An incredibly rare dinosaur embryo discovered perfectly preserved inside its egg has shown scientists new details of the development and appearance of sauropods which lived 80 million years ago.
Sauropods were the giant herbivores made famous as being ‘veggie-saurs’ in the 1993 film Jurassic Park. The incredible new find of an intact embryo has shown for the first time that these dinosaurs had stereoscopic vision and a horn on the front of the face which was then lost in adulthood.
The international research team say that this is the most complete and articulate skull known from any titanosaur, the last surviving group of long-necked sauropods and largest land animals known to have ever existed.
The sauropod egg was discovered in Patagonia, Argentina, in an area not previously known to provide evidence of dinosaur fossils. It was imperative the egg was repatriated to Argentina however as it is illegal to permanently remove fossils from the country.
Dr John Nudds from The University of Manchester said: “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.”
The examination of the amazing specimen enabled the team to revise opinions of how babies of these giant dinosaurs may be hatched and to test previously held ideas about sauropodomorph reproduction. The elongated horn is now thought to have been used as an ‘egg tooth’ on hatching to allow babies to break through their shell.
The findings, published today in Current Biology, were the result of a novel technique to reveal embryonic dinosaurs in their shells. The embryo within the egg was revealed by carefully dissolving the egg around it using an acid preparation. The team were then able to perform a virtual dissection of the specimen at the European Synchrotron Radiation Facility (ESRF) in Grenoble.
Sauropod embryology remains one of the least explored areas of the life history of dinosaurs. The first definitive discovery of sauropod embryos came with the finding of an enormous nesting ground of titanosaurian dinosaurs discovered in Upper Cretaceous deposits of northern Patagonia, Argentina, 25 years ago. This new discovery however, is the first time a fully intact embryo has been able to be studied.
Other eggs were also found at the Argentinian site which the scientists now aim to examine in a similar fashion. It is thought that some of the eggs could contain well-preserved dinosaur skin which could help further piece together the mysteries of some of the most fascinating animals to ever walk the Earth.
Martin Kundrát, Rodolfo A. Coria, Terry W. Manning, Daniel Snitting, Luis M. Chiappe, John Nudds, Per E. Ahlberg. Specialized Craniofacial Anatomy of a Titanosaurian Embryo from Argentina. Current Biology, 2020; DOI: 10.1016/j.cub.2020.07.091