Geoscience Reference
In-Depth Information
So, like a burrowing dinosaur cutting through substrata, we uncovered even
more evidence that connected the remains of this dinosaur to its probable trace
fossil. Using the bones to reconstruct the size of the dinosaur, Dave calculated that
it was just more than 2 m (6.7 ft) long, with much of that taken up by its tail. Its
torso (from hips to shoulders) length was about 70 cm (28 in) long; its body was
26 to 30 cm (10-12 in) wide, and its mass (weight) somewhere in the range of 20
to 30 kg (44-66 lbs). Take away its tail, and it was about the size of a collie. When
documenting the burrow at the field site, Dave and I had noted the regular lengths
of tunnel segments, and that it was slightly higher than it was wide. This got us to
thinking about “burrow fit.” In other words, how easily could this dinosaur squeeze
into it and turn in the tunnel?
If the burrow was too small for this dinosaur, then we had to come up with a
very complicated (but still possible) scenario in which one adult and two juveniles
ofthe same species hadtheir bonesdeposited andburied together insome other un-
knownanimal'sburrow.Iftheburrowwastoobig,thenthatsuggestedtheadultand
its young were squatters, taking over a burrow made by another, larger animal: a
Cretaceous version of the “Occupy” movement, 95 million years ahead of its time.
So let's look at those numbers again. The torso length of the reconstructed di-
nosaur was about 70 cm, and the tunnel lengths were 70 cm. The width of the bur-
row was 30 to 38 cm, and the width of the dinosaur was 26 to 30 cm. So far, so
good.Butwasthereawaytocalculatetheweightofananimalbasedonitsburrow?
Why,yes,therewas.Inastudypublishedthesameyearthedinosaurwasdiscovered
(2005), a zoologist compared the cross-sectional areas of burrows made by a wide
variety of modern burrowing animals to the weights of their makers and found a
positive correlation between these. He had even provided a handy formula, which
we applied to the cross-sectional area of our burrow. Taking into account the slight
variations of tunnel width along its length, we came up with a range of 22 to 32 kg
(48-70lbs),which overlapped with the mass Dave calculated forthe adult dinosaur
on the basis of its bone. The burrow dimensions matched the dinosaur.
