About the Animal
At about 110 cm long, Puijila darwini was a medium-sized, semi-aquatic carnivore with a long, slender tail. It lived 24 to 20 million years ago, in what is now Canada's High Arctic.
One can loosely describe Puijila as having the head of a seal and the body of an otter. Indeed, many characteristics suggest that the animal is related to pinnipeds (true seals, sea lions and the walrus).
Puijila's thick neck and shoulders were very well muscled. And, the robust jaw musculature, large canine teeth and short snout suggest that the animal had a formidable bite.
Puijila has a mix of terrestrial and semi-aquatic characteristics, and represents an intermediate form in the transition from land carnivores to flippered, marine pinnipeds. For example, it had the legs of a terrestrial carnivore. However, its feet were webbed and it had an elongated, streamlined body that would have allowed it to move through the water with agility and speed. It used its fore and hind feet to swim.
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This powerful predator hunted on land and in the water, eating terrestrial and freshwater animals. What appears to be stomach contents were found with the skeleton of Puijila. An initial inspection suggests the contents may include a small rodent and a duck. Further study is underway.
Puijila lived around lakes, and probably along rivers and in coastline areas as well. Notably, at that time, the Arctic was warmer than it is today. The crater lake that preserved Puijila was surrounded by mixed deciduous and coniferous forests.
Hunting under Water
Underwater hunting offers new challenges to a land predator, even a semi-aquatic one such as Puijila. Senses that animals rely on while hunting on land—hearing, sight and smell—are much less effective under water.
In the Arctic, such challenges are even greater in winter when the region experiences 24-hour darkness. Puijila's eyes were very large, which indicates that it could see prey in low light conditions. A boost on land, this adaptation would also have helped the animal see under water.
Intriguingly, an enlarged feature (the infraorbital foramen) near the front of Puijila's face suggests that it may have had specialized whiskers to help it detect prey by touch. In seals, whiskers can be very important for foraging in water. Studies of seals have shown that the whiskers can detect and track the wake of a fish.