Geoscience Reference
In-Depth Information
wasps may have peacefully co-existed, just like most people and wasps do today,
with only a few sting-induced exceptions.
Insummary,becauseofawonderfullycompleteamountofbothbodyandtrace
fossil evidence—but especially trace fossils—
Troodon formosus
of Montana is ar-
guablythebestunderstoodofnestingdinosaurs,onlyrivaled byitsneighborsinthe
same field area,
Maiasaura
. This is not to say that we have stopped learning about
Troodon
and its nesting, but the holistic approach taken toward its study, including
ichnological perspectives, gave paleontologists a superb model for comparing with
other nesting dinosaurs.
Big Dinosaurs Scratching Out Big Nests
Thanks to
Maiasaura
and
Troodon
for their tracemaking abilities, as well as ex-
ceptionallygoodfortuneinbothfossilpreservationanddiscoveries,paleontologists
had a new search image for dinosaur ground nests as trace fossils going into the
21stcentury.Thusitwasnotsurprisingthatoneofthesamepeoplewhostudiedthe
Troodon
nests and eggs with Varricchio in Montana, Frankie Jackson, later noticed
and defined similar structures in Late Cretaceous rocks of Patagonia, Argentina, in
2004.However,whatwasastonishingaboutthesenestswasthattheywerenotfrom
a mere 3-m (10 ft) long dinosaur like
Troodon
, but were made by titanosaur sauro-
pods, which were among the largest animals to ever walk the earth.
The wealth of evidence supporting nest building in these sauropods included
rimmed nest structures, but also complete egg clutches, embryonic titanosaur bones
inside the eggs (some preserved with skin impressions), and at least four horizons
containingnestsoreggs.Thelattershowedthatthetitanosaursreturnedtothisnest-
ing site over years and perhaps generations, suggesting site fidelity in these dino-
saurs too. Further supporting this idea, paleontologists working at this site figured
it held thousands of egg clutches, varying from eggshell fragments to entire eggs.
Thenumberofeggswas15to35perclutch,andeachindividualeggwasbig,about
13 to 15 cm (5-6 in) wide. Also, eggs were shaped like slightly squashed balloons:
round ones, that is, not the cylindrical ones used to make funny balloon animals
