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- It wouldn’t have been suited to life at sea and probably lived and hunted in freshwater, suggesting that seals made the transition from land to sea via rivers and lakes. It lived in the Arctic and 23 million years ago, this region was cool and temperate, with freshwater lakes that would have frozen over in winter.
www.nationalgeographic.com/science/article/puijila-the-walking-seal-a-beautiful-transitional-fossil
Mar 20, 2024 · A prehistoric seal that lived along an ancient shore where waves, scavengers and other processes break down a body was much less likely to be preserved in the fossil record than a marine mammal...
- Riley Black
Apr 22, 2009 · Scientists have found the first skeleton of a land-dwelling relative of seals, sea lions, and walruses. The 20-million- to 24-million-year-old Arctic fossil sports webbed feet instead of flippers, providing a long-sought glimpse of what such animals looked like before they dove into the sea.
Puijila darwini is an extinct species of stem-pinniped (seal) which lived during the Miocene about 21 to 24 million years ago. About a metre (3 feet) long, the animal had only minimal physical adaptations for swimming.
- Overview
- More on transitional fossils:
Seals and sea-lions gracefully careen through today’s oceans with the help of legs that have become wide, flat flippers. But it was not always this way. Seals evolved from carnivorous ancestors that walked on land with sturdy legs; only later did these evolve into the flippers that the family is known for. Now, a beautifully new fossil called Puijila illustrates just what such early steps in seal evolution looked like. With four legs and a long tail, it must have resembled a large otter but it was, in fact, a walking seal.
Natalia Rybczynski unearthed the new animal at Devon Island, Canada and worked out that it must have swam through the waters of the Arctic circle around 20-24 million years ago. She named it Puijila darwini after an Inuit word referring to a young seal, and some obscure biologist. The skeleton has been beautifully preserved, with over 65% of the animal intact, including its limbs and most of its skull.
Puijila is a massive boon for biologists trying to understand the evolution of pinnipeds, the group that includes seals, sea lions and walruses. It’s not itself a direct ancestor, having branched off the evolutionary path that led to modern pinnipeds. It did, however, retain many of the same features that a direct ancestor would have had. “Puijila is a transitional fossil,” Rybczynski explains. “It gives us a glimpse of what the earliest stages of pinniped evolution looked like, before pinnipeds had flippers. And it suggests that in the land-to-sea transition, pinnipeds went through a freshwater phase.”
This familiar group evolved from land-dwelling carnivores and their closest living relatives are the bears and the mustelids (otters, weasels, skunks and badgers). For other marine mammals like whales and dolphins, the fossil record has given us dramatic visuals for the gradual transformation from land-dweller to full-time swimmer. But for pinnipeds, that transition is much murkier because until now, the earliest known seal Enaliarctos already had a full set of true flippers. Puijila changes all of that.
In the Origin of theSpecies, the ever-prescient Darwin wrote, “A strictly terrestrial animal, by occasionally hunting for food in shallow water, then in streams or lakes, might at last be converted into an animal so thoroughly aquatic as to brave the open ocean”. This year, on the 150th anniversary of the book’s publication, the walking seal that bears his name pays a fitting tribute to Darwin’s insight.
Puijila was just over a metre in length and had a long tail. Its four legs were short but strong, and would have been attached to its trunk by powerful muscles. The bones of its toes were somewhat flattened, which strongly suggests that they were webbed. In many ways, its skeleton was very similar to a modern otter’s but the shape of its skull and teeth mark it out as a seal.
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PS: I guarantee that someone, somewhere will get these details wrong, so two points are worth clarifying:
Apr 22, 2009 · A fossil of a primitive "walking seal" with four legs and webbed feet has been found in the Canadian Arctic and dated to be at least 20 million years old.
May 24, 2024 · Compared to the other groups of seals, walruses have gone through huge rates of speciation and extinction, leading to a massive array of fossil walruses, including short-tusked and giant species. But today, all of that diversity is only survived by one species.
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Nov 12, 2020 · Two seal fossil discoveries are rewriting experts’ understanding of the evolution of “monachines”, a group of seal relatives comprising the two living species of monk seal, the elephant seals and Antarctic seals – what they were like, and where they evolved.
