About 21 to 24 million years ago, the High Arctic looked very different from today. The climate was cool temperate to boreal, with forests, wetlands, and freshwater lakes covering areas that are now barren polar desert. Puijila darwini lived in this environment, and it helps explain how seals and sea lions gradually transitioned from land to water.

Puijila darwini was discovered on Devon Island in Nunavut, Canada, within sediments laid down inside the Haughton impact crater, which once held a long-lasting crater lake. Fossil material was first recovered in 2007, with additional specimens found soon after, and the species was formally described in 2009. The deposits date to the late Oligocene to early Miocene, a time when many modern marine mammal lineages were beginning to emerge.

Puijila did not look like a seal. It had a long body, a flexible spine, and well-developed legs with distinct toes. Unlike modern seals, its limbs were not modified into flippers. Instead, its arms and legs were strong and fully weight-bearing, allowing it to move effectively on land. This shows that Puijila could walk and maneuver on solid ground far better than any living pinniped.

At the same time, its skeleton shows clear signs of adaptation for swimming. The proportions of its limbs and the structure of its joints indicate strong muscles capable of powerful strokes in water. Rather than using flippers, Puijila likely swam by paddling with all four limbs, like modern otters. This style of movement would have been effective in freshwater lakes, rivers, and calm coastal environments.

Puijila’s skull provides more clues about its lifestyle. Its teeth were sharp and well-suited for catching fish, pointing to a carnivorous diet focused on aquatic prey. The shape of the jaws suggests it relied on quick grasping rather than chewing, which fits a hunting strategy based on rapid captures in water.

What makes Puijila especially important is its position near the base of pinniped evolution. Early relatives of seals were fully terrestrial carnivorous mammals within the broader carnivoran group. Later pinnipeds developed flippers, reduced their ability to walk on land, and became specialized for open marine life. Puijila represents an early stage in this transition, combining strong land mobility with increasingly effective swimming ability.

Its Arctic setting is also significant. Seasonal environments with abundant freshwater, shifting shorelines, and nearby coasts likely favored animals that could exploit both land and water. Puijila was not yet committed to the sea, but it shows how a semi-aquatic lifestyle could emerge in response to these conditions.

Puijila darwini was not a seal, not an otter, and not a simple missing link. It was a distinct species adapted to a specific place and time. Its name comes from an Inuit word referring to a young seal, while the species name honors Charles Darwin.

Did You Know? Puijila darwini lacked the thick blubber layer of modern seals. Early pinnipeds likely relied on activity and habitat choice to manage body temperature before heavy insulation evolved.