Climate change and vegetation shifts have had a great influence on the evolution of canids, a new study suggests.
Climate and environmental change have been known to drastically affect the evolution of herbivores and inform adaptation mechanism or the extinction of some species. Yet, the same influence pattern hasn’t been studied in connection with carnivores before.
As such, professor of ecology and evolutionary biology at Brown University, Christine Janis and professor Borja Figueirido with the Universidad de Málaga, Spain, took a closer look at dog fossils dating back to as much as 40 million years in order to understand the role that climate and habitat played in their evolution.
North America’s climate was warm 40 million years ago. The land, heavily wooded, was home to predators, among which, dogs. According to the researchers, these would have looked quite different than what we know today.
Rather than the large predators that dogs are associated with, the 40 million years old fossils suggest that the dogs of the time would have looked more similar to mongooses. Given their climate and habitat, these dogs were not too agile hunters. Their limbs lacked the specialization for running and their prey would have been whatever smaller animal happened to pass by.
As the climate began to change and became much cooler in North America, so did the vegetation. Woods heeded way to open grasslands.
To understand how these climate and environmental changes affected gods, the researchers took to studying teeth and elbows coming from 32 species of dogs from 40 million years ago until 2 million years ago.
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.
“The elbow is a really good proxy for what carnivores are doing with their forelimbs, which tells their entire locomotion repertoire”,
explained Christine Janis.
The joining of the humerus and forearm is the key to unlocking these evolutionary patterns. The paws of the oldest dogs were more fit for ambush purposes, grabbing prey and pinning it to the ground. These paws could be swiveling, as is the case with the majority of cats today.
However, as the dogs evolved, their paws became increasingly downwards-facing. This indicates that they are better fit for long pursuits and running after the prey. Sturdier paws, better chances to catch their next meal.
The research team also looked at the dogs’ teeth. The enamel covering the teeth is a good indication of how strong these are and what type of prey they are fit for. As the dogs evolved and split into more species, so did their teeth. Criss-cross enamel of the teeth suggests that these are fit for stronger, sturdier foods captured outside of the woods and thoroughly gritted.
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.
Rather, they are the result of both climate and environmental change. According to the authors of the study, this could shed light on how the evolution of modern day predators could be understood in relation to anthropogenic climate change
Photo Credits: thalabeach.com.au
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