Ancient dinosaur nursery oldest nesting site yet found

Toron­to, ON —  An exca­va­tion at a site in South Africa has unearthed the 190-mil­lion-year-old dinosaur nest­ing site of the prosauro­pod dinosaur Mas­sospondy­lus—reveal­ing sig­nif­i­cant clues about the evo­lu­tion of com­plex repro­duc­tive behav­iour in ear­ly dinosaurs. The new­ly unearthed dinosaur nest­ing ground pre­dates pre­vi­ous­ly known nest­ing sites by 100 mil­lion years, accord­ing to study authors.

A new study led by U of T Mis­sis­sauga pale­on­tol­o­gist Robert Reisz, with co-author David Evans of the Roy­al Ontario Muse­um and a group of inter­na­tion­al researchers, describes clutch­es of eggs, many with embryos, as well as tiny dinosaur foot­prints, pro­vid­ing the old­est known evi­dence that the hatch­lings remained at the nest­ing site long enough to at least dou­ble in size.

At least ten nests have been dis­cov­ered at sev­er­al lev­els at this site, each with up to 34 round eggs in tight­ly clus­tered clutch­es. The dis­tri­b­u­tion of the nests in the sed­i­ments indi­cate that these ear­ly dinosaurs returned repeat­ed­ly to this site, a behav­iour known as “nest­ing fideli­ty”, and like­ly assem­bled in groups to lay their eggs, (“colo­nial nest­ing”), the old­est known evi­dence of such behav­iour in the fos­sil record. The large size of the moth­er, at six metres in length, the small size of the eggs, about six to sev­en cen­time­tres in diam­e­ter, and the high­ly orga­nized nature of the nest sug­gest that the moth­er may have arranged them care­ful­ly after she laid them.

“The eggs, embryos, and nests come from the rocks of a near­ly ver­ti­cal road cut only 25 metres long,” says Reisz, a pro­fes­sor of biol­o­gy at U of T Mis­sis­sauga. “Even so, we found ten nests, sug­gest­ing that there are a lot more in the cliff, still cov­ered by tons of rock. We pre­dict that many more nests will be erod­ed out in time as nat­ur­al weath­er­ing process­es con­tin­ue.”

The fos­sils were found in sed­i­men­ta­ry rocks from the Ear­ly Juras­sic Peri­od in the Gold­en Gate High­lands Nation­al Park in South Africa. This site has pre­vi­ous­ly yield­ed the old­est known embryos belong­ing to Mas­sospondy­lus, a rel­a­tive of the giant, long-necked sauropods of the Juras­sic and Cre­ta­ceous peri­ods.

“Even though the fos­sil record of dinosaurs is exten­sive, we actu­al­ly have very lit­tle fos­sil infor­ma­tion about their repro­duc­tive biol­o­gy, par­tic­u­lar­ly for ear­ly dinosaurs,” says David Evans, asso­ciate cura­tor, Ver­te­brate Palaeon­tol­ogy at the Roy­al Ontario Muse­um. “This amaz­ing series of 190 mil­lion year old nests gives us the first detailed look at dinosaur repro­duc­tion ear­ly in their evo­lu­tion­ary his­to­ry, and doc­u­ments the antiq­ui­ty of nest­ing strate­gies that are only known much lat­er in the dinosaur record.”

An exhi­bi­tion cur­rent­ly on dis­play at the Roy­al Ontario Muse­um (ROM) until May 2012, Dinosaurs Eggs and Babies: Remark­able Fos­sils from South Africa fea­tures the old­est fos­silized dinosaur eggs with embryos ever found, as well as oth­er impres­sive dis­cov­er­ies

The study, co-authored by Drs. Hans-Dieter Sues (Smith­son­ian Insti­tute, USA), Eric Roberts (James Cook Uni­ver­si­ty, Aus­tralia), and Adam Yates (Uni­ver­si­ty of the Wit­wa­ter­srand, South Africa), is pub­lished in the Pro­ceed­ings of the Nation­al Acad­e­my of Sci­ences.

*Interviews/ images avail­able

Fore more infor­ma­tion, please con­tact: