A 508 million-year-old predatory 'lobster' has been discovered in Canada that held a "key position" in the food network at the time. Yawunik kootenayi had two pairs of eyes and prominent grasping appendages resembling those seen on modern beetles or shrimps.
The animal was named after Yawunik, a mythical figure described as a huge and fierce marine creature that caused so much mayhem and death it triggered an epic hunt by other animals to bring it down.
Yawunik lived 250 million years before the first dinosaurs appeared on Earth. The fossil was discovered by researchers from the University of Toronto, the Royal Ontario Museum and Pomona College in California. It was found in the Marble Canyon site in the Canadian Burgess Shale fossil deposit.
The creature's long frontal appendages resemble the antennae of modern beetles. However, they are composed of three long claws, two of which have opposing rows of teeth that helped it catch prey.
Findings of the study suggest Yawunik was able to move its frontal appendages backwards and forwards, as well as spreading them out during an attack and retracting them under its body while swimming.
It also had a whip-like flagella that extended from the tip of the claws, making the appendages some of the most versatile and complex of all known arthropods.
Lead author Cedric Aria said: "Unlike insects or crustaceans, Yawunik did not possess additional appendages in the head that were specifically modified to process food. Evolution resulted here in a combination of adaptations onto the frontal-most appendage of this creature, maybe because such modifications were easier to acquire.
"We know that the larvae of certain crustaceans can use their antennae to both swim and gather food. But a large active predator such as a mantis shrimp has its sensory and grasping functions split up between appendages. Yawunik and its relatives tell us about the condition existing before such a division of tasks among parts of the organism took place."
The researchers note that Yawunik is the most abundant of the large new species from the Marble Canyon site. As a predator, it would have held a "key position in the food network", so having an important impact on the ecosystem at the time.
Aria said: "This creature is expanding our perspective on the anatomy and predatory habits of the first arthropods, the group to which spiders and lobsters belong.
"It has the signature features of an arthropod with its external skeleton, segmented body and jointed appendages, but lacks certain advanced traits present in groups that survived until the present day. We say that it belongs to the 'stem' of arthropods."