Geoscience Reference
In-Depth Information
Meanwhile on land, lowly mammals imparted their distinctive incisor in-
cisionsonavarietyofLateCretaceousdinosaurbonesfromAlberta,Canada.These
toothmarks were not made by mammals feeding on dinosaurs, exacting revenge for
all of their consumed relatives. Instead, they were trace fossils like the tooth-marks
leftbymodernrodentsthatchewbonestoweardowntheirconstantlygrowingteeth
and get more calcium into their diets.
Insect borings are other trace fossils in dinosaur bones that, at first glance,
might be mistaken for dinosaur toothmarks. Carrion beetles, which dine on dead
bodies, or termites, which make small pits or tunnels in bones, could have made
these. Carrion beetles would have chipped bones with their strong mandibles while
stripping flesh for food, just like they do today. Not all termites restrict themselves
to wood or soil, and some modern species drill into bone, making themselves at
home. As many people might know from watching lurid crime shows on TV, spe-
cificinsectsandtheirlifecycles aredirectlyassociated withcolonizingdeadbodies.
Hencetheseinsecttracefossilstelldinosaurresearchersmuchaboutwhathappened
after the dinosaurs died, such as whether their bodies were exposed for long or bur-
ied quickly.
Sobetweensharks,smallmammals,andinsects,recentlydeaddinosaurbodies
were valuable sources of nutrition and potential homes, with the bones lending
themselves to lots of tracemaking. What about marks left on bones that were not
traces of animal behavior? This is where paleontologists and overzealous ichnolo-
gists (guilty as charged) must exercise caution. For instance, plant roots can invade
any available spaces in bones and push them apart, making trace fossils that could
be mistaken for insect borings. Bones also can gain nicks, scrapes, and dinks from
being dragged along a stream bottom. There's also something about having several
kilometersofsedimentaryrockoverheadthattendstocrushbones.Allofthesenon-
living phenomena could have wrought false traces, the bane of ichnologists every-
where.
Bang Your Head, Wake the Dead
