based primarily on the stratigraphic overlap of the phytosaur Parasuchus with the Adamanian index aetosaur Stagonolepis." The claim that Parasuchus is present is, explicitly, based on the lumping of everything currently called "Paleorhinus" â itself probably a grade rather than a clade â into Parasuchus; and you have just shown that Stagonolepis is probably not known from anywhere outside Scotland...