Steg on display © NHM, London

Scientists reveal the body weight of the world’s most complete Stegosaurus

Scientists at the Natural History Museum and Imperial College London have discovered the body mass of the Museum’s 150 million year old Stegosaurus stenops specimen.

Professor Paul Barrett, lead dinosaur researcher at the Natural History Museum says; “these findings identify just how important exceptionally complete specimens like this are for scientific research and collections. Now we know the weight, we can start to find out more about its metabolism, feeding requirements and the growth rates of Stegosaurus. We can also use the same techniques on other complete fossils to find out much more about the wider ecology of dinosaurs”.

Dr Charlotte Brassey, palaeontologist from the Museum and lead author of the study adds “because this incredible specimen is so complete, we have been able to create a 3D digital model of the whole fossil and each of its 360 bones, which we can research in excellent detail without using any of the original bones. We also took the skeleton’s leg bone circumference and compared it to a modern animal of similar size, and came up with matching estimates for the dinosaur’s weight.”

The scientists discovered the body mass of this dinosaur by fitting simple shapes to the digital skeleton and calculating its volume. They then converted this into a body mass using data collected from similar modern animals.  When compared to figures calculated using the alternative method of measuring leg bone circumference in conjunction with the overall weight of various living animals, the results are in close agreement. Both techniques produced an estimate of 1600 kg and, combined, are now considered the most accurate way of measuring the body weight from nearly complete fossil skeletons. 

Dr Susannah Maidment, researcher at Imperial College London says: “calculating body mass in animals that have been dead for many millions of years is no easy task, and there are several different ways to do it. Often different methods come up with very different results. Our study is the first to attempt different methods on the same animal, and has highlighted how and why different body mass estimation methods come up with different results. The age of the animal when it died is very important.”

Since the stegosaur arrived at the Museum in December 2013 and before it went on permanent public display one year later, researchers created the 3D model of the skeleton by scanning, photographing and measuring each of its 360 bones. In addition to the findings in this study, the data will underpin a series of future scientific studies, which will uncover more about the unusual lifestyle of Stegosaurus.

The Stegosaurus is now part of the Museum’s collection of 80 million specimens, of which eight million are fossils. We are extremely grateful to the 70 generous donors, with particular thanks to Jeremy Herrmann, who made this iconic acquisition possible.

The world-renowned collection is actively used by 300 Museum scientists as well as 9,000 visiting researchers from around the world every year, and inspires millions of visitors to connect with our natural world and consider its past, present and future. 

Notes for editors 

Relevant images for this release can be downloaded.

  • The Natural History Museum welcomes more than five million visitors a year and is also a world-leading science research centre. Through its unique collection and unrivalled expertise it is tackling the biggest challenges facing the world today. It helps enable food security, eradicate disease and manage resource scarcity. It is studying the diversity of life and the delicate balance of ecosystems to ensure the survival of our planet. For more information go to www.nhm.ac.uk
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