A perennial criticism of
evolutionary theory is so-called "missing links" lack of
ancestor species, or older species recently diverged from an
ancestor. Researchers have been able to eliminate some of that
skepticism with the discovery
of a human-sized miniature tyrannosaurid.
The beast was
excavated in an illegal dig in Mongolia and sold to a private
collector. That collector had paleontologist Paul Sereno
evaluate the remains and then agreed to donate the fossil to science,
with the intent that it eventually be returned to China.
Professor Sereno has published
a paper on the creature in the journal Science.
dinosaur brings significant surprises. Scientists long thought
that the T. Rex's giant proportions were the result of a sharp
divergence and were not present in earlier tyrannosaurid.
However, the new species, Raptorex kriegsteini shared the same
bizarre proportions its descendant, albeit in a much smaller body.
This finding shakes of the traditional assumptions about the T.
Rex and its evolution, and show just how much remains to be
discovered in the field of paleontology.
Stephen Brusatte, a
paleontologist at the American Museum of Natural History, who
co-authored a paper states, "The most interesting and important
thing about this new fossil is that it is completely unexpected.
As we learn more and more about dinosaurs and the evolution of life
over time, it’s harder and harder to find fossils like this that
throw us for a curve."
Scientists determined that the
dinosaur was an adolescent by looking at its level of bone fusion.
Certain bones tended to fuse or merge over the life span of
dinosaurs, providing an important indicator of age. Raptorex’s
pelvic girdle was completely fused and its scapula and shoulder blade
were nearly so, showing that it is a full grown adult.
Holtz, a paleontologist at the University of Maryland, not involved
with the research, lauds the discovery, stating, "To most people
in dinosaur paleontology, we’d regard it as significant because it
helps us more completely understand the origin of the classic tyrant
dinosaurs and how they became what they were. When Raptorex
was around, the ancestors of Triceratops are similarly very
small, but the ancestors of Triceratops don’t have their
horns or frills yet. They are not down on all fours and so forth.
It’s almost like finding a tiny Triceratops at this stage
that is four-on-the-floor with the big horns and the big
The T. Rex is 90 times larger than its
recently discovered predecessor in body mass. The fact that its
body design was able to scale so well is incredible and rather unique
states Professor Sereno.
While some may hope to see the new
beast in a future Jurassic
Park sequel, for paleontologists, it's reviving a perennial
debate over the T. Rex. The dinosaur had speed features,
which now appear to be vestigial remnants of those of its smaller
ancestor. Were those features meant for hunting? Some
don't believe that. Jack Horner, a paleontologist at the Museum
of the Rockie argues that both beasts were scavengers, stating in an
email to Wired.com, "It is interesting that the
authors imply that it was a predator on account of its small size, as
though scavenging was only possible for large tyrannosaurids. I
think their evidence clearly supports an hypothesis that
tyrannosaurids were small scavengers early on in their
Professor Holtz disagrees, stating, "No
carnivore passes up a free meal, [but Raptorex] was a well
built little animal for running fast and catching small dinosaurs."