This is what a fossil dinosaur nest looks like!

  • Fossilised bones from two or three baby dinosaurs have been identified in samples from ‘Dragons Tomb’, a region of the Gobi Desert, Mongolia.
  • At least two eggshell fragments were also found, indicating that the specimens were part of a nest.
  • The young dinosaurs were so young that they were unable to leave the nest. When they died, they were buried quickly and preserved for millions of years.

 

The fossilised remains of these late Cretaceous dinosaur bones were removed from ‘Dragon’s Tomb’, Mongolia by fossil poachers. They sat in a private collection for an unknown amount of time, until scientists got hold of them.

Now analysis of the remains has shown them to be a dinosaur nest, complete with the remains of the youngest specimens of Saurolophus angustirostris ever found surrounded by fragments of eggshells.

Among the finds are the fossilised bones from two or three babies, and at least two eggshell fragments. The remains detail the early stages of development of this species of dinosaur, a type of giant hadrosaur.

The research is published in the open-access journal PLOS ONE

Bridging a gap in knowledge of the Saurolophus

Writing in PLOS ONE, the authors of the new study describe how the small, fragile juvenile bones can fill in some of the gaps in their knowledge about how this group of dinosaurs developed:

“The skull length of these babies is around 5% of that of the largest known S. angustirostris specimens, so they document the earliest development stages of this giant hadrosaur and bridge a large gap in our knowledge of the ontogeny of Saurolophus angustirostris,” they write.

One characteristic feature of Saurolophus had not yet developed in these young dinosaurs–the cranial crest at the top of the head, which is characteristic of this group of dinosaurs.

Other areas of the skull were not yet fused, indicating the dinosaurs’ young age.

An exceptionally well-preserved nest of baby hadrosaurs

Exceptional preservation of fragile bones suggests that the nest was buried quickly by sandy sediments that over time turned into the sandstone rock in which the fossilised remains were found.

Specimens of a baby dinosaur a member of the Saurolophus angustirostris family. The bones of the left of the photo are more decomposed than those on the right, indicating that these babies (on the left) were probably the first to die in the nest. (Photo: Dewaele et al.)

Specimens of a baby dinosaur a member of the Saurolophus angustirostris family. The bones of the left of the photo are more decomposed than those on the right, indicating that these babies (on the left) were probably the first to die in the nest. (Photo: Dewaele et al.)

“The babies were apparently already dead and partly decomposed when they were buried by sediment entrained by the river current during the wet summer season,” they write.

This places the nest near to a river, and importantly, provides the first evidence for the timing of hatching season for this group of dinosaurs:

“Coincidence of hatching and the wet summer season has widely been assumed but rarely been observed among hadrosaurids,” they write.

What’s more, they could even assume that the young dinosaurs all died within a short time of each other, indicated by “the close association of the bones of the different individuals, their similar age profiles and the similar degree of weathering,” they write. [wp-svg-icons icon=”mug” wrap=”div”]

 

Photo Credit: Dewaele et al.

 

Time for a bit more? Read on…

Looking for more reading on this topic? First off, why not try reading the original open-access scientific article.

If that is a step too far, then try the original press release form EurekAlert.

Check out the lead-scientist Leonard Dewaele’s research profile on Research Gate.

 

Dewaele, L., Tsogtbaatar, K., Barsbold, R., Garcia, G., Stein, K., Escuillié, F., & Godefroit, P. (2015). Perinatal Specimens of Saurolophus angustirostris (Dinosauria: Hadrosauridae), from the Upper Cretaceous of Mongolia PLOS ONE, 10 (10) DOI: 10.1371/journal.pone.0138806

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