Geoscience Reference
In-Depth Information
However,if
Baryonyx
onlyhadoneorafewgastroliths,suchrockscouldhavebeen
accidentally grasped and swallowed as it scooped up a slippery fish. Lastly, a few
brokenbonesin
Baryonyx
wereexplainedasthetracefossilsofotherdinosaursthat
irreverently stepped on its body after it had already died and been buried.
Nearly all of the trace fossils mentioned thus far were enterolites, food items
that only made it down as far as the proventriculus, gizzard, or whatever else func-
tionedasastomachinadinosaur.Whataboutcololites,inwhichthisfoodwasmore
digested, passing through the intestines for further nutritive absorption, and almost
ready to explode from a dinosaur's other end but never quite made it?
Onlyafewsuchtracefossilsareknownindinosaurs,butoneofthebestisalso
inthemostcompletedinosaurfromanentirecontinent,
Minmi paravertebrata
.This
Early Cretaceous dinosaur lived about 115
mya
in Queensland, Australia, and was
anankylosaur;recallthatankylosaurswerearmoreddinosaursthatlivedthroughout
muchoftheJurassicandalloftheCretaceousperiods.Ihaveseenacastofthisspe-
cimen displayed at a small museum in Richmond, Queensland, and it is incredible.
Although flattened so that it looks like Cretaceous road kill and about the size of an
adult sheep, nearly every hard part of its body is intact and articulated.
Fortunately,thisexceptionalpreservationincludeditsgutcontents,whichcon-
sisted of a compacted mixture of leaves, seeds, small fruits, and other parts from a
varietyofplantsinsidetheareaofitship.Alloftheseplantremainswerethesizeof
coarsecoffeegrounds,measuringonlyafewmillimetersacross.“Thenitmusthave
had gastroliths!” you shout excitedly. In response, I smile, nod, and thank you for
outwardlyexpressingsuchenthusiasmforthosetracefossils,butthengentlyinform
you that this ankylosaur had no gastroliths. This means that it more likely chewed
its food thoroughly in its mouth before swallowing, rather than relying on its stom-
ach to reduce food to a more digestible texture.
Okay, time to get skeptical. Dinosaurs, like other vertebrates, probably spilled
theirgutsafterdying,whetherfromdecomposition,scavengers,oracombinationof
thetwo.Onceopened,adeaddinosaur'sbodycavitywouldhaveinvitedtheoutside
