A new study has determined that a Homo antecessor fossil that was found in northern Spain is the oldest human fossil species ever to be discovered in western Europe and dates back from 772,000 to 949,000 years ago.

After further work was conducted at the archaeological site known as unit TD6 of Atapuerca Gran Dolina, a team of scientists hailing from Spain, France, Australia and China were able to accurately date a tooth belonging to the H. antecessor fossil to determine its true age, showing it to be by far the most ancient hominin species found in this area, as Cordis report.

Scientists had previously estimated the age of the Homo antecessor fossil by analyzing the remains of fossil teeth belonging to animals as well as sediment that was found in the vicinity of where the H. antecessor had been discovered, and the new results are not that far off from the originally estimated age. It is thought that Homo antecessor is the last species of humans that Homo sapiens and neanderthalensis both had in common.

The Atapuerca cave system in Spain where H. antecessor was first spotted is an area that is rife with stone tools and fossils, and even after the 1990s scientists can count approximately 160 other fossils of humans that have also been discovered here, with scientists concluding that these almost certainly belong to Homo antecessor as well.

Remains confirmed as the oldest known species of human fossil found in Western Europe https://t.co/nOtMfQpRjb #archaeology — APANB (@APANB_AAPNB) May 28, 2018

Due to the highly advanced age of the tooth that was found, scientists were unable to use carbon dating to assess its age. Instead, they used the two-pronged method of uranium-series (U-series) dating in conjunction with electron spin resonance (ESR). ESR dating is particularly useful as it is able to accurately gauge the natural radiation that has been taken in by fossils.

Before scientists count attempt to use electron spin resonance, they first had to make certain that no uranium had been leached from the tooth to date the uranium concentration contained in it.

According to Griffith News, Professor Rainer Grün explained that dating the Homo antecessor tooth meant that scientists had to return to the site of its discovery on multiple occasions to analyze the sediment that had been found around it.

“We had to use the most advanced analytical techniques to date this tooth fragment, and had to go several times to the site in order to accurately reconstruct the sedimentary environment.”

The task of dating the tooth was such a large one that scientists from interdisciplinary fields that include geochronology, geology, archaeology, and palaeoanthropology were all called in to help, with Dr. Mathieu Duval noting that accurate dating of the H. antecessor fossil would never have been possible without so many dedicated researchers.

“We faced many challenges during this study, and without the active participation of all these specialists, it would not have been possible to obtain any meaningful and reliable result.”

The new study on the determination of the Homo antecessor fossil to be the oldest human remains in western Europe has been published in Quaternary Geochronology.