Geoscience Reference
In-Depth Information
• Ankylosauridsandnodosaurids—rearandfrontfeet(quadrupedal),fourdi-
gits in the front and four or three in the rear; most ankylosaurids (perhaps
all) had three.
• Ceratopsians—rear and front feet (quadrupedal), four digits in the rear and
five in the front.
Granted, paleontologists, just like any other scientists, delight in pointing out ex-
ceptions. So just to get those distracting thoughts out of the way, here are a few
dinosaur-foot oddities to keep in mind:
Therizinosaurs
—These were unusual theropods, so unusual that no self-re-
specting dinosaur paleontologist discussing them can complete a sentence with
these as the subject without also saying “strange,” “odd,” “weird,” “bizarre,” and
other synonyms denoting their differences from other theropods. As an example of
their unusualness, therizinosaurs, unlike all other theropods, had four toes pointing
forward on their rear feet. As of this writing, a few therizinosaur tracks are known,
withthemostastonishingrecentlyfoundinCretaceousrocksofAlaska.Thesefour-
toed feet may represent some ancestral condition in theropods that was somehow
retained in therizinosaurs well into their evolutionary history.
Dromaeosaurids
—These were bipedal theropods with three toes retained on
theirrearfeet,butonlytwoofthosedigitscontactedtheground.Oneofthethreedi-
gitswasraisedandsportedanasty-lookingclaw,whichevidentlywasusedforgrip-
ping and holding down prey, climbing, or slashing. Consequently, dinosaur trackers
sometimes do a double-take when they spot dromaeosaurid tracks, which look as if
their theropod trackmakers somehow lost a digit. This notion is quickly discarded,
though, once those paleontologists realize both feet are missing exactly the same
toe, which surely is not a coincidence. Once considered rare, dromaeosaurid tracks
are now being discovered in some of the same places and geologic formations as
dromaeosaurid bones, helping paleontologists to fill out more complete pictures of
their life habits.
