M is for Montanoceratops

Of all the dinosaurs that have ever lived, ceratopsians were some of the most impressive. There was the huge, three-horned Triceratops; Kosmoceratops, the so-called “horniest dinosaur“; and the hook-horned Einiosaurus, to name just a few. Yet ceratopsians were not just prickly giants. (All the big-bodied forms fall into a particular ceratopsian subgroup called ceratopsids.) The wider ceratopsian family included smaller forms with deep tails and skulls that generally lacked the imposing ornaments of their larger cousins. Protoceratops from the Cretaceous of Mongolia’s Gobi Desert is the most familiar of these often-overlooked ceratopsians, but North America sported a variety of genera, too. Among them was Montanoceratops, a comparatively small horned dinosaur that coexisted with its burlier, spikier relatives.

Paleontologists Barnum Brown and Erich Schlaikjer described the specimen that would come to represent Montanoceratops in 1942. Only they didn’t call the dinosaur that. Based on a partial skeleton found in the roughly 72 million year old strata around Buffalo Lake, Montana, the researchers reconstructed the dinosaur as a new species of the previously-discovered Leptoceratops. They called the dinosaur Leptoceratops cerorhynchos, and believed that the ceratopsian was a Protoceratops-like animal with a prominent, rounded nasal horn.

Nine years later, Canadian paleontologist Charles M. Sternberg realized that the dinosaur Brown and Schlaikjer found wasn’t really Leptoceratops. He kept the species name, but placed the animal in a new genus – Montanoceratops. Further studies by other researchers seemed to show that this ten-foot ceratopsian was the sister group to the huge, many-horned ceratopsids, making Montanoceratops look like a late-surviving prototype of Triceratops, Einiosaurus, and kin.

Ceratopsian systematics have changed dramatically in the past few years, though, and it turns out that Montanoceratops was not quite so primitive as researchers thought.

In 2010, as part of the New Perspectives on Horned Dinosaurs volume, paleontologist Peter Makovicky reviewed Brown and Schlaikjer’s original Montanoceratops material and several specimens that had been referred to the genus. The dinosaur’s nose horn, Makovkicky found, had led paleontologists astray for years. That bone was actually a misidentified cheekbone, and this change – along with a suite of other skeletal characteristics – recast Montanoceratops as part of a spread of similar Late Cretaceous forms.

Montanoceratops belonged to a lineage of ceratopsians called leptoceratopsids. While these dinosaurs don’t get nearly as much attention as the bigger ceratopsids, they lived in the same habitats and were about as diverse. Rather than representing a rare, relict lineage of archaic ceratopsians, the leptoceratopsids embody a radiation of horned dinosaurs that branched out in tandem with the evolutionary profusion of ceratopsids. Many of these dinosaurs are poorly known and have yet  to be properly identified, but, little by little, we’re starting to get a finer look at this hidden ceratopsian story.

Previous entries in the Dinosaur Alphabet series:

L is for Leaellynasaura

K is for Kileskus

J is for Juravenator

A-I at Dinosaur Tracking.

References:

Brown, B., Schlaikjer, E. 1942. The skeleton of Leptoceratops with the description of a new species. American Museum Novitates. 1169: 1-15

Chinnery, B., Weishamphel, D. 1998. Montanoceratops cerorhynchus (Dinosauria: Ceratopsia) and relationships among basal neoceratopsians. Journal of Vertebrate Paleontology. 18, 3: 569-585

Makovicky, P. 2010. A redescription of the Montanoceratops cerorhynchus holotype with a review of referred material, pp. 68-82, in Ryan, M., Chinnery-Allgeier, B., Eberth, D., eds., New Perspectives on Horned Dinosaurs. Bloomington: Indiana University Press.