Regaliceratops peterhewsi – The Curious World of Royal Chasmosaurines
Recently published in the journal “Current Biology” comes a description of the remarkably flamboyant Regaliceratops, the name translates as “royal horned face”, a new species of horned dinosaur from south-western Alberta (Canada) that highlights once again that the Dinosauria have a few more surprises for palaeontologists awaiting in the Upper Cretaceous aged sediments of North America.
A large fossilised skull of a horned dinosaur was discovered by geologist Peter Hews back in 2005. The fossil material consists of much of the cranial material, but the rostral bone and lower jaw are missing. Although the exact stratigraphical location of the fossil find is a little uncertain (blame the lack of distinctive marker beds in the locality), it is likely that this horned dinosaur lived in the Middle Maastrichtian faunal stage of the Cretaceous around 68 million years ago.
Geologist Peter Hews with the Prepared Regaliceratops peterhewsi
Picture Credit: Royal Tyrrell Museum
Horned dinosaurs are well known for their huge heads and flamboyant crests. Surrounding the skull frill was a crest of large, plate-like epoccipitals, that reminded the palaeontologists responsible for the study of the fossil (Dr. Caleb Brown and Dr. Donald Henderson, both from the Royal Tyrrell Museum, Alberta), of a crown, hence, in part this dinosaur’s genus name representing royalty. The genus name also honours the Royal Tyrrell Museum in Drumheller, a leading centre of palaeontological research into Late Cretaceous prehistoric animals. The species name honours Peter Hews for his work in researching the strata of the St Mary’s River, from which the fossil was extracted.
An Illustration of the Royal Dinosaur (Regaliceratops)
Picture Credit: Julius Csotonyi
Although no post cranial material has been found, based on the skull dimensions and using an analysis of closely related genera such as Anchiceratops, it has been estimated that this herbivorous dinosaur was around five to six metres in length and that it may have weighed as much as 1.5 tonnes, possibly a little more. The frill ornamentation reminded team members at Everything Dinosaur of the dermal plates found on Stegosaurs, but this similarity is superficial. These structures in combination with the overall shape of the skull, along with the pair of fenestrae (holes) within the crest, were probably used to communicate visually with other members of the herd, although that large crest and the big nose horn may have had defensive functions also.
A number of media outlets have reported that this dinosaur was nick-named “Hellboy” due to the small pair of brow horns that this dinosaur possessed. They reminded the palaeontologists of the horns on the top of the head of the comic book character, we suspect that the main reason for the nick-name was the great difficulty the scientists had when trying to remove the very hard matrix that surrounded the fossil material. Although this part of Alberta has not yielded a great deal of dinosaur fossil material, least not when compared to geological formations such as the Dinosaur Park Formation and Horseshoe Canyon Formation which occur to the west of the fossil site, but this discovery hints that many more species of bizarrely crested horned dinosaurs await discovery.
Characteristics of Chasmosaur as well as Centrosaurine Dinosaurs
The Ceratopsidae (horned dinosaur) family can be split into two distinct sub-families, the Chasmosaurinae and the Centrosaurinae. Up until a few years ago, it was a relatively straight forward process when it came to classifying a horned dinosaur into one of these groups. Centrosaurines tended to have shorter neck shields, small brow horns and a prominent bump or large nose horn. In contrast, the Chasmosaurs were classified as having relatively longer neck frills, a small nose horn and much larger brow horns. This rather simplistic assessment has fallen out of favour as the myriad of new North American dinosaur species described in the last decade or so have rather “muddied the phylogenetic waters somewhat”, as an Everything Dinosaur team member has stated.
Regaliceratops has Centrosaurine characteristics despite its classification of a member of the Chasmosaurinae.
Regaliceratops Compared to Styracosaurus (Centrosaur) and Triceratops (Chasmosaur)
Picture Credit: Royal Tyrrell Museum
The picture above shows the skull and horns Regaliceratops (middle) compared to those of the Centrosaurine Styracosaurus (left) and the Chasmosaurine Triceratops (right). Regaliceratops has the relatively long neck frill associated with the Chasmosaurinae, but it has very much reduced brow horns which is a typical trait of the Centrosaurines.
Late Cretaceous horned dinosaurs of North America, diversified in a relatively short time (geologically) into a huge range of different types. The authors of the paper published in “Current Biology” undertook a phylogenetic study of Chasmosaurs and they propose the these Chasmosaurine dinosaurs can be further split into two groups. The first, older group of Chasmosaurs, containing dinosaurs such as Pentaceratops, Utahceratops, Chasmosaurus and Mojoceratops that lived during the Late Campanian and into the very Early Maastrichtian faunal stage, were smaller and possessed anatomical features that resembled the Centrosaurines. The second group represents those Chasmosaurs that lived towards the very end of the Cretaceous, the likes of Ojoceratops, Eotriceratops, Torosaurus and the most famous horned dinosaur of them all Triceratops. These Chasmosaurs tended to be larger and to have more highly developed Chasmosaur features (large brow horns and big, simple neck frills).
Based on the known fossil material, the authors state that as the Centrosaurine-like Chasmosaurs such as Pentaceratops et al seem to have become extinct at the same time as the true Centrosaurs, then a common cause may have been responsible for both these two groups demise. The second more derived group of Chasmosaurines, the group that includes Triceratops, may have diversified to occupy the niches in the ecosystem that were subsequently vacated. If this phylogenetic study is examined carefully, then an argument can be made for there being a common ancestor of the two groups of Chasmosaurines, but no candidate fossil material has been discovered to date, so there is likely to be a number of surprises in the shape of Late Cretaceous horned dinosaurs that represent new species awaiting discovery in North America.
The Skull Material within the Extremely Hard Matrix
Picture Credit: Royal Tyrrell Museum
This latest report on the bizarre horned dinosaurs raises a fascinating, yet highly controversial point. If the authors are correct in their conclusions, then we have Chasmosaurine dinosaurs diversifying to fill the ecological niches left empty with the extinction of the Centrosaurines. To fill those niches, the Chasmosaurs developed anatomical characteristics that resembled the Centrosaurs. This is an example of convergent evolution and it is unique in the Dinosauria as far as we at Everything Dinosaur can work out. Horns and bony display structures that evolve in two separate groups of dinosaurs which are very similar in appearance and apparent function.
We can’t draw to a close our brief examination of “royal horned face” without mentioning the extremely romantic gesture included in the scientific paper by Caleb Brown. At the bottom of the acknowledgements section of the paper, Caleb sneaked in a marriage proposal to his partner Dr. Lorna O’Brien who works as a technician at the museum. In the sometimes dry world of academic publishing, the addition of this very personal message may come as a surprise to some, but there have been a number of cases of comments, plays on words or even outright jokes being published in such papers. However, none of us here can recall a marriage proposal being contained within such a publication.
Proposal Appearing at the Very Bottom of the Paper
Picture Credit: Current Biology
Lorna said yes and we wish the happy couple a peaceful and prosperous future.