T. rex hits puberty
Tyrannosaurus
rex at age 14 may have been a wee 1,500-pound juvenile, but it then underwent
a massive teenage growth spurt to put on its bulk, according to new research
that maps out the life of T. rex from toddler to old age.
New research based on growth ring counts
from the bones of Tyrannosaurus rex shows that the dinosaur put on the bulk
of its mass during its teenage years and then died shortly after its growth
spurt. Image courtesy of University of California Museum of Paleontology.
Gregory Erickson of Florida State University and his colleagues used growth
ring counts from 60 bones of four related tyrannosaurid species, along with
size estimates of specimens between the ages of two and 28, to compile a growth
curve. This curve, published in the Aug. 16 Nature, depicts T. rex’s
developmental history and identifies the point at which T. rex grew most
rapidly.
Between 14 and 18 years old, T. rex was packing on as much as 5 pounds
per day, and “growing three to six times faster than its ancestors,”
Erickson says, making for one hungry teenager. “Tyrannosaurids had a long
childhood for a dinosaur,” says Thomas Holtz, a vertebrate paleontologist
at the University of Maryland.
At maturity, the T. rex reached a hefty 11,000 pounds or more, and lived
to be about 30 years old. Sue, the oldest T. rex specimen known, provided
the clues to this age limit with her arthritis and broken bones, Erickson says.
“She’s a real train wreck. That suggests she wasn’t going to
live much longer.”
“These dinosaurs did not live particularly long after they had stopped
growing,” Holtz says. In contrast, comparably sized modern mammals, such
as elephants, rhinos and hippos, live to 50, 60 or 70 years old, he says. “T.
rex reached its larger size by growing faster during its growth spurt, rather
than by having a longer lasting growth spurt.”
Laura Stafford
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