In a new study in the Journal of Vertebrate Paleontology, analysis of the orodromine material from the Belly River Group of Canada supports the association of a partial skeleton from the upper Oldman Formation of southern Alberta to a new species, Albertadromeus syntarsus. The dinosaur is hypothesized to have lived in the late Cretaceous period, about 77 million years ago.
Identified by a partial hind leg, Albertadromeus syntarsus sports skeletal elements indicating it was a speedy runner. In fact, its name stems from its place of origin, “Alberta,” and the Greek word for runner, “dromeus.” The Greek words “syn” and “tarsus,” meaning “together” and “ankle” respectively, make up the species name and pay homage to its characteristic fusion of the distal fibula to the distal tibia. That is, its two lower leg bones are fused together, aiding speed and agility.
The bipedal runner was small-bodied, measuring only five feet long and weighing in at approximately 30 pounds. It is the smallest known herbivorous dinosaur in the ecosystem, and probably used its speed to avoid predators in the ancient coastal plains.
Albertadromeus was Canada’s smallest plant-eating dinosaur.
Due to their vulnerability to destruction by carnivores, scavengers, and weathering processes, smaller animals are less likely to fossilize. For a long time, this has impeded the study and understanding of smaller species such as Albertadromeus syntarsis. This information, though, is vital to a thorough understanding of the ancient ecosystem as a whole.
For example, according to Michael Ryan of the Cleveland Museum of Natural History, “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. 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.”
The specimen is now housed in the collection of the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta.
The study was published this year in the Journal of Vertebrate Paleontology.
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