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Re: Spinosaurus teeth



>
>
>As I mentioned earlier, I found a Spinosaurus tooth at a rock shop in 
>Denver.  When I got home I started combing through all my books to find 
>out more about it.  Apparently it comes from Egypt and Marocco ( at least 
>that general area ).  Spinosaurs lived some 75 to 95 mya (hope I used 
>that mya correctly) and were identified from a partial jaw bone.  Additionaly,
>vertibrae were found that are larger than than of T-Rex, thus several of 
>my books classify the Spinosaur as the largest meat eating theropod.

(Actually, you should have used "Ma" there, because you are referring to
particular dates).

Spinosaurus was known from a fairly decent specimen (as good as some other
theropods, such as Eustreptospondylus, Torvosaurus, or Afrovenator).
However, the original specimens were destroyed in Allied bombing in WWII.

Spinosaurus had conical teeth, rather like a crocodile.  There is some
dispute as to serration size (Stromer implies that there were no serrations,
but all the "referred" specimens I've seen have very fine serrations).

The type was found in the Baharije Formation of Egypt, but there are many
equivalen-aged units throughout North Africa.  In these, large conical teeth
are fairly common.  While these could be Spinosaurus teeth, I wouldn't be
suprised if the teeth of the giant crocodillian Saurosuchus imperator (from
the same age and localities) were very similar.

Because Spinosaurus had fairly elongate vertebral centra (not to be confused
with the elongate neural spines which make up the sail), it may have been
larger than T. rex.  However, it may have been less compactly built, and so
lighter weight.  We will have to wait for additional specimens to confirm
this.

>It seems only fragments of this giant have been found.  I'm wondering what 
>the likelyhood of me having an actual tooth are?  It was very 
>inexpensive.  Secondly, many of my books, once again, piont to body 
>temprature regulation when talking about the sail on his back.  Is this
theory
>synonymous with cold bloodedness, or could a sailback coexist in Bakkers 
>warm blooded model.

Temperature radiators might be useful for either warm or cold blooded
animals, so it's hard to say.  What is more interesting (to me, anyway) is
the fact that sails appear in bursts in geologic time, but across many
different evolutionary lines (as Greg Paul has pointed out).  The first of
these was the Late Pennsylvanian-Early Permian, when the sphenancodontid
Dimetrodon, the edaphosaurids Ianthasaurus and Edaphosaurus, and the
amphibian Platyhystrix all developed sails.  The second was in the late
Early Cretaceous, when the dicraeosaurid Amaragasaurus, the sauropod
incertae sedis Rebbachisaurus, the spinosaurid Spinosaurus, and the
iguanodontid Ouranosaurus all developed sails.  Weird, huh?

Thomas R. Holtz, Jr.
Vertebrate Paleontologist
Dept. of Geology
University of Maryland
College Park, MD  20742
Email:Thomas_R_HOLTZ@umail.umd.edu (th81)
Fax: 301-314-9661
Phone:301-405-4084