Geoscience Reference
In-Depth Information
bone ailments would not count as trace fossils is if diseases caused them, because
these would
not
be related to dinosaur behavior.
Unlike
Tyrannosaurus
,
Allosaurus
is one of the best represented of all dino-
saurs in the fossil record, with thousands of its bones identified. This means that
paleontologists are seeing a more complete range of its bones, which accordingly
more closely reflect the overall health of an
Allosaurus
population at a given time.
In that respect,
Allosaurus
was more likely to get hurt than another copiously rep-
resented theropod dinosaur, the Late Triassic
Coelophysis
of the southwestern U.S.
Hundreds of specimens of
Coelophysis
have been studied, and very few of these
show signs of healed bone injuries. One of the reasons for this may be an easy one:
Coelophysis
was a much smaller dinosaur than
Allosaurus
, measuring about 3 m
(10 ft) long and weighing about 45 to 50 kg (100-110 lbs). In contrast, an adult
All-
saurus
could have been as much as 10 m (33 ft) long and weighed about 2.5 tons
(more than 5,000 lbs). Yet another factor to keep in mind is that
Allosaurus
(on av-
erage) probably lived longer than
Coelophysis
, meaning it had more opportunities
to rack up injuries.
Bigger was not better for a bipedal dinosaur, owing to the effects of gravity.
As elaborated in a previous chapter, if a large two-legged dinosaur tripped, both its
greater weight and height would conspire against it once it hit the ground, fulfilling
the old saying “the bigger they are, the harder they fall.” Big theropods also may
have gone for accordingly larger prey items, which would have objected to a thero-
pod'sinvitationtodinnerandfoughtback.Lastbutnotleast,bigtheropods,justlike
ceratopsians or pachycephalosaurs, may have competed with other large members
oftheirownspecies,whetheroverrealestate,sustenance, ordesirablemates.Allof
these possibilities add up to a greater likelihood of a hefty theropod suffering phys-
ical damage during its lifetime, especially if compounded by aggressive behaviors.
Inconveniently, other than the few examples here, most healed bone breaks in
dinosaurs have not been interpreted more narrowly as trace fossils made by other
dinosaurs or by the dinosaur itself. In most instances, paleopathologists are rather
