Geoscience Reference
In-Depth Information
However facile this checklist might seem, it represents a lot of previous work
on dinosaur nests. Knowledge of some of the history behind it may provide a per-
spective on how what we know now about dinosaur nests also reminds paleontolo-
gists how much we still need to learn about these trace fossils.
The First Recognized Dinosaur Nests
Anyone who has not studied the history of dinosaur studies might be astonished to
know that the first genuine dinosaur nests were not interpreted until 1979. At the
time of this discovery, more than a hundred years had elapsed between paleontolo-
gists first linking fossil eggs to dinosaurs, which was in 1869. Furthermore, only a
few of the previously mentioned criteria were applied to these nests, showing how
far paleontologists have come since then in defining them.
In what became a revolutionary discovery, inspiring nearly everyone to recon-
sider what they thought they knew about dinosaur parenting, John (“Jack”) Horner
and his friend Robert (“Bob”) Makela, while prospecting Late Cretaceous rocks in
Montana,founddepressionsfilledwitheggsandpartlygrownjuvenilesofthelarge
ornithopoddinosaur
Maiasaura peeblesorum
.HornerandMakelainferredthepres-
enceofnestsonthebasisofmanynearlyentireandidentical eggs,somecontaining
embryonic skeletons of
Maiasaura
, which were in the bottom of what looked like
indentations to them. These former hollows were visible as differently colored sed-
iment above and below the eggs; unfortunately, though, no sedimentary rims were
present. Soeither these dinosaurs didnotmake suchrims, therims hadbeeneroded
and not preserved, or these researchers missed them because of too-subtle differen-
ces in the sediment.
Still, on the basis of localized assemblages of eggs and baby dinosaur bones in
the same small areas, they hypothesized that this part of Montana was a
Maiasaura
nesting ground about 75 to 80
mya
. The close spacing of the nests also hinted, for
the first time, that dinosaurs nested communally. Subsequent field work done in the
same area yielded more and different eggs, which at first were linked to the small
ornithopod dinosaur
Orodromeus makelai
(yes, this species was named in honor of
