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Re: Mammal - Like - Reptiles
> I am trying to find some information about
> the mammal-like-reptiles such as:
> Lystrosaurus Thrinaxodon and Cynognathus.
As a matter of fact, the name "mammal-like reptiles" should be
discarded and replaced by "synapsids" (or non-mammalian synapsids in
a strict The concept "Reptile" in the old 'natural history' meaning
and in its new cladistic definition has nothing to do with synapsids.
In the history of amniotes, the two lineages (Synapsida and Reptilia,
or Theropsida and Sauropsida) diverged very early from a common
amniote ancestor and evolved independently. Features that are
considered typically reptilian, such as presence of scales and
uricotely (excretion of nitrogen mainly as uric acid) are probably
unique apomorphies of Reptilia and were not present in synapsids. The
"reptilian"-like appearance of synapsids is in fact the retainment
of a primitive basal amniote "Bauplan", which together with
the cumulative acquisition of more mammal-like characters gave
rise to the mosaic of "reptilian" and "mammal-like" features which
has given synapsids their familiar nickname.