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stay upright through the rest of the Jurassic and Cretaceous periods, too busy to sit
down or otherwise take it easy? This scenario seems absurd, although it also poses
a good question as to how some of the largest of dinosaurs, especially those with
small arms, would have managed to both lie down and get up (I'm looking at you,
T. rex
). As many of us experience each morning, getting up is the hardest part fol-
lowing our resting. Still, the Middle and Late Jurassic, as well as the Cretaceous,
abounded with small dinosaurs, too, which would have had no problem stopping
and becoming supine. So perhaps it's only a matter of time before paleontologists
start recognizing more such trace fossils that record when a dinosaur took the pause
that refreshed.
Swimming Dinosaurs
Dinosaurs and water have had an odd back-and-forth relationship in our ima-
ginations. At some point in the initial studies of sauropod and “duckbill” dinosaurs
(hadrosaurs), paleontologists started wondering how such large animals kept them-
selvesuprightonlandwithoutalsoplacingincrediblestressontheirmuscles,bones,
and joints. So all paleontologists needed was a little bit of suggestive evidence to
nudge these big animals into the water, where their weights would have been sup-
ported through buoyancy.
For hadrosaurs, this evidence was scanty but persuasive for those who wanted
thesedinosaurstobeaquatic. Forexample, onehadrosaurtrace fossilspecimen had
skin impressions around its hand that stretched between its fingers. This led pale-
ontologists to conclude that this skin was webbing that aided it in paddling around
in bodies of water. Only later did paleontologists realize this “webbing” was actu-
ally a result of skin drying around its bones after the dinosaur had died. Another
hadrosaur,
Paralophosaurus
, also had a tall hollow crest on its skull, which was ex-
plained as a “snorkel” that allowed the dinosaur to breathe while most of its body
was hidden underwater from predators. A major flaw in this seemingly marvelous
adaptation was that the hollow tube in the center of the crest, once studied in more
detail later, actually makes a U-turn which would have constituted a perfectly inept
