New whale species unearthed in fossel dig
A newly described, as-yet-unnamed, species of early baleen whale is one of several new species that was unearthed through a California Highway Dig, suggesting toothed baleen whales didn’t go extinct as long ago as thought.
The Laguna Canyon outcrop, excavated between 2000 and 2005, turned out to be a treasure trove containing hundreds of marine mammals including 30 cetacean skulls as well as an abundance of other ocean dwellers such as sharks. Among those finds, were four newly identified species of toothed baleen whale — a type of whale that scientists thought had gone extinct 5 million years earlier. Whales, the general term for the order Cetacea, comprise two suborders: Odontoceti, or toothed whales, which include echolocators like dolphins, porpoises, and killer whales; and Mysticeti, or baleen whales, the filter-feeding giants of the deep such as blue whales and humpback whales. The two suborders share a common ancestor. Mysticeti comes from the Greek for mustache, a reference to the baleen that hangs down from their jaw but the earliest baleen whales actually had teeth (although they’re still called mysticetes). Those toothy remnants still appear in modern fin whale fetuses, which start to develop teeth in the womb that are later reabsorbed before the enamel actually forms.
The new fossils date to 17 to 19 million years ago, or the early-mid Miocene epoch, making them the youngest known toothed whales. Three of the fossils belong to the genus Morawanocetus, which is familiar to paleontologists studying whale fossils from Japan, but hadn’t been seen before in California. These three, along with the fourth new species, which is of a different genus, represent the last known occurrence of aetiocetes, a family of mysticetes that coexisted with early baleen whales. Thus, they aren’t ancestral to any of the living whales, but they could represent transitional steps on the way to the toothless mysticetes.
The fourth new species—dubbed “Willy”—has its own surprises. Although modern baleen whales are giants, that’s a fairly recent development (in the last 10 million years) but Willy was considerably bigger than the three Morawanocetus fossils. Its teeth were also surprisingly worn and based on the pattern of wear as well as the other fossils found in the Laguna Canyon deposit that may be because Willy’s favorite diet may have been sharks. Modern offshore killer whales, who also enjoy a meal of sharks, tend to have similar patterns of wear in their teeth due to the sharks’ rough skin.
The new fossils are a potentially exciting find, says paleobiologist Nick Pyenson of the Smithsonian Institution’s National Museum of Natural History as although it’s not yet clear what the team has got and what the fossils will reveal about early baleen whale evolution, it will be exciting to see what they come up with. Pyenson himself is no stranger to roadcut science and the rush to preserve fossils on the brink of destruction: In 2011, he managed, within a week, to collect three-dimensional images of numerous whale fossils found by workers widening a highway running through Chile’s Atacama Desert.
The paper describing the fossils is still in preparation but the author hopes to have more data on the three Morawanocetus, at least, published by the end of the year. As for the fourth fossil it might take a bit longer as there’s still some more work to do to fully free Willy from the rock.