[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: New refs. (and a correction)



Tom Holtz <tholtz@geochange.er.usgs.gov> wrote: 

>Just received my copy of the March issue of the Journal of Vertebrate
>Paleontology (which actually came out in March!!).  A few dinosaur papers
>in here:
>
>Chinsamy, A.  1995.  Ontogenetic changes in the bone histology of the Late
>Jurassic ornithopod Dryosaurus lettowvorbecki.  JVP 15: 96-104.
>        More great work from the "Queen of Dinosaurian Histology" ;-).
>Dryosaurus is seen to differ from other dinosaurian growth patterns in that
>there aren't any distinct lines of arrested growth (LAG).  This suggests
>that Dryosaurus grew continuously uninteruppted throughout life (as opposed
>to most dinosaurs, which had periodic (annual?) starts and stops in
>growth).  However, unlike mammals and birds, there is no evidence of a
>determinate growth pattern (i.e., a specific size at which growth stops).

  The thing about that paper that really caught my attention was the
exceptionally-large medulary cavity in the adult femur of Dryosaurus.  The
cavity (i.e., referring to "hollow bones", folks) is so large that a
juvenile femur from the same species can be stuffed into the cavity (and it
was; photograpic drama!).  Since Dryosaurus is an orithopod, the blanket
statement that "any large dinosaur long-bone fragment that contains a large,
smooth medulary cavity has to be from a theropod" is false.  I was wondering
about that.  I see "hollow bones" in some diagnoses of dinosaur species, but
I have never seen that character trait used in cladistics.  I wonder why?  Is it
because it is too often a convergent feature that would obscure
relationships? 

Another pleasant revelation about this issue of J.V.P. was how THICK
the issue was.  That means that they are stuffing more papers in, and
relieving the backlog of manuscripts.....
        :-)