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A sauropod dinosaur has been named as a new species nearly 80 years after it was first discovered in a remote Colombian mountain range.

A half-metre-long vertebra of the dinosaur was dug up by a geologist working for an oil company in the northern Colombian state of Cesar in 1943. It has been stored at the University of California, Berkeley, ever since.

It was preliminarily described in 1955 as a sauropod, part of the group of long-necked herbivorous dinosaurs that includes Diplodocus and Brontosaurus. But little more was known about the specimen as the isolated mountains where it was uncovered were dominated by armed guerrilla groups.

The demobilisation of the Revolutionary Armed Forces of Colombia (FARC), following a 2016 peace agreement, opened the way for at the University of Michigan and his colleagues to return to the site.

Comparing sediment on the fossil in California with sediment at the location near the Venezuelan border where the fossil was uncovered confirmed the precise rock layer it was recovered from. This allowed the researchers to date it to 175 million years ago.

They named the species Perijasaurus lapaz after the mountain range of Serranía del Perijá in which it was discovered and the Spanish word for “peace” as a tribute to the historic peace agreement.

It is the northernmost sauropod specimen ever found and the only one from the early Jurassic period, when some of the first sauropods roamed Earth, to be found in South America outside of Argentina.

“Most of what we know about South America for almost the entirety of the dinosaur era is from the Southern Cone of the continent,” says Wilson Mantilla.

Perijasaurus lapaz is similar to other sauropods of this period found in Asia, northern Africa and southern Patagonia, which were smaller than later dinosaurs from this group. It would have been around 12 metres long, half the size of the gargantuan Diplodocus, but shared the iconic lofty neck, barrel-shaped body and small head. Only minor changes in the architecture of the bony struts on the vertebrae differentiated it from other contemporary species.

While dinosaurs such as Brachiosaurus, which lived around 150 million years ago, have entirely hollow vertebrae, in Perijasaurus only the upper part wasn’t solid, suggesting the evolution of hollow bones was just beginning.

According to the researchers’ calculations, the hollowing shaved off 20 per cent of the weight of the vertebral column in Perijasaurus, while those of later species were 70 per cent lighter.

As in modern birds, reducing the weight of the skeleton in certain areas would have made it lighter but also more robust by reducing load. “It’s very much like the way a bike frame is structurally sound but light by virtue of being hollow,” says Wilson Mantilla.

Mapping the progression of the bone hollowing and other skeletal traits suggests Perijasaurus and other sauropods of this period are precursors to dinosaurs such as Brachiosaurus and Brontosaurus that evolved elsewhere after the supercontinent Pangaea began fragmenting.

“Our hypothesis is that Perijasaurus and species from Africa and India are part of the stem that lead to this great radiation of sauropods that have exaggerated this trait,” says Wilson Mantilla.