A new dinosaur unearthed in Wyoming had such large teeth
that its mouth perpetually looked to be smiling a huge grin.
The dinosaur, described in the latest Journal of Systematic
Paleontology, is called Kaatedocus siberi, with its name deriving from Diplodocus and the Native American Crow word for "small." Diplodocus was yet another dinosaur with
a winning smile. This latest find was an early ancestor to that dino.
"Kaatedocus
walked on four limbs, had a long neck and a whiplash tail, such as the famous Diplodocus did," co-author Octavio
Mateus told Discovery News.
Mateus, of the Universidade Nova de Lisboa & Museu
da Lourinhã, is one of the world's leading paleontologists, and is particularly
known for his work on sauropods — iconic large, plant-eating dinosaurs with long
necks and tails. He has studied sauropods on four continents.
Kaatedocus
was one such dino. Its herbivorous diet helps to explain its "grin."
"Kaatedocus
had a set of pencil-like teeth in the front part of the muzzle," Mateus
explained. "They were adapted for eating plants. As for many sauropods, because
those teeth were not adapted for chewing, Kaatedocus
probably ingested gastroliths or gizzard stones."
Mateus and an international team
studied the well-preserved remains of Kaatedocus.
Often quite a bit of artistic license is needed during reconstructions, but in
this case, even the skull makes evident the dinosaur's "smiling" appearance.
Kaatedocus
lived 150 million years ago, during the Late Jurassic period. A relative of Diplodocus, this dinosaur lived earlier
and was smaller. The vast majority of species from this dino family come from
the Jurassic Morrison Formation of the Western United States. In contrast, this
new dinosaur was found further north, suggesting that subsequent generations
slowly moved southward over time.
In addition to the smiling expressions, this family of
dinosaurs holds another memorable distinction: they apparently weren’t too
bright.
Ke-Qin Gao, a researcher at Peking University's School of
Earth and Space Sciences, and colleagues reconstructed basic features of
dinosaur brains based on endocraniums, or the inside surfaces of dino skulls,
if these features survived in the fossil record.
Gao and his team used an Encephalization Quotient, or EQ, to
speculate upon the complexity, or lack thereof, of brain activity in dinosaurs.
The EQ is a ratio of brain mass to body size.
At the very bottom of the EQ ratings is Diplodocus, with a meager .05 EQ. One of the longest known
dinosaurs, Diplodocus could measure
around 90 feet in length. Twenty feet of that was neck, topped off with a tiny
head and an even tinier brain case. Its long tail could inflict some serious
damage to predators, though, as could a kick from one of its four sturdy legs.
Kaatedocus likely
had a similar EQ, but it managed to survive in an environment with a lot of
other formidable dinosaurs. According to Mateus, these included Barosaurus, Stegosaurus and large carnivorous Allosaurus.
In terms of the recent Wyoming discovery, Mateus said, "This species is smaller and
slightly older than other dinosaurs of the same family, it is important for
understanding the evolution of all Diplodocus-like
dinosaurs."
Dino buffs can see the remains of Kaatedocus. They currently are on display at the Museum of Jurassic
Aathal in Switzerland.
(Images: Octavio Mateus, Universidade Nova de Lisboa & Museu
da Lourinhã)
