Geoscience Reference
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for different reasons than eating another dinosaur”)? It all comes down to a com-
mon dilemma in dinosaur ichnology, and one that has been around for more than
two hundred years, which is how to distinguish three-toed dinosaur tracks from one
another and interpret who made the tracks.
So let's look at how the continuing dilemma of three-toed dinosaur tracks fig-
ures in all of this. The 2011 study of the Lark Quarry dinosaur tracksite by Romilio
and Salisbury involved: a close look at the dinosaur tracks as they are preserved
today at Lark Quarry; studying casts that were made of the dinosaur tracks soon
aftertheywereexcavatedinthe1970s;andlotsofstatistics,whichIwilldomybest
to explain to any non-scientific (yet admirably geeky) readers who might need it.
Still, the heart of Romilio and Salisbury's 2011 interpretation was a focused reex-
amination of the large dinosaur tracks. Although these large tracks dwarf the others
at Lark Quarry, as mentioned before, they are relatively few in number, with only
eleven such footprints recorded on a surface that contains more than 3,300 tracks.
That's right: The key plot element of the original story of Lark Quarry hinges on a
sequence of only eleven tracks, and identifying what made those tracks.
Why identifying the maker of these big tracks is so difficult is mostly attribut-
abletothetracksonlyhavingthreetoes,atraitalsoknownas
tridactyl
.Thesetracks
are also more or less mirror images on either side of the middle toe, a condition
called
mesaxonic
. Furthermore, because bipedal dinosaurs made such tracks, their
trackways normally show an alternating right-left-right diagonal walking. (Incid-
entally, now that you know these nifty terms, be sure to incorporate them in your
daily conversations, such as “Wow, your chicken leaves some of the best tridactyl
mesaxonic tracks in a bipedal trackway I've ever seen!”)
Thislittlechecklisthelpstonarrowdownthepossibledinosaurtrackmakers,in
that we know it is definitely not a stegosaur, ankylosaur, sauropod, or ceratopsian,
all of which walked on four legs (quadrupedally) and had feet with more than three
toes. Well, except for stegosaurs which had tridactyl rear feet, but as far as we
knowstegosaursneverwalkedbipedally,sothey'reeliminatedassuspectstoo.This
