A multinational group of paleontologists has described a prehistoric lobster-like animal from the Marble Canyon site, part of the renowned Canadian Burgess Shale fossil deposit.
Yawunik kootenayi. Image credit: University of Toronto.
The newly-discovered marine creature, named Yawunik kootenayi, lived during the middle Cambrian, approximately 508 million years ago.
The species name, kootenayi, honors the Ktunaxa People, who have long inhabited the Kootenay area where the Marble Canyon locality was found.
The genus name comes from ‘Yawunik,’ a mythological figure described as a huge and fierce marine creature, killing and causing such mayhem that it triggered an epic hunt by other animals to bring the threat down.
“We wanted to acknowledge the Ktunaxa culture, and given the profile of Yawunik, it looked like a natural choice of name,” said team member Cedric Aria, a PhD candidate at the University of Toronto.
“Yawunik is a central figure in the Ktunaxa creation story, and, as such, is a vital part of Ktunaxa oral history. I am ecstatic that the research team recognizes how important our history is in our territory, and chose to honor the Ktunaxa through this amazing discovery,” added Donald Sam, Ktunaxa Nation Council Director of Traditional Knowledge and Language, who was not involved in the study.
“Yawunik kootenayi is expanding our perspective on the anatomy and predatory habits of the first arthropods, the group to which spiders and lobsters belong,” Aria said.
“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.”
Yawunik kootenayi had evolved long frontal appendages that resemble the antennae of modern beetles or shrimps, though these appendages were composed of three long claws, two of which bore opposing rows of teeth that helped the animal catch its prey.
The animal was capable of moving its frontal appendages backward and forward, spreading them out during an attack and then retracting them under its body when swimming.
Coupled with the long, sensing whip-like flagella extending from the tip of the claws, this makes the frontal appendages some of the most versatile and complex in all known arthropods.
Yawunik kootenayi. Image credit: Jean-Bernard Caron / Royal Ontario Museum.
“Unlike insects or crustaceans, Yawunik kootenayi did not possess additional appendages in the head that were specifically modified to process food,” said Aria, who is the first author of the paper published online in the journal Palaeontology.
“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 kootenayi and its relatives tell us about the condition existing before such a division of tasks among parts of the organism took place.”
“Yawunik kootenayi is the most abundant of the large new species of the Marble Canyon site, and so, as a predator, it held a key position in the food network and had an important impact on this past ecosystem,” said Dr Jean-Bernard Caron of the University of Toronto.
“This animal is therefore important for the study of Marble Canyon, and shows how the site increases the significance of the Burgess Shale in understanding the dawn of animals.”
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Cédric Aria et al. A large new leanchoiliid from the Burgess Shale and the influence of inapplicable states on stem arthropod phylogeny. Palaeontology, published online March 27, 2015; doi: 10.1111/pala.12161
