The findings suggest that sea cows have been engineering ecosystems in the Persian Gulf for tens of millions of years

Mary Randolph - Staff Contributor

December 10, 2025 7:00 a.m.

An illustration of ancient sea cows Alex Boersma

Some members of the sea cow species called dugongs spend their days feasting on seagrass in the Persian Gulf. By doing so, the bulbous marine mammals act as “ecosystem engineers,” reshaping the seafloor and digging up nutrients that help nourish the rest of the area.

It turns out that their ancient relatives performed the same vital task there 21 million years ago, according to a fossil analysis by researchers at the Smithsonian’s National Museum of Natural History (NMNH), the Qatar Museums and other institutions. Moreover, the unearthed distant cousins belong to a newfound species of extinct sea cow, *Salwasiren qatarensis, *the team reports Wednesday in the journal *PeerJ. *

“We know today that many marine mammals can have a disproportionate impact on ocean ecosystems. [But] we don’t know how long that’s been going on,” Nick Pyenson, the study’s lead author and curator of fossil marine mammals at NMNH, tells *Smithsonian magazine. *“So, this is one of the first times, I think, we can point and say, ‘Gosh, this has probably been going on for tens of millions of years.’”

The fossils came from Al Maszhabiya, a bonebed in southwestern Qatar that Pyenson calls “the world’s richest sea cow deposit.” Geologists discovered the fossil trove in the 1970s, but researchers didn’t realize the remains came from sea cows, a group that includes manatees, until the early 2000s, per NMNH’s press release.

Fossilized ribs of a 21-million-year-old sea cow in Al Maszhabiya, a bonebed in southwestern Qatar Clare Fieseler

Pyenson learned about Al Maszhabiya more recently. In 2016, study co-author Christopher Marshall, who was researching living dugongs in the region, had heard stories about the bonebed from his colleagues and encouraged Pyenson to check it out.

“To fully understand modern dugongs, you must look back to the past, understand their origins—how this region is important to the evolution of the species and the allies,” says Marshall, an ecologist at Texas A&M University at Galveston, to *Smithsonian magazine *in an email. “Only by taking on a holistic approach can the [importance] of the evolution of these ecosystem engineers be truly appreciated and understood.”

Quick fact: How are dugongs doing today?

Dugongs swim in the coastal waters of the Indian Ocean and the western Pacific Ocean. They are considered vulnerable to extinction, and their long lifespans of 70 or more years and slow reproduction rates make them particularly sensitive to human-caused disturbances.

Following several hurdles to exploring Al Maszhabiya, including the Covid-19 pandemic and the 2022 World Cup in Qatar, the researchers obtained permits to study fossils at the site in 2023. Since then, the team has found almost 200 fossil locations—a “spectacular density” compared with other areas near this trove, Pyenson says.

In the new study, researchers recovered more than 300 remains of ancient dugong relatives from at least 6 individuals from 172 locations in Al Maszhabiya, where the exposed rock layers are estimated to be about 23 million to 21.6 million years old. The fossils were found less than 10 miles away from a bay with seagrass meadows where dugongs thrive today, Pyenson says in the press release.

Additionally, the bones’ shapes and genetic analyses revealed that the fossils came from a previously unknown species. Named Salwasiren qatarensis for the nearby Bay of Salwa, the Sirenia group of sea cows and Qatar, the extinct animals may have looked like miniature versions of today’s dugongs, but with straighter snouts and smaller tusks, per the press release. The findings suggest that the region contained plenty of seagrass when the species was alive, and that many varieties of sea cows have evolved in the Persian Gulf over the past tens of millions of years.

Fossils of the newly discovered ancient sea cow species, Salwasiren qatarensis Qatar Museums, Doha, State of Qatar. Photo by James Di Loreto / Smithsonian

This “carefully constructed” research could uncover more information about the sea cows’ history, which can, in turn, help protect biodiversity today, says Erik Seiffert, a paleontologist at the University of Southern California who was not involved in the study. By munching on seagrass, the modern-day mammals contribute to the maintenance of healthy, balanced ecosystems.

“If you see a video of a dugong, it seems like they’re not doing much, and it wouldn’t matter if they go extinct,” he says. “But they do play a really important role.”

The collaboration between NMNH and the Qatar Museums is ongoing, and Pyenson says the team plans to continue studying the sea cow and other marine fossils at Al Maszhabiya. Researchers at the Qatar Museums are also planning to nominate the area as a UNESCO World Heritage Site, he adds.

“There’s so much about the natural history of the animals that live alongside us that we don’t understand, and we should because they’re part of this natural climate solution,” Pyenson says. “If we protect these marine animals, that is incredibly important to the future.”

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