COLCHESTER.- A 154-million-year-old theropod fossil that may be the key to discovering a new dinosaur species is on display for the first time at Hollytrees Museum in Colchester, from 3 April 2026 to 1 November 2027.

London-based natural history and antiquities gallery David Aaron sold the fossil to a private collector in 2024 and has been instrumental in facilitating the loan of the specimen to the Colchester + Ipswich Museums.

Nicknamed ‘Juliasaurus’, the fossil was excavated in 2020 from the Late Jurassic Morrison Formation in Wyoming. Initial palaeontological inspection of the fossil indicated similarities to Allosaurus or Marshosaurus, but the differing anatomy of the ‘Juliasaurus’ means further research is required to determine whether the fossil represents a new species.

What is remarkable about this specimen is the completeness of the fossil and the potential for new paleontological discoveries. Research into the specimen could provide fresh insights into the evolution of carnivorous dinosaurs, along with determining the species of ‘Juliasaurus’. The display at Colchester will coincide with the opportunity to undertake scientific research into the fossil for the first time.

‘Juliasaurus’ is an incredible example of a medium-sized theropod measuring six metres in length and weighing around 600 kilograms. The fossil comes from the mostly carnivorous theropod dinosaur group and predates its distant relative, the Tyrannosaurus Rex, by roughly 90 million years.

This landmark partnership is the first time a dinosaur has been displayed in Colchester, bringing an impressive prehistoric predator to Essex for dinosaur lovers to experience in their local area.

“David Aaron is honoured to be a part of the world premiere display of this world-class and potentially groundbreaking dinosaur. This specimen is one of the most important dinosaur fossils to have been discovered in North America in recent years, and the collaboration with Hollytrees Museum has the potential to discover an entirely new species”, said Salomon Aaron, Director, David Aaron.

“It’s been wonderful collaborating with the Colchester Museums team, an exemplary regional Museum who work tirelessly to enrich their community,” said Aaron.
Pippa Pickles, Manager, Colchester Museums, said: “This dinosaur has not been publicly displayed anywhere else in the world, so it is a wonderful and exciting opportunity to view this 6.2-metre-long specimen in the Georgian mansion. The remarkable specimen of Juliasaurus, which may be a new species, further highlights that this globally significant Morrison Formation still has secrets left to discover.”
Scientific discovery plays an important role in David Aaron’s display and sale of dinosaur fossils, with significant breakthroughs in recent years serving to further the scientific community’s understanding of prehistoric specimens.

David Aaron was involved in the 2025 discovery of a new species, the Enigmacursor, a dinosaur from the Late Jurassic period, 152–145 million years ago. Upon acquiring the fossil, David Aaron presented the specimen to the Natural History Museum, who identified the potential for a new discovery. The gallery identified a generous private benefactor to purchase and donate the fossil to the Museum, enabling the scientific revelation. Previously considered a Nanosaurus, researchers at the Museum confirmed that the fossil was a new species of two-legged herbivore.

Further, in 2023 David Aaron exhibited ‘Chomper’, a rare juvenile Tyrannosaurus Rex fossil, one of the most complete examples in existence, with one of the most complete skulls ever discovered. Some scientists speculated ‘Chomper’ could be the much-hypothesized Nanotyrannus species; however, the fossil is classified as one of very few surviving juvenile Tyrannosaurus Rex specimens, making it extremely rare. Scientific knowledge of the Tyrannosaurus Rex species has been greatly expanded through study of similar juvenile skeletons.

David Aaron encourages collectors to work with and support the museum and science sectors; the possibility to discover a new species from ‘Juliasaurus’ further reinforces the gallery’s support of such research outcomes.

‘Juliasaurus’ is on display in the ‘Discover’ Museum Wonders exhibition from 3 April 2026 to 1 November 2027 at Hollytrees Museum, Colchester.