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RE: Eodromaeus, new basal theropod from Triassic in Argentina



>
>   My argument does not presuppose that all dinosaurs were squamous rather
> than "fuzzy," but is based only on the logic of presupposition involved.
> It is likelier that many dinosaurs, based on direct evidence and their own
> bracketing (most of them sauropods and ornithischians, were squamous, but
> the issue depends on at which point we consider the squamous integument to
> have taken over (if it did) or whether size is a factor:  very few
> lagerstaetten preserve sauropodomorphans, larger ornithischians, larger
> theropods in the same detail they do the smaller-bodied forms (>3 meters
> seems to be problematic).
>
>   I would caution direct evidence as the best explanation for integument
> type, but logical inference projects two bases for reasoning an assumption
> that "fuzz" can be assumed _a priori_ for the basal Dinosauria, and would
> permit one to assume basal sauropodomorphans might actually be "fuzzy" and
> not squamous.

What's more, this creates a false dichotomy. It assumes the state
"squamoous" and the state "fuzzy" are mutually exclusive, when positive
evidence (birds, Juravenator, Psittacosaurus, etc.) show that they are
not.

It is perfectly reasonable to expect both conditions to be present in the
same lineage, and that in any given species in the lineage for the
relative distribution of these features on the surface area to vary
compared to its relatives, and for any given individual in a species for
it to vary ontogentically.