[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Fruitafossor - new Mesozoic mammal

> A glace through the data matrix shows an ommission of palaeoanodonts.
> *Metacheiromys,* *Eurotamandua,* and others are substantially more
> complete than *Fruitafossor,* but not included? What about *Manis*? I > am not
> convinced the xenarthran features are not so easily dismissed.

Uh... the thing's MUCH too primitive to be a eutherian, Jaime. It has a
coracoid for Pete's sake! And middle ear bones connected to the mandible.
Seems like an obvious case of convergence to me.

Rich, T. H., J. A. Hopson, A. M. Musser, T. F. Flannery, and P. Vickers-Rich.
2005. Independent Origins of Middle Ear Bones in Monotremes and Therians.
_Science_ 307:910-914.

It is just as easy, as the authors therein state, for two mammalian lineages
to develop the "mammalian middle ear" convergently as it is for THREE mammalian
lineages to do it.

The university library's institutional subscription is "on hold", so I can't read the article... but if you want to take Palaeanodonta out of Placentalia, Eutheria, Theria, Cladotheria, Trechnotheria, and Theriiformes, you better find lots of apomorphies that argue for that.

As for the coracoid bone, I beleive it's fusion and/or
transformation into a coracoid process has ALSO been proposed.

Which one? The procoracoid or the metacoracoid? Monotremes retain both. In Trechnotheria (spalacotheriids + us), at least, the procoracoids form the caps on the medial ends of the clavicles, while the metacoracoids form the processus coracoidei on the scapulae.

Minimalization
of the coracoid is recorded during mammalian evolution,


Yes, once AFAIK.

I made the point about including palaeanodonts because, while they were even
brought up in the differential diagnosis, no other mammals BUT palaeanodonts
have such broad and short humeri, xenarthrous vertebrae, tubular
non-enamellated teeth.

In short, no others are so strongly adapted to digging and myrmecophagy, right?

I love convergence and have pointed out such animals as
palaeoanodonts as exhibiting convergent lineages with several other mammal
groups, including arboreal, fossorial, and anteater-like, but this
*Fruitafossor* is stretching the limits of morphological space,


Does it have epipubes? I bet it does... and I bet palaeanodonts don't...

I do note the authors find a Xenarthra-Carnivora [...] grouping. 

Weird.

On the other hand, I'd certainly love to find out what palaeanodonts are. Related to Xenarthra? To Pholidota? To some other placentals?