RE: T-rex as ankylosaur specialist?

[Ken.Carpenter@dmns.org]

Ah, that explains why Tyrannosaurus became extinct! Only four
Ankylosaurus specimens are known, compared with the 24+ T rex. Obviously
they starved to death. Silly me! All this time I thought it was due to
some other cause.


Kenneth Carpenter, Ph.D.
Curator of Lower Vertebrate Paleontology/
Chief Preparator
Department of Earth Sciences
Denver Museum of Nature & Science
2001 Colorado Blvd.
Denver, CO 80205
 
Phone: 303-370-6392
Fax: 303-331-6492

for PDFs of some of my publications, as well as information of the Cedar
Mountain Project: 
https://scientists.dmns.org/sites/kencarpenter/default.aspx
++++++++++++++++++

-----Original Message-----
From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] On Behalf
Of Jerzy.Dyczkowski@unibas.ch
Sent: Tuesday, May 30, 2006 9:50 AM
To: dinosaur@usc.edu
Subject: T-rex as ankylosaur specialist?


Just waking up endless thread about T-rex ;) Several puzzling
adaptations can be well explained as specialization for predation of
ankylosaurids.

Adaptation for walking instead of speed is well supported by that
ankylosaurids were even slower.

Extremely strong jaws fit as adaptation to grasping and eating armored
prey.

Combination of short arms and strong shoulder bones could be adaptation
to wrestling with such prey. I suggest, that T-rex first grasped
ankylosaurid avoiding both tail club and spikes. It then used arms,
together with jaws and weight to pull ankylosaurid to the side, exposing
vulnerable underbelly.

Suggested sociability of carnosaurs means that armor and tail club of
ankylosaurids was poorer defense than we think. Lone ankylosaurid could
not defend itself from all sides. It was relatively hapless towards
several tyrannosaurs at once. At the same time, such meal provided food
for several tyrannosaurids.

One thing worth considering is that tyrannosaurids, predators or not,
could steal prey between themselves. This could promote social lifestyle
also if social hunting was not advantage.

I read that lions hunt most efficently (in kilograms of meat gained per
lion per hour) if they hunt alone smaller prey, or in groups of few for
buffalo-sized prey. However, lions consistently hunt in packs too small
and too big to be efficent. Reason is communal defense of prey from
other predators (including hostile lions) and males hanging around
hoping to bully or steal some meat.

Similarily, juvenile Tyrannosaurus could hang by related adults hoping
to steal some food, breeding female could take some prey from males, and
related tyrannosaurs could hang together to protect prey.

I wonder if there are ankylosaurid skeletons with appropriate scratches
and damages?

Jerzy Dyczkowski



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