image: Section through the mouthparts of the euthycarcinoid Heterocrania rhyniensis from the Devonian Period in Scotland. This image was taken with a confocal laser scanning microscope. The field of view is about 3 mm wide in the actual fossil. view more
Credit: Image credit: Tomasz Góral and Christine Strullu-Derrien
Researchers report fossils that extend and clarify the evolutionary history of myriapods, the group containing millipedes and centipedes. The evolutionary history of arthropods, including insects and arachnids, is thought to originate in an aquatic environment based on marine fossils from the Cambrian Period and molecular dating, but fossils of insect or myriapod ancestors in aquatic environments have not been found. Gregory D. Edgecombe and colleagues examined fossils from Scotland of a group called the euthycarcinoids, a putative relative of myriapods. Details of the head structure of the euthycarcinoid, which dates to the Devonian Period, were similar to those in living myriapods, suggesting that myriapods may be the closest relatives to euthycarcinoids. Euthycarcinoids extend back to the Cambrian Period, providing an early aquatic ancestor to land-dwelling modern arthropods. Fossilized tracks and other traces of euthycarcinoids included tracks on tidal flats, suggesting a transition from marine to terrestrial environments, where most current diversity in arthropods is found. According to the authors, the results help reconcile the molecular and fossil evolutionary record for myriapods and provide a clarified picture of the process by which this group transitioned from water to land.
Article #19-20733: "Aquatic stem group myriapods close a gap between molecular divergence dates and the terrestrial fossil record," by Gregory D. Edgecombe et al.
MEDIA CONTACT: Gregory D. Edgecombe, The Natural History Museum, London, UNITED KINGDOM; tel: +44 20 7942 6464; e-mail: g.edgecombe@nhm.ac.uk
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Journal
Proceedings of the National Academy of Sciences