Newly discovered fossil revealed as the mother of modern-day molluscs

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The Independent Online

It looks like something out of a Salvador Dali dreamscape but this bizarre sea creature, which lived about 500 million years ago, turns out to have been the mother of all squids – indeed it is the ancestor of octopuses, cuttlefish and all other cephalopod molluscs.

Scientists discovered the creature, named Nectocaris pteryx, after studying samples of fossilised rocks from the famous Burgess Shale of Canada, which provides a remarkably preserved snapshot of the weird and immensely diverse forms of life that evolved during the Cambrian period of geological history.

Nectocaris, which grew to a length of about 5cm, including its two front tentacles, is thought to have been a fast-moving predator which swam using its undulating, wing-like fins.

But crucially it could also shoot a jet of water from a funnel-like nozzle which it could swivel in various directions – a hallmark of modern-day cephalopods.

The researchers believe that this key anatomical detail, discovered by analysing 91 newly discovered fossils of Nectocaris, strongly suggests that it must be the original common ancestor of squids, octopuses and the beautiful chambered-shelled nautilus; the reason is that no other group of animals uses this form of jet propulsion.

"Our discovery allows us to push back the origin of cephalopods by at least 30 million years, to the famous Cambrian explosion about a half-billion years ago," said Jean-Bernard Caron of the Royal Ontario Museum in Toronto.

"Soft tissues of cephalopods tend to decay quickly, so it was difficult to know what primitive cephalopods looked like. The Burgess Shale is well known for its exceptional preservation of soft-bodied animals," Professor Caron said.

Until 500 million years ago, most life on Earth took the form of simple, single-celled micro-organisms. But during the Cambrian period it exploded into a huge variety of macroscopic, multicellular forms, with a diverse range of body architecture; some of these life forms gave rise to the major groups of animals alive today.

The cephalopods – the word means "head-feet" – are the most intelligent of the invertebrates, animals without backbones.

They have large brains, good vision and can use camouflage to hide from predators or ambush their prey. Despite the fascination they generate, scientists had been unsure of their origins, believing that they had evolved from snail-like molluscs with shells that became filled with gas to allow them to swim freely.

However, the latest study, published in the journal Nature, suggests that all cephalopods can now be traced back to Nectocaris, which shares the ability to hunt its prey using its two stalked eyes and a sophisticated system of jet propulsion, said Martin Smith of the University of Toronto.

"It's long been thought that cephalopods evolved in the late Cambrian period, when gradual modifications to the shells of creeping, snail-like animals made them able to float. Nectocaris shows us that the first cephalopods actually started swimming without the aid of gas-filled shells," Dr Smith said.

"Modern cephalopods are very complex, with intricate organs and startling intelligence.

"We go from very simple pre-Cambrian life forms to something as complex as a cephalopod in the geological blink of an eye, which illustrates just how quickly evolution can produce complexity," he said.

"We think that this extremely rare creature is an early ancestor of squids, octopuses and other cephalopods. This is significant because it means that primitive cephalopods were around much earlier than we thought, and offers a reinterpretation of the long-held origins of this important groups of marine animals.

"Our findings mean that cephalopods originated 30 million years earlier than we thought, and much closer to the first appearance of complex animals in the Cambrian explosion," he added.

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