Bethesda, MD—Dinosaurs are often thought of as large, fierce animals, but new research highlights a previously overlooked diversity of small dinosaurs. In the Journal of Vertebrate Paleontology, a team of paleontologists from the University of Toronto, Royal Ontario Museum, Cleveland Museum of Natural History and University of Calgary have described a new dinosaur, the smallest plant-eating dinosaur species known from Canada. Albertadromeus syntarsus was identified from a partial hind leg, and other skeletal elements, that indicate it was a speedy runner. Approximately 1.6 m (5 ft) long, it weighed about 16 kg (30 lbs), comparable to a large turkey.
Albertadromeus lived in what is now southern Alberta in the Late Cretaceous, about 77 million years ago. Albertadromeus syntarsus means "Alberta runner with fused foot bones". Unlike its much larger ornithopod cousins, the duckbilled dinosaurs, its two fused lower leg bones would have made it a fast, agile two-legged runner. This animal is the smallest known plant-eating dinosaur in its ecosystem, and researchers hypothesize that it used its speed to avoid predation by the many species of meat-eating dinosaurs that lived at the same time.
Albertadromeus was discovered in 2009 by study co-author David Evans of the Royal Ontario Museum as part an on-going collaboration with Michael Ryan of the Cleveland Museum of Natural History to investigate the evolution of dinosaurs in the Late Cretaceous of North America. The known dinosaur diversity of this time period is dominated by large bodied plant-eating dinosaurs.
Why are so few small-bodied dinosaurs known from North America some 77 million years ago? Smaller animals are less likely to be preserved than larger ones, because their bones are more delicate and are often destroyed before being fossilized. “We know from our previous research that there are preservational biases against the bones of these small dinosaurs,” said Caleb Brown of the University of Toronto, lead author of the study. “We are now starting to uncover this hidden diversity, and although skeletons of these small ornithopods are both rare and fragmentary, our study shows that these dinosaurs were more abundant in their ecosystems than previously thought.”
The reason for our relatively poor understanding of these small dinosaurs is a combination of the taphonomic processes (those related to decay and preservation) described above, and biases in the way that material has been collected. Small skeletons are more prone to destruction by carnivores, scavengers and weathering processes, so fewer small animals are available to become fossils and smaller animals are often more difficult to find and identify than those of larger animals.
“Albertadromeus may have been close to the bottom of the dinosaur food chain but without dinosaurs like it you'd not have giants like T. rex,” said Michael Ryan. “Our understanding of the structure of dinosaur ecosystems is dependent on the fossils that have been preserved. Fragmentary, but important, specimens like that of Albertadromeus suggest that we are only beginning to understand the shape of dinosaur diversity and the structure of their communities.”
“You can imagine such small dinosaurs filling the niche of animals such as rabbits and being major, but relatively inconspicuous, members of their ecological community” said Anthony Russell of the University of Calgary.
Figure 1. Life reconstruction of the new small-bodied, plant eating dinosaur Albertadromeus syntarsus. Art by Julius T. Csotonyi.
Figure 2. Skeletal outlines illustrating both the relative size and completeness of two of the small ornithopod specimens described in the paper. Bones indicated in white are present. Human (in grey) for scale. Illustration by C. Brown.
Figure 3. Photograph and interpretive drawing of the lower jaw, as well as a complete tooth, of one of the small ornithopods described in the study. Human (in grey) for scale. Illustration by C. Brown.
Figure 4. View of the badlands of the Milk River Valley, southern Alberta, from the quarry of one of the specimens described in the study. Photo by C. Brown.
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About the Society of Vertebrate Paleontology
Founded in 1940 by thirty-four paleontologists, the Society now has more than 2,300 members representing professionals, students, artists, preparators, and others interested in VP. It is organized exclusively for educational and scientific purposes, with the object of advancing the science of vertebrate paleontology.
Journal of Vertebrate Paleontology
The Journal of Vertebrate Paleontology (JVP) is the leading journal of professional vertebrate paleontology and the flagship publication of the Society. It was founded in 1980 by Dr. Jiri Zidek and publishes contributions on all aspects of vertebrate paleontology.
For complimentary access to the full article, visit:http://www.tandfonline.com/doi/full/10.1080/02724634.2013.746229#.UZzxoMiRNQA
The article appears in the Journal of Vertebrate Paleontology 33(3) published by Taylor and Francis.
Citation: Brown CM, Evans DC, Ryan MJ, and Russell AP. 2013. New data on the diversity and abundance of small-bodied ornithopods (DINOSAURIA: ORNITHISCHIA) from the Belly River Group (Campanian) of Alberta. Journal of Vertebrate Paleontology 33(3):1-26.
Society of Vertebrate Paleontology: http://www.vertpaleo.org
AUTHOR CONTACT INFORMATION
Caleb Marshall Brown: Department of Ecology and Evolutionary Biology, University of Toronto, 25 Wilcocks Street, Toronto, Ontario, Canada M5S 3B2, 416-586-5591 x2 firstname.lastname@example.org
David C. Evans: Department of Natural History, Palaeobiology, Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario, Canada, M5S 2C6, email@example.com
Michael J. Ryan: Department of Vertebrate Paleontology, Cleveland Museum of Natural History, 1 Wade Oval Drive, University Circle, Cleveland, Ohio 44106, firstname.lastname@example.org
Anthony P. Russell: Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada, T2N 1N4, email@example.com
OTHER EXPERTS NOT DIRECTLY INVOLVED WITH THE STUDY
Dr. Paul Barrett: Department of Earth Sciences, The Natural History Museum, London.
Dr. David Eberth: Royal Tyrrell Museum, Drumheller, 403-820-6216
Dr. Allison Beck: Black Hawk College, Moline, Illinois, 309-796-5240, firstname.lastname@example.org
About the University of Toronto
Originally founded as King’s College in 1827, the University of Toronto is public research university located in Toronto, Ontario, Canada. Canada’s largest university, it is home to more than 60,000 undergraduate and 14,000 graduate students spread across three campuses. University of Toronto is the top rated research university in Canada, and has been the home of pioneering science research in insulin, stem cells and was the site of the first practical electron microscope.
About the Royal Ontario Museum (ROM)
Opened in 1914, Canada’s largest museum of natural history and world cultures has six million objects in its collections and galleries showcasing art, archaeology and natural science. Collections and research are the basis of the ROM’s international reputation. The ROM is the largest field-research institution in Canada with research and conservation activities that span the globe. At the forefront of such international projects as the Barcode of Life, the ROM originates new information towards a global understanding of historical and modern change in culture and environment. The Royal Ontario Museum is an agency of the Government of Ontario’s Ministry of Tourism, Culture and Sports. For 24-hour information in English and French, please call 416.586.8000 or visit the ROM’s web site at www.rom.on.ca
About The Cleveland Museum of Natural History
The Cleveland Museum of Natural History, incorporated in 1920, is one of the finest institutions of its kind in North America. It is noted for its collections, research, educational programs and exhibits. The collections encompass more than 5 million artifacts and specimens, and research of global significance focuses on 11 natural science disciplines. The Museum conserves biological diversity through the protection of more than 5,400 acres of natural areas. It promotes health education with local programs and distance learning that extends across the globe. Its GreenCityBlueLake Institute is a center of thought and practice for the design of green and sustainable cities.
About The University of Calgary
The University of Calgary is a public research university located in Calgary, Alberta, Canada. Founded in 1966, it consists of 14 faculties and more than 85 research institutes and centres. More than 25,000 undergraduate and 5,500 graduate students are currently enrolled. The U of C has graduated over 145,000 alumni, including the current Prime Minister of Canada, Stephen Harper, and Canadian astronaut Robert Thirsk. It is one of Canada’s top research universities (based on the number of Canada Research Chairs) and is a member of the U15 (the 15 most research-intensive universities in Canada).