New Montana T-rex and separate status for Nanotyrannus

[bh480@scn.org]

From: Ben Creisler bh480@scn.org

News story indicates a Montana T-rex find may support 
separate status for Nanotyrannus:

http://www.billingsgazette.com/index.php?
id=1&display=rednews/2004/09/05/build/local/32-fossil-
hunters.inc

T-rex roamed near Roundup: Fossil hunters stumbled across 
bones 2 years ago 
By ED KEMMICK
Of The Gazette Staff 
One of the smallest and youngest Tyrannosaurus rex 
skeletons ever found was discovered northeast of Roundup 
and is being prepared at a new dinosaur museum in 
Colorado. 
Walter Stein, curator of the Rocky Mountain Dinosaur 
Resource Center in Woodland Park, Colo., said he found the 
fossil, dubbed "Sir William," on a ranch about 25 miles 
from Roundup two years ago. 
Stein said he and Mike Triebold, the owner and founder of 
Triebold Paleontology Inc., for which Stein is the field 
collections manager, had just received permission to look 
for fossils on the ranch and were on their first visit in 
late July 2002. Stein said it was blazing hot and they 
were scouting out likely dig sites they could come back 
to "when it was a little cooler." 
They were interested mainly in what is known as the Bear 
Paw shale formation, deposits of dark-gray to dark-brown 
shale that are known to contain marine reptiles. 
They hadn't gone far, he said, when "we saw this little 
strip of Hell Creek out in the middle of nowhere." The 
Hell Creek formation, which sits above the Bear Paw, dates 
from the end of the dinosaur period, the late Cretaceous, 
67 million to 65 million years ago. 
Despite the heat, they got out to take a look, and within 
half an hour Stein "stumbled across" a specimen that had 
weathered out of a hillside. It proved to be a piece of 
the young T-rex. After two years of "intense field 
collection," Stein said, they are ready to announce their 
discovery. 
He said they waited this long because they wanted to be 
sure what they had and because last year they were 
preoccupied with building their new museum, which barely 
opened as scheduled last Memorial Day. 
Stein said the T-rex found near Roundup was estimated to 
be about 15 years old when it died. It was about 20 feet 
long and weighed about 3,500 pounds, considerably smaller 
than the average 6-ton adult T-rex. 
Sir William was among 20 partial T-rex skeletons examined 
by a team headed by Gregory Erickson of Florida State 
University as part of a study of T-rex growth rates. 
According to Stein, his find was the smallest and youngest 
partial skeleton of the group, and is second in youth and 
size only to a fossil represented by a skull fragment. 
Only 35 or so partial T-rex skeletons have been collected 
over the past 100 years, he said. 
Erickson's study, the results of which were reported in 
the journal Nature in August, showed that the T-rex "lived 
fast and died young," as Erickson said in an Associated 
Press story. He said the T-rex went into an explosive 
growth spurt in its teen years, between 14 and 18, stopped 
growing around age 20 apparently died at about 30. 
Stein said Sir William, which he named after his 9-month-
old son, is important for several reasons. For one, it 
supports the theory that a creature called the 
Nannotyrannus is a separate genus of dinosaur, not merely 
an immature T-rex, as some paleontologists have surmised. 
Although the question is still open to debate, Stein said, 
Sir William appears to differ markedly from Nannotyrannus 
specimens. 
Examination of Sir William also is likely to advance 
understanding of T-rex behavior, Stein said. Found around 
the fossil were more than 50 Nannotyrannus teeth, which 
may mean that the young T-rex was ambushed and killed by 
the closely related dinosaurs. There is also some evidence 
that another T-rex chewed on one of Sir William's bones. 
If so, Stein said, it would be the first evidence of 
cannibalism within Tyrannosaurs. 
"This specimen's eventually going to tell us a whole lot 
about T-rex behavior," Stein said. 
Preparation of Sir William will take another one to two 
years, Stein said, but it appears it will be between 30 
and 50 percent complete and will include elements of the 
skull, forelimbs, hind limbs, pelvis and backbone.