Hot, dry cli­mate long kept di­nosaurs out of trop­ics: study

The China Post - - LIFE -

An un­pre­dictable, yet scorch­ing and dry cli­mate kept large, grass- eat­ing di­nosaurs out of the trop­ics for some 30 mil­lion years af­ter they first ap­peared on Earth, a study out Mon­day found.

It has been a long­stand­ing mys­tery: why did long-necked di­nosaurs seem to avoid the trop­ics when there were many dif­fer­ent types of them lived at dif­fer­ent lat­i­tudes well north and south of the equa­tor? There are fos­sil re­mains, how­ever, of meat-eat­ing dino- saurs in the trop­ics.

Sci­en­tists work­ing at a site in north­ern New Mexico worked with rocks from 215 to 205 mil­lion years ago and were able to recre­ate the cli­mate from that time, the Late Tri­as­sic Pe­riod.

They found that the trop­i­cal cli­mate var­ied greatly, but was usu­ally too hot for plants, and as such for her­bi­vores, to thrive.

The car­bon-loaded at­mos­phere had hu­mid phases and then long droughts with tem­per­a­tures of about 600 de­grees.

“Our data sug­gest it was not a fun place,” study co-au­thor Ran­dall Ir­mis of the Univer­sity of Utah said in a state­ment.

“It was a time of cli­mate ex­tremes that went back and forth un­pre­dictably. Large, warm-blooded di­nosaurian her­bi­vores weren’t able to ex­ist close to the equa­tor — there was not enough de­pend­able plant food.”

An in­ter­na­tional team of re­searchers led by geo­chemist Jes­sica White­side had their find­ings pub­lished in the jour­nal Pro­ceed­ings of the Na­tional Academy of Sciences.

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