New discovery shows that dogs used to look more like cats

The researchers looked at fossils of 32 species of dogs that lived in North America between 40 million and 2 million years ago, paying particular attention to their elbows.

What these findings underline is that the evolutionary patterns of predators such as dogs are not necessarily informed just by the anatomical traits of their prey. When this change occurred, long-legged, grazing herbivores such as bison and deer rose in numbers, and the dog ancestors evolved to cope. “We selected the shape of the elbow because it is an established anatomical indicator of locomotor/predatory behaviour in living carnivores, as it reflects the relative range of forearm motion”, affirmed study’s lead researcher Borja Figueirido of Universidad de Málaga.

According to the study, the fossils have shown that the species at that time were small animals that would have looked more like mongooses than any dogs alive today and were well adapted to that habitat.

Christine Janis, who is a co author of the study and professor of ecology and evolutionary biology at Brown University said that this study may have a broader impact than on dogs alone.

Janis explained, “The elbow is a really good proxy for what carnivores are doing with their forelimbs, which tells their entire locomotion repertoire”. The study suggests dogs evolved as predators as a result of climate change.

It turns out old dogs – prehistoric ones, even – can learn new tricks.

Their findings indicated that as climate change was clearing out the woods of North America and grasslands were an increasingly common sight, the dogs were gradually evolving to pursuit-bound predators, leaving ambushing behind. “Although this seems logical, it hadn’t been demonstrated before”. As the animals evolved, always downward-facing limbs became more common to aid in their running ability. They found that over time, canid teeth became more durable, which reflected a shift in the prey they hunted.

The research team analyzed the joint structure of canids an animal family which includes foxes, wolves and dogs. Their forelimbs were not specialized for running, and retained the flexibility to grapple whatever meal happened to walk by. It wouldn’t have made sense, they say, to evolve more cat-like physiology until the terrain allowed for such a strategy. Its teeth became stronger, perhaps in a way to deal with the dry, tough hides or the tough grit in the plains mixed into the meat of its prey. The researchers point to climate change being behind the forerunners of dogs becoming the dogs we know today.