A remarkable new taxon of ceratopsian has been described from northern Montana. This new horned dinosaur, a centrosaurine, has been named Lokiceratops rangiformis. The authors of the scientific paper, published in the journal PeerJ, suggest that the large number of similar taxa identified from this region suggests that dinosaur diversity has been underestimated. In addition, mounting evidence indicates dinosaurs were living and evolving in a small geographic area (high endemism). This high endemism identified in centrosaurines contrasts with the extensive (historic) ranges seen in most large mammals today.
Reconstruction of Lokiceratops surprised by a crocodilian in the 78-million-year-old swamps of northern Montana, USA. Picture credit: Andrey Atuchin for the Museum of Evolution in Maribo, Denmark.
Picture credit: Andrey Atuchin.
Lokiceratops rangiformis
The fossils were collected from the lower portion of the McClelland Ferry Member of the Judith River Formation in the Kennedy Coulee region close to the Canadian border. The fossil material consists of most of the skull, although the lower jaws were not found. Postcranial material includes the right scapula and coracoid plus some vertebrae and elements from the hips.
Lokiceratops is one of the largest centrosaurines known to science. It had an estimated body length of around 6.7 metres and is thought to have weighed 5 tonnes. As well as being one of the largest members of the Centrosaurinae described to date, it is also one of the most ornate. Lokiceratops possessed two, huge blade-like horns on the back of its frill (epiparietal 2). The super-sized epiparietal 2 horns are relatively larger than any other parietal epiossification within the Centrosaurinae.
Lokiceratops had two large brow horns, but unlike most of its close relatives it lacked a nose horn. The frill ornamentations of Lokiceratops demonstrate bilateral asymmetry. There is considerable variation in the shape of the seven epiparietals on the left and right sides of the frill.
The stunning frill and horns of Lokiceratops rangiformis. Picture credit: Fabrizio Lavezzi © Evolutionsmuseet, Knuthenborg.
Picture credit: Fabrizio Lavezzi © Evolutionsmuseet, Knuthenborg.
What’s in a Name?
The bilateral asymmetry gave rise to the species name. The genus is named after the blade-wielding Norse god Loki, a god that causes chaos and mischief in Norse mythology. The genus name translates as “Loki’s horned face”. Whereas the species epithet comes from the reindeer/caribou genus Rangifer. This is a reference to the differing horn lengths on each side of the frill, similar to the asymmetric antlers of caribou and reindeer.
Co-author of the study Joseph Sertich, a palaeontologist with the Smithsonian Tropical Research Institute and Colorado State University stated:
“This new dinosaur pushes the envelope on bizarre ceratopsian headgear, sporting the largest frill horns ever seen in a ceratopsian. These skull ornaments are one of the keys to unlocking horned dinosaur diversity and demonstrate that evolutionary selection for showy displays contributed to the dizzying richness of Cretaceous ecosystems.”
Portrait reconstruction of Lokiceratops rangiformis. Picture credit: Andrey Atuchin for the Museum of Evolution in Maribo, Denmark.
Picture credit: Andrey Atuchin
High Endemism in Centrosaurines
Lokiceratops rangiformis fossils come from the same narrow stratigraphic interval and geographic area as three other centrosaurines (Wendiceratops pinhornensis, Albertaceratops nesmoi, and Medusaceratops lokii) and one chasmosaurine (Judiceratops tigris). Phylogenetic analysis indicates that Lokiceratops is closely related to Wendiceratops and Albertaceratops. Indeed, it has been placed in the tribe Albertaceratopsini along with Albertaceratops and Medusaceratops.
To read Everything Dinosaur’s blog post from 2010 about the scientific description of Medusaceratops lokii: A New Horned Dinosaur from Montana.
The research team concludes that the Albertaceratopsini, was one of multiple centrosaurine clades to undergo geographically restricted radiations, with Nasutuceratopsini restricted to the south and Centrosaurini and Pachyrostra restricted to the north.
Whilst ceratopsian ancestors were widespread across the Northern Hemisphere throughout the Cretaceous, their isolation on Laramidia led to the evolution of huge body sizes, and most characteristically, distinctive patterns of horns above their eyes and noses, on their cheeks and along the edges of their elongated head frills. Yet, based on current evidence and acknowledging uneven temporal and geographic sampling, all known centrosaurine species exhibit relatively small geographic ranges.
This pattern is seen not only in genera and species, but also above the species level. That is, centrosaurine subclades—including Albertaceratopsini—also show restricted geographic distributions. Fossils recovered from this region suggest horned dinosaurs were living and evolving in a small geographic area, a high level of endemism that implies dinosaur diversity is underestimated.
Co-author Mark Loewen (Natural History Museum of Utah) explained:
“Previously, palaeontologists thought a maximum of two species of horned dinosaurs could coexist at the same place and time. Incredibly, we have identified five living together at the same time. The skull of Lokiceratops rangiformis is dramatically different from the other four animals it lived alongside.”
Reconstruction of Lokiceratops in the 78-million-year-old swamps of northern Montana, USA as two Probrachylophosaurus move past in the background. Picture credit: Fabrizio Lavezzi © Evolutionsmuseet, Knuthenborg.
Picture credit: Fabrizio Lavezzi © Evolutionsmuseet, Knuthenborg.
Fossils Discovered in 2019
The fossils represent a mature, adult animal. The material is found in the late spring of 2019 by Mark Eatman on private land of the Wolery Ranch in Kennedy Coulee. It was excavated under a lease in the autumn. The holotype specimen number is EMK 0012. The individual fossilised skull bones of Lokiceratops were integrated into a state-of-the-art reconstruction of the complete skull and is permanently reposited and displayed at the Museum of Evolution in Maribo, Denmark. A reconstruction of the skull, alongside a full-sized sculpture, will be displayed at the Natural History Museum of Utah in Salt Lake City for the next few months.
Lokiceratops rangiformis lived around 78 million years ago (Campanian faunal stage of the Late Cretaceous).
Andrew Farke from the Raymond M. Alf Museum of Paleontology and another co-author of the paper commented:
“We now recognise over thirty species of centrosaurines within the greater group of horned dinosaurs, with more like Lokiceratops being described every year”.
Ceratopsians were much more diverse than previously thought. This new research also demonstrates some groups such as the Albertaceratopsini had relatively small distributions across the island landmass of Laramidia. Centrosaurine dinosaurs demonstrate geographically restricted radiations. High speciation rates may have been driven in part by sexual selection or as a result of regional variations in climate or flora. The high endemism seen in centrosaurines and other dinosaurs implies that dinosaur diversity is presently underestimated and contrasts with the large (historic) geographic ranges seen in most extant mammalian megafauna.
Everything Dinosaur acknowledges the assistance of a media release from the Natural History Museum of Utah in the compilation of this article.
The scientific paper: “Lokiceratops rangiformis gen. et sp. nov. (Ceratopsidae: Centrosaurinae) from the Campanian Judith River Formation of Montana reveals rapid regional radiations and extreme endemism within centrosaurine dinosaurs” by Mark A. Loewen, Joseph J. W. Sertich, Scott Sampson, Jingmai K. O’Connor, Savhannah Carpenter, Brock Sisson, Anna Øhlenschlæger, Andrew A. Farke, Peter J. Makovicky, Nick Longrich and David C. Evans published in PeerJ.
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