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Re: Fruitafossor - new Mesozoic mammal



Mickey Mortimer <Mickey_Mortimer111@msn.com> wrote:
> Jaime A. Headden wrote-
> 
> >   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. As for the coracoid bone, I beleive it's fusion and/or
transformation into a coracoid process has ALSO been proposed. Minimalization
of the coracoid is recorded during mammalian evolution, and eventual fusion of
this bone to the scapula during this process while retaining muscular and
tendinous attachments enforces that it remains, until these in turn relocated
to the scapula, clavicle, or may remain on the nascent coracoid; calling this
process the coracoid process does not mean the coracoid disappeared and a
process grew to replace it, when biologically simply integrating the tiny
coracoid AS a coracoid process is just as feasible. Reversals can happen,
though not likely as much as parallel or convergent evolution.

  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. 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, and I would
have liked to see the authors include palaeanodonts as well as a tamandua,
sloth, and several armadillos into their mammal matrix; this may effect the
tree somewhat.

  I do note the authors find a Xenarthra-Carnivora and a Fereeuungulata (or
whatever it's called) grouping. Dare I say clade, though the author's prefer
ranks.

  So pipe down Mickey ;) I wasn't calling it a palaeanodont. I simply prefer
thouroughness.

  Cheers,

Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


                
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