Big John is a fossilized Triceratops horridus skeleton discovered in South Dakota's Hell Creek geological formation in 2014.

[1][2] The fossil was located on a private ranch in Mud Butte, South Dakota, part of the Hell Creek geological formation.

[3] After only "10–15 minutes of searching" at the discovery site, Stein noticed a debris field of skeleton fragments leading into a hillside.

[3] The remains of a brow horn suggested that the fossil was a large Triceratops,[3] one of the most common dinosaurs found in the Hell Creek Formation.

[8] The authors of a 2022 study concluded that the lesion was not simply an anatomical variation, based on the irregularity of its margins and the lack of similar structures in other Triceratops or Anchiceratops specimens.

[8] The remains of Big John were purchased for €150,000[10] and assembled over eight or nine months by the Zoic workshop in Trieste, Italy, who had previously restored two Triceratops skeletons.

[17][18] This three-day exhibition was celebrated with the release of a children's book, A dinosaur walking around Trieste, written by Barbara Battistelli and illustrated by Luca Vergerio and Gianpaolo di Silvestro.

[1] In January 2023, it was announced that Siddhartha Pagidipati and his family would be loaning Big John to the Glazer Children's Museum in Tampa, Florida, for a three-year public exhibition.

[23] Upon its arrival in Tampa, Big John was reconstructed in less than a week by technicians from Zoic workshop and displayed at the museum's annual gala on 3 February.