Tyrannosaurus rex: The Perfect Puzzle

By GCG Committee Member Nigel Larkin – a freelance palaeontological preparator, conservator and curator based in the UK.

Introduction

Do you like jigsaws? What’s the best jigsaw you’ve ever done or can think of? Imagine having a 3D jigsaw that is 12 metres long, over 4 metres high, weighs over half a tonne, and you have no clear image of what it should look like in any detail. You also have to assemble it in a way that is easy to disassemble and remount in sections. You’ll need to know about dinosaur anatomy, how to design a mount, and have carpentry, blacksmithing and welding skills, plus have a head for heights as well as a very large space to do the work in. And you have a very tight deadline but can’t take on any help with it because you are in the middle of a pandemic! How was your Covid Lockdown? This was mine. At least I wasn’t bored. Far from it. And a I do love a challenge – which is just as well, being a freelance palaeontological preparator, conservator and curator. I get given all sorts of problems to solve but this has been one of the most complex mounting projects I have undertaken. 

A full-size unmounted T. rex skeleton must be the best 3D jigsaw the world has to offer (as long as you have almost infinite patience). OK, there may be bigger skeletons out there to play with, but surely none are as cool or as iconic as a T. rex. This particular skeleton had to be mounted from scratch for a temporary display (July 2021 to August 2022) at Nottingham’s Natural History Museum, Wollaton Hall, in the UK. You can read a National Geographic article about the specimen here.

This skeleton, known as ‘Titus”, is a partial Tyrannosaurus rex skeleton excavated in Hell Creek, Montana, USA, by Craig Pfister in 2018. It was my job last autumn/winter/spring to assess and conserve the bones, then merge them with casts from a replica of ‘Stan’, one of the most complete T. rex skeletons to have been found. I had to arrange the real bones and the casts into an accurate life-like pose and create a sturdy metal armature to hold all the bones securely in place. This armature had to be made in sections so that the mounted skeleton could be dismantled, crated, loaded on to lorries, and be transported to Nottingham. So it is a 4D jigsaw really as you have to plan your work to be executed in a certain order, and always have to bear in mind that the whole specimen will need to be disassembled in a particular order and transported, manhandled and remounted again. Also, at Wollaton Hall the specimen would have to be carried manually up stairs and through narrow doorways into the room where it would be re-assembled and put on display.

3D Scanning the Bones

Before the mounting of the skeleton could begin, all of the real bones and bone fragments were recorded in great detail with 3D photogrammetry scanning in my conservation workshop by Steven Dey of ThinkSee3D, a specialist in 3D imaging for heritage institutions. Detailed digital 3D models were created from these scans and replicas of all of the bones were then 3D printed in colour in gypsum by ThinkSee3D for use in the exhibition. The digital 3D models were shared with palaeontologists in America specialising in pathology and they were able to study the bones and assess them for signs of injury and disease. They finished their studies and produced a report before the mounting of the specimen was even finished!  

Mounting the Bones

Titus was to be reconstructed in a walking pose, as if searching for prey or returning home after a hunt, with a pleasing lateral undulation to the whole vertebral column. The missing portion of the skeleton was filled by purchasing a complete set of unmounted replica bones of the T. rex known as Stan, one of the more complete T. rex specimens to have been found (at ~63% complete). These polyurethane casts were purchased directly from the Black Hills Institute of Geological Research in South Dakota and are of good quality with a lot of detail. Titus was exactly the same size as Stan, judging by how well the complete metatarsal and pes and almost complete tibia, articular, prearticular and angular of Titus matched the replicas of Stan’s bones. The Black Hills Institute gave permission for the new skeleton to be called by another name as it represented a different individual.

The bones of Titus that were complete simply replaced the relevant bones in Stan’s skeleton. For the incompletely preserved bones of Titus, the relevant replica bone of Stan in each case was cut and shaped to accommodate the portion of real bone, and the gap between the two was filled with Apoxie Sculpt (a self-hardening epoxy resin paste) which was then shaped and given relevant texture. A thick Paraloid B72 consolidant was already applied to the bones to form a barrier layer between the epoxy and the surface of the fossil material. All the casts and associated Apoxie Sculpt fillers were then painted with artist’s acrylic paints to closely match the colour of the real fossil bones.

Detailed plans of a generic T. rex skeleton were produced in the agreed pose by Wollaton Hall and I designed and fabricated the armature according to this pose and the actual size and shape of Stan’s replica bones, to reduce handling of the original fossil material. Getting all the bones in to their right positions relative to one another was quite a juggling act, involving webbing, ropes, pulleys and temporary supporting woodwork (Fig. 1). Only then could I make appropriate metal armature.

Figure 1: Temporary support for the skeleton. © Nigel Larkin.

I heated and shaped lengths of steel and MIG welded (Figs. 2 and 3) some pieces together and bolted others as required to provide an armature that could safely hold the real and replica bones in place in a way that meant the skeleton could be assembled, disassembled and transported with relative ease. Standing 12 m long and 4.35 m high (allowing for a plinth 1m high under its feet) this did still involve gantries, chain hoists, slings and quite a bit of effort. Whilst the original intention was to have only a single supporting vertical pole under the pelvis, a second upright pole was added between the forearms during mounting to help spread the weight as it was to be displayed on an upper floor of a large Grade 1 listed Elizabethan mansion and there was some concern about floor loading.

Figure 2: MIG welding the armature. © Nigel Larkin.
Figure 3: Cleaning the armature after welding. © Nigel Larkin.

It took almost a year’s worth of work to complete all these tasks.  But this was condensed into just 7 months of very long days, due to the various deadlines I was juggling at the time. As I said, I like a challenge. (Fig. 4).

Figure 4: The final skeleton, fully mounted. © Nigel Larkin.

The Exhibition

The skeleton of Titus was put on display at Wollaton Hall as part of a larger exhibition about the species Tyrannosaurus rex, titled ‘Titus: T. rex is King’. This opened to the public on the 3rd July 2021 and is scheduled to run until the end of August 2022. The exhibition is divided into five sections or galleries: Titus Unearthed, Meet Titus, Past and Present, Explore Titus, and Create Titus. As well as the 12 m long, 3 m high T. rex skeleton (Fig. 5), material on display includes fossils from the museum collections, models, artwork, some impressive and engaging interactive consoles, a mock-up of the excavation and a film that put the specimen into context. All this content was created by Nottingham Museum staff and other specialists and has been very well reviewed by the public. The digital interactive stations were designed to minimise the risk of spreading the covid virus and are impressively manipulated by the public using touchless controls by swiping the air. There are three types of digital interactive: six ‘Create Titus’ interactive stations allow visitors to get creative and add colour, patterns, texture (feathers) and sound to a base model of Titus; four ‘Explore Titus’ interactive stations allow visitors to recreate the soft tissues over the skeleton of Titus; and two more interactive stations recreate the excavation of Titus by allowing visitors to first dig for the bones (these are digital 3D models produced from the photogrammetry scanning) and then fit these into the digital skeleton of Titus. These touchless digital interactives were produced by Hot Knife Digital Media.

Figure 5: Titus on display at Wollaton Hall. © Nigel Larkin.

Discussion

TheTyrannosaurus rex skeleton known as ‘Stan’ was sold in 2020 for 31.8 million US dollars to an unknown buyer, pushing up the price of all such skeletons even further beyond the budget of most museums. Very wealthy private individuals can purchase such specimens and may sometimes put them on public display but this can leave the fossil in an intellectual limbo, unable to be studied and published.

However, unusually, right from the outset the owner of Titus was keen that although ownership of the physical specimen would remain in private hands, the skeleton should be on public display and, more importantly, insisted that despite this the material should be as accessible as possible to researchers. They wanted this to be seen as an exemplar project to encourage other private owners of important fossils to go to similar lengths to make their material genuinely accessible. Therefore, all the bones were 3D scanned and replicas were 3D printed, making the specimen relatively easy to study by anyone in the world. The material therefore became genuinely more accessible to researchers than many dinosaurs on permanent display in museums. As the 3D printed replicas of the bones have been accessioned in to the collections at Wollaton Hall by the Curator of Natural Sciences, Dr Adam Smith and the 3D digital scans have been archived no matter what happens to the mounted skeleton of Titus in the future this material can still be studied and referenced in academic papers.

This project is currently being written up in full for publication in Geological Curator, the journal of the Geological Curators Group.

You can see more about the project, including many more photos, here.

Here is a link to a fun time lapse video of the installation filmed, edited and produced by the talented Dominic Day:

Acknowledgements:

With thanks to: Dr Adam Smith at Wollaton Hall for his curatorial work; Dr Dean Lomax and Dr Dave Hone for advice on the anatomy; Steven Dey of ThinkSee3D for 3D Photogrammetry scanning; Susan Jones of Redhead Business Films for filming the project; Dominic Day for the time lapse photography; Philip Rye for help with crating, transportation and installation; and the team at Wollaton Hall.


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