Big John

Big John is a fossilized Triceratops horridus skeleton discovered in South Dakota's Hell Creek geological formation in 2014. It is the largest known Triceratops skeleton, according to the team that assembled the fossil. Big John's 2021 auction price of €6.6 million (US$7.7 million) made it the most expensive Triceratops skeleton; its high price signaled increasing demand for dinosaur fossils among private collectors and prompted discussion about the drawbacks of private fossil ownership for scientific research. Discovery and description The skeleton is roughly 66 million years old, and was discovered in May 2014 by paleontologist and professional fossil hunter Walter W. Stein. The fossil was located on a private ranch in Mud Butte, South Dakota, part of the Hell Creek geological formation. After only "10–15 minutes of searching" at the discovery site, Stein noticed a debris field of skeleton fragments leading into a hillside. The remains of a brow horn suggested that the fossil was a large Triceratops, one of the most common dinosaurs found in the Hell Creek Formation. The remains were scattered over an area of 100 square metres. The fossil's excavation was completed by August 2015. The skeleton is over 60% complete, with a skull that is 75% complete. It was nicknamed "Big John", after the owner of the ranch where it was found. The skeleton is high and long. The remains, which weigh over , include a 2.62-metre (8 ft 7 in) collarbone. The two top horns are over a metre long. According to Zoic, the team that assembled the fossil, Big John is about 5–10% larger than any other known Triceratops.