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Re: primers, and South American dinosaurs



On 2/12/04 1:26 pm, "Phil Bigelow" <bigelowp@juno.com> wrote:

> Currently, practitioners of morphology-based cladistics and gene-based
> cladistics only *pretend* that their respective data are in some way
> related, and for the last decade each side has been giving the other side
> a grudgingly respectful bow of the head.  On the surface it appears to be
> sort of a gentleman's agreement not to humiliate the other side.  But in
> the next 10-20 years, and with a greater understanding of various
> organisms' genomes and how genes are expressed (and how these same gene
> expressions can be repressed), I predict that the gloves will come off
> and a greater rift will develop between the two subdisciplines.
> 

    After a certain recent abstract derived from theraspid evolution, and a
certain recent paper on development of mammalian teeth, both discussed on
this list, it's nice to see something which suggests morphology isn't a
total lost cause - Strait, D. S., & F. E. Grine, in the most recent 'Journal
of Human Evolution': 'Inferring hominoid and early hominid phylogeny using
craniodental characters: the role of fossil taxa' (available on Science
Direct). Basically, disagreements between morphological and molecular
phylogenies of hominoids disappear when enough fossil taxa are included to
bridge the gaps. It's all a matter of sampling.

> So, the question remains:  Morphologically, is a pug skeleton of the same
> species as a whippet skeleton?  Is it even in the same genus?

    From just bones, I'd say 'of course not'. We should never forget that
any species identification is, at the end of the day, a hypothesis, and
should never be treated as the final word.

And returning you to your regularly scheduled archosaurs, this just out
today:

Candeiro, C. R. A, C. T. Abranches et al. 2004. Dinosaurs remains from
western São Paulo state, Brazil (Bauru Basin, Adamantina Formation, Upper
Cretaceous). Journal of South American Earth Sciences 18 (1): 1-10.

'In this contribution is presented the preliminary results of a
paleontological expedition to five Upper Cretaceous fossil sites in the
western part of the state of São Paulo, Brazil. Although the material is
fragmented, the recovered fossils constitute an important record of the
theropod dinosaur; some isolated teeth are the first record of
Carcharodontosauridae in the Upper Cretaceous period in Brazil. The authors
group the teeth of the theropod into five morphological groups on the basis
of the general morphology of each tooth's cross-section and the presence of
wrinkles on the crown. Spinosaurid and abelisaurid are also represented in
this assembly, though other morph groups remain undetermined. One tooth in
particular and a caudal vertebra indicate the presence of sauropods from the
family Titanosauridae family.'

    Cheers,

        Christopher Taylor