Geoscience Reference
In-Depth Information
combination of activities, but especially their nesting, flamingo traces had signific-
antly changed the environments around these lakes.
Were dinosaur ground nests ever so numerous and closely spaced that these
formed nesting grounds and likewise changed their local environments? We don't
know for sure yet. Jack Horner originally proposed that the Late Cretaceous hadro-
saur
Maiasaura
ofMontanamayhavehadnestingcolonies,butnotenoughofthese
werepreservedtosaywhetherornotnestsaffectednearbyrivers,lakes,orotheren-
vironments. Near the
Maiasaura
nests are
Troodon
nests, which are rimmed, bowl-
like depressions that outwardly resemble flamingo nests. However, these nests are
much lower and wider and not nearly as numerous.
Anotherintriguingideaaboutdinosaurnestinginspiredbymodernbirdsisthat
perhaps some made massive nest mounds for incubating their eggs. Remember the
mallee fowls (
Leipoa ocellata
) of Australia and the 4-m-high hills they make with
their nest mounds? How about the recently extinct mound-nesting birds of New
Caledonia,
Sylviornis neocaledoniae
and
Megapodius molistructor
, which made
mound nests so big that archaeologists at first mistook these for human burial
mounds? Of these two birds,
Sylviornis
was the bigger one, weighing about 25 kg
(55 lbs), but still much smaller than most Jurassic and Cretaceous theropods. In at
least one recent documentary (
Dinosaur Revolution
, 2011),
Tyrannosaurus rex
was
depicted as a mound nester with an accordingly huge mound for its eggs. Sadly,
though, such nest mounds may have been made mostly of vegetation, not sediment,
so these would have had a much lower chance of being preserved as trace fossils.
Alternatively,ifcomposedmoreofsediment,remnantsofmassivenestmoundslike
thesemighthavebeenleftbehind,althoughifunaccompaniedbydinosaureggshells
or embryos these might be tough to discern.
Still, there is much we need to learn about dinosaur nesting. For example, no
onehasfoundnestsofstegosaurs,ankylosaurs,andmanyotherdinosaurs,including
those commonly preserved as adults, such as
Allosaurus
and
Triceratops
. Perhaps
some of these dinosaurs—especially those for which we have evidence of gregari-
