Scientists discovered the fossils of the oldest arthropod with a mandible — a 508 million year old marine animal.
Tokummia katalepsis was first discovered in Burgess shale of Kootenay National Park in British Columbia, Canada. This arthropod was identified as a four-inch long predator from the late Cambrian period.
Tokummia walking on the bottom of the seafloor.
The lobster-like animal had fifty legs, a bivalve shell, and most strikingly, jagged mandibles. Tokummia katalepsis is officially the oldest creature with mandibles to date. Two tiny eyes at the base of its antennae complete its unusual portrait.
Mandibulata, which include all animals with mandibles, is the most diverse and plentiful group of arthropods in the world, and retracing their evolutionary history has been one of biology’s greatest challenges.
Animals with mandibles include myriapods ad pancrustaceans such as lobster and shrimp. Evidence shows that Tokummia evolved after spiders and mites (chelicherata) broke off into their own evolutionary branch.
The fossils uncovered in Kootenay National Park serve to prove that Tokummia is at the base of the evolutionary tree of all mandibulates.
In addition to being the ancestors of all mandibulata, the unique fossils have given scientists rare insight into how these animals functioned physiologically. Attributing researcher Cédric Aria stated to Live Science about its fifty limbs, “it allowed for the development of additional segments and structures at and around the base of the limb, called ‘coxae,’ and from which the mandibles themselves likely [arose].”
The full account is published in the journal Nature.
