Geoscience Reference
In-Depth Information
CHAPTER 6
Broken Bones, Toothmarks, and Marks on Teeth
Dinosaurs and Their Embodied Trace Fossils
This is where I cheat. Take a look at the title of this topic again, and you will see an
absence—“without bones”—as a central theme. So in defiance of that dictum, I will
now turn to dinosaur bones and other body parts, such as teeth, for whatever wisdom
these can provide.
Thisconcessiontobodyfossilsisnecessarybecausemanydinosaurtracefossils
are in their bones and teeth, or in bones and caused by teeth. A few of these
trace fossils announce themselves as broken or otherwise injured bones, some of
whichcouldonlyhavebeeninflicted byotherdinosaurs.Sometimes thisevidence of
dinosaur-on-dinosaur violence suggests that it originated from within a species and
perhaps was inspired by competition, whether over territory, a mate, or food. In oth-
er instances, injuries were caused by another species of dinosaur that attempted to
kill and eat the assaulted dinosaur, although most trace fossils in bones are marks
made after their owners perished. In short, the bodies of dinosaurs or other verteb-
rates—notsediments—weretheplaceswherethesemarksofdinosaurbehaviorwere
recorded.
How do you imagine such trace fossils? You already have. Recall that this topic
began with a piece of fiction set about 70 million years ago, opening with two rival
male
Triceratops
that squared off in combat, and with one losing face. A few other
dinosaurs in this tableau—small anonymous feathered theropods—were chewing on
pterosaur bones while this ceratopsian drama played out nearby. A tyrannosaur, ini-
tially interested in the outcome of the ceratopsian battle but ultimately disappointed
with its results, switched her ravenous attention to a herd of
Edmontosaurus
. With
these dinosaurs, she bungled her ambush of a young male
Edmontosaurus
but man-
