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Fw: Tyrannosaurs as ambushers... how? (reply with pictures)




Hello J.S. Lopes,


Even fairly young Tyrannosaurids have long legs and high centres of
gravity. However, ambush seems very much a possibility for eight metre
long, three metre high, ~1500kg Tyrannosaurids.


Regarding cover:

People are often surprised in "dinosaur parks" which combine trees and
models. It should also be remembered that these parks tend to keep down
the size, number and complexity of shrubs in order to minimise
vandalism.

The lack of grass isn't necessarily a problem. It is likely that there
were herbaceous gymnosperms and ephedroids in dry environments, as well
as a great variety of ferns and shrub sized plants from numerous groups.

If one goes into most environments and measures the size of most bushes
one finds a lot which are taller than two or three metres and have large
enough cross sections. We tend to chronically underestimate the size of
plants.

Our experiments for the Lost World Returns project showed that it is
possible to get within a couple of metres of a G. libratus without
spotting it. In open scrub where >60% of the animal is complete visible
it is still possible to miss it when dozens of metres away.

Here are two examples (please ignore the gun - it was already in the
rendering engine we were using and I didn't both to remove it):
http://www.flora.org/paleo/images/LWRhidegood2reduced.jpg
http://www.flora.org/paleo/images/LWRhidegood4reduced.jpg


Regarding anatomy:

Large theropod anatomy is also relatively well suited to ambush,
especially static ambush:
- The long body, with the flexible neck means that a relatively small
  turn can move the head over a much larger arch relative to the
  movement of the body.
- Even assuming conservative acceleration rates, stride lengths in
  excess of three metres mean that an animal can cover a reasonable
  distance with just one or two steps.

Some Abelisaurids like Majungasaurus seem especially well adapted to
ambush: Having relatively shorter legs (lowering the body and making it
easier to go prone), but still very powerful legs for acceleration. As
well as having a greater degree of binocular vision (which is used by
ambushers to see around vegetation blocking one eye).

With their longer legs, many Tyrannosaurids give a strong impression of
being optimised for walking. Bipeds are generally more efficient than
quadrupeds and a form of endurance hunting seem plausible in open
country. So, both strategies may have been common.


- Jonas Weselake-George

Fern Spike Studios / Digteam




On Wed, 13 Apr 2011 07:46:08 -0700 (PDT)
"Joao S. Lopes" <josimo70@yahoo.com.br> wrote:

> Lions and tigers are large hunters who can ambush their prey, for
> example, hiding themselves in the grass. My question is: How could a
> mamooth-sized Tyrannosaurus rex hide itself? What sort of hiding such
> giant would use to apporach its prey? Ambush approachments seem
> plausible and efficient for lion-sized young tyrannosaurs (even if we
> consider that there was no "grass" in Cretaceous), using trees, rocks
> or something like, but a could full-grown gigantic Tyrannosaurus get
> it? 
> 
> J. S. Lopes
> 
> 
> 
>