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MADRID (Euronews) – A new study led by paleontologists from the Royal Ontario Museum (ROM) is helping to resolve the evolution of Odaraia, a burrito-shaped Cambrian marine animal that was one of the first animals to have jaws.
Paleontologists can finally classify it as a mandible, ending its long and mysterious classification within arthropods since it was first discovered in the Burgess Shale formation more than 100 years ago and revealing more about its early evolution and diversification.
The research was published in the journal Proceedings of the Royal Society B: Biological Sciences.
The authors of the study were able to identify a pair of large appendages with serrated edges near the mouth, which clearly indicated that it had jaws, one of the key and distinctive features of the group of jawed animals.
This suggests that the 500-million-year-old Odaraia was one of the earliest known members of the group. The researchers also made another surprising discovery: A detailed analysis of its more than 30 pairs of legs revealed a complex system of spines, large and small. These spines could have been used to entangle and capture smaller prey like a fishing net, suggesting that some of these early jawed animals left the seafloor and explored the water, laying the foundation for their future ecological success, the authors say.
“Odalaya’s head shield surrounded almost half of its body, including its legs, almost as if it were enclosed in a tube. Previous researchers have suggested that this shape allowed Odalaya to capture its prey, but the capture mechanism was unknown to us until now,” said lead author Alejandro Izquierdo-López, who worked at the ROM as a doctoral student at the University of Toronto during this work, in a statement.
“Odalaia was brilliantly described in the 1980s, but given the limited number of fossils and their odd shape, two important questions were left unanswered: Is it really a mandible? And what did it feed on?”
The authors explain that the first jaws like Odaraia, which measured nearly 20 centimeters in size, were part of large communities of animals that were likely able to migrate from the bottom-marine ecosystems that characterized the Cambrian to the upper layers of the water column. These types of communities could enrich the water column and facilitate the transition to more complex ecosystems.
Cambrian fossils record the greatest divergence of animal groups, originating more than 500 million years ago. This period saw the evolution of numerous innovations, such as eyes, legs or shells, and the first diversification of many animal groups, including the jaws, one of the main groups of arthropods (animals with articulated limbs).
Mandibles are an example of evolutionary success, as they represent more than half of all species alive today on Earth. Today, mandibles are found everywhere: from crabs living in the sea to centipedes lurking in the bush to bees flying across the grasslands, but their origins were more humble. During the Cambrian period, the earliest mandibles were marine animals, most with distinctive cranial shields or shells.
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