Geoscience Reference
In-Depth Information
quitoes and other blood-sucking insects (which are ectoparasites) had ingested di-
nosaur DNA in their meals.
Although some insects or other Mesozoic arthropods could have parasitized
dinosaurs,wehadnoactualevidenceoftheirhavinghostedendoparasites.Soitwas
time to look at modern analogs for guidance. Knowing that most modern endopara-
sites live atleast partoftheir life cycles inanimals' guts,wealsoknowthat eviden-
ce of these parasites—live or dead bodies, eggs, and dormant stages (
cysts
)—is of-
ten included in host animals' feces. For that reason, dinosaur coprolites might like-
wise hold such signs.
Indeed, some do. In 2006, two paleontologists, George Poinar and Art Boucot,
documented three types of endoparasites in a dinosaur coprolite: protozoans, which
are one-celled amoeba-like organisms; trematodes, a group of flatworms that in-
cludes flukes; and nematodes, which consist of “round worms” and horsehair
worms. The coprolites were from an Early Cretaceous deposit in Belgium that also
contained many skeletons of the ornithopod dinosaur
Iguanodon
, which were dis-
covered in the 1870s. This did not mean, however, that the coprolites were dropped
by
Iguanodon
,as some had bone fragments, pointing toward meat-eating theropods
as the culprits. The coprolites, first identified in 1903, ranged from 2 to 5 cm (1-2
in) wide and 11 to 13 cm (4.3-5 in) long, or human-sized. Poinar and Boucot took
one of them, broke it up, subjected it to strong acids, and centrifuged it: the most
action its contents had received in about 125 million years. What survived this pre-
paratoryprocesswereprotozoancysts,atrematodeegg,andnematodeeggs.Incred-
ibly,oneofthenematodeeggsevenheldthecoiledbodyofababynematode,which
had just missed hatching after exiting a dinosaur's body in its feces.
Althoughallofthesefossilswerenewtoscience,theycloselyresembledmod-
ern pathogenic species seen in amphibians, reptiles, and birds. So thanks to this
dinosaur coprolite and its 125-million-year-old secrets, biologists interested in the
evolution of endoparasites have a minimum time for when such perfidious behavi-
