Daniel DvorkinBrought out from a discussion elsenet: would Earth now be warm enough to support large, #nonavian #dinosaurs today? This is a fair question, because as bad as global warming is—and it's going to get worse—we're still nowhere near the hottest times of the #Mesozoic.
The answer is, it was *generally* warmer than the present day, but #global #temperatures went up and down considerably, as you'd expect over such a long stretch of time—about 175 million years from the first dinosaurs to the #Chicxulub impact. Dinosaurs as a #clade did fine the whole way through, although of course with plenty of various groups dying out in the meantime.
Also, the planet has always had warmer and cooler regions. Many large dinosaurs lived comfortably in polar regions that had #climates comparable to the cooler parts of the temperate zones today. The idea that non-avian dinosaurs exclusively inhabited steaming jungles or baking deserts has been embedded by generations of paleoart, but it's just wrong. If the impact hadn't happened, they'd still be thriving.
That being said, #sauropods in particular seemed to prefer warmer environments, so their range might be a lot more limited now than it was then, and it's possible the ice age(s) would have finished them off. Other famous giants like #tyrannosaurs, #ceratopsians, and #hadrosaurs would still be widespread, and smaller ones like #dromaeosaurs ("raptors") would be as numerous as coyotes and wildcats are in our world.
Twarda
Carson Hill
John Conway