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actionthatdidnotendwellforoneofthem.Allinall,thesebodyfossilsof
Sinocal-
liopteryx
and their enclosed trace fossils tell us that
Sinocalliopteryx
was probably
a formidable ground-hunter.
Luckily, not all Cretaceous theropods with stomach contents were magically
restricted to China. Ably representing North American theropods and their meals,
DavidVarricchio—introducedinapreviouschapter—discoveredaLateCretaceous
tyrannosaurid (
Daspletosaurus
) in Montana with a few anomalous bones in its ab-
dominal region. These consisted of four tail (caudal) vertebrae and part of a lower
jaw(dentary)fromunidentifiedjuvenilehadrosaurs.Noticetheplural:thevertebrae
belonged to a hadrosaur that was likely about 3 m (10 ft) long, whereas the dentary
came from one that was about 1 m (3.3 ft) long. Juvenile hadrosaurs typically had
a thin layer of outer (cortical) bone on their caudal vertebrae, but this was missing;
the spongy bone underneath was exposed and pitted. Low-pH stomach acids in the
theropod's proventriculus probably dissolved cortical bone on the caudal vertebrae,
and the dentary was likewise in bad shape. So based on their identity as juvenile
hadrosaurs, appearance, and location inside a
Daspletosaurus
skeleton, Varricchio
concludedthatbothhadrosaursusedtobefood.Althoughthiswasnotenoughevid-
ence to say whether this
Daspletosaurus
actively preyed on these two differently
aged hadrosaurs or munched on already-dead ones, the close proximity of these
bones as gut contents implies that the theropod must have eaten one immediately
after the other.
The Early Cretaceous theropod
Baryonyx walkeri
of England is yet another
largetheropodwithstomachcontents,butsurprisingones.Thefirstspecimenofthis
dinosaurwasdiscoveredinaclaypitminein1983;paleontologistsAlanCharigand
Angela Milner named it several years later, in 1986. It died before growing to full
adult size, but was still an impressively large theropod at about 10 m (33 ft) long,
or half the length of a healthy tapeworm. Yet its most noteworthy features were: a
snout shaped more like that of a crocodile; a kink in its jaw also like that of a cro-
codile; nearly a hundred teeth in its jaws; robust arms; huge claws on its “thumbs”;
