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

Geologist Peter Hews with the skull of Regaliceratops.

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.

Honouring Royalty and a Museum?

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)

A right royal member of the Ceratopsidae.

Picture credit: Julius Csotonyi

An Absence of Postcranial Material

Although no postcranial 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.

Hellboy!

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 Chasmosaurine 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)

Characteristics of centrosaurines as well as chasmosaurines.

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 and Regaliceratops peterhewsi

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).

Regaliceratops peterhewsi

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

Extremely hard limestone matrix (hard work digging out “hell boy”).

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.

Romantic Palaeontologists

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

By “Royal Command”.

Picture credit: Current Biology

Lorna said yes and we wish the happy couple a peaceful and prosperous future.

Origins of Feathers More Complex Than Previously Thought

Over the last week or so, team members at Everything Dinosaur have reported upon new research into whether dinosaurs were warm-blooded or not.  In addition, in response to requests from readers, we discussed the lack of feathers in dinosaurs such as the fearsome Velociraptors that are featured in the forthcoming movie “Jurassic World”.

Feathered Dinosaurs

This morning, we turn once again to the “were dinosaurs feathered” debate as a new study published in the journal “Biology Letters” suggests that the common ancestor of the Dinosauria was not covered in feathers and indeed, most dinosaurs probably were scaly.

Analysis undertaken by scientists from the Natural History Museum (London), Uppsala University (Sweden) and the Royal Ontario Museum (Toronto, Canada) suggest that feathered dinosaurs were probably the exception amongst the Order Dinosauria.  A comprehensive review of known dinosaur skin fossils coupled with an in-depth study of the dinosaur family tree was used to assess the probability of feathers appearing in different types of dinosaur.

The team conclude that the majority of non-avian dinosaurs were more likely to have had scales like a crocodile or lizard rather than exhibiting signs of feathers or “feather-like” structures.

Once Again Palaeontologists Debate the Extent of Feathers in the Dinosauria

Adult and juvenile feathered dinosaurs.

Picture credit: Xing Lida and Song Qijin

Why do Scientists Get into a Flap over Feathers?

If the majority of dinosaurs had feathers then this has huge implications for dinosaur biology and behaviour.  Insulating feathers infer that the animal that possesses them must be warm-blooded (endothermic), so this argument links directly into the cold-blooded versus warm-blooded dinosaur debate.

To read the article on the research from Stony Brook University that challenges 2014 data on mesothermic dinosaurs and argues that dinosaurs were indeed warm-blooded: Dinosaur Warm-blooded Debate Hots Up.

Thanks to the astonishing fossils from Liaoning Province (China) scientists have been able to identify feathers in a number of different types of theropod dinosaur.  It is widely accepted that many different types of meat-eating dinosaur were feathered or at least partially feathered.

Those dinosaurs which are believed to be closely related to birds provide the greatest number of candidates for feathers rather than scales.  Dinosaurs such as Caudipteryx (Oviraptoridae), Beipiaosaurus (Therizinosauridae), Microraptor (Dromaeosauridae) and Deinocheirus (Ornithomimosauria) were all very probably feathered.  All these dinosaurs are classified as coelurosaurian theropods, the clade of dinosaurs that taxonomically are placed close to the evolutionary line leading to the Aves (birds) fossil evidence supports this hypothesis.

Beautifully Feathered Dinosaur Fossil from Liaoning Province (Microraptor)

Feathers found preserved in many dinosaur fossils from China.

Scored for the Presence of Absence of Feathers

The researchers included thirty-four ornithischian dinosaurs, six sauropods and forty theropods (which included some Mesozoic birds).  These taxa along with a number of others were scored for the presence of feathers or proto-feathers in the fossil record.  Where on the body feathers had been found was also taken into account along with the type of depositional environments that allowed the preservation of filamentous feathers or scaly skin.

Pterosaurs as a group related to the Dinosauria and also archosaurs were included in the study.  Although the fossil record is extremely poor, the team were able to conclude that, based on the probability analysis and the consensus tree that was constructed, it was likely that the ancestor of the dinosaurs was not feathered.  In addition, the research suggests that although the majority of coelurosaurian theropods were indeed feathered to some degree, the majority of other dinosaurs were very probably not feathered.

Commenting on the research, one of the authors of the paper, Nicolás E. Campione (Uppsala University) stated:

“As palaeontologists we are at the mercy of available data, which given the interest in the field are ever changing.  Our study shows that dinosaurs experimented extensively with their “outer look” and potentially independently along separate evolutionary lineages.  That is what the data allows us to say at present.”

The Way Flying Reptiles (Pterosaurs) Were Assessed Affected the Results

Intriguingly, the single biggest influence on the feather versus scales debate in this analysis was the way in which the Pterosauria (flying reptiles) were treated.  Pterosaurs are not dinosaurs, but a related group belonging to the archosaurs just like the Dinosauria.  How closely related the pterosaurs are to the dinosaurs remains an area of controversy.  This research showed that if the ancestor of the Pterosauria was assumed to be scaly then different feather probabilities in the Dinosauria resulted when compared with the study with a fuzzy Pterosaur ancestor included in the database.

Professor Paul Barrett, (Natural History Museum), one of the co-authors of this report summarised the team’s findings:

“Using a comprehensive database of dinosaur skin impressions, we attempted to reconstruct and interpret the evolutionary history of dinosaur scales and feathers.  Most of our analyses provide no support for the appearance of feathers in the majority of non-avian dinosaurs and although many meat-eating dinosaurs were feathered, the majority of other dinosaurs, including the ancestor of all dinosaurs, were probably scaly.”

Feathered Dinosaurs

The biology of the dinosaurs is going to remain a hotly debated topic.  Work such as this new study helps to move the debate forward by reflecting evidence put forward by new fossil discoveries.  However, the fossil record is far from complete and conclusions such as the ones made in this research need to be tested in the light of further fossil finds that help to fill in important and significant gaps in our knowledge of the epidermal coverings of dinosaurs and their close relatives.

To read an article about a fossil find that suggests a Jurassic Ornithischian dinosaur was feathered: Kulindadromeus – Did All Dinosaurs Have Feathers?

A consequence of the inference that most coelurosaurian theropods were probably feathered is that the most famous dinosaur of all Tyrannosaurus rex may also have been covered in a coat of feathers.  Perhaps a young T. rex had a shaggy coat of feathers to help keep it warm.  As the animal grew and became more massive, the need to insulate its body (surface area to volume ratio), became less important.  An adult Tyrannosaurus rex, however, may indeed have been feathered, at least in part.

As fossils of filaments and feathers are associated with low energy depositional environments and finely grained substrates (not a description readily given to much of the Hell Creek Formation), then palaeontologists may never find a feathered T. rex fossil.

CollectA Will Introduce a Feathered T. rex Model in the Summer of 2015

1:40 scale model of a feathered T. rex.

To view the CollectA scale model range and the feathered T. rex (from late summer 2015): CollectA Prehistoric Life Models.

Partial Theropod Femur – Right People, in the Right Place at the Right Time

News broke this week of the discovery and subsequent description of a partial left femur from a theropod dinosaur that had been found on the south-west tip of Sucia Island, which is part of Washington State.  This is the first time that a dinosaur fossil has been recorded from Washington State.  Sucia Island is part of the San Juan archipelago group of islands, it is a conservation area, part of a marine park (Washington State Marine Park).  Sucia Island is very small, it covers approximately 0.88 square miles, making the island about the size of the Queen Elizabeth Olympic Park in London, the site of the 2012 Olympic Games.

The Shoreline where the Theropod Fossil was Discovered (Sucia Island State Park)

The shoreline where the fossil was found.

Picture credit: Burke Museum

The First Dinosaur

The fossil was collected by a team of palaeontologists from the Burke Museum of Natural History and Culture (Seattle) in May 2012.  The partial femur was located in very hard, silty sandstone rocks which represent a shallow marine environment.  The discovery of the fossil had been made earlier by Burke museum field workers who had been excavating ammonite fossils and other invertebrates from the same bed.  It has taken three years to prepare the fossil for further study by carefully removing the extremely hard matrix and then to identify what type of animal the partial thigh bone might represent.

Based on comparative studies the bone has been ascribed to a tyrannosaur, but more about that later.

Scientists Proudly Show Off Washington State’s First Dinosaur Fossil

Dr Christian Sidor (right), Burke Museum curator of vertebrate palaeontology, and Brandon Peecook (left), University of Washington graduate student, show the size and placement of the fossil fragment compared to the cast of a Daspletosaurus femur.

Picture credit: Burke Museum

Right People at the Right Time

This really is an example of the right people, in the right place at the right time.  Occasionally vertebrate fossils are found in marine deposits, in the United Kingdom, the Dorset coast provides an example of this.  The “Jurassic Coast” around Charmouth and Lyme Regis in Dorset represent a shallow marine environment but the fossilised bones of a dinosaur (Scelidosaurus) have been found.  It seems likely that the corpses of dinosaurs were washed out to sea and once the body cavity had ruptured the carcase sank to the bottom and became covered in sediment permitting the fossilisation process to begin.

The picture above shows Dr Sidor holding the partial femur fossil, Brandon is holding a cast of femur from a tyrannosaur called Daspletosaurus (D. torosus) to allow a visual comparison to be made.  Both scientists are showing the back view of the objects (the posterior view), the photographer is looking at the back of the fossil, this is important to note as an anatomical feature located at the back of the fossil bone is helping palaeontologists to classify the sort of dinosaur the Washington State bone represents.

A Rare Find

To find a dinosaur fossil in an marine environment is very rare and given the strong waves and tides associated with Sucia Island the fossil material could have been quickly washed out to sea and lost forever, so it really is a question of the right people being in the right place at the right time.  The analysis and identification of the femur was undertaken by Dr Sidor (Burke Museum of Natural History and Culture) and Brandon Peecock (University of Washington), their paper has just been published in the on line journal PLOS One.  It is highly unlikely that other fossils related to this individual will be found at the site.

Why a Tyrannosaur?

To answer this question we first have to take a step back.  How do we know that this is a dinosaur bone in the first place?  The fossils are found in a horizon that makes up a member of the Cedar District Formation, Upper Cretaceous strata that outcrops along the north-western coast of the United States and the extreme southern portion of the Canadian Pacific coast around Vancouver.

The exact age of these rocks is debated, but the rocks were probably laid down in the Campanian faunal stage and are perhaps around 80 million-years-old.  During this time, in the Late Cretaceous, North America was divided into several landmasses by the Western Interior Seaway.

Laramidia

The island of Laramidia lay to the west and this strip of land is represented by strata found in Alaska all the way down to Mexico on the western seaboard of this continent.  Dinosaurs were the dominant terrestrial megafauna and much is known about the dinosaurs that roamed the eastern side of Laramidia.  Less is known about those from the western provinces of this landmass, this is due to the relative paucity of fossil material found to date on America’s Pacific coast.  Hence the significance of the Sucia Island discovery.

Dinosaur and Prehistoric Bird Fossil Locations (Western Laramidia)

The Sucia Island fossil site is 3 (highlighted in red).

Picture credit: PLOS One

Three Tell-tale Signs

There are three tell-tale signs that indicate that this fossil fragment represents a potential tyrannosaur, let’s briefly go through these:

• The Size of the Fossil (UWBM 95770)

Although only a fragment of the top part of the femur (see picture below to gain an understanding of which part of the thigh bone has been preserved), the fossil measures a whopping 42.5 cm long and 22.4 cm wide at its widest part (the top end of the fossil, this represents that portion of the femoral head that articulates with the hip socket.  This fossil is from a very large animal, hence the confident dinosaur diagnosis.

The researchers writing in PLOS One undertook a comparative analysis study, comparing this fragment to the bones of theropod dinosaurs.  Based on this analysis, the projected actual size of this thigh bone would be about 1.17 metres long (1.167 metres +/- 63 mm with 95% degree of confidence in the result).

• Anatomical Features Indicate a theropod dinosaur

Although the bone is fragmentary, there is evidence of matrix infill in the medullary cavity (the middle of the bone, where marrow was present).  This indicates that this bone was hollow in the middle, this feature is only seen in theropod dinosaurs in this geological period. Thus, the hollow middle cavity is diagnostic of this bone having come from a theropod dinosaur.

The Fourth Trochanter

• The Clincher!  The Fourth Trochanter

An anatomical feature on the back of the thigh bone (posterior), called the fourth trochanter suggests a theropod dinosaur.  The fourth trochanter is a prominent bump or ridge of bone that indicates muscle attachment.  In this specimen, the fourth trochanter is located in the top third portion of the thigh bone, close to the hip socket.  Its shape and position on the bone suggests Theropoda.  All dinosaurs (all archosaurs for that matter), have this characteristic, but in other big, Late Cretaceous dinosaurs such as ceratopsians and hadrosaurs, the fourth trochanter is shaped differently and in a different position at the back of the femur.

In hadrosaurids for example, the fourth trochanter is located near the middle of the femur and is triangular in shape.  In horned dinosaurs (ceratopsians) the fourth trochanter is typically a long, low, straight ridge, which is also positioned towards the middle portion of the thigh bone.

An Illustration of the Fossil Fragment and Comparison with Left Femur of Daspletosaurus

An illustration of the fossil find.

Picture credit: Burke Museum of Natural History and Culture with additional annotation by Everything Dinosaur

 If you look carefully at the picture above, the bottom end of the fourth trochanter is wider and roughened (distal end).  The top portion (proximal) appears smooth and thinner.  A similar morphology is found on the fourth trochanter of the Late Cretaceous tyrannosaur known as Daspletosaurus (D. torosus).

Daspletosaurus spp.

This explains why the research team have tentatively assigned this fossil fragment to the tyrannosaur family and used Daspletosaurus fossil material as a direct comparison.

An Illustration of Daspletosaurus (D. torosus)

Larger tyrannosaur present in the ecosystem.

Picture credit: Everything Dinosaur

Commenting on the significance of the fossil discovery, Dr Sidor stated:

“This fossil won’t win a beauty contest.  But fortunately it preserves enough anatomy that we were able to compare it to other dinosaurs and be confident of its identification.”

The First Dinosaur from Washington State – A Tyrannosaur?

The partial thigh bone, now tentatively assigned to the same dinosaur clade as Tyrannosaurus rex is on display at Burke Museum.  It is worth noting that based on the thigh bone’s total estimated size, the individual meat-eater the fossil material represents would have been over eight metres in length.  The dinosaur would have been approximately the same size as a Daspletosaurus, a Gorgosaurus or an Albertosaurus (all tyrannosaurids).  Although the tyrannosaurid diagnosis cannot be confirmed with absolute certainty and a definition down to genus level is not possible, the tyrannosaurs dominate the apex predator positions within the Laramidia fossil sites.

Perhaps as many as nine genera have been identified to date, the Late Cretaceous seems to mark the peak in the Superfamily Tyrannosauroidea diversity.

Tyrannosaurs Present in Laramidia

Team members at Everything Dinosaur have tried to list the nine genera of tyrannosaurs identified thus far from strata that represent Laramidia.

1. Albertosaurus
2. Gorgosaurus
3. Tyrannosaurus
4. Daspletosaurus (to read an article about face biting in potential Daspletosaurs): Cannibal Daspletosaurus?
5. Lythronax (to read an article about this dinosaur discovery): The King of Gore.
6. Nanotyrannus (Nomen dubium) – to read more about this potential new genus of tyrannosaurid and the debate surrounding it: Duelling Dinosaurs.
7. Bistahieversor (for a review on the CollectA Bistahieversor model: CollectA Bistahieversor Reviewed.
8. Teratophoneus (refer to the Lythronax article for more information): “Monstrous Murderer” of a Tyrannosaur.
9. Nanuqsaurus – the polar tyrannosaurid: Nanuqsaurus hoglundi.

Dinosaur Provinciality

Palaeontologists have proposed that there was a great deal of dinosaur provinciality within the landmass of Laramidia.  The idea of different parts of the landmass being home to different types of dinosaur has been studied for the last two decades.

Unfortunately, due to the tectonic activity on the Pacific coast of western North America, it is difficult to determine where exactly in Laramidia this new tyrannosaur came from.  It has been suggested that since the end of the age of dinosaurs there has been around 1,800 miles of tectonic displacement in roughly a northerly direction.  This tyrannosaur could have lived as far south as what is now southern California.

CollectA have introduced a wide selection of tyrannosaur models into their not-to-scale range of replicas including a model of Daspletosaurus: CollectA Prehistoric Life Figures.