A three million-year-old fossil tooth found on the southwest coast of Victoria tells two stories: that truly ancient seal that lived on the Australian coastline millions of years ago, and that an uncertain future awaiting fur seals and lions the sea that lives there today.
- The seal fossil found on Victoria’s southwest coast in 1998 is about three million years old
- Scientists believe ancient seal species became extinct due to changes in sea level related to climate change
- They warned the evidence could explain how current climate change could affect current seal species
The fossil was taken off the Portland coast in 1998 and donated to the Melbourne Museum but was recently studied by a team from Monash University and Victoria Museum.
Researcher James Rule, who studies the evolution of seals, says the extinction of seals is ‘right’ or without ears can explain how rising sea levels associated with climate change will currently affect seals that now inhabit our coastlines.
Everything is in the ears
The use of the word ‘right’ to describe types of dental seals comes from two categories that broadly define different seal species.
Earless seals, or true seals, have no visible earmuffs and have smaller fins, meaning that it is more difficult for them to move on land.
The crab eater seal belongs to a group of seals called earless seals or true seals. (ABC News: Karen Barlow)
Eared seals, which fall into the category of fur seals and sea lions, have visible ears and larger fins that allow them to get around more easily.
“This true seal is not on the coast of Australia today,” Rule said.
“However, in the past, they were the only seal that was here.
“This discovery basically tells us that at a time in the past when the climate changed seals became extinct.
“After they went extinct, furry seals and sea lions colonized Australia and New Zealand from the North Pacific.”
This fossil seal tooth was found on a beach in Portland in southwestern Victoria three million years old. (Provided: James Rule)
The only other fossil that shows the seals that lived along the coastline millions of years ago was found at Beaumaris, Melbourne, and is six million years old.
The earth cools changing coastal habitats
Mr Rule said higher sea levels linked to warmer periods in Earth’s history would present ideal habitats for true seals.
He said the climate began to cool about two and a half million years ago, which means more ice is formed at the poles and sea levels are falling.
“When the sea level drops it basically removes the shallow coastal environment, this seal will be relied on for life,” Rule said.
“It will expose many rocky islands and beaches along the coast, and this environment is perfect for fur seals and sea lions.”
Australian seals love to inhabit islands and rocky beaches made of large rocks and gravel. (Provided: Phillip Island Nature Parks)
“Fur seals and sea lions can actually walk when they are on the beach and on rocks because they can bring their back fins forward to help them.
“Unfortunately … true seals can only get up and when they don’t have a flat coastal environment to reflect, they can’t go up there to rest.”
Sea level rise can see fur seals and sea lions suffer a similar fate
Rule said research on the fate of ancient seals illustrates how climate change can affect the seal population, and rising sea levels can now threaten sea lions and seal colonies in Australia.
“If the Earth continues to warm and temperatures rise, we will continue to lose polar ice like we have today,” he said.
“When sea level rises, we will lose the environment they rely on to rest, breed, and feed.”