June 19, 2009 As I have written about many times here on
Dinosaur Tracking, paleontologists presently have an
overwhelming amount of evidence that birds are living dinosaurs.
That doesn’t mean that everything about the dinosaur-to-bird
transition is well-understood, though. For years scientists have
been faced with a puzzle involving the hands of living birds and
bird-like dinosaurs. The dinosaurs most closely related to birds
appeared to have a thumb and two fingers (digits I-II-III) while
studies of the embryonic development of birds showed that they
have fingers II-III-IV. This difference would have to be
accounted for, and a bizarre new theropod dinosaur described by
an international team of scientists in yesterday’s edition of
Nature provides a crucial clue to this fossil puzzle. The new
dinosaur, named Limusaurus inextricabilis, is so strange that I
almost don’t know where to start describing it. It lived about
156 million to 161 million years ago in what is now western
China, and it was one of the dino