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Titanosaur eggs in France

Titanosaur eggs in France | Titanosaur eggs | Resources

Titanosaur eggs

Dinosaur eggshell by the tonne
It used to be thought that dinosaur eggs were rare fossils, and when the first dinosaur nest was discovered in Mongolia in 1925 many scientists greeted the discovery with scepticism. In fact, dinosaur eggs are common where the conditions are conducive to their preservation, and we now know of South American rocks in which dinosaur eggshell is preserved by the tonne. In addition, while many experts had assumed that the Mongolian eggs were the first to be discovered, there was actually a long history of dinosaur egg discovery in a far less remote, less exotic location: France.

Dinosaur eggshell was first discovered in France in 1859 and was initially thought to have been produced by gigantic birds. By the 1870s, though, several palaeontologists had connected these eggshells with the discovery of dinosaur skeletons in the same region. Although their conclusions were largely ignored until the 1920s, it is now clear that these early experts were right. One of the richest French sites yielding dinosaur eggs is the Aude Valley, deep in the south of the country, in the foothills of the Pyrenees.

Which dinosaur laid which eggs?
Working out which kind of dinosaur laid which eggs is difficult and often based on circumstantial evidence. Large, rounded eggs such as those common in southern France are found in places where most dinosaur bones belong to sauropods, the giant long-necked herbivorous dinosaurs. More specifically, the most abundant Cretaceous sauropods were the titanosaurs, a group characterised by the presence of bony armour in their skin.

The Aude Valley sauropods
The best-known sauropod of the Aude Valley is Ampelosaurus atacis, a titanosaur named in 1995. Based on the Greek word for vineyard, the name Ampelosaurus commemorates the site where the first specimen was discovered. More than a thousand bones belonging to the species have now been discovered; and a complete, articulated skeleton was discovered in 2001. Though some titanosaurs were giants, many were only 'medium-sized' sauropods, growing to lengths of 15 metres or so. Ampelosaurus seems to have been of about this size.

Evidence that titanosaurs like Ampelosaurus laid the large, rounded eggs found in the Aude Valley comes from South America where eggs of this type have been found with titanosaur embryos inside them. Because eggshells have distinctive surface textures and cross-sectional features when examined under a microscope, experts can compare these definite titanosaur eggs with unidentified eggshell fragments from elsewhere to see if the eggshell types match. The French eggshell does match in eggshell type with the definite South American titanosaur eggs.

Nesting behaviour
Though the French titanosaur eggs don't reveal much information about the baby dinosaurs that hatched from them, the manner in which the eggs are arranged and where they are preserved do tell us some things about titanosaur nesting behaviour. Rather than being scattered randomly within the rocks, most of the French eggs are preserved in the same rock layers. This suggests that the majority of the eggs were laid at about the same time – in other words during a nesting season. Many of the eggs are arranged in large circles, so like living crocodilians and birds, titanosaurs practised some sort of nesting behaviour.

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