1.85" Fossil Ankylosaur/Nodosaur Armor Spike - Judith River Formation

In 2014, the most complete ankylosaur to be found within the Judith River Formation was discovered accidentally when excavating a potential gorgosaurus. This ankylosaur (described as Zuul crurivastator) was found slightly disarticulated, but mummified and nearly complete. The preservation of this Ankylosaur included extremely rare soft tissue and in situ skin impressions. This discovery provided an excellent reference skeleton for other fragmentary ankylosaur specimens, as well as some insight into the epidermal anatomy of ankylosaurids.



Ankylosaurs were herbivorous dinosaurs that lived during the Cretaceous and evolved complete body armor covered in plates, scutes, and spikes. They wielded a massive tail club which could have been used to defensive purposes against predators such as Tyrannosaurs. Adult Ankylosaurs are believed to have reached up to 25 feet in length.

The Judith River Formation is one of the world's most prolific sources of Late Cretaceous vertebrate fossils. At least sixteen Orders containing more than forty Genera are known from the formation. These include fish, amphibians, mammals, and insects in addition to reptiles and avian (birds) and non-avian dinosaurs. Among the more interesting specimens is Leonardo, a mummified and fossilized Brachylophosaurus. This is a hadrosaur, a duck-billed dinosaur found with amazing soft-tissue preservation: skin impressions can be found on 90 percent of its body! The pattern in the skin on its feet is even preserved. In addition to Leonardo, the Judith River Formation contains the remains of the theropod Hesperornis, the only known freshwater Hespernorthid, a penguin-like bird.