Re: *Fruitafossor*

[Tim Williams <twilliams_alpha@hotmail.com>]

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