Re: T.Rex predation etc...

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

Wayne Anderson wrote:

>         Which leads me to another question: both that bite and one taken, if
> I'm not mistaken, from another Rex were verterbral attacks. How many docu-
> mented T.Rex bites are there, and from what regions of the target? 

Erickson, G.M. & Olson, K.H. 1996: Bite marks attributable to 
     Tyrannosaurus rex: preliminary description and implications.  
     Journal of Vertebrate Paleontology 16(1): pp 175-178.

      In addition to the DMNH Edmontosaurus tail and the Triceratops 
femur mentioned in The Ultimate T.rex, the authors mention a Triceratops 
pelvis from the Hell Creek Formation in the Museum of the Rockies 
collections (MOR 799) that apparantly has at least 58 bite marks (I am not 
sure if they mean individual teeth or "mouth outlines", I assume the former) 
judged to belong to an adult (based on the size) T.rex (based on the 
shape: molds taken are shaped just right).  They also point out that no 
other theropod from the Hell Creek Formation is yet known that large 
enough to have made the marks.
     The sacrum has bite marks on the bottom AND BOTH SIDES, implying it 
was moved around while being chewed on.  There are also "bite 
furrows" made from the T.rex dragging its teeth along (there is a 
photograph of this in Ultimate T.rex with a penny for scale, the authors 
apparently didn't realize that this specimen was briefly mentioned there as 
well).  Also kind of neat, there are some shallow furrows the authors 
interpret as "nip marks" from the premaxillary teeth.  There are 
apparently more bite marks on the sacrum then the illium, which 
seems a little strange from the standpoint that the illium probably had 
more meat.  Part of the illium was bitten repeatedly until it 
came off.  The authors guess from the shape of the marks that this 
was done with the larger maxillary teeth.
     The author's conclusions based on the shape and number 
of bite marks is that T.rex did most of its chewing damage 
with its big lateral teeth, and also nipped with the 
premaxillary teeth.  They also speculate that the long 
furrows were caused by a "puncture and pull" strategy 
involving digging in and yanking with the neck muscles and 
body mass (I'd think this might help to explain why T.rex teeth 
aren't really that sharp: the serrations are cubical, not 
pointy and "steak knife" shaped.  If they were digging 
in and stripping of big chunks rather than slicing, 
they wouldn't need as sharp edges).                      
     The authors also mention an Edmontosaurus toe bone found nearby 
extremely large bite furrows.  
  
>From the paper's bibliography, on the subject of the Edmontosaurus tail:

Carpenter, K. 1988: Evidence of predatory behavior by Tyrannosaurus: in 
     J.R. Horner (ed.) International Symposium on Vertebrate Behavior as 
     derived from the Fossil Record.  Museum of the Rockies, Montana 
     State University, Bozeman, Montana, unpaginated.  

     In an edition of EARTH that came out last year (there is a big 
fossil human skull from the Out of Africa story, if anyone would care 
to dig up the issue) was a blurb about a South Dakota T.rex that had 
apparently been worked over by another (no bone regrowth, so 
intraspecific homicide cannot be added to the cannibalism charge).  I can't 
remember all the places that were chewed, but I remeber that apparently 
the vertebrae were badly chewed, with at least one vertebrae actually 
bitten in half.
     The most interesting thing to me from these articles (which Erickson 
and Olson talk about) is that T.rex apparently was perfectly willing to bite 
off and through bone, rather then just stripping meat.  The authors 
mention this provides Ca and K, in adiiton to marrow.  All in all, 
feeding habits sound awfully similar to mammalian carnivores.  Is there 
a lot of marrow in vertebrae?  The Triceratops illium seems like a strange 
part to bite off if that is what they were after.     
     Were Sue's injuries ever published?

LN Jeff
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