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Marine animals near North America, Antarctica and New Zealand are most at risk of extinction, according to a new study.

Researchers looked at fossils to examine which marine life was under the greatest threat, based on previous rates of extinction.

Animals in small geographic ranges are most at risk - with whales, dolphins and seals proving particularly vulnerable in the past.

The study was led by the University of Berkeley in California. Scientists examined extinction rates in fossils over 23 million years. They found that the tropics and Antarctica are most at risk and animals such as whales and dolphins are especially vulnerable

The study, to be published in the journal Science, was conducted by scientists at the University of Berkeley in California and other institutions.

The researchers used patterns from the fossil record to assess the natural extinction risk of animals living in the oceans today.

Comparing these patterns with areas where human activities, such as fishing, impact the oceans revealed areas that may be particularly sensitive.

These areas included regions of the tropics such as the Indo-Pacific and the Caribbean, as well as regions such as Antarctica that harbour many unique species.

'The implications of these patterns for the future of coastal marine ecosystems will depend on how natural risk and current threats interact,' said co-author Dr Paul Harnik, an assistant professor of geosciences at Franklin and Marshall College in Lancaster, Pennsylvania.

'By understanding these patterns in the past, we hope to provide a framework for understanding global change.'

The detailed study examined 2,397 fossil genera over the past 23 million years.

They found that worldwide patterns of extinction remained remarkably similar over the whole period, with the same groups of animals showing similar rates of extinction.

The researchers used patterns from the fossil record to assess the natural extinction risk of animals living in the oceans today. On the left in this image are fossil examples used, and on the right are living examples, with whales and sharks shown top and bottom respectively

The detailed study examined 2,397 fossil genera over the past 23 million years across a variety of animal groups. The team then compared the 'natural' risk of extinction, based on historic evidence, with current threats from humans and climate change

By combining this 'natural' extinction risk with threats from humans and climate change, they created a global map of future hotspots of extinction.

'Our goal was to diagnose which species are vulnerable in the modern world, using the past as a guide,' said lead author Dr Seth Finnegan, an assistant professor of integrative biology at UC Berkeley.

'We believe the past can inform the way we plan our conservation efforts.

'However, there is a lot more work that needs to be done to understand the causes underlying these patterns and their policy implications.' 

Shown are the top here are echinoids (sea urchins), and at the bottom are clams. Clams and mussels - so-called bivalves - had about one-tenth the extinction risk of mammals