Australasia’s oldest sea cow fossils change view of marine ecosystems

Image: Flickkerphotos
Source: Flickkerphotos

Media contact: Alex Dook

A gap in Australasia’s marine evolutionary record has been filled by a group of sea cow fossils recently identified by museum scientists as the oldest ever found in the region.

The 12-million-year-old fossils were discovered in a cave under the remote central highlands of New Guinea more than 30 years ago, but remained unstudied. Last year, they were rediscovered in a museum drawer by scientists from Museum Victoria and the Smithsonian Institution, who immediately found the fossils curious.

“Until now, Australasia didn’t have a particularly ancient fossil record of sea cows, the group of marine mammals that includes our living dugongs,” said Dr Erich Fitzgerald, Museum Victoria’s Senior Curator of Vertebrate Palaeontology. “The records only went back some five million years. Elsewhere in Asia, sea cow fossils are found in much older rocks, so it was always a mystery as to why the fossils hadn’t been found in this part of the world. Now, with this one discovery, we’ve more than doubled the length of their evolutionary history in Australasian seas.”

Dr Fitzgerald says the fossils provide a vital perspective on the relationship modern sea cows have with Australia’s northern marine ecosystems.

“Modern-day dugongs are major consumers of sea-grass, and, by doing so, have a tremendous impact on the structure of the ecosystem,” said Dr Fitzgerald. “They participate in a delicate balancing act: their feeding allows diversity in sea-grass and animal species that would otherwise be lacking.”

“Previously, it was thought that sea cows were fairly new arrivals in Australasia, and that their relationship with sea-grass ecosystems here was a recent event. This new evidence suggests sea cows have been an important component of Australasia’s marine ecosystems for at least 12 million years and that their role in the long-term health of these environments may be substantial.”

Museum Victoria Public Relations contact:
Alex Dook, 8341 7141 / 0478 348 880,

For all general public enquiries, contact the museum's Discovery Centre

Image Gallery

Dugong Sea cow fossil casts