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Baby dino reveals secrets
March 7,
2006
By Robert Sanders, UC Berkeley
and World Science staff
With its big, hockey puck-sized eyes, shortened face and nubby horns, it was probably as cute as a button—at least to its mother, a three-horned dinosaur called
Triceratops who could weigh as much as 10 tons (9,000 kg).
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(Mark Goodwin, UC Berkeley Museum of Paleontology)
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Visitors to the Valley Life Sciences Building at the University of California, Berkeley,
now can judge for themselves.
Displayed there is a cast of the foot-long (30 cm) skull of what scientists say is youngest known
Triceratops fossil.
It’s dwarfed by a skull
six times longer, that of an adult Triceratops, which had one of the biggest skulls of any land animal.
The university’s Mark Goodwin described the little skull, which is in pieces at the school, in the March issue of the
Journal of Vertebrate Paleontology. He argued that the find suggests horns weren’t used only for sexual display, as
is commonly believed, but to help animals recognize each other.
Despite the pup’s size, he said, its remains are revealing much about how dinosaurs grew, the purpose of their head ornaments and the characteristics of their ancestors. In particular, since the horns and frill are present from a very early age, it is unlikely they served only for sexual display, he argued.
The baby skull shows features—a shortened face and big eyes—that scientists believe have made babies lovable
to their parents throughout the ages, Goodwin added. The horns grow to three feet
(91 cm) in the adult, while the scalloped edges of the frill, which can grow to seven feet across, become more wavy and develop scales.
“The horns and frill of the skull likely had another function other than sexual display or competition with rivals, which people have often argued, and allows us to propose that they were just as important for species recognition and visual communication,” Goodwin said.
Triceratops horridus, as it is fully called, was a strictly North American dinosaur,
Goodwin explained. However, relatives with different but equally formidable ornamentation roamed China and Mongolia during the Cretaceous period,
65 million to 144 million years ago.
Adult Triceratops could be nearly 10 feet (3 meters) tall and 26 feet
(8 meters) long, with a bony frill around the head. Two three-foot horns typically curved forward from the brow, while a third horn erupted from the nose above a narrow, horny beak.
The baby’s skull, along with other bone fragments, were found by amateur fossil hunter Harley Garbani in 1997 in Montana’s Hell Creek Formation, the source of many
Triceratops and Tyrannosaurus rex fossils. Goodwin assembled the pieces into a skull and lower jaw that is missing the nose and beak.
The fossil is a unique addition to the world’s existing, mostly adult
Triceratops specimens, Goodwin said. The skull of the roughly year-old baby, he added, fits into a study he is conducting with Montana State University’s
Jack Horner on dinosaur growth patterns.
The skull surface shows grooves where blood vessels used to be, which apparently nourished a fingernail-hard coating, Goodwin argued. Such horny coverings are often brightly colored in
dinosaurs’ living descendants—birds—suggesting Triceratops may have been colorful, too.
The baby’s hazelnut-sized brain, hidden beneath the bony frills of the skull, fit snuggly within protective bones not yet fused, so as to allow further brain growth, he noted. In the adult,
fused bones fully encased the brain, which is thought to have been the shape and size of a small sweet
potato.
“The baby skull shows us how the bones that make up the skull actually grew and fit together,”
Goodwin said. “It’s an incredible specimen, with beautiful preservation.” Goodwin and Horner also have made casts of the skull for the American Museum of Natural History in New York and for Montana’s Museum of the Rockies.
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