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Fossils suggests dogs evolved with climate change

The long stride and the signature pounce of modern dog species wasn't practical until Earth's changing climate opened up the landscape.

By Brooks Hays
Fossils suggests dogs evolved with climate change
Dog species, such as coyotes, evolved to adapt to a changing climate and landscape. Photo by Aspen Photo/Shutterstock

PROVIDENCE, R.I., Aug. 18 (UPI) -- Climate change isn't new, it's just manmade, now. Earth's climate and has been fluctuating for millions of years. And with each shift, climate has influenced the evolution of the planet's flora and fauna.

New analysis of canine fossils suggests dogs' evolutionary path has been strongly influenced by climate change. Dog fossils across time reveal a shift in body size and morphology that follows the trajectory of a drying climate, transitioning from forests to grasslands.

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"It's reinforcing the idea that predators may be as directly sensitive to climate and habitat as herbivores," Christine Janis, professor of ecology and evolutionary biology at Brown University, said of the new findings -- published in the journal Nature Communications. "Although this seems logical, it hadn't been demonstrated before."

Researchers from Brown University and New York's American Museum of Natural History looked at North American canine fossils dating from 40 million years ago to 2 million years ago.

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At the outset, North America was warm and densely forested. But within a few million years, the planet began to cool. Precipitations totals shrunk and forests transitioned to grasslands.

Researchers say these climatic changes can be seen in canine adaptations, specifically in the changing structure of their elbows and forearms. Early dog species were quite small and not built to run. Instead their flexible forearms allowed them to seize prey in close quarters -- whatever small animal happened to be making its way through the forest.

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But as the landscape opened up, dogs were forced to cover longer distances and adopt a new approach to hunting. Their elbows and forearms -- which once promoted flexibility and produced paws capable for swiveling and ideal for wrestling -- became permanently downward and forward facing, better-suited for endurance running.

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"The elbow is a really good proxy for what carnivores are doing with their forelimbs, which tells their entire locomotion repertoire," Janis explained.

This morphological transition marks the evolution and diversification of the dog family, from one of ambushers to one of pursuit-pounce predators (foxes and coyotes) and all-day trackers (wolves).

The long stride and the signature pounce of modern dog species wasn't practical until their was open space.

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"There's no point in doing a dash and a pounce in a forest," Janis added. "They'll smack into a tree."

Janis and her colleagues are now looking into how future climate change might impact the evolution of dogs and other predators.

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