Bird-like di­nosaurs hatched eggs like chick­ens: Study

Kuwait Times - - HEALTH & SCIENCE -

Feath­ered di­nosaurs that walked on two legs and had par­rot­like beaks shared an­other char­ac­ter­is­tic with mod­ern birds they brooded clutches of eggs at a tem­per­a­ture sim­i­lar to chick­ens, a study showed Wed­nes­day. Ostrich-sized ovi­rap­tors, an­ces­tors to birds, sat on their eggs to in­cu­bate them at 35 to 40 de­grees Cel­sius — a range com­pa­ra­ble with mod­ern hens, re­searchers re­ported in the jour­nal Pa­le­on­tol­ogy.

A team from China and France mea­sured oxy­gen atoms from the shells and em­bryo bones of seven ovi­rap­tor eggs from the Up­per Cre­ta­ceous pe­riod some 100 to 66 mil­lion years ago. The anal­y­sis re­vealed the tem­per­a­ture at which the em­bryo was form­ing dur­ing its in­cu­ba­tion, ex­plained study coau­thor Ro­main Amiot, a pa­le­on­tol­o­gist at France’s CNRS re­search in­sti­tute. Amiot and a team used the eggs of ovi­rap­tors be­cause they are known to have been egg brood­ers. Sev­eral fos­silised adult ovi­rap­tors have been found in a brood­ing pos­ture on clutches of eggs.

In fact, this is how the crea­ture got its Latin name-un­fairly-of ovi­rap­tosaur, mean­ing “egg thief lizard”. The first spec­i­men was dis­cov­ered in 1924 on top of a nest full of eggs, lead­ing pa­le­on­tol­o­gists to as­sume the crea­ture was eat­ing them when it died. But later finds re­vealed the eggs in fact con­tained baby ovi­rap­tors, mean­ing that the lurk­ing lizard was not a preda­tor but a car­ing par­ent tend­ing its nest.

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Whether di­nosaurs were war­mor cold-blooded has been a long­stand­ing sci­en­tific rid­dle. In 2015, a study sug­gested they were nei­ther, but some­thing in-be­tween. Di­nosaurs were prob­a­bly able to pro­duce in­ter­nal heat and raise their body tem­per­a­ture, but not main­tain it at a con­sis­tently high level as mod­ern warm-blooded an­i­mals do, it said. Rais­ing their body tem­per­a­ture above the am­bi­ent range would have al­lowed di­nosaurs to with­stand cold cli­mates at high lat­i­tudes-like pen­guins hatch­ing their eggs in freez­ing con­di­tions.

The lat­est study sug­gests that ovi­rap­tors “had a body tem­per­a­ture at least as high as the in­cu­ba­tion tem­per­a­ture” of the eggs an­a­lyzed, said Amiot. Ac­tive brood­ing would al­most cer­tainly not have been a uni­ver­sal di­nosaur egg-hatch­ing strat­egy, he added. “It is hard to imag­ine a diplodocus sit­ting on its clutch... with­out break­ing its eggs or de­stroy­ing the nest,” Amiot said. Some 30 me­ters long and weigh­ing more than 10 tons, Diplodocus was one of the largest an­i­mals ever to walk the Earth.

Fos­sil ev­i­dence has shown that some di­nosaurs warmed their eggs by bury­ing them, while oth­ers put theirs in nests of veg­e­ta­tion that gave off heat as it de­cayed.—AFP

CHINA: This handout im­age shows de­tail on an Ovi­rap­torosaur di­nosaur’s clutch of eggs from the Up­per Cre­ta­ceous pe­riod, re­cov­ered from Jiangxi in China.—AFP

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