Dinosaur eggs found in Aragón 'may contain embryos'

And they may even still have embryos inside them, say historians.

Each of the 20 or so eggs is around 20 centimetres (eight inches) in diameter, and are thought to have been laid by titanosaurus sauropods – four-legged herbivores with long necks and long tails.

Given that '20' seems to be the key number, the shock discovery – made in 2020 after 14 years of searching and a year after stumbling upon the dig – it is no surprise that the eggs were probably laid by a species known to have been 20 metres long when fully grown.

The site was initially found at the end of last year by palaeontologist and off-road athlete José Manuel Gasca when he was out training with the Club Alpino Universitario, a college-based trail-running association, through the mountains just outside Loarre in the province of Huesca, the northern part of which borders onto the Pyrénées.

At first, it was thought the dig might contain dinosaur fossils – some of the best-preserved of these have been found throughout Aragón and the province of Teruel has capitalised on the fact with its much-loved Dinópolis theme park – or perhaps, if archaeologists were really lucky, fossilised remains of eggs.

But what they found were piles of intact eggs in what they suspect is just one of four nests in the area, and which could even still contain unborn dinosaurs.

It is probably unlikely they would be able to hatch them after 68 million years, so there is virtually no chance of the dinosaurs being brought back from extinction and Aragón becoming a 21st-century Jurassic Park, but if the eggs do, indeed, contain titanosaurus embryos, palaeontologists will be able to make giant leaps forward in their research into dinosaur reproduction.

And a pre-foetal dinosaur might be the closest the modern human race ever gets to seeing a real-live one.

Dr Miguel Moreno Azanza, a palaeontologist originally from Huesca but now living in Portugal, is leading the research and says he was 'shocked' by the discovery, given that his team had been working on dinosaur eggs in Aragón for the past 14 years and 'never expected to find a nest of this magnitude' in its northernmost province.

Very little is known about dinosaur embryos, he says, so the studies could be ground-breaking.

Dr Moreno Azanza leads up an international team comprising palaeontologists from Lisbon's Universidade Nova, in the Portuguese capital, and Zaragoza University's 'Aragosaurus Group', or IUCA.

“In the pre-Pyrénéen area there are plenty of rocks with the potential to 'house' dinosaurs,” Azanza admits.

He said research into the reproduction methods of these giant prehistoric reptiles is plagued with uncertainties and with untested hypotheses, particularly about the species' preferred breeding and nesting grounds, and that the eggs uncovered would tell them whether these theories were accurate or not.

It is believed dinosaurs would seek out 'sanctuaries', or remote, sheltered areas such as caves, to lay their eggs, and that they stayed there with their hatched offspring, protecting them – unlike some species of reptile which lay eggs and then disappear, not needing to guard them while they hatch and never actually meeting their 'children'.

The photograph, taken by Zaragoza University, shows Dr Miguel Moreno Azanza and trail-runner José Manuel Gasca with one of the dinosaur eggs found in Loarre.