Geoscience Reference
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fractured and moved them after burial. This meant that some eggs laid by different
sauropod mothers at different times were mixed together. The egg arrangements of
Troodon
and these titanosaurs were as different as the rooming habits of Felix and
Oscar (respectively) in
The Odd Couple
.
So although these titanosaur nests shared some of the same traits as the
Troodon
nests, they also differed enough to raise more questions about how they
were made. For instance, one can more easily imagine a small theropod using its
hands, rear feet, and maybe its snout to dig into loose sediment, neatly compos-
ing a ground nest. This same creative exercise becomes more challenging with
massivesauropods.Forone,theirsmallheadsdon'tlookasiftheywouldhavebeen
much help in excavating a nest, and their snouts seemed ill suited for doing much
more than grabbing plants. Looking elsewhere on a sauropod body, a quick cursory
glance at sauropod feet also disappoints, as these do not have any obvious adapta-
tions for scratching out a nest. Or do they?
Let's take a closer look at sauropod feet. One might initially think that the
feet of sauropods and elephants were similar, considering that, just like elephants,
sauropods were large terrestrial herbivores that greatly outweighed all of their con-
temporaries. Yet when their feet are compared, striking differences emerge, with
the most obvious being their toes. Elephants tend to have blunt
unguals
(“nails”),
whereas most sauropods have pointed unguals, which are especially apparent on
their rear feet. Even more odd is how the ungual on the first digit of the rear foot of
a sauropod—homologous with our “big toe”—is significantly larger than all of the
others. Then the unguals in that same foot are all oriented so that they point away
from the center of the body, instead of straight forward. This same skewed orient-
ation shows up in well-preserved sauropod tracks, so we know that this was a real
traitinlivingsauropodsandnotsomethinginferredmistakenlyfromputtingtogeth-
er their foot bones the wrong way. All of this evidence thus led paleontologists to
ask a simple question: What's with the weird feet?
