World's longest sauropod trackway exposed

by Mary Caperton Morton
Friday, February 23, 2018

Artist's rendition of the sauropod that made the tracks at Plagne. Credit: drawing: A. Bénéteau; photo: Dinojura.

A sauropod trackway found in 2009 in the French village of Plagne extends for more than 155 meters. Credit: P. Dumas.

Excavations at a dinosaur trackway found in 2009 in the French village of Plagne, 200 kilometers east of Lyon, revealed 110 sauropod footprints spanning a distance of 155 meters, making the site the world’s longest sauropod trackway. In a new study published in the journal Geobios, researchers report that the tracks were made roughly 150 million years ago and that the largest tracks measure more than a meter across. Analysis of the trackway suggested the prints were left by an animal at least 35 meters long and weighing more than 35 tons, that traveled about 4 kilometers per hour with an average stride of 2.8 meters. The prints were assigned to a new ichnospecies — a species only known from trace fossils — named Brontopodus plagnensis.

During the Late Jurassic, what is now eastern France was covered by a warm shallow sea dotted with low islands sprouting enough vegetation to support large herbivores and the carnivores that hunted them. The Plagne trackway, discovered on a limestone shelf deposited in the shallow sea, may have represented a mudflat. In addition to the sauropod tracks, the research team, led by Jean-Michel Mazin of the Pterosaur Beach Museum in Crayssac, France, also identified 18 three-toed tracks attributed to a large carnivorous theropod from the Megalosauripus ichnogenus.

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