Scipionyx
My high school calculus teacher, Mr. Surovchak, once told me about a competition he and his brother had every Thanksgiving. They would weigh themselves before and after dinner to indisputably measure who was able to eat the most. When it comes to dinosaurs, it’s typically much harder to tell what and how much they ate. However, a few fossils give us windows into the guts of dinosaurs – literally! Paleontologists are extremely thankful for spectacular fossils like that of Scipionyx samniticus, a small theropod dinosaur with several internal organs preserved!
Oil painting of Scipionyx samniticus in its Early Cretaceous environment by Emiliano Troco, used with permission. You can find more of their work on their Tumblr and contact them via their WordPress site.
Theropods, like Scipionyx, are dinosaurs that stand on two legs, usually with only three prominent toes on each hind foot. Some of the most famous dinosaurs are theropods, like Tyrannosaurus, Velociraptor, and previous Mesozoic Monthly honoree Citipati (does that make it famous? I like to think so). Most theropods interacted with the world primarily with their heads rather than their hands, hence why several of them look like they have oversized skulls and relatively underdeveloped forelimbs. Many also had hollow bones, and, as we can see in extremely well-preserved fossils, feathers. Is this all starting to sound familiar? That’s because these are also features of birds! If you’ve ever heard someone say that birds are dinosaurs, that’s because modern birds, which are called Aves or Neornithes, are just one evolutionary subset of theropod dinosaurs! Birds have all these features of theropod dinosaurs, plus others like toothless beaks and wings made partly from fused wrist and hand bones. If you are eating turkey for Thanksgiving dinner, remember that you’re eating a dinosaur!
Scipionyx didn’t look much like a turkey, though. It belonged to a group of theropods called compsognathids, which were long-tailed, slender, and relatively small predators. It wasn’t imposing size or an especially fascinating appearance that made Scipionyx special – it was the way the only known specimen was fossilized. It is so well preserved that many of its internal organs are intact in its body cavity! Petrified tissue from the trachea, small intestine, and even rectum can be seen in the fossil, as well as muscle tissue, blood vessels, and traces of other organs. We can tell from the bones and scales in its digestive tract that it ate several meals of lizards and fish before it died. There is such a wealth of biological information preserved in this single specimen, and we can learn even more when we consider its relatives. Although skin didn’t preserve in Scipionyx, at least one fossil of another compsognathid named Sinosauropteryx has such well-preserved skin and filament-like ‘protofeathers’ that we can even see pigments preserved! Based on Sinosauropteryx, we can assume that Scipionyx had some sort of filamentous or fuzzy covering as well, at least over some parts of its body.
The incredible fossil of Scipionyx preserves the dinosaur’s internal organs in 3D! For example, the sinuous shape of the small intestine is visible immediately behind the right elbow. Photo by Giovanni Dall’Orto on Wikimedia Commons. You can read more about this specimen in a paper by Dal Sasso and Maganuco (2011).
The fossil of Scipionyx is very small because the individual in question was just a hatchling when it died. Paleontologists can tell it was a hatchling, and not a small adult animal, because its proportions are similar to those of other juvenile dinosaur fossils and many of its bones had not yet fused together (you can learn more about how bones fuse as organisms get older in the Nemicolopterus edition of Mesozoic Monthly). The baby Scipionyx individual represented by the fossil would have measured around 18 inches (46 cm) long in life, and estimates based on how other compsognathids grew suggest that its species reached about 7 feet (2.1 meters) in length at adulthood. Not much is known about its habitat, but it was likely one of the largest animals around. Scipionyx was found in deposits laid down in a marine environment in what is now Italy. Back in the early part of the Cretaceous Period (the third and final division of the Mesozoic Era, or ‘Age of Dinosaurs’), when Scipionyx was alive, Italy was mostly under a shallow sea dotted with small islands, and the dinosaur would have lived on one of these. Since then, tectonic activity has dramatically changed the region, creating new mountains and lowering sea level to what it is today.
So, this Thanksgiving, if you’re looking for a conversation starter at the dinner table/family video call (or if you urgently need to divert discussion from a more sensitive topic), here’s an idea: ask your dining partners whether they think non-avian theropods like Scipionyx would have tasted more like turkey or chicken! Or, if your loved ones would rather learn than debate, you could perhaps offer to read them any of the 12 Mesozoic Monthly animal spotlights (that’s right, December makes one whole year of Mesozoic Monthly!). I’d certainly feel honored to make an appearance at your Thanksgiving feast.
Lindsay Kastroll is a volunteer and paleontology student working in the Section of Vertebrate Paleontology at Carnegie Museum of Natural History. Museum staff, volunteers, and interns are encouraged to blog about their unique experiences and knowledge gained from working at the museum.