Recent Dino Articles in Science News

[Richard W Travsky <rtravsky@uwyo.edu>]

In the Sept 9th issue of Science News (vol 158 no 11)was an article
on using tooth enamel as an indicator of warm bloodedness.

The full article is not online, only the references:

 http://www.sciencenews.org/20000909/fob5ref.asp
 Fricke, H.C., and R.R. Rogers. 2000. Multiple
 taxon-multiple locality approach to providing
 oxygen isotope evidence for warm-blooded
 theropod dinosaurs. Geology 28(September):799

The study measured oxygen isotope ratios (oxygen 18 and oxygen 
16) from "three different types of theropod dinosaurs collected
from sites between Madagascar and Alaska". These were compared 
with measurements from crocodile teeth from the same time periods 
and localities.

The measurements showed more variation in the crocodile teeth
than theropod teeth, suggesting that the theropds were at least
partially warm blooded.


The Nov 4th issue had an article on the triceratops reconstruction
at the National Museum of Natural History in DC. This topic has 
been covered in this list, but I don't recall seeing the URL
for the nice animations:

 http://www.nmnh.si.edu/paleo/dino/trinew.htm


The Nov 11th issue (vol 158 no 20) has two articles of interest. 
The first is about the stress levels the skull of an Allosaurus
can take:

 http://www.sciencenews.org/20001111/note7ref.asp

 The skull of the carnivorous dinosaur Allosaurus fragilis can
 resist levels of stress much higher than those expected from
 chewing, which may provide insight into the animal's method of
 attacking its prey.

 Rayfield, E.J. 2000. Allosaurus fragilis:
 Mechanical behavior of the skull and implications
 for feeding strategy. Society of Vertebrate
 Paleontology 60th Annual Meeting. Oct. 25-28.
 Mexico City.

Analysis of computerized tomography scans of an allosaurus skull
show it can withstand much more stress than would result from 
simple chewing would. The jaw had a weak bite force and a flexible
lower jaw, and the strength was in the upper jaw, leading to 
speculation that it could slam into its prey at "high speed with
jaws agape to drive in its upper teeth".

I went and looked at the allosaurus mount at the University
of Wyoming. The head is mounted with the jaws closed

 http://w3.uwyo.edu/~rtravsky/alhead.gif

The method of attack they propose would imply that the jaws could
open very wide. The teeth of the upper jaw don't strike me as being
suited to this, and I would also expect a broader, not a pointed
jaw. However, this individual has fourteen skeletal injuries, so 
perhaps that's related to such an attack method.


Also in this issue was an article on a new theropod from
Madagascar - a buck toothed one:

 http://www.sciencenews.org/20001111/toc.asp
 
 Researchers have unearthed fossils of a theropod dinosaur
 whose front teeth grew almost directly forward, which sets it
 apart from all other related species.

 Sampson, S.D, M.T. Carrano, and C.A. Forster.
 2000. A theropod dinosaur with bizarre dentition
 from the Late Cretaceous of Madagascar. Society
 of Vertebrate Paleontology 60th Annual Meeting.
 Oct. 25-28. Mexico City.

Sounds fascinating. Does anyone have a URL for a picture of this?