Geoscience Reference
In-Depth Information
original feces lost volume with dehydration before burial. Too much information?
No, it's more like the more you know, the more you wonder.
Just how long has such carnivory been a part of dinosaurs? According to cop-
rolites, as long as there were dinosaurs. At the opposite end of the geologic-age
spectrum from tyrannosaurid coprolites are the oldest probable dinosaur coprol-
ites. These are about 228
mya
, coming from Late Triassic rocks of Argentina and
the same strata bearing bones of two of the oldest dinosaurs in the fossil record,
Eoraptor
and
Herrerasaurus
. Reported in 2005 by paleontologist Kurt Hollocher
and three colleagues, these coprolites, like the tyrannosaurid ones, had bone frag-
ments and were cemented with apatite. Out of the ten found, two were studied in
great detail. Both of these were similarly sized, measuring about 2 cm (0.7 in) wide
and 3.1 to 3.7 cm (1.2-1.4 in) long, about the average size of what might be en-
countered in a dog park.
Like the
Maiasaura
coprolites, these had invertebrate burrows in them, al-
though only a few millimeters wide. Hence they were probably not from dung
beetles but perhaps fly larvae or worms. Because
Herrerasaurus
was a carnivorous
theropod,anditsbodypartswerethemostcommonofanycarnivoreinthosestrata,
plus it was about the right size for these coprolites, Hollocher and his cohorts pro-
posed that they came from that dinosaur. Still, other archosaurs may have been re-
sponsible for them, too.
Thesetheropodcoprolites,fromtheLateTriassicthroughtheLateCretaceous,
demonstrated how carnivory was a dietary mainstay in this lineage for at least 160
million years. Furthermore, this evolutionary tradition continues today with predat-
ory birds, although fortunately for us and many other animals, none of these thero-
pods are producing feces on the scale of a tyrannosaur.
Passing Grass: The First Grasses and the Dinosaurs That Ate Them
Today we take grasses for granted. They occupy most of the soils in our lawns,
parks, pastures, athletic fields, and university quadrangles, but are also ubiquitous
inourdailydiets.Grassesweeatincludecorn,wheat,orrice,andotherswedrinkin
