Researchers have discovered rare dinosaur eggshells left abandoned by huge meat-eating animals that roamed a vast floodplain about 150 million years ago in Portugal.
Many of the eggshells, which belonged to two Jurassic-Era theropods, or a group of carnivorous dinosaurs, once harboured embryos of Torvosaurus, the largest predator of its day.
"It was the equivalent of the T-rex in the Cretaceous," said study co-author Vasco Ribeiro, a paleontologist at the Universidade Nova de Lisboa in Portugal.
Ribeiro and his colleagues aren't sure how the eggs came to be abandoned, 'LiveScience' reported.
Since the dinosaur eggs are so delicate, they are a relatively rare find, researchers said.
Researchers found the eggshell fragments at two separate sites, both of which were part of the Lourinha Formation, a geological formation known for its rich Jurassic dinosaur nest sites.
The eggshells were shattered and there was no trace of the dinosaur embryos that once coiled inside. However, by analysing the size, shape and texture of eggshells, the team was able to deduce which animals left those eggs so long ago.
The shells found at one site came from spherical eggs that were about 15 centimetres in diameter.
They likely belonged to a Torvosaurus, a massive, bipedal dinosaur that grew up to 11 meters tall.
The eggs at the other site were harder to identify.
Researchers believe the eggs may have contained embryos of Lourinhanosaurus antunesi, a theropod that was about 4.5 metre long when full-grown.
When intact, the eggs from that site would have been about 13 cm along the long axis and 9 cm along the short axis.
Researchers don't know exactly how the eggs came to be abandoned.