Spanish vertebrae point to the first Diplodocus outside North America

Fourteen tail vertebrae and several chevrons — V-shaped bones beneath the vertebrae — provide new evidence that Diplodocus lived in Europe. The remains belong to a single animal excavated at El Castellar in Spain's Teruel province. If the authors' classification holds, this will be the first record of the genus outside North America.

The fossils came from the Villar del Arzobispo Formation, in rocks from the end of the Jurassic about 150 million years ago. The material preserves only part of the tail, not a complete skeleton. Even so, the vertebral series is well preserved and represents one of the most informative diplodocid finds from Europe.

To identify the animal, Sergio Sánchez-Fenollosa and colleagues compared the anatomy of the Spanish bones with other sauropods and entered the observed characters into phylogenetic analyses. This method arranges species in evolutionary trees according to combinations of traits. Both maximum parsimony, which seeks the tree requiring the fewest changes, and Bayesian inference, which compares the probability of different trees given the data, placed the specimen within Diplodocus.

Until now, fossils accepted as Diplodocus were known only from the Morrison Formation in the western United States. Europe had already yielded other diplodocids, the broader group to which the genus belongs. The result therefore does not announce the first European relative of Diplodocus; it makes the more specific claim that the genus itself was present in an Iberian formation of similar age.

Finding the genus on opposite sides of the young proto-Atlantic supports the hypothesis of episodic faunal exchanges between North America and Europe late in the Jurassic. The find alone, however, does not reveal the route or timing of that dispersal. It adds anatomical and chronological evidence to a connection already suggested by other dinosaurs, without demonstrating a continuous land bridge.

The novelty is therefore geographic and taxonomic: a section of tail plausibly expands the known range of one of the most famous dinosaurs. The peer-reviewed conclusion remains testable. Additional bones from the same animal or comparable specimens could confirm whether the anatomical combination is unique to Diplodocus and perhaps reveal which species lived on the Iberian Peninsula.