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Re: *Fruitafossor*



Jaime Headden wrote:

I would try to resolve wether palaeanodonts are a natural grouping, first,
given some ideas that they may be a paraphyletic with regards to xenarthrans,
that xenarthrans are paraphyletic with regards to palaeanodonts, any
relationship with pholidotes that are NOT based on parallel or convergent
evolution, etc.

The situation regarding 'palaeanodonts' is messy, to say the least. The Palaeanodonta has a lot of baggage as a wastebasket taxon. The connection between palaeonodonts, xenarthrans and pholidotes is similarly unresolved. For example, _Eurotamandua_ was put in its own order by Szalay and Schrenk (1998), called the Afredentata, and held to be unrelated to xenarthrans and pholidotes.


This is a problem I was trying to point out with regards to the
presence of tubular teeth lacking enamel, since it HAS developed twice in
living mammals, given tubulidentates and xenarthrans.

It may be even more complicated than that. The Madagascan taxon _Plesiorycteropus_ was separated by MacPhee (1994) into its own order (Bibymalagasia) separate from aardvarks. I understand that this does not have universal support, with other authors putting _Plesiorycteropus_ back in the Tubulidentata. If MacPhee is correct, then aardvarks may have their own example of convergence.


Unfortunately this limited extant sampling may be enforcing the homoplasy of
less derived clades that would share common features with *Fruitafossor*, and
the absence of *Orycteropus* and *Manis* are rather glaring as they had been
mentioned in the text.

I agree that the aardvarks and pangolins are conspicuous by their absence from the analysis. Nevertheless, the case for _Fruitafossor_ being a basal mammal convergent upon xenarthrans appears pretty compelling to me.


To swing this thread back to dinosaurs (belatedly), I would point out that dedicated myrmecophagy is not known for any Cretaceous mammal, AFAIK. However, it has been suggested for the alvarezsaurids, which were widespread in the Cretaceous period, having been found in Asia, Europe, North America, South America, and Australia.


Tim