520-million-year-old trilobite fossil discovered in western Spain

A paleontological expedition from several Spanish universities to the La Rinconada de la Sierra area, near the western Spanish city of Salamanca, has found what could be the oldest trilobite fossil so far unearthed.

Spanish palaeontologists have found what could be the oldest 
trilobite fossil unearthed to date [Credit: EFE]

The 520-million-year-old fossil of the ancient undersea crustacean was found thanks to the work of several geologists, including paleontologist Eladio Griñan, of the University of Zaragoza, and Rodolfo Gozalo, a geology professor at the University of Valancia, who explained to EFE the relevance of the discovery.

This type of trilobite – arthropods that lived on the ocean bottom during the Paleozoic Era – so far has only been found in Siberia, Morocco and along the U.S.-Mexican border.

The find was made several weeks ago as part of a research project in which paleontologists are working as part of a UNESCO team to redefine the so-called Cambrian Period, a geological age lasting from between 570 million and 500 million years ago.

The so-called Sierra de Francia is one of the two most favorable areas for research into this geologic period, given that it contains mountainsides that have eroded, exposing ancient rocks and strata where fossils several hundred million years old can readily be found.

The paleontological team examined a highway cut made more than a decade ago and decided to undertake a series of more intensive diggings into certain exposed rock layers at the site, located about 1.3 miles from La Rinconada, to see what they might find.

"After an entire day of poking around, we discovered the fossil some 520 million years old," said Gozalo.

Although many trilobite fossiles have been found worldwide, there is only one other example of this particularly ancient species, tentatively dubbed Lunagraulos Tamamensis, said Gozalo, and it is currently being held at the University of Zaragoza Museum awaiting further study.

Source: EFE [June 30, 2015]