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RE: misc questions...



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Marc Dezemery
>
> Hi everyone,
>
> Although i've been consulting the archives for a few time, i'm
> quite new to this list, and have a few questions & requests to
> "those who know":

I'll answer a couple: other people might have a better feel for questions 2
and 4.

> 1. Looking at the femur / tibia proportions in dromaeosaurs, i am
> wondering about their running ability. Were they the fast
> runners, as often referred to, or more ambush hunters / jumpers ?

Okay, in bivariate space (plotting femur vs. tibia) dromaeosaurs have
"typical" non-avian theropod values for the tibia at any given femur length,
unlike (for example) troodontids, ornithomimosaurs, and tyrannosaurids
(which have longer than expected tibia relative to other theropods).  Under
this criteria we would not expect dromaeosaurs to be exceptionally fast.
Also, the metatarsals of dromaeosaurs tend to be either "typical" or
relatively short relative for a given femur or tibia length compared to
other theropods.

(Note, incidentally, that paleontologists have not argued that dromaeosaurs
were exceptionally fast creatures *relative to other theropods*.  That idea
is the product of fiction writers' imaginations.)

In ternary space (a plot of the relative percentages of femur, tibia, and
metatarsal length), as done by Gatesy & Middleton (1997. JVP 17:308-329), it
becomes a bit more complicated.  The few dromaeosaurs included in that study
are big ones (specimens of Deinonychus and an unnamed form) plot closest to
some galliform birds (chickens, pheasants, and their relatives).  For what
it is worth, these birds are not specialized runners, although they can move
swiftly AND can move pretty well in trees, too (peacocks, despite their
bulk, can roost quite high in trees).

Plotting some of the smaller newly discovered dromaeosaurs in this manner
finds them mixed up with Archaeopteryx specimens (shouldn't be a surprise to
anyone!).

Be that as it may, I have argued on the list and elsewhere (as have plenty
of others, such as Greg Paul) that this and other evidence suggests an
ambush predation technique.

> 3. There's been some discussion a while ago about a theropod
> close to but "bigger than Giganotosaurus". Has it been named
> yet? Any web ressources about it?

No, and (to my knowledge) no.


                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796