In 2014, Theropoda Expeditions LLC was excavating a possible Gorgosaurus specimen near Havre, Montana.
On 16 May, a skid-steer loader removing a 12 m (39 ft)-high overburden unexpectedly hit upon an ankylosaurian tail club.
An almost complete ankylosaur skeleton proved to be present.
As it had not been eroded on the surface, it was in pristine condition.
It was found overturned, with the belly facing upwards.
The skeleton was largely articulated, but the skull and some neck vertebrae were separated from the main torso, while five ribs and the left ilium had shifted from their original position.
The company secured the specimen in two main blocks, the largest of which weighed over 15 tonnes (17 tons).

Initially identified as a new species of Euoplocephalus, the scientific importance of the specimen was immediately recognised.
After preparation of the skull and tail section, Theropoda Expeditions offered it for sale.
The company nicknamed the specimen "Sherman".
In June 2016, it was acquired by the Canadian Royal Ontario Museum.
The museum performed a laser scan of the skull, allowing its original form to be determined by the process of retro-deformation, or compensating for compression of the fossil.
In 2017, before the torso had been prepared, a preliminary description was published of the skull and tail.

In 2017, based on the specimen the type species Zuul crurivastator was named and described by Arbour and Evans.
The generic name was adopted from the demon and demi-god Zuul, the Gatekeeper of Gozer, featured in the 1984 film Ghostbusters.
This was due to Zuul's head resembling that of an ankylosaur.
The specific name is derived from Latin crus, "shank", and vastator, "destroyer".
The epithet, read as "Destroyer of Shins" by the naming authors, refers to a presumed defensive tactic of ankylosaurids, smashing the lower legs of attacking predatory theropods with their tail clubs.

The specimen, which is stored as ROM 75860, was found in a sandstone layer of the Judith River Formation, part of the middle Coal Ridge Member with an age of between 76.2 and 75.2 million years.
According to Theropoda Expeditions, it was 99% complete.
It was described as a "dinosaur mummy", due to its preservation of soft tissues.
Many osteoderms and small ossicles of the armour are present in their original position.
Additionally, there are remains of keratin sheaths of the spikes and of keratin, non-bony, scales, in the form of a black film.
The specimen is, as of 2017, the most complete ankylosaur find from the Judith River Formation.
It was also the first North American ankylosaur specimen with well-preserved material from both the skull and tail.
In 2014, Theropoda Expeditions LLC was excavating a possible Gorgosaurus specimen near Havre, Montana. On 16 May, a skid-steer loader removing a 12 m (39 ft)-high overburden unexpectedly hit upon an ankylosaurian tail club. An almost complete ankylosaur skeleton proved to be present. As it had not been eroded on the surface, it was in pristine condition. It was found overturned, with the belly facing upwards. The skeleton was largely articulated, but the skull and some neck vertebrae were separated from the main torso, while five ribs and the left ilium had shifted from their original position. The company secured the specimen in two main blocks, the largest of which weighed over 15 tonnes (17 tons).
Initially identified as a new species of Euoplocephalus, the scientific importance of the specimen was immediately recognised. After preparation of the skull and tail section, Theropoda Expeditions offered it for sale. The company nicknamed the specimen "Sherman". In June 2016, it was acquired by the Canadian Royal Ontario Museum. The museum performed a laser scan of the skull, allowing its original form to be determined by the process of retro-deformation, or compensating for compression of the fossil. In 2017, before the torso had been prepared, a preliminary description was published of the skull and tail.
In 2017, based on the specimen the type species Zuul crurivastator was named and described by Arbour and Evans. The generic name was adopted from the demon and demi-god Zuul, the Gatekeeper of Gozer, featured in the 1984 film Ghostbusters. This was due to Zuul's head resembling that of an ankylosaur. The specific name is derived from Latin crus, "shank", and vastator, "destroyer". The epithet, read as "Destroyer of Shins" by the naming authors, refers to a presumed defensive tactic of ankylosaurids, smashing the lower legs of attacking predatory theropods with their tail clubs.
The specimen, which is stored as ROM 75860, was found in a sandstone layer of the Judith River Formation, part of the middle Coal Ridge Member with an age of between 76.2 and 75.2 million years. According to Theropoda Expeditions, it was 99% complete. It was described as a "dinosaur mummy", due to its preservation of soft tissues. Many osteoderms and small ossicles of the armour are present in their original position. Additionally, there are remains of keratin sheaths of the spikes and of keratin, non-bony, scales, in the form of a black film. The specimen is, as of 2017, the most complete ankylosaur find from the Judith River Formation. It was also the first North American ankylosaur specimen with well-preserved material from both the skull and tail.
Zuul