May 23, 2016

By Brian Switek

Two New Discoveries Add to a Horned Dino Revolution

Everyone knows Triceratops. Old “three-horned face” has stood as the ultimate in spiky dinosaurs since it was named in 1889. Yet Triceratops was only the last in a long line of horned dinosaurs. Horned dinosaurs thrived on prehistoric Asia and North America for over 100 million years, and it’s only now that paleontologists are uncovering a wealth of ceratopsians that are weirder and more varied than anyone ever expected.
When paleontologist Peter Dodson published his then-comprehensive book The Horned Dinosaurs in 1996, experts recognized about 23 different horned dinosaurs. Now the count has more than tripled, ranging from lanky little creatures known only from bits of jaw like Gryphoceratops to hulking, spiky herbivores such as Kosmoceratops (hailed as the “horniest dinosaur ever” when discovered). The rate of discovery is blistering, and, in fact, just this week paleontologists announced two new horned dinosaurs simultaneously.

One of the new dinosaurs, discovered in the 77-million-year-old rock of southern Utah, is a variation of something familiar. Named by Ohio University paleontologist Eric Lund and colleagues, Macharioceratops cronusi – meaning “bent sword face” -- looks like a close cousin of the sinister-looking Diabloceratops found in older strata of the same region. About four million years separate the two, and Machairoceratops can immediately be told apart by two forward-pointing spikes jutting from the back of its frill.

The other new ceratopsid on the block is Spiclypeus shipporum. This dinosaur lived around 76 million years ago in what is now northern Montana, Canadian Museum of Nature paleontologist Jordan Mallon and coauthors report, and its “boldly audacious” look comes from brow horns jutting out to the side and an unusual arrangement of frill spikes with some pointing outward and others folded down. That array gave the dinosaur its genus name, meaning “spiked shield.”

In fact, Mallon says, this curious combination of ornament styles might explain how some other dinosaurs got their distinctive headgear. Spiclypeus was a close relative of Kosmoceratops from Utah and Vagaceratops from Alberta, both of which had frill spikes that jutted downwards instead of out. “I suspect what we’re seeing is an interesting transitional morphology in Spiclypeus between the more primitive forms where the spikes all radiate outward and the more advanced forms, like Kosmoceratops and Vagaceratops, where they curl forward,” Mallon says.

Together Macharioceratops and Spiclypeus give a big boost to the count of known horned dinosaurs and give diehard dino-fans a pair of new names to master. There are now so many of these pointy plant-eaters, Mallon says, that “It’s getting hard to keep up!” But given that the dinosaurs have been waiting in the ground for over 66 million years, why are we experiencing such a great Dinosaur Rush now?

The answer, much like the frill of Machaerioceratops, is two-pronged. The first, Raymond M. Alf Museum paleontologist Andrew Farke says, is that there are simply more people and more museums searching for dinosaurs than ever before. “Whenever you have more people out on the ground looking, you’re going to find more stuff,” Farke says. That goes for museum collections, too. In 2011 Farke and colleagues announced they had found a previously-unknown horned dinosaur tucked away in the collections of London’s Natural History Museum. They named this long-lost dinosaur Spinops sternbergorum.

But it’s not just a numbers game. There are still great patches of western North America that have been little-explored. The rocks that Macharioceratops was found in are a good example, Farke says, as the deserts of southern Utah were thought to be either too remote or lacking in fossils until recently. With persistence, these isolated places are yielding unexpected dinosaurs.

Now crews are taking another look at spots that have been previously overlooked with an eye to filling in more parts of the horned dinosaur story. For example, Farke says, paleontologists don’t yet know what was going on with North America’s ceratopsids between 90 and 80 million years ago, the time period when these dinosaurs started to get big and evolve into a spiky variety of new forms. “The fossils are probably out there,” Farke says, waiting to be found. And, Mallon says, there’s much to be learned from what experts have already collected. “There’s probably some interesting variation [in already-collected fossils] that people just haven’t been looking for,” Mallon says, and these clues can help paleontologists get a better idea of how these magnificent animals evolved.

The discovery of a new dinosaur or two isn’t just another addition to the ever-growing list of dinosaur names. “The power in these things is that when we have large numbers of specimens and large numbers of species, you can start asking and answering big-picture evolutionary questions,” Farke says. Horned dinosaurs were around for 100 million years, and so, Farke says, filling gaps in time and space with new species can allow paleontologists to look into whether these dinosaurs co-evolved with flowering plants, competed with other herbivores of their time, and how they might have been affected by shifting climates. Macharioceratops, Spiclypeus, and all the rest were undoubtedly awesome, but they have so many stories left to tell.

http://www.smithsonianmag.com/science-nature/paleontologists-are-digging-more-horned-dinos-ever-180959181/?no-ist