Re: Cretaceous taeniodont

["Jaime A. Headden" <qilongia@yahoo.com>]

John Bois (jbois@umd5.umd.edu) wrote:

<<<Many large dinsoaurs were secondarily on four. The fact that no small
dinosaurs did this (so far) _may_ indicate that others had the edge
here.>>>

and Nick Pharris (npharris@umich.edu) replied:

<<Psittacosaurs (facultative?) and basal neoceratopians?>>

to which John Boise replied:

<Do you see these as burrowers?>

  Sounds like he was contradicting the statement "there are not small
dinosaurs this this (so far)." In fact, there are quite a few plentiful
small quadrupeds. One major example is *Bagaceratops* at about less than a
meter, easily at mass only maybe twice the size of the largest Cretaceous
mammal. As it survived in the latest Cretaceous, one would assume this is
a faculative usefulness to small quadrupeds; the "protoceratopsid"
*Microceratops* would have done so in Asia and Mongolia, at roughly the
same time. These forms are nested within taxa nearly two to three times
their size, suggesting faculative dwarfism or size reductionism.
*Leptoceratops* was less than two meters and very light in anatomy and
lived in the very latest Cretaceous, Maastrichtian. *Archaeoceratops* was
an earlier form (mid-Cretaceous, Aptian or Albian, Mazongshan Formation,
same general time as *Atokatherium*) that was barely a meter in length.
All these forms would likely have weighed on the order of 25lbs or less.

  Funny thing to note: birds, like chukars, using WAIR are effectively
quadrupedal, as are hoatzin chicks climbing or clambering.

=====
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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