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