on a well-preserved fossil, says Ashley C.
Morhardt, a vertebrate paleontologist at
Western Illinois University in Macomb.
Small openings called neurovascular foramina pepper the facial bones
of vertebrates. These holes — typically
around 0.2 millimeters across, about the
diameter of the body of a sewing pin, but
sometimes larger — make space for the
arteries that supply blood to the lips and
cheeks and for the nerves that allow for
sensation, Morhardt says. The number
of neurovascular foramina on the bones
around a creature’s mouth relates to the
type and amount of overlying soft tissue,
she and her colleagues reported in September in Bristol, England, at the annual
meeting of the Society of Vertebrate
Paleontology. By counting the foramina
on a fossil’s facial bones, the team suggests, scientists can start to reconstruct
a dinosaur’s countenance.
During the study, the researchers dis-
sected modern animals with different
types and amounts of facial tissue and
then counted foramina. Most creatures
that had a toothy smile with exposed
teeth and little if any soft tissue around
the mouth, such as crocodiles and their
relatives, had more than a hundred small
foramina on each bone around the jaw-
line. For those with beaks made of non-
pliable material, such as birds, turtles and
tortoises, average foramina counts on
each facial bone ranged from 50 to 100.
Based on these trends, the research-
ers proposed at the vertebrate pale-
ontology meeting that Herrerasaurus,
an early predatory dinosaur with few
neurovascular foramina, had lizardlike
lips. Camarasaurus, a large herbivorous
sauropod with peglike teeth, probably
had fleshy cheeks that could form a seal
and hold a mouthful of vegetation. For
Triceratops, another vegetarian, the data
aren’t so clear: These dinos could have
had either lizardlike lips or small cheeks.
“It’s pretty obvious that they had some
kind of extra-oral covering,” Morhardt
says. “We just haven’t been able to tease
out what kind.”
Knowing the type and amount of soft
tissue surrounding the mouth helps sci-
entists picture the dinosaurs and pro-
vides clues about how dinosaurs fed and
what they ate, says Matthew Bonnan, a
paleontologist at Western Illinois Uni-
versity and Morhardt’s graduate adviser.
By counting neurovascular foramina on
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January 30, 2010 | SCIENCE NEWS | 23
