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QM reconstructs Kronosaurus

Kronosaurus queenslandicus jaw. Source: Queensland Museum

Reconstructing the Kronosaurus, The Queensland Museum Network Blog, 12 December 2018

Kronosaurus queenslandicus was the largest predatory reptile to swim the seas of western Queensland 105 million years ago. This icon of the paleontological world is thought to have grown up to 11 metres in length, with around two metres of that dedicated to its unusually large skull, containing a mammoth set of jaws and dozens of enormous teeth.

Recently, an opportunity arose for the Queensland Museum to add to the State Collection with the acquisition of two lower jaw pieces from a large individual Kronosaurus. Although the Kronosaurus is an iconic animal, surprisingly little is known about its biology, with skulls and jaws a relatively rare find.

Kronosaurus queenslandicus was named in 1924 by Queensland Museum palaeontologist and former museum Director, Heber Longman, based on a piece of jawbone that was discovered near Hughenden, in central Queensland. It was named after the Greek Titan Kronos; so horrible that he ate his own children. Kronosaurus is a pliosaur, an extinct short-necked marine reptile. Its powerful jaws – which worked in a similar way to a crocodile’s – contain rows of large conical teeth, the biggest of which are nearly 30 centimetres long. Kronosaurus was a fierce predator – remains of its stomach contents found in central western Queensland indicate that it fed on turtles and other long-necked marine reptiles. Kronosaurus fossils have been found in the sediments deposited by the inland seas and turned to rock, ranging in age from 112-100 Million years, during the Early Cretaceous Period.

Reconstructing the Kronosaurus

Kronosaurus queenslandicus was the largest predatory reptile to swim the seas of western Queensland 105 million years ago. This icon of the paleontological world is thought to have grown up to 11 metres in length, with around two metres of that dedicated to its unusually large skull, containing a mammoth set of jaws and dozens of enormous teeth.
Recently, an opportunity arose for the Queensland Museum to add to the State Collection with the acquisition of two lower jaw pieces from a large individual Kronosaurus. Although the Kronosaurus is an iconic animal, surprisingly little is known about its biology, with skulls and jaws a relatively rare find.

Kronosaurus queenslandicus was named in 1924 by Queensland Museum palaeontologist and former museum Director, Heber Longman, based on a piece of jawbone that was discovered near Hughenden, in central Queensland. It was named after the Greek Titan Kronos; so horrible that he ate his own children. Kronosaurus is a pliosaur, an extinct short-necked marine reptile. Its powerful jaws – which worked in a similar way to a crocodile’s – contain rows of large conical teeth, the biggest of which are nearly 30 centimetres long. Kronosaurus was a fierce predator – remains of its stomach contents found in central western Queensland indicate that it fed on turtles and other long-necked marine reptiles. Kronosaurus fossils have been found in the sediments deposited by the inland seas and turned to rock, ranging in age from 112-100 Million years, during the Early Cretaceous Period.

“The base is made of timber but each one contains an individual cradle sculpted from polymer plaster to suit the weight, angle and intricacies of each piece of jaw. The cradle was glued to the timber and filled in with expandable polyurethane foam, which was then sanded off to create the shape of the base’s sides. Over that, two layers of fibreglass were carefully applied to give the structure strength. The final step was a coat of paint in a specially chosen shade that would not detract from the ‘hero’, our Kronosaurus jaw.”

As the teeth and part of the bone were missing, careful work was done to demonstrate this as accurately as possible. The teeth were made using 3-D modelling and printing – technology that Dr Scott Hocknull, Senior Curator, Geosciences, has developed within Queensland Museum and has become a key feature of his research and engagement work.

“In this case, the benefits of this technology served as a huge time saver,” said Scott.

The usual method for producing replicas is creating a plasticine sculpture and using that to make a mould and then cast from it. In this case, the process would need to be repeated for each individual tooth – all 16 of them – which Debra and Scott estimate could have taken a month of work or more. The same result using 3-D modelling and printing took about 36 hours, with most of this made up of printing time rather than manual labour. This is achieved through digitally modelling one tooth, then digitally sculpting a 3-D model of each of the 16 teeth. Using photographs of the original tooth, a 3-D model of it was created, which can then be modified and printed out. Debra then hand painted each tooth in a colour that matched the remaining bone. The final piece of the puzzle was to come up with a way that the teeth could be displayed so that it was obvious to viewers which part was original fossil and which was a reconstruction.

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