In Depth
The holotype specimen of Scipionyx was first discovered in 1981, though it did not garner wider attention until 1993 when its existence was announced to the wider public. It would not be until 1998 however that the genus and species name Scipionyx samniticus would be created. The holotype was discovered by amateur palaeontologist Giovanni Todesco who then took the specimen home and prepared it himself. During this time and thinking that he had a primitive bird, Todesco added a tail made from polyester resin to the specimen, however when this was removed before the official naming of Scipionyx in 1998, the soft tissue remains of internal organs were discovered. It is the soft tissue impressions of the holotype that have made Scipionyx one of the most exciting dinosaur discoveries. Another fact that adds to the excitement of the Scipionyx genus is that it is the first dinosaur to be discovered and named in Italy. Scipionyx was a compsognathid dinosaur, a type of small theropod that would have been near the bottom of the predatory food chain. Because the holotype specimen of Scipionyx, and at the time of writing remains the only known specimen, is a juvenile the true adult size of the species can only be speculated. Other compsognathids however typically range between one and a half an two meters in length, with a few exceptions slightly shorter and longer than this range. Although the fossils of compsognathid dinosaurs have been recovered from all over the world, European finds of these dinosaurs are well documented. This may be because during the Mesozoic Europe was more of a chain of smaller islands rather than the mostly singular landmass that it is today, and the reduced amount of space would have better suited to smaller dinosaur types such as compsognathids (though larger theropod types such as spinosaurs, megalosaurs, allosauroids and tyrannosaurs are also known).
Another factor about the Scipionyx holotype that must be born in mind is that the body proportions of the juvenile were probably not an exact match for the adult. The snout in particular is very short on the holotype specimen, but this is a common trait seen in the juveniles of other dinosaurs. As individual Scipionyx matured, the snout would probably lengthen to be more similar to other known compsognathid genera.
As already briefly mentioned above, the remains of soft tissues have been the key area of study regarding Scipionyx. These remains include muscles, ligaments, cartilage, intestines, blood vessels, part of the respiratory system, horn sheaths and softer bone tissues. The rock within which the specimen shows a reddish stain in the rock probably from a blood rich organ like the heart or the spleen. It should be remembered that this stain was left not so much by the blood but from the iron oxide that was once suspended in the blood. This iron oxide would have been a constituent part of the haemoglobin in the blood that would have allowed oxygen to be carried in the blood stream.
One of the most revealing features of the holotype is the digestive tract. This has not been preserved in whole, but it can still be followed due to observable stomach contents and faecal matter. The stomach itself is not present, probably due to the soft tissues being dissolved by stomach acid before the tissue of the stomach could be preserved. Some stomach contents however have been preserved and these show the remains of fish and lizards, revealing the kind of animals that juvenile compsognathids ate. Due to their inherent small size, compsognathids are also widely believed to have been predators of smaller vertebrates in adult life too, possibly occasionally scavenging the carcasses of larger animals. The presence of a muscular gizzard in Scipionyx has been credited as being likely though now gastroliths were found with the holotype. It may be that gastroliths were not present because of the young age of the Scipionyx holotype, or perhaps they were simply not used at all even in adults. Some theropod dinosaurs however have been found with gastroliths, one well known example being Lourinhanosaurus from Portugal.
The respiratory system in the Scipionyx holotype is only partially preserved, but it has still been a matter of contention amongst palaeontologists. One study (Ruben et al, 1999) identified the presence of a diaphragm by a reddish colouration on the rock. In addition to this the study noted that the liver would have been of a large size, indicating that the internal arrangement was dissimilar to birds. This study concluded that the respiratory system of Scipionyx was more like that of a crocodile than a bird.
A later study however (dal Sasso & Maganuco, 2011) cast serious doubts upon the crocodilian hypothesis. They pointed out that the ‘fibrous muscle’ of the supposed diaphragm was actually a product of the fossil preparation process when the specimen was polished. They also pointed out that large livers are known in some types of birds. In addition to that it was noted the liver may have also been squashed and distorted during fossilisation to give the false impression of being larger than it truly was in life. The wider modern consensus today is that Scipionyx, like other theropod dinosaurs, were distinctly more bird-like than crocodile-like.
Further Reading
– Prima segnalazione di uno scheletro fossile di dinosauro (Theropoda, Coelurosauria) in Italia (Cretacico di Pietraroia, Benevento), - Paleocronache 1993: 7-14 - G. Leonardi & G. Teruzzi - 1993. - Scipionyx samniticus (Saurischia, Theropoda): the first Italian dinosaur - Third European Workshop on Vertebrate Paleontology, Abstract: 23 - Marco Signore & Cristiano dal Sasso - 1998. - Exceptional soft tissue preservation in a theropod dinosaur from Italy - Nature, 392: 383-387. - Marco Signore & Cristiano dal Sasso - 1998. - Scipionyx samniticus (Theropoda: Coelurosauria) and its exceptionally well preserved internal organs - Journal of Vertebrate Paleontology 18 (3): 37A - Marco Signore & Cristiano dal Sasso - 1998. - Pulmonary Function and Metabolic Physiology of Theropod Dinosaurs - Science 283 (5401): 514–516 - John A. Ruben, Cristiano Dal Sasso, Nicholas R. Geist, Willem J. Hillenius, Terry D. Jones and Marco Signore - 1999. – Scipionyx samniticus (Theropoda: Compsognathidae) from the Lower Cretaceous of Italy – Osteology, ontogenetic assessment, phylogeny, soft tissue anatomy, taphonomy and palaeobiology, - Memorie della Societ� Italiana de Scienze Naturali e del Museo Civico di Storia Naturale di Milano XXXVII(I): 1-281 - Cristiano dal Sasso & Simone Maganuco - 2011.
