November 1, 2012 If an Allosaurus fell in the Jurassic, would it
leave a trace fossil? We know that resting dinosaurs can leave
body impressions behind, as shown by a theropod trace found in
St. George, Utah, but what if a dinosaur lost its footing and
fell over onto a mudflat or sand dune? Such events surely must
have happened. The question is whether the embarrassing moments
ever became set in stone. A trace fossil would be the obvious
mode of preservation for a dinosaur fall. A messy footprint,
recording the slip, paired with a body impression would be a
gorgeous snapshot of a dinosaur’s tumble. Sadly, no one has yet
found such a fossil, but paleontologists have identified a more
subtle clue of a dinosaur fall. In 2007, paleontologist Oliver
Wings and colleagues described a Middle Jurassic dinosaur
tracksite described in China. Among the dozens of tracks was
what appeared to be a slip footprint–parallel grooves made when
the dinosaur’s foot slipped backward or foreword over the wet
mud of the ancient envir