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Introducing Mercuriceratops

June 18, 2014

New Horned Dinosaur Reveals Unique Wing-Shaped Headgear

Today, we annnouce the discovery of  a new species of horned dinosaur (ceratopsian) based on fossils collected from Montana in the United States and Alberta, Canada. Mercuriceratops (mer-cure-E-sare-ah-tops) gemini was approximately 6 meters (20 feet) long and weighed more than 2 tons. It lived about 77 million years ago during the Late Cretaceous Period. Research describing the new species is published online in the journal Naturwissenschaften.

Mercuriceratops (middle) compared to a typical centrosaurine (left) and chamosaurine (right). Courtesy Danielle Dufault.jpg

Mercuriceratops (middle) compared to a typical centrosaurine (left) and chasmosaurine (right). Courtesy Danielle Dufault.

Mercuriceratops (Mercuri + ceratops) means “Mercury horned-face,” referring to the wing-like ornamentation on its head that resembles the wings on the helmet of the Roman god, Mercury. The name “gemini” refers to the almost identical twin specimens found in north central Montana and the UNESCO World Heritage Site, Dinosaur Provincial Park, in Alberta, Canada. Mercuriceratops had a parrot-like beak and probably had two long brow horns above its eyes. It was a plant-eating dinosaur.

Mercuriceratops took a unique evolutionary path that shaped the large frill on the back of its skull into protruding wings like the decorative fins on classic 1950s cars. It definitively would have stood out from the herd during the Late Cretaceous,” said lead author Dr. Michael Ryan, curator of vertebrate paleontology at The Cleveland Museum of Natural History. “Horned dinosaurs in North America used their elaborate skull ornamentation to identify each other and to attract mates—not just for protection from predators. The wing-like protrusions on the sides of its frill may have offered male Mercuriceratops a competitive advantage in attracting mates.”

“The butterfly-shaped frill, or neck shield, of Mercuriceratops is unlike anything we have seen before,” said co-author Dr. David Evans, curator of vertebrate palaeontology at the Royal Ontario Museum. “Mercuriceratops shows that evolution gave rise to much greater variation in horned dinosaur headgear than we had previously suspected.”

The new dinosaur is described from skull fragments from two individuals collected from the Judith River Formation of Montana and the Dinosaur Park Formation of Alberta. The Montana specimen was originally collected on private land and acquired by the Royal Ontario Museum. The Alberta specimen was collected by Susan Owen-Kagen, a preparator in Dr. Philip Currie’s lab at the University of Alberta. “Susan showed me her specimen during one of my trips to Alberta,” said Ryan. “When I saw it my jaw dropped open as I instantly recognized it as being from the same type of dinosaur that the Royal Ontario Museum had from Montana.”

The holotype squamosal of Mercuriceratops from Montana (left) and the referred specimen from Alberta (right)

The holotype squamosal of Mercuriceratops from Montana (left) and the referred specimen from Alberta (right)

The Alberta specimen confirmed that the fossil from Montana was not a pathological specimen, nor had it somehow been distorted during the process of fossilization,” said Dr. Philip Currie, professor and Canada research chair in dinosaur paleobiology at the University of Alberta. “The two fossils—squamosal bones from the side of the frill—have all the features you would expect, just presented in a unique shape.”

This dinosaur is just the latest in a series of new finds being made by Ryan and Evans as part of their Southern Alberta Dinosaur Project, which is designed to fill in gaps in our knowledge of Late Cretaceous dinosaurs and study their evolution. This project focuses on the paleontology of some of oldest dinosaur-bearing rocks in Alberta and the neighbouring rocks of northern Montana that are of the same age.

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Body Mass Evolution and Adpative Radiation in Dinosaurs

May 6, 2014

Today we announced the results of a major study on dinosaur body size evolution in a new paper published in PLoS Biology.

From the Press Release: An international, led by scientists at Oxford University and the Royal Ontario Museum, estimated the body mass of 426 dinosaur species based on the thickness of their leg bones. The team found that dinosaurs showed rapid rates of body size evolution shortly after their origins, around 230 million years ago. However, these soon slowed: only the evolutionary line leading to birds continued to change size at this rate, and continued to do so for 170 million years, producing new ecological diversity not seen in other dinosaurs.

Dinosaurs evolved into a huge range of shapes and sizes over 170 million years. Courtesy of Julius Csotonyi.

Dinosaurs evolved into a huge range of shapes and sizes over 170 million years. Courtesy of Julius Csotonyi.

“Dinosaurs aren’t extinct; there are about 10,000 species alive today in the form of birds. We wanted to understand the evolutionary links between this exceptional living group and their Mesozoic relatives, including well-known extinct species like T. rex, Triceratops, and Stegosaurus,” said Dr Roger Benson of Oxford University’s Department of Earth Sciences, who led the study. “We found exceptional body mass variation in the dinosaur line leading to birds, especially in the feathered dinosaurs called maniraptorans. These include Jurassic Park’s Velociraptor, birds, and a huge range of other forms, weighing anything from 15 grams to 3 tonnes, and eating meat, plants, and more omnivorous diets.”

The team believes that small body size might have been key to maintaining evolutionary potential in birds, which broke the lower body size limit of around 1 kilogram seen in other dinosaurs.

“How do you weigh a dinosaur? You can do it by measuring the thickness of its leg bones, like the femur. This is quite reliable,” said Dr Nicolás Campione, of the Uppsala University, a member of the team. “This shows that the biggest dinosaur Argentinosaurus, at 90 tonnes, was 6 million times the weight of the smallest Mesozoic dinosaur, a sparrow-sized bird called Qiliania, weighing 15 grams. Clearly, the dinosaur body plan was extremely versatile.”

The team examined rates of body size evolution on the entire family tree of dinosaurs, sampled throughout their first 170 million years on Earth. If close relatives are fairly similar in size, then evolution was probably quite slow. But if they are very different in size, then evolution must have been fast.

“What we found was striking. Dinosaur body size evolved very rapidly in early forms, likely associated with the invasion of new ecological niches. In general, rates slowed down as these lineages continued to diversify,” said Dr David Evans at the Royal Ontario Museum, who co-devised the project. “But it’s the sustained high rates of evolution in the feathered maniraptoran dinosaur lineage that led to birds – the second great evolutionary radiation of dinosaurs.”

The evolutionary line leading to birds kept experimenting with different, often radically smaller, body sizes – enabling new body ‘designs’ and adaptations to arise more rapidly than among larger dinosaurs. Other dinosaur groups failed to do this, got locked in to narrow ecological niches, and ultimately went extinct. This suggest that important living groups such as birds might result from sustained, rapid evolutionary rates over timescales of hundreds of millions of years, which could not be observed without fossils.

Open-Access Article:

Benson R. B. J., N. E. Campione, M. T. Carrano, P. D. Mannion, C. Sullivan, P. Upchurch, and D. C. Evans. 2014. Rates of dinosaur body mass evolution indicate 170 million years of sustained ecological innovation on the avian stem lineage, PLOS Biology 12(5): e1001853.

PLoS Biology Primer:

Moen D, Morlon H (2014) From Dinosaurs to Modern Bird Diversity: Extending the Time Scale of Adaptive Radiation. PLoS Biology 12(5): e1001854

ScienceNOW: How Birds Survived the Dinosaur Apocalypse by Michael Balther

Museum Diaries Dinos ReDiscovered Episode Airs

April 28, 2014

Museum Diaries” is a six-part series commissioned by TVO to celebrate the inner workings of the Royal Ontario Museum during its centennial year. “Dinos Rediscovered” embarks on a stunning journey following the ROM Vertebrate Paleontology team on a field expedition to the Alberta badlands to discover treasures from 75 million years ago. This episode also features PM Project Manager Jason French and his team as they carefully deconstruct one of the ROM’s recent dinosaur exhibits, Ultimate Dinosaurs: Giants of Gondwana, and prepares the exhibition to travel to other Museum.

Learn more here.

 

David Evans

In Alberta with a truck load of dinosaur bones, as featured on the Museum Diaries episode.

Season’s Greetings from Santa Claws!

December 26, 2013
Season's Greetings from the Cretaceous Santa Claws by Danielle Dufault

Season’s Greetings from the Cretaceous Santa Claws by Danielle Dufault

Check out this fun and fanciful holiday ecard from talented paleoartist Danielle Dufault, which incorporates the latest data on the mysterious theropod Deinocheirus mirificus- now revealed to have stayed enigmatic so long due to strong connections with the master of secrecy Santa himself. Awesome job Danielle!

New Hell Creek Dromaeosaurid Described

December 16, 2013
Holotype maxilla and associated dentary of Acheroraptor temertyorum. Copyright Royal Ontario Museum.

Holotype maxilla and associated dentary of Acheroraptor temertyorum. Copyright Royal Ontario Museum.

Today we formally announced publication of a new species of a small, meat-eating dinosaur (‘raptor’) based on newly discovered fossils from Montana, USA. Acheroraptor temertyorum is based on associated upper and lower jaw fossils from the Hell Creek Formation of Montana. It was relatively large for a “raptor”, approaching Deinonychus in size, with a long-snouted skull and dagger-like ridged teeth.

Acheroraptor was one of the last non-avian dinosaurs. It lived 67 to 66 million years ago in western North America, in a community that included Tyrannosaurus rex and  Triceratops. As such, Acheroraptor gives us a more complete picture of the ecosystem in North America just before the great extinction that marked the end of the Age of Dinosaurs.

The unique ridged teeth of Acheroraptor have been recognized for decades, but the lack of reasonably complete diagnostic material did not permit determination of the taxonomic affinities and evolutionary relationships of the Hell Creek dromaeosaur until now.  Interestingly, the jaw bones of Acheroraptor compare more closely to those of Velociraptor and other long-snouted Asian species than those of older North American species. Dromaeosaurid evolutionary relationships and biogeography will continue to be contentious. Phylogenetic analysis based on the dataset of Longrich and Currie (2009) recovered Acheroraptor as a velociraptorine dromaeosaurid, nested within a group of Asian species. The close evolutionary relationship of Acheroraptor to a  group of late-occurring Asian species that includes Velociraptor suggests that migration from Asia may have continued to shape North American dinosaur communities right up until the end of the Cretaceous period.

The research describing Acheroraptor was published in the latest issue of Naturwissenschaften:

Evans, D. C.,  D. Larson, and P. J. Currie. 2013. A new dromaeosaurid (Dinosauria: Theropoda) with Asian Affinities from the latest Cretaceous of North America. Naturwissenschaften 100 (11): 1041-1049. Available online here.

The Press Release from the Royal Ontario Museum can be found here.

Two Acheroraptor feeding at a Triceratops carcass as Tyrannosaurus rex approaches. Courtesy of Julius Csotonyi .

Two Acheroraptor feeding at a Triceratops carcass as Tyrannosaurus rex approaches. Courtesy of Julius Csotonyi .

Congrats to Dr. Caleb Marshall Brown

October 8, 2013
Dr. Caleb Brown in the Gobi Desert, Mongolia in 2009. Courtesy of M. J. Ryan.

Dr. Caleb Brown in the Gobi Desert, Mongolia in 2009. Courtesy of M. J. Ryan.

Caleb Brown successfully defended his Ph.D. in the Department of Ecology and Evolutionary Biology at the University of Toronto last week. His thesis is entitled “Advances in Quantitative Methods in Vertebrate Palaeobiology: A Case Study in Horned Dinosaur Evolution”. His thesis explores the limits of several quantitative methods in paleobiological research and applies best practices to a pioneering study on centrosaurine ceratopsid evolution based on specimens collected in Dinosaur Provincial Park, Alberta. This study is the first to quantify cranial morphological variation at essentially the population-level (based on huge collections from successive mass-death bonebeds), and employ sophisticated model-fitting methods to assess evolutionary modes in dinosaurs. In the analysis, he finds strong support for morphological stasis in Centrosaurus and Styracosaurus, and finds no evidence for directional evolution in these lineages.

ABSTRACT: Discerning modes and rates of biological evolution and speciation are some of the primary objectives of evolutionary biology. Much palaeobiological work has focused on developing robust methods for testing and fitting evolutionary models to samples of fossils across a stratigraphic or temporal axis, with most analyses centering on marine invertebrates. Recent extensive sampling of dinosaur deposits now allows for testing of evolutionary modes in this clade, a first for large-bodied terrestrial vertebrates. Within dinosaur palaeobiology, the relative roles of anagenesis and cladogenesis in diversification, particularly for horned dinosaurs, are hotly debated. Due to their large sample sizes, well-documented stratigraphic positions, highly diagnostic ornamentation, and monodominant bonebeds (representing populations), centrosaurine dinosaurs from the Belly River Group of Alberta make an ideal model system for testing the predictions of these two divergent evolutionary modes. Despite this unparalleled fossil record, it (as well as most fossil records) is limited by missing data, small sample size, taphonomic biases, and stratigraphic error. In this thesis, I present case studies that attempt to quantify and better understand these limitations, and inform best practices for overcoming them. The first four chapters, utilizing data sets for crocodilians (extant archosaurs) and a model geological system (upper Belly River Group), allow for a better- constrained quantitative evolutionary analysis of the Belly River Group centrosaurines in chapter five. Correlations and time-series analyses of morphology and stratigraphic position of Centrosaurus apertus and Styracosaurus albertensis are used to test for directional trends and evolutionary model fitting. Evolutionary results are robust to multiple simulations of stratigraphic uncertainty, and overlap between the taxa depends on a single locality. Results find no support for anagenesis, and rather are consistent with taxonomic turnover due to punctuated evolutionary events or, more likely, ecological replacement due to habitat tracking.”

Congrats to Caleb on completion of his degree, and I also want to thank him for all of his help in the lab and in the field over the last four years. Caleb is moving on to the position of Elizabeth Nichols Postdoctoral Fellow  at the Royal Tyrrell Museum of Paleontology starting in December.

Congrats Nic Campione, Ph. D.

June 15, 2013
Dr. Nicolas Campione measuring hadrosaur bones in China.

Dr. Nicolas Campione measuring hadrosaur bones in China.

Congrats to Nic Campione for successfully defending his PhD thesis, which he handed in last week.  Nic’s thesis was entitled “Inferring Body Mass in Extinct Terrestrial Vertebrates and the Evolution of Body Size in a Model-Clade of Dinosaurs (Ornithopoda)” (see abstract  below).

ABSTRACT– Organismal body size correlates with almost all aspects of ecology and physiology. As a result, the ability to infer body size in the fossil record offers an opportunity to interpret extinct species within a biological, rather than simply a systematic, context. Various methods have been proposed by which to estimate body mass (the standard measure of body size) centering on two main methods: volumetric reconstructions and extant scaling models. The latter models are particularly contentious when applied to extinct terrestrial vertebrates, particularly stem-based taxa for which living relatives are difficult to constrain, such as non-avian dinosaurs and non- therapsid synapsids, resulting in the use of volumetric models that are highly influenced by researcher bias. However, criticisms of scaling models have not been tested within a comprehensive extant dataset. Based on limb measurements of 200 mammals and 47 reptiles, linear models were generated between limb measurements (length and circumference) and body mass to test the hypotheses that phylogenetic history, limb posture, and gait drive the relationship between stylopodial circumference and body mass as critics suggest. Results reject these and instead recover a highly conserved relationship that provides a robust method to estimate body mass in extinct quadrupedal tetrapods. The constrained model is then used to derive a mathematical correction that permits the body mass of bipedal taxa to be estimated from the quadrupedal-based equation. These equations thus form the empirical baseline dataset with which to assess the accuracy of mass estimates derived from volumetric reconstructions, which, although subjective, are crucial for interpreting biomechanical and physiological attributes in extinct forms. The models developed through this research provide accurate and consistent estimates of body size in terrestrial vertebrates, with important implications for generating large datasets aimed at reconstructing macroevolutionary patterns of body size in association with changing Earth systems.

Nic has already accepted a postdoctoral post at Uppsala University in Sweden, where he will be working with Drs. Ben Kear and Per Alhberg on Palaeozoic fish diversity and evolutionary dynamics- as well as dinosaur work. All of us in the lab wish him the very best in his new post!