Giganotosaurus and monotremes

[Jeffrey Martz <martz@holly.ColoState.EDU>]

      "Discovery News" a few weeks ago featured a blurb on Giganotosaurus
and Charcarodontosaurus, in which measuments of AMNH 5027 and the
Chacharodontosaurus and Giganotosaurus RECONSTRUCTIONS placed T. rex in
third place.  The Giganotosaurus RECONSTRUCTION measured about 6"1',
which, if I am not mistaken, isn't much larger then Sue.  And if the
reconstruction is really too large....  It doesn't really matter.  The 
sample size is mediocre for T.rex and atrocious for the other two.  Like
the American supersauropod debate, this has seemingly dissolved into
another case of "mine's bigger then yours."  All anyone can really say at
this point is that Tyrannosaurus, Giganotosaurus, and Charcharodontosaurus
are about the same size, and this seems to represent the (known) upper
size range for theropods.  How complete is the Charcharodontosaurus skull,
and how much postcranial material did they recover?

> Investigation of mitochondrial DNA sequences of the platypus and an 
> Australian kangaroo species (Macropus robustus or wallaroo), strongly 
> supports the position of the platypus on the marsupial lineage, or 
> in cladistic terms: platypus and the marsupials shear a more recent 
> common ancestor than each with placental mammals.
> This also suggests that the view of monotremes as being 
> 'primitive' as reflecting the ancestral state and not having 
> developed the 'advanced' features of the other mammals
> should give way to the vision that considers the characteristics of the 
> Australian mammals as adaptations to specific environments that have 
> been existing in Australia, for example harsh conditions with periods 
> of prolonged drought.

     That may be true of the marsupials, but that is no reason to assume
that monotremes have NOT retained the ancestral characteristics.  The
family tree may look something like this...


   monotremes     marsupials          placentals
         -         *                #
           -     *              #
              -            #
                -     #
                   - 
                     -
      With the dashes representing primitive characteristics, and the *
and # representing derived characteristics for marsupials and placentals.
Monotremes may still display primitive features not found in marsupials or
placentals.

LN Jeff
O-