A new study reveals that major changes in canid morphology mirror historical climate shifts, suggesting that dogs may have evolved alongside climate change.
Many scientists believe that climate change didn’t really affect carnivores, but a new study released in the journal Nature Communications challenges this notion. According to a Forbes report, dogs have a storied evolutionary timeline that goes back at least 50 million years, and some of their most significant changes occurred alongside to major historical climate shifts.
Climate change has been shown to affect animals that eat plants, as they must adapt to changes in vegetation patterns caused by shifts in the climate. Ungulates, or hoofed mammals like horses and deer, have developed a wide range of tooth-shapes over the years to cope with the evolution of plants.
The introduction of grasslands across North America some 23 million years ago led to a shift that resulted in extremely high-crowned teeth in herbivores, helping them deal with the abrasiveness of tough grasses. According to the study’s lead author, Borja Figueirido of Universidad de Málaga, “While large herbivores are the faunal components directly impacted by vegetational change, the effect on such changes on large carnivores has been less studied.”
The study’s authors looked at the elbow joints of 139 canid specimens from various periods throughout the past 37 million years to try and connect measurable shifts in canid morphology to historical climate events. The elbow was chosen because it is a good indicator of predatory behavior and can provide insight into the way dogs used to hunt.
The study shows a stunning level of diversity between the different kinds of dogs. According to Jack Tseng, one of the study’s authors, “The range of body sizes and diets inferred from fossil dog specimens are broader than what is seen in living dog species,” adding that many specialized predators resembling cats and hyenas are now entirely extinct.
Some of the earliest canid fossils, dating back to the Oligocene period, showed that dogs used to be ambush predators. Their elbow joints allowed significant rotation so that they could pin their prey to the ground. More recent elbow fossils, however, are more rigid and offer a lower range of motion. This indicates a shift to a hunting strategy based on chasing and sprinting, rather than an catching prey off guard.
The change in hunting patterns as shown by the fossils’ elbow shapes mirrors the climatic shift that led to the expansion of grasslands in North America millions of years ago. As the environment became less icy and dense, pounce-pursuit predators became the norm. Dogs began chasing larger prey and tackling it from behind instead of hiding and waiting.
Changes in the climate over time can also be connected to changes in dogs’ teeth. The scientists tested the durability of fossilized teeth by shooting light through the specimens and analyzing the different patterns of enamel. They found that over time, canid teeth became tougher, reflecting a shift in the types of prey the animals would go after.
The study shows that dogs, similar to other animals that have been present on Earth through different climatic periods, have consistently adapted to better fit their environments.