Oops, evolutionary theory really works
The creationists are not going to like this one! This is not necessarily a brand new find as it's discovery has been known for while. The full analysis including cladistics was just published this month in the Journal of Paleontology and thus Albertaceratops is getting a bit of a publicity boost. The original skull was named by it's discoverer, Michael Ryan as "Medusaceratops". The Press reports state:
A new dinosaur species was a plant-eater with yard-long horns over its eyebrows, suggesting an evolutionary middle step between older dinosaurs with even larger horns and the small-horned creatures that followed, experts said.
The dinosaur's horns, thick as a human arm, are like those of triceratops - which came 10 million years later. However, this animal belonged to a subfamily that usually had bony nubbins a few inches long above their eyes.
I really liked the last few paragraphs of the story.
Unquestionably, it's an important find," said Peter Dodson, a University of Pennsylvania paleontologist. "It was sort of the grandfather or great-uncle of the really diverse horned dinosaurs that came after it."
Ryan named the new dinosaur Albertaceratops nesmoi, after the region and Cecil Nesmo, a rancher near Manyberries, Alberta, who has helped fossil hunters.
The creature was about 20 feet long and lived 78 million years ago.
The oldest-known horned dinosaur in North America is called Zuniceratops. It lived 12 million years before Ryan's find, and also had large horns.
That makes the newly found creature an intermediate between older forms with large horns and later small-horned relatives, said State of Utah paleontologist Jim Kirkland, who with Douglas Wolfe identified Zuniceratops in New Mexico in 1998. He predicted then that something like Ryan's find would turn up.
"Lo and behold, evolutionary theory actually works," he said.
So this new find lies somewhere between the horned triceratops and the less ornamented protoceratops. I put the skulls in order below. Protoceratops, Albertaceratops and Triceratops. It is also the basal clade for the centrosaurines (see cladistic analysis below).
Albertaceratops Skull (copyright J. Paleontology, 2007)
One gap down, two new ones opened!
Reference: A NEW BASAL CENTROSAURINE CERATOPSID FROM THE OLDMAN FORMATION, SOUTHEASTERN ALBERTA. M. RYAN Journal of Paleontology.2007; 81: 376-396.