Snowmass, Colorado recently became known as a fossil hotspot thanks to the fortuitous discovery of an Ice Age bonebed nearby. But mastodons and mammoths aren’t the only fossils in the area. Another, far-older discovery has just been described by paleontologists John Foster and Mathew Wedel in the Jurassic rocks just a mile from the ski town.
The bones in question – including parts of the spine and ribs – belonged to a sauropod dinosaur named Haplocanthosaurus. This is a rare dinosaur. Around 155-152 million years old, this long-necked herbivore is only known from a few isolated bones and associated skeletons, not to mention that some parts of that dinosaur’s anatomy – such as the skull – are completely unknown. Compared to other sauropod dinosaurs of the Jurassic West that are known from over 100 individuals – such as Camarasaurus and Apatosaurus – this makes any Haplocanthosaurus a lucky find.
The new Haplocanthosaurus described by Foster and Wedel is the tenth known, and adds another location to the map of where this dinosaur roamed. And the researchers had to fight hard for this one. In addition to the regular challenges of excavating and removing large jackets of rock and bone from the field, Foster and Wedel write that preparing the dinosaur in the lab was especially tough.
Fossils can have rough afterlives. In the case of this Haplocanthosaurus, the frost of the Ice Age and the growth of more modern roots cracked and fractured the bones. All of those broken parts had to be put back together again in the lab before study, a delicate osteological puzzle.
Those rescued bones are part of even bigger quandaries that surround Haplocanthosaurus and its world. A significant part of the dinosaur’s skeleton remains unknown, and Haplocanthosaurus is from a lower part of the Morrison Formation that isn’t as well-known as higher sections represented by bonebeds like Dinosaur National Monument’s Carnegie Quarry and Wyoming’s Bone Cabin Quarry. This is not so much reason for despair as inspiration to keep walking the outcrops. Despite over a century of exploration and study, the American west still holds Jurassic mysteries waiting to be uncovered.
Foster, J., Wedel, M. 2014. Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison Formation (Upper Jurassic) near Snowmass, Colorado. Volumina Jurassica. XII (2): 197-210. doi: 10.5604/17313708.1130144