Discovery of New Seal Species Rewrites Evolutionary History

An artist impression of the newly discovered extinct monk seal species. Credit: Illustration by Jaime Bran.
Copyright_Museum of New Zealand Te Papa.

An international team of biologists, led by Monash University, has discovered a new species of extinct monk seal from the Southern Hemisphere – describing it as the biggest breakthrough in seal evolution in 70 years.

The discovery, published on November 11, 2020, in the Proceedings of the Royal Society, radically changes scientists’ understanding of how seal species evolved around the world.

It came after researchers examined seven preserved fossil specimens, including a complete skull, found by local fossil hunters on south Taranaki beaches in New Zealand between 2009 and 2016.

The new species is named Eomonachus belegaerensis, (meaning ‘dawn monk seal from Belegaer’) after the sea of Belegaer, which lies west of Middle Earth in J.R.R. Tolkien’s Lord of the Rings.

Around 2.5 metres in length and weighing around 200 – 250kg, Eomonachus belegaerensis lived in the waters around New Zealand some 3 million years ago.

It was previously thought that all true seals originated in the North Atlantic, with some later crossing the equator to live as far south as Antarctica.

Eomonachus now shows that many ancient seals, including the ancestors of today’s monk, elephant and Antarctic seals, actually evolved in the Southern Hemisphere.

Monash paleontologist James Rule, a PhD candidate at the Monash Biomedicine Discovery Institute (BDI), led the research as part of a trans-Tasman collaboration involving Monash University and Museums Victoria in Australia, and Te Papa and Canterbury Museum in New Zealand. The study was supervised and co-authored by Dr. Justin Adams (Monash BDI), Dr. Erich Fitzgerald (Museums Victoria), and Associate Professor Alistair Evans (School of Biological Sciences).

“This new species of extinct monk seal is the first of its kind from the Southern Hemisphere. Its discovery really turns seal evolution on its head,” Mr. Rule said.

“Until now, we thought that all true seals originated in the Northern Hemisphere, and then crossed the equator just once or twice during their entire evolutionary history. Instead, many of them appear to have evolved in the southern Pacific, and then criss-crossed the equator up to eight times.”

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