Dolphin ancestors had super weird teeth: A new study on the ‘grandparents of modern dolphins’

British military intelligence revealed earlier this week that Russia has weaponized dolphins to assist in their government’s invasion of Ukraine. They appear to be trained to “counter enemy divers” who may target the country’s main military base in the Black Sea, diligently guarding the port of Sevastopol. These militarized sea mammals are hardly the only cetaceans to make international news in 2023: Millions have watched in awe as orcas have attacked and even sunk ships near Europe. It seems that, no matter where humans turn, their news cycles have been brimming with the briny antics of these hyper-intelligent animals.

Now there may be even weirder news on the marine biology front: A new paper from the scientific journal PeerJ details crucial new information about the ancient ancestors to these odontocetes, or “toothed whales.” In the process, the paper has raised provocative new questions about the forebears to modern cetaceans — and highlighted the importance of maintaining comprehensive fossil records.

The new study — authored by Dr. Jorge Velez-Juarbe, a paleontologist at the Natural History Museum of Los Angeles County’s Department of Mammalogy — analyzed fossils of three ancient odontocetes, which are completely new species to science. In the process, Velez-Juarbe learned that their teeth were very different from the smiles sported by many modern cetaceans. In a way, they are eerily similar to the teeth found in human mouths, at least in terms of diversity and not shape.

“Some of these ancient, very early dolphins still retained teeth,” Velez-Juarbe told Salon. “They were more like their ancestors’ teeth, that are more complex in terms of their shape and features.”

Just as humans can look at their own teeth and distinguish between incisors, canines and molars, “this is what we see in these early toothed whales.” The same is not true, however, for today’s odontocetes, which include dolphins, porpoises, sperm whales and orcas. This can tell us much about how these animals hunted and fed, with some perhaps using suction feeding like a vacuum on the ocean floor versus hunting prey like raptors. Olympicetus thalassodon, for example, may have switched between hunting strategies.

“In modern ones, all the teeth are the same,” Velez-Juarbe explained. “They’re like copies of one other. And they’re very, very simple. They’re usually like this kind of cone shape with very simple points. The teeth of these ancient whales, though, have many different points. The front ones have a particular shape, and as we move along the tooth line they change.”

This was not the only notable difference between ancient toothed whales and their contemporary counterparts — their nostrils were also in strange positions.

“The other one is that the nostrils are located in front of the eyes,” Velez-Juarbe pointed out. “This is more like land animals, where the nose is pointing forward. In some of the early whales, the nose is all the way on the tip of the snout. With these new fossils, the nostrils are closer to the eyes than we would expect, but they’re not above the orbit or behind the orbit, like in the living species.”

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Velez-Juarbe, who described the three fossilized species as “like the great-great grandfathers or grandparents of modern dolphins” and “one of the oldest known toothed whales, which is what we’ll call them in general,” concluded that “to me, it’s a very cool combination of features. It’s like a step in between early whales and more modern ones.”

The report includes an understated, but nonetheless pointed, criticism of the paltriness of scientific literature about North Pacific odontocetes species from the Oligocene epoch, which lasted roughly from 33.7 to 23.8 million years ago. The lack of info has left scientists in the dark about the full evolutionary story of these creatures.

Fossils that last millions of years are hard to make in the first place and especially in the ocean. While odontocetes from this period are not entirely missing from the scientific literature, Velez-Juarbe and colleagues write that they are often vaguely “identified informally as ‘non-squalodontid odontocetes’, ‘agorophiid’ or ‘Agorophius-like,'” referring to Agorophius, an extinct genus of toothed whale that lived during the Oligocene period.

“However, given their importance, most of these have yet to be properly described, and our understanding of species richness and relationships between Oligocene odontocetes from the North Pacific is not fully understood,” the authors write.

With more information about these early cetacean ancestors, researchers “can potentially advance our understanding of the origins and early diversification of odontocetes, as well as acquisition of some of their distinguishing features, such as echolocation.”

As Velez-Juarbe insisted when speaking with Salon “there is still a lot that we need to discover about the early evolution of ancient whales. One aspect of this early group I’ve been working on is we don’t know if as adults they were echolocating — if they were using bio-sonar, which is the way modern species find a way around their environments. They have some features of the skull that hint at the presence of some key elements for echolocation.”

Velez-Juarbe also stressed the urgency of preserving accurate and thorough fossil records, without which his own research would have been impossible.

“I could highlight the importance of museum collections because these fossils have been in our collections for several decades,” Velez-Juarbe told Salon. “It takes time for people to study them, and the fossils being in a museum collection ensures that someone at some point in history will be able to study them, or we will have the expertise to study them, as opposed to if the specimens were not in a collection and would be lost to humanity and lost to science. We wouldn’t be able to tell these types of stories.”