When you watch butterflies flutter through the sky and lobsters waddle in the sea, you may not readily believe that the two far off species have anything in common. But along with spiders, butterflies and lobsters share quite an interesting collective history-one where an ancient ancestor may have emerged from the sea. Covering the ocean, the land and the skies above, the radiation of species into many forms are believed to have originated with a common ancestor as long as 508 million years ago. And in a new study published this week in the journal Paleontology researchers are finally giving a face to ancestor known as Yawunik kootenayi.
The newly identified species, Yawunik kootenayi, was a marine creature with two sets of eyes and quite an interesting set of appendages much akin to antennae, which helped the early arthropod live nearly 250 million years before the first dinosaur set foot on the Earth. The first of its species to be discovered by researchers, Yawunik was found by an international team of palaeontologists with the University of Toronto and Pomona College, at the Canadian Burgess Shale fossil deposit. And with a little fossil, researchers are now opening up a whole new lineage of relatives between modern-day species who shared the common ancestor.
"This creature is expanding our perspective on the anatomy and predatory habits of the first arthropods, the group to which spiders and lobsters belong" lead author of the study of the University of Toronto, Cédric Aria says. "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."
What's so interesting about the early arthropod?
Well, while it may not seem like a small organism, possible of fitting in the palm of your hand, could make quite an impact, Yawunik is quite unique in its appearance and anatomy. Utilizing related information from the fossil record, and evidence from the remnants recovered at the shale deposit, researchers with the study were able to use computer graphics to give the cute creature a face again. And while it may look like a fairly common sea creature, when it comes to Yawunik there is far more than meets the eye.
Evolving long frontal appendages, resembling antennae, Yawunik was equipped with three long claw appendages, two of which had rows of teeth that allowed the organism to catch its prey. And from what researchers could discern about the early aquatic environment, they were quite efficient killers indeed. Coupled with a whip-like flagella at the tip of the claws that could sense prey, Yawunik were early predators of the sea.
"Unlike insects or crustaceans, Yawunik did not possess additional appendages in the head that were specifically modified to process food," Aria says. "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."
