Susannah Maidment
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  • $s1 department
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Natural History Museum
Cromwell Road


Evolution of quadrupedality in ornithischian dinosaurs

The first dinosaurs walked on two legs (they were bipedal), with forelimbs modified for grasping, but they radiated into a diverse range of shapes and sizes and four-leggedness (quadrupedality) evolved at least four times in different lineages of dinosaurs independently of each other. In the lizard-hipped saurischian dinosaurs, quadrupedality evolved in the sauropodomorphs, animals like Diplodocus and Brachiosaurus. In the bird-hipped ornithischian dinosaurs, however, quadrupedality evolved at least three times independently: once in the armoured dinosaurs, like Stegosaurus, once in the horned dinosaurs, like Triceratops, and at least once in the duck-billed dinosaurs, like Edmontosaurus. The aims of my work involve understanding the 'hows' and 'whys' regarding the changes from bipedality in primitive ornithischian dinosaurs, to quadrupedality. Along with my collaborators Paul Barrett, Don Henderson and Karl Bates I use methods that include comparative anatomy with the extant phylogenetic bracket (crocodiles and birds), quantitative morphometrics, computational modelling and centre of mass reconstruction to test a series of hypotheses that have been proposed to explain the repeated evolution of quadrupedality in the ornithischian dinosaurs.

3D scanning a dinosaur specimen

3D scanning the holotype of the stegosaurian dinosaur Dacentrurus

Systematics and phylogeny of Thyreophora (armoured dinosaurs)

Thyreophora are a group of ornithischian (bird-hipped) dinosaurs whose members are characterized by the presence of plates and spines extending down their backs. Although they include such iconic taxa as Stegosaurus and Ankylosaurus, relationships between different species of armoured dinosaur is poorly understood. My research includes the description, taxonomic stabilization and phylogeny of these dinosaurs, which provides a foundation for further palaeobiological study into this interesting yet poorly understood clade.

British and Chinese dinosaur faunas

The first fossils to be recognised as giant reptiles were found in Sussex, here in the UK, in the 19th century, and places such as Lyme Regis and the Isle of Wight have become world renowned for the spectacular fossil vertebrates that are revealed as the cliffs erode. In contrast, China has come to the forefront of dinosaur research relatively recently, with the discovery of the spectacularly preserved Jehol Biota, which preserves numerous feathered dinosaur fossils. However, dinosaur research in China has been going on much longer; the first dinosaurs were reported from China in the 1950s. My colleagues Paul Barrett, Paul Upchurch and Phil Mannion and I are engaged in ongoing research to revise the taxonomy and systematics of the British dinosaurs, and those from China that were discovered prior to the 1990s and are now rather eclipsed by China's dinobirds. 




PhD, University of Cambridge, funded by a Domestic Research Studentship; Title - Systematics and phylogeny of Stegosauria (Dinosauria, Ornithischia)


Imperial College London, 1st class (Hons) MSci degree in Geological Sciences and Associateship of the Royal School of Mines

Work Experience

July 2009 – present

The Natural History Museum -  Postdoctorial researcher, NERC funded

 August 2008 – May 2009

Talisman Energy Vietnam - Exploration geologist                                         

January 2004 – October 2006

Qube Software - Palaeontological consultant                                                            

June – September 2003

Imperial College - Research assistant                                                          

June – September 2002

BP - Geoscience intern                                                                 

Students and Teaching


2009 - 2010

Richard Thompson, Imperial College: MSc Thesis - Phylogeney of Ankylosauria (Dinosauria: Ornithischia)

2008 - 2009

Holly Barden, University of Sheffield: M.Biol.Sci Thesis - Sexual dimorphism in the stegosaurian dinosaur Kentrosaurus aethiopicus

2007 - 2008

Mark Logie, Cambridge University: MSci Thesis - Limb bone scaling as a proxy for physiology in dinosaurs

Teaching experience

2009  –  Department of Earth Science and Engineering, Imperial College
  • Lectures and practicals for dinosaur vertebrate palaeontology, 3rd and 4th year students
2003 – 2007, Department of Earth Sciences, University of Cambridge
  • Supervisions and demonstrations for palaeobiology and sedimentology, 1st year students
  • Group leader and demonstrator, Arran field course, 1st year students
  • Supervisions and demonstrations for vertebrate palaeontology, map interpretation and basin analysis, 2nd year students
  • Demonstrations for skills, 3rd year students
Jan – June 2007, Clare College, University of Cambridge
  • Acting Director of Undergraduate Studies: Earth Sciences


  • Barden, H. E. and Maidment, S. C. R. ( 2011 ) Evidence for sexual dimorphism in the stegosaurian dinosaur Kentrosaurus aethiopicus from the Upper Jurassic of Tanzania Journal of Vertebrate Paleontology 31 : 641-651 . Journal of Vertebrate Paleontology | 10.1080/02724634.2011.557112
  • Barrett, P. M and Maidment S. C. R. ( 2011 ) Dinosaurs of Dorset: Part III, the ornithischian dinosaurs (Dinosauria, Ornithischia) with additional comments on the sauropods. Proceedings of the Dorset Natural History and Archaeolgical Society 132 : 145-163 .
  • Barrett, P. M. and Maidment, S. C. R. ( 2011 ) Wealden armoured dinosaurs, In: English Wealden Fossils: Field Guide to Fossils 14 . The Palaeontological Association 769 pp .
  • Maidment, S. C. R and Barrett, P. M. ( 2011 ) The locomotor musculature of basal ornithischian dinosaurs Journal of Vertebrate Paleontology 31 : 1265-1291 .
  • Maidment, S. C. R. and Barrett, P. M. ( 2011 ) A new specimen of Chasmosaurus belli (Ornithischia: Ceratopsidae), a revision of the genus, and the utility of postcrania in the taxonomy and systematics of ceratopsid dinosaurs. Zootaxa 2963 : 1-47 .
  • Maidment, S. C. R. ( 2010 ) Stegosauria: a historical review of the body fossil record and phylogenetic relationships Swiss Journal of Geosciences 103 : 199-210 . 10.1007/s00015-010-0023-3
  • Maidment, S. C. R. and Porro, L. B. ( 2010 ) Homology of the palpebral and the origin of the supraorbital ossifications in ornithischian dinosaurs Lethaia 43 : 95-111 .
  • Mateus, O., Maidment, S. C. R., and Christiansen, N. A.   ( 2009 ) A new long-necked 'sauropod-mimic' stegosaur and the evolution of the plated dinosaurs. Proceedings of the Royal Society B 276 : 1815-1821 .
  • Maidment, S. C. R., Norman, D. B., Barrett, P. M., and Upchurch, P. ( 2008 ) Systematics and phylogeny of Stegosauria (Dinosauria: Ornithischia) Journal of Systematic Palaeontology 6 : 367-407 .
  • Norman, D. B., Butler, R. J., and Maidment, S. C. R. ( 2007 ) Reconsidering the status and affinities of the ornithischian dinosaur Tatisaurus oehleri Simmons 1965 Zoological Journal of the Linnean Society 150 : 865-874 .
  • Lonergan, L., Maidment, S. C. R., and Collier, J. ( 2006 ) Pleistocene subglacial tunnel valleys in the central North Sea basin: 3D morphology and evolution. Journal of Quaternary Research 21 : 891-903 .
  • Maidment, S. C. R., and Wei, G.-B. ( 2006 ) A review of Late Jurassic stegosaurs (Dinosauria, Stegosauria) from the People's Republic of China. Geological Magazine 143 : 621-634 .
  • Maidment, S. C. R., Wei, G.-B., and Norman, D. B. ( 2006 ) Re-description of the postcranial skeleton of the Middle Jurassic stegosaur Huayangosaurus taibaii. Journal of Vertebrate Paleontology 26 : 944-956 .