Trix, the T. rex

Sunday, August 6, 2017

Artist impression of T. rex Trix according to the latest scientific theories and showing her actual wounds. (Naturalis Biodiversity Center)

Trix is a Tyrannosaurus rex specimen excavated in 2013 in Montana, USA by a team of paleontologists from the Naturalis Biodiversity Center in Leiden in the Netherlands. It is the oldest known Tyrannosaurus specimen, with an age of more than thirty years, and has been considered the third most complete tyrannosaurus found, with between 75% to 80% of its bone volume recovered. The specimen was named Trix after the Dutch former Queen Beatrix and is the only Tyrannosaurus specimen on permanent exhibit in mainland Europe.

In 2012, Naturalis Biodiversity Center at Leiden, the largest natural history museum of the Netherlands, planned to open a new exhibition hall in 2017. In order to increase the structural number of visitors from 300,000 to 400,000 per annum, the management decided to try and procure an authentic Tyrannosaurus skeleton, preferably one excavated by the museum itself. In September 2012, a museum delegation travelled to the US to contact the Black Hills Institute, a company that had been involved in nine Tyrannosaurus excavations. As it happened, the BHI had just received a report from a farmer in Wyoming about a Tyrannosaurus discovery. Senior Naturalis paleontologist John Vos immediately visited the site and identified the remains as those of Tyrannosaurus. As it was late in the season, it was decided to postpone the excavation until the next Spring. In April and May 2013, the site was thoroughly excavated but apart from some foot bones, a skeleton proved to be absent. However, five Triceratops skeletons were present elsewhere on the farm land and procured by the museum for exhibition.

In the evening of 27 May 2013, Blaine Lunstad, an amateur paleontologist, with his wife Michele Lunstad who is of Dutch descent, stumbled upon some bones in the “East Pasture”, part of the land of farmer Lige M. Murray, fifty kilometres south of Jordan, Montana. Local fossil hunter Clayton “Dino Cowboy” Phipps confirmed that it was a tyrannosaur skeleton. Rumours of the find reached the BHI, which informed Naturalis. In August 2013, a team of paleontologists from the Naturalis Biodiversity Center, now headed by Anne Schulp, again travelled to the USA. From 29 August to 9 September they unearthed a big and remarkably complete Tyrannosaurus rex specimen. The fossil was found in the Hell Creek Formation. The pattern of geomagnetic reversal showed it had an age of at least 66.4 million years. The excellent preservation had been caused by the skeleton being surrounded by a three metres thick sandstone lens with a high chalk content, neutralizing damaging acids. The Black Hills Institute collaborated with the team in the excavation, which was also assisted by Phipps and the Lundstads. On 5 September, paleontologist Philip Manning of the University of Manchester performed a lidar-laserscan of the site surface to precisely determine the position of all bones.

Presentation of the Tyrannosaurus specimen RGM 792.000 in the 2016-2017 exposition “T. rex in town” of the Naturalis Biodiversity Center, Leiden, the Netherlands. Author: Rique

In May 2015, a CAT-scan of the skull was made in a large industrial scanner of the Fraunhofer Entwicklungszentrum Röntgentechnik of the Fraunhofer Institut at Fürth in Germany.

According to Peter Larson, director of the Black Hills Institute, Trix is the third most complete Tyrannosaurus found, after Sue and Stan. About half of the bones have been found. These represent between 75% and 80% of its bone volume. The main missing parts include the tip of the snout, the front lower jaws, at least seven vertebrae of the middle tail, the point of the tail, the right shoulder blade, the arms, the left hindlimb and the right foot. Parts never before discovered in a Tyrannosaurus fossil include a turbinal bone in the nasal cavity. A rare element present is the furcula and the stapes of the ear. There is some root damage from plant growth and some bones had been gnawed by scavengers. A smaller shed tooth was found, attributed to Nanotyrannus. Trix in 2016 was the most complete Tyrannosaurus specimen permanently exhibited outside of the USA. Tyrannosaurus skeletons part of the collection of the Natural History Museum, London, are more fragmentary.


For formal use, the BHI referred to the skeleton as the “Murray T. rex”. Because of her age, gender and face injuries, the tyrannosaurus was nicknamed “grandma pusface”. Naturalis preferred Grand Old Lady. Wim Pijbes, the director of the Amsterdam Rijksmuseum, called the skeleton “the Nightwatch of Natural History”. She has also been called the “Mona Lisa of Naturalis”, because of her enigmatic smile. Both Larson and the museum concluded it was “the most beautiful tyrannosaurus of the world”. Naturalis decided that the skeleton needed an official name, as all main exemplars of Tyrannosaurus possess. In the press, it was speculated it would be called “Michelle” after its discoverer, as had happened with many specimens. Naturalis asked the Dutch public to suggest a name. On 23 June 2016 it was announced that the name overwhelmingly chosen was “Trix”, as both an allusion to “T-rex” and former Queen Beatrix of the Netherlands. Trix thus became known as the “Queen of the Cretaceous”.

T. rex in Town is a temporary exhibit from September 10, 2016 to June 5, 2017 in the Naturalis Biodiversity Center in Leiden, The Netherlands.