Geoscience Reference
In-Depth Information
ous predator. How about a sharp rock? Another hadrosaur in a fight over a mate or
meal? Or, most ignoble of all, a festering sore caused by a bacterial or fungal infec-
tion?
Just like the hadrosaur, you get the point. Trace fossils of injuries preserved
in dinosaur bodies become difficult to interpret when we can't distinguish whether
these wounds were caused by another dinosaur, a non-dinosaur animal, or self-
inflicted (albeit accidentally). Also, some of these marks may have been made
through other means, such as infections, which are not trace fossils at all. This is
where the study of dinosaur health problems enters a realm of forensics that gets
contentious, just like evidence for a court case going to trial.
Actingastheprosecutingattorney,however,Ipurposefullywithheldsomecru-
cial evidence until the last part of the trial so that it would have a maximum effect
on the jury. You see, the skin impression from this hadrosaur was directly next to
its skull, and the skull had toothmarks. Furthermore, the toothmarks were widely
spaced, and most were from an animal with pointy teeth and large enough to attack
an adult
Edmontosaurus
. Even better, these toothmarks on its skull also show signs
of healing. So, ladies and gentlemen of the jury: Is it not true that these toothmarks
came from a carnivorous dinosaur? Is it not true that they match the lineup of teeth
in the mouth of a tyrannosaur? Is it not true that tyrannosaurs liked to dine on
Ed-
montosaurus
? Is it not true, then, that the puncture mark on the skin came from the
same attack as the skull?
Well, maybe. After all, even with healed toothmarks on its skull and a nearby
patch of skin with a healed puncture wound, this specimen of
Edmontosaurus
may
have had two mishaps separated in time, with only one inflicted by a large thero-
pod. However, if I were a betting ichnologist, I would wager that the toothmarks in
the skull comprise the real evidence of a tyrannosaur attack. In contrast, the healed
wound in the skin impression is more circumstantial and might be from a separate
injury that the hadrosaur did to itself.
