A new study of American dog fossils at Brown University found that climate change and consequential shifts in habitat turned native dogs from being an ambush predator to relentless trackers and pouncers like wolves, reports NBC News.

"It's reinforcing the idea that predators may be as directly sensitive to climate and habitat as herbivores," said Christine Janis of Brown University who worked on the study, in a news release.

The study, lead by Borja Figueirdo, who is now at Spain's Universidad de Málaga, appeared in the journal Nature Communications yesterday.

Forty million years ago, much of the Central Plains of the United States had dense, extensive forest with a warmer and wetter climate. It was a biome for small predators like native wild dogs of that period that could come out of hiding and take down their prey.

Over the time, the area grew more cold and dry, and the forests thinned out giving way to vast plains in many places. This marked the evolution of herbivores, and long-legged herd animals like bison and deer proliferated. But the predators evolved with this shift in habitat too, as study determined from close inspection of the fossil records.

The all-purpose forelimbs of wild dogs evolved to provide more support and less flexibility and became specialized for long-distance running. Their teeth also became more durable in order to deal with tough, dry hides or high-plains grit mixed with the meat.

The researchers also suggested that perhaps the changes in climate and shifts in habitat induced by humans may lead to more changes in the physiology of the predator.