Previously unknown extinction of marine megafauna discovered

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Over two million years ago, a third of the largest marine animals like sharks, whales, sea birds and sea turtles disappeared. This previously unknown extinction event not only had a consid-erable impact on the earth's historical biodiversity but also on the functioning of ecosystems. This has been demonstrated by researchers at the University of Zurich.

The disappearance of a large part of the terrestrial megafauna such as saber-toothed cat and the mammoth during the ice age is well known. Now, researchers at the University of Zurich and the Naturkunde Museum in Berlin have shown that a similar had taken place earlier, in the oceans.

New extinction event discovered

The international team investigated fossils of marine megafauna from the Pliocene and the Pleisto-cene epochs (5.3 million to around 9,700 years BC). "We were able to show that around a third of marine megafauna disappeared about three to two million years ago. Therefore, the marine mega-faunal communities that humans inherited were already altered and functioning at a diminished diver-sity", explains lead author Dr. Catalina Pimiento, who conducted the study at the Paleontological Insti-tute and Museum of the University of Zurich.

Above all, the newly discovered event affected marine mammals, which lost 55 per cent of their diversity. As many as 43 per cent of sea turtle species were lost, along with 35 per cent of and 9 per cent of sharks. On the other hand, the following new forms of life were to develop during the subsequent Pleistocene epoch: Around a quarter of animal species, including the polar bear Ursus, the storm petrel Oceanodroma or the penguin Megadyptes, had not existed during the Pliocene. Overall, however, earlier levels of diversity could not be reached again.

Effects on functional diversity

In order to determine the consequences of this extinction, the research team concentrated on shallow coastal shelf zones, investigating the effects that the loss of entire functional entities had on coastal ecosystems. Functional entities are groups of not necessarily related, but that share similar characteristics in terms of the function they play on ecosystems. The finding: Seven functional entities were lost in coastal waters during the Pliocene.

Even though the loss of seven functional entities, and one third of the species is relatively modest, this led to an important erosion of : 17 per cent of the total diversity of ecological functions in the ecosystem disappeared and 21 per cent changed. Previously common predators vanished, while new competitors emerged and were forced to adjust. In addition, the researchers found that at the time of the extinction, coastal habitats were significantly reduced due to violent sea levels fluctuations.

Large warm-blooded marine animals are more vulnerable to global environmental changes

The researchers propose that the sudden loss of the productive coastal habitats, together with oceanographic factors such as altered sea currents, greatly contributed to these extinctions. "Our models have demonstrated that warm-blooded animals in particular were more likely to become ex-tinct. For example, species of sea cows and baleen whales, as well as the giant shark Carcharocles megalodon disappeared", explains Dr. Pimiento. "This study shows that marine megafauna were far more vulnerable to global environmental changes in the recent geological past than had previously been assumed". The researcher also points to a present-day parallel: Nowadays, large marine spe-cies such as whales or seals are also highly vulnerable to human influences.


Explore further

Prey scarcity and competition led to extinction of ancient monster shark

More information: Catalina Pimiento et al, The Pliocene marine megafauna extinction and its impact on functional diversity, Nature Ecology & Evolution (2017). DOI: 10.1038/s41559-017-0223-6
Journal information: Nature Ecology & Evolution

Citation: Previously unknown extinction of marine megafauna discovered (2017, June 26) retrieved 25 May 2019 from https://phys.org/news/2017-06-previously-unknown-extinction-marine-megafauna.html
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Jun 26, 2017
If the first humans to venture into the oceans for food started targeting marine megafauna for their obvious resources, it could have tipped the balance towards their extinction. The ecological vacuum that resulted is nothing compared to what will happen if humans were to disappear tonight.

Jun 27, 2017
If the first humans to venture into the oceans for food started targeting marine megafauna for their obvious resources, it could have tipped the balance towards their extinction.

2 million years ago? It is hard to believe those humans could have hunted whales on the sea. That requires a lot of skill and reliable technologies.

Jun 27, 2017
If the first humans to venture into the oceans for food started targeting marine megafauna for their obvious resources, it could have tipped the balance towards their extinction.

I don't think you realize how few hominids there were during that time (or even up until quite recently)..and how large the oceans are.

Also it's pretty unlikely that they had ocean going capability 2 million years ago. (The invention of harpoons are also quite recent. With the oldest findings a scant 100k years old. and they were nowhere near sophisticated enough to bring down a whale. That type of harpoon appeared about only 1000 years ago.)

Jun 27, 2017
Once you set aside the assumption of geological uniformitarianism (i.e. Charles Lyell: "the present is the key to the past"), this discovery makes perfect sense in the light of the Biblical global Flood.

Jun 27, 2017
Once you set aside the assumption of geological uniformitarianism (i.e. Charles Lyell: "the present is the key to the past"), this discovery makes perfect sense in the light of the Biblical global Flood.

Once you set aside the assumption of a biblical global flood this makes perfect sense in the light of science and rationality.

There - fixed it for ya.

Now go play somewhere else with your insane delusions.

Jun 27, 2017
Once you set aside the assumption of geological uniformitarianism (i.e. Charles Lyell: "the present is the key to the past"), this discovery makes perfect sense in the light of the Biblical global Flood.

The flood receded slowly if I remember well, so it doesn't quite fit with a marine extinction. And is it considered global?

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