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be drawn from one track to the next. I have seen this trackway pattern made by
birds as small as sanderlings (
Calidris alba
) to as large as cassowaries and emus,
and by birds with anisodactyl, palmate, totipalmate, or zygodactyl feet. However,
the biggest difference between bird and human diagonal-walking pattern is how
bird trackways typically have very narrow straddles, as if they are walking on a
tightrope.Forexample,ifsomeprankstersdecidedtocreatefakemoatracksinNew
Zealand by wearing big three-toed “feet” and wanted to make the trackway look
more convincing to experts, they would need to swing their hips, placing one foot
almost directly in front of the other. On the other hand (or foot, rather), walking
normally would cause a wider-straddle trackway, which would be a dead giveaway
that someone wearing oversized three-toed shoes had fabricated them. (However,
the fact that a few idealistic people would happily accept such tracks as evidence
that 3-m-tall flightless birds are somehow winning a centuries-long game of “hide-
and-seek” is another matter.)
The most important variation onthe diagonal-walking trackway pattern is run-
ning, in which the footprints are farther apart from one another, reflecting increased
stride length. With this increase in speed, trackway straddles become even tighter,
and individual tracks may show signs of claws digging in deeper, and sand or mud
having been pushed behind where the feet registered. In this respect, nearly every
non-avian theropod and most ornithopod trackways bear similar basic patterns or
features like those made by equivalently sized modern birds. Thus, despite having
anatomies that differ from Mesozoic dinosaurs, it is no wonder that dinosaur ichno-
logists still turn to birds—especially large flightless ones—as their default models
for how bipedal dinosaurs moved and made tracks.
Has a bipedal dinosaur trackway—whether from a theropod or ornitho-
pod—ever shown hopping and skipping patterns like those made by some modern
birds? Not yet, and no one is holding their breath in anticipation of finding these in
the fossil record. Even so, non-avian feathered theropods might have been capable