Diplodocus belongs to the iconic group of long-necked dinosaurs called the Sauropods. These massive creatures once lived on six continents, powering their massive bodies with their herbivorous diet. Discovered in 1877 amidst the Bone Wars, Diplodocus was at the time the longest dinosaur yet discovered, setting off a race as collectors sought out a specimen for their own. Steel baron Andrew Carnegie set his sights on a Diplodocus of his own for the Carnegie Museum of Natural History, sending teams of paleontologist into the field to assemble Dippy, the Diplodocus carnegie holotype.

This specimen is a beautiful fossil with a section of Diplodocus fossil skin material. It was discovered in the Morrison Formation, dating to the Jurassic Period around 149 million years ago.

When we think of dinosaur fossils we usually imagine bones and teeth, but fossilized skin and scales have also been discovered along with feathers. Scales are rigid plates which grow out of the skin and afford protection. They occur in many animals including birds, reptiles, fish, mammals, and even butterflies and moths. In dinosaurs, scales occur in many different sizes with varied arrangements. The function of scales, aside from what we know from scales in other animals, is still under investigation as is the complex relationship to the development of feathers.

Preservation of dinosaur skin and other soft tissues requires a combination of many factors including sedimentation and the presence of microbial mats. This delicate arrangement creates certain challenges for paleontologists when recovering skin. Early methods of extraction often bypassed these delicate structures entirely, but new methods are yielding surprising discoveries including the extraction of connective tissue and intact cellular structures.

With a long, whip-like tail, Diplodocus was one of the longest dinosaurs, stretching out to 33m (110ft) from head to tail. This genus, native to western North America of the Late Jurassic, consists of at least two species: D. carnegii, which reached 80 feet and perhaps more, and D. hallorum. Paleontologists continue to debate whether Diplodocus held its neck in a more horizontal or vertical position, though recent modeling suggests it and other diplodocids may have had more mobile necks, both laterally and dorsoventrally, than other sauropods. 

Multiple sauropod species shared habitats, and variations in their dentition and other physical traits likely allowed them to minimize competition by focusing on different herbivorous lifestyles (niche partitioning). For example, Apatosaurus (a fellow diplodocid) and Camarasaurus (a macronarian), both of which rubbed shoulders with Diplodocus, are thought to have fed on tougher plant material, such as conifers, than Diplodocus, which may have preferred ferns, horsetails, and other comparatively soft vegetation.

It’s long been speculated that Diplodocus and its relatives could browse higher in the forest canopy by adopting a “tripod” posture, rearing on their hindlegs and bracing themselves against the ground with their tails. A 2017 study suggested Diplodocus may have been able to strip branches at a maximum height of about 36 feet in such a pose, and speculated that diplodocids may have been generalist herbivores, bridging the ground and high-browsing lifestyles into which sauropods have often been ecologically divided.