Media Releases

Small, speedy plant-eater extends knowledge of dinosaur ecosystems

May 22, 2013

TORONTO, ON – 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 palaeon­tol­o­gists 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. At approx­i­mate­ly 1.6 m (5 ft) long, it weighed about 16 kg (30 lbs) – com­pa­ra­ble to a large turkey – and 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 it like­ly used its speed to avoid pre­da­tion by the many species of meat-eat­ing dinosaurs that lived at the same time.

Caleb Brown, a PhD can­di­date in the Depart­ment of Ecol­o­gy and Evo­lu­tion­ary Biol­o­gy at the Uni­ver­si­ty of Toron­to and lead author of the study, offers some expla­na­tion for the scarci­ty of knowl­edge about small-bod­ied dinousaurs from the peri­od.

“We know from our pre­vi­ous research that there are preser­va­tion­al bias­es against the bones of these small dinosaurs, in that they are less like­ly to be pre­served than larg­er ones because they are more del­i­cate and are often destroyed before being fos­silized,” said Brown. “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.”

Alber­tadromeus was dis­cov­ered in 2009 by study co-author David Evans of the Roy­al Ontario Muse­um as part an on-going inves­ti­ga­tion with Michael Ryan of the Cleve­land Muse­um of Nat­ur­al His­to­ry into 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.

The rel­a­tive­ly poor under­stand­ing of these small dinosaurs comes from a com­bi­na­tion of the process­es relat­ed to decay and preser­va­tion, and bias­es in the way that mate­r­i­al has been col­lect­ed, with larg­er bones being eas­i­er to find and work on. 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 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.

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Note to media: Vis­it http://www.artsci.utoronto.ca/main/media-releases/small-bodied-dinosaur-study for images and the jour­nal arti­cle for the research described here.

For more infor­ma­tion, con­tact:

Caleb Mar­shall Brown
Depart­ment of Ecol­o­gy and Evo­lu­tion­ary Biol­o­gy
Uni­ver­si­ty of Toron­to
416–586-5591 ext. 2
caleb.brown@mail.utoronto.ca

David C. Evans
Depart­ment of Nat­ur­al His­to­ry, Palaeo­bi­ol­o­gy
Roy­al Ontario Muse­um
d.evans@utoronto.ca

Michael J. Ryan
Depart­ment of Ver­te­brate Pale­on­tol­ogy
Cleve­land Muse­um of Nat­ur­al His­to­ry
mryan@cmnh.org

Antho­ny P. Rus­sell
Depart­ment of Bio­log­i­cal Sci­ences
Uni­ver­si­ty of Cal­gary
arussell@ucalgary.ca

Sean Bet­tam
Com­mu­ni­ca­tions, Fac­ul­ty of Arts & Sci­ence
Uni­ver­si­ty of Toron­to
416–946-7950
s.bettam@utoronto.ca