Paleontologists at a dig site in Portugal have unearthed significant examples of some of the oldest known dinosaur embryos ever found.

The fossilized embryos were discovered in eggs of a Torvosaurus, a cousin of the T. rex that roamed the Earth during the Jurassic period about 150 million years ago. A bi-pedal, 36-foot-long beast, the Torvosaurus is thought to have been one of the largest carnivores of its time.

As it often goes with paleontological news, the Torvosaurus eggs were actually found some time ago, back in 2005 when an amateur fossil hunter on vacation stumbled across some fossilized egg shells on the ground and found an entire net of them on a cliff, but the recent publication of a paper on the eggs has given new life to the story.

Scientist report the discovery of the Torvosaurus, a genus of megalosaurid theropod, closes an important gap in the dinosaur fossil record. Prior to the discovery of the eggs, the oldest known eggs on record were from species not considered basal representatives of theropods. The eggs are so primitive that they are only comprised of one layer.

Speaking with LiveScience, Ricardo Araújo, an author of a research paper on the eggs and a doctoral candidate in paleontology at Southern Methodist University in Texas , said that while other found dinosaur embryos date back to earlier eras, the Torvosaurus embryos are the most primitive in terms of dinosaur evolutionary relationships.

"This is the first evidence for a one-layered eggshell for theropod dinosaurs ever found," Araújo said.

In addition to the age of the eggs, the fossilized embryo bones found inside are extremely rare.

"There's probably a handful of situations like this in the world," Araújo said.

An open-access copy of the research paper is published in the journal Nature.