The Newest (and Horniest) Dinosaur: the Kosmoceratops

According to a delightful new paper published Sept. 22 in the online science journal PloS One, the Kosmoceratops lived indeed — a good 76 million years ago, according to the scientists' reckoning

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The movie trailer writes itself: Long ago, on the lost continent of Laramidia, lived the mysterious Kosmoceratops, a three-ton, 15-horned beast that roamed — and ruled — the swamps it called home. O.K., you might want to lose the lost-continent bit, and 15 horns kind of jumps the shark, but tweak it a little and you could have a winner.

The thing is, however, you can't tweak any of this. According to a delightful new paper published Sept. 22 in the online science journal PloS One, the Kosmoceratops indeed lived a good 76 million years ago, according to the scientists' reckoning. And Laramidia — better known today as the Western United States, with bits of Canada and Mexico — was a real place, separated from the eastern half of the North American continent by a great inland sea. The PLoS paper reveals intriguing new things about both the animal and its ancient home.

The division of North America into two land masses prevailed for about 27 million years during the late Cretaceous Period, 95 million to 68 million years ago. As sea levels rose worldwide, the central region of the continent flooded, producing a long but shallow body of water called the Cretaceous Western Interior Seaway. Contemporary scientists have dubbed the area to the east Appalachia and to the west Laramidia, after Laramie, Wy., which is part of the old minicontinent.

Though small — just 20% of the area of modern North America — Laramidia became what the authors of the paper call "a crucible of evolution," likely because of its lush vegetation and swampy coasts. Most of the animals that lived there were large-bodied — from one to two tons (about 1,000 to 2,000 kg) — and included the duck-billed hadrosaur, the armored ankylosaur and the dome-headed pachycephalosaur.

The Kosmoceratops was unknown to science until 2007, when Scott Richardson, a volunteer bone hunter who was part of a University of Utah expedition in the southern part of the state stumbled across a pair of skulls unlike any ever seen before. They were similar to that of the Triceratops except that they had a horn over each eye, one over the nose, one protruding from either cheekbone and no fewer than 10 forming a frill resembling bangs across the top of the head.

"[It's] one of the most amazing animals ever known," Scott Sampson, a University of Utah paleontologist and the lead author of the PloS paper, told the Christian Science Monitor, "with a huge skull decorated with an assortment of bony bells and whistles." The full name of the animal is Kosmoceratops richardsoni: kosmos meaning "ornate" in Latin, and richardsoni a tip of the hat to Richardson — an extraordinary honor for a mere volunteer. As with most such discoveries, it can take years of study after a fossil is found before a paper can be released granting it a name and declaring it a species; these two events at last happened this week.

The almost comical array of horns on the Kosmoceratops' skull is, the investigators believe, a good example of a sort of natural selection on steroids. The protrusions would have been largely useless in battling predators and might even have hindered the animal's mobility — much like the tail feathers on a peacock or the extravagant antlers on some species of ungulates. Rather, as with those physical features, the Kosmoceratops' horns would probably have been used principally to intimidate other males of the species and attract females.

The Kosmoceratops was not the only dinosaur included in the new paper; also described was the Utahceratops. With a less remarkable array of just three horns, the animal is notable mostly for its size: 6,600 to 8,800 lb. (3,000 to 4,000 kg) and 18 to 22 ft. (6 to 7 m), compared with the 5,500-lb. (2,500 kg), 15-ft. (5 m) Kosmosaurus. The fact that one paper included two new animals is an indicator of the explosion of paleontological discoveries in southern Utah ever since a 1.9 million–acre tract known as the Grand Staircase-Escalante National Monument (GSENM) was set aside for protection in 1996.

Prior to the expeditions that have taken place at the GSENM, paleontologists were long puzzled by the seeming division between the types of animals that once lived in north and south Laramidia. On a land mass so comparatively small and narrow, there should have been a wide commingling of creatures, yet while large-bodied animals were abundant everywhere, at the species level there was not a lot of crossover between north and south.

The mystery was particularly hard to crack because of a lack of good data: the majority of Laramidian fossils came from Alberta, with a relatively sparse bone record in the south. But a decade's worth of collecting has yielded the fossils of large and small herbivores and carnivores, as well as the remains of plants, fish, amphibians and insects. The GSENM is, the researchers write, one of the most "fossiliferous" zones in Laramidia, and this has helped them develop new theories to explain the north-south species schism.

Among the possible explanations for the animals' segregation are a now vanished mountain range that blocked migration, an east-to-west river that presented a similar obstacle, and seasonal flooding that washed out low-lying habitats and discouraged repopulation. The lack of much geological evidence of such features — so far at least — rules those theories out for now. The remaining likely causes are subtle temperature, precipitation and other climatic differences between the north and south to which the local animals adapted. This idea is supported by samples of ancient pollen that are distinct to the regions. "Dinosaurs appear to have been sensitive to latitudinal zonation in environments," the scientists wrote in their study — science-paper-speak for "Some liked it hotter; some liked it cooler; some liked it wetter; some liked it dryer."

The Kosmoceratops may be the most whimsical new dino to come along in a while, but it surely will not be the last. Indeed, 200 million years of dinosaur history will probably never yield all its secrets. With Utah's Grand Staircase open to science and off-limits to development, however, more of the discoveries that do get made are likely to be conveniently close to home.