 |
 |
Dozens of oviraptorosaur
specimens have been found in Asia, particularly in Mongolia
and China. On the other hand, decades of searching for these
dinosaurs on other continents were almost fruitless - until
the fall of 1998, when two skeletons of the new oviraptorosaur
were discovered only 165 feet (50 meters) apart in the fossil-rich
Hell Creek badlands of northwestern South Dakota. CMNH's new
skeletons are the most complete oviraptorosaur specimens known
outside of Asia, and firmly establish the presence of this
group in western North America. But how can this be? How can
oviraptorosaurs, which were land-dwelling animals (and probably
poor swimmers), be found on two continents that today are
separated by the Pacific Ocean?
 |
 |
|
Eurasia
in the Late Cretaceous
The
majority of oviraptorosaurs are from this general
location. |
North
and South America
in the Late Cretaceous
Discovery site of the new CMNH oviraptorosaur. |
Click
maps for larger images |
|
The answer
to this puzzle lies in the arrangement of the Northern Hemisphere
continents during the Cretaceous Period. Based on multiple
lines of geologic and paleontologic evidence, scientists believe
that northwestern North America (what is now Alaska) and northeastern
Asia were connected by a "land bridge" for at least
part of the Cretaceous. Along with many other kinds of dinosaurs,
oviraptorosaurs seemingly used this land bridge to move between
the two continents.
But where
did oviraptorosaurs come from in the first place? Asia, North
America, or someplace else? The most ancient and primitive
oviraptorosaurs we know of (Incisivosaurus and Caudipteryx)
both hail from China. Consequently, it seems that oviraptorosaurs
originated in Asia before they colonized North America. However,
if an even earlier oviraptorosaur were to be discovered outside
of Asia, it would cast serious doubt on this idea. Therefore,
a single fossil could completely overturn our current thinking
on the birthplace of oviraptorosaurs!
|
 |
 |