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Re: Limusaurus Inextricabilis



Sorry for the off-topic, but in relation to beaks, it may not only be
that beaks in dinosaurs present much convergence, but perhaps also
reversals!!
I was seeing the analysis of Brusatte et al. (2008, superiority,
competition, etc., in Science) and there you have that the primitive
character state for Dinosauria seems to be presence of horny beak
(they are present in three sucessive outgroups of Saurischia:
Ornithischia, Silesaurus and Sacisaurus). Were the ancestral dinosaurs
herbivores? (this last possibility is countered by the carnivorous
dentition of Lewisuchus, however, according to that analysis).

Regarding gastroliths,
according to Bakker (1986, Dinosaur Heresies), gastroliths are also
used to process food in crocodiles, as can be seen (according to him)
on x-rays. May it be that the absence of gastroliths in dinosaurs
reflect more difficulty of preservation than herbivorous diet? As far
as I remember, gastroliths are also rare in herbivorous sauropods,
according to Calvo, 1994 (in Gaia), and not so functional according to
Wings and Sanders (2007, Proceedings B). May gastroliths just be
primitive for archosaurs? They are known in some ornithopods, so we
may see how many small ornithopods with roughly similar dentition are
known from similarly complete skeletons, and see the proportion of
them lacking gastroliths in order to approach the question if we can
say some animal did not used gastroliths just because we do not see
them. The same may apply for thyreophorans, "prosauropods" and
sauropods, and be compared with what is seen for carnivorous
neotheropods (and see if the difference is significant).
Alternatively, we would hypothesize many independent acquisitions, or
a very variable behavioral trait (that of eating rocks).

Are there gastroliths in aetosaurs?