Horned Baby Dinosaurs But Not a Ceratopsian in Sight!

A team of international researchers have published a new scientific paper that reports on the discovery of a beautifully preserved embryo of a dinosaur.  The fossil specimen representing a titanosaur, that lived around 80 million years ago, has permitted palaeontologists to demonstrate that these herbivores had stereoscopic vision, just like most of the carnivorous dinosaurs that would have hunted them.  Furthermore, the embryonic skull has revealed that these sauropods had small horns on the front of the face, which they later lost as they grew up.

A Close-up View of the Embryonic Titanosaur Skull

A view of the embryonic skull of the titanosaur

A close-up view showing the embryonic titanosaur articulated skull preserved inside the dinosaur egg.

Picture Credit: The University of Manchester

An Amazing Fossil Discovery

The research team, which included Dr John Nudds (Manchester University), state that this is the most complete and articulate skull known from any titanosaur, a group of temporally and geographically diverse sauropods, members of which evolved into some of the largest land animals that ever existed.  The egg fossil was discovered in southern Argentina (Patagonia) and heralds from strata laid down during the Cretaceous (Campanian faunal stage of the Late Cretaceous).

A Life Reconstruction of a Group of South American Titanosaurs

Titanosaurs illustrated.

An illustration of a group of Titanosaurs.  New study suggests that these herbivores had stereoscopic vision and the babies had a facial horn to help them break out of their egg.

Picture Credit: Marcos Paulo

It was imperative the egg was repatriated to Argentina however as it is illegal to permanently remove fossils from the country.

Commenting on the significance of the fossil discovery, Dr John Nudds (Manchester University) stated:

“The preservation of embryonic dinosaurs preserved inside their eggs is extremely rare.  Imagine the huge sauropods from Jurassic Park and consider that the tiny skulls of their babies, still inside their eggs, are just a couple of centimetres long.  We were able to reconstruct the embryonic skull prior to hatching.  The embryos possessed a specialised craniofacial anatomy that precedes the post-natal transformation of the skull in adult sauropods.  Part of the skull of these embryonic sauropods was extended into an elongated snout or horn, so that they possessed a peculiarly shaped face.”

Revising Opinions About Baby Dinosaur Anatomy

The analysis of the fossil specimen allowed the research team to revise opinions on how babies of these huge dinosaur might hatch and to test previously held ideas about sauropodomorph reproduction.  The elongated facial horn may have been used as an “egg tooth” to help the babies to break out of their eggs.

New Study Tests Ideas about Sauropodomorph Reproduction

Fragment of dinosaur eggshell (A) and the embryonic titanosaur skull (B).

Eggshell fragment (A) and the skull of the embryonic dinosaur (B).  Note scale bar = 2 cm.

Picture Credit: The University of Manchester

The paper has been published today in the academic journal “Current Biology”.  The fossilised bones of the embryo were revealed by dissolving the matrix using an acid preparation.  The researchers were able to perform a virtual dissection of the fossil material by bombarding the specimen with powerful X-rays to build up a three-dimensional image.   The European Synchrotron Radiation Facility (ESRF) at Grenoble was employed for this purpose.

Dinosaur embryology remains one of the least explored and poorly understood areas of research when it comes to the Dinosauria.   Argentina has provided palaeontologists with evidence of titanosaur nesting sites and embryos before, most famously the nest sites discovered in northern Patagonia associated with Saltasaurus loricatus that were studied by the famous Argentinian palaeontologist José Bonaparte.   Saltasaurus was named and described in 1980, the first titanosaur to be named from South America.  Since then, many more genera have been erected including Argentinosaurus, Andesaurus, Barrosasaurus, Bonatitan, Dreadnoughtus and Futalognkosaurus.

However, this is the first time a fully intact embryo has been studied.  Other fossilised eggs are also known from this site, the scientists hope to repeat their work with other specimens and are optimistic that some of the eggs might even retain the preserved remains of dinosaur skin.

The scientific paper, “Specialized Craniofacial Anatomy of a Titanosaurian Embryo from Argentina” is published in Current Biology.  The lead author on the paper is Martin Kundrat, Evolutionary Biodiversity Research Group Pavol Jozef Šafárik University.

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