The Road to Dinosauria

Dinosaurs – one of the most famous groups of extinct animals – are ubiquitous in popular culture today. From Jurassic Park to The Lost World, their images are everywhere and instantly recognisable. It can be difficult, therefore, to cast our minds back to a time when dinosaurs were completely unknown, when they were first being described. At this time, discoveries of fossils from around Britain were revealing a new world, one that came before our own and was populated by creatures that were unlike any seen today. As Gideon Mantell (1790-1852) described in his paper ‘The Geological Age of Reptiles’ (1831), ‘Among the numerous interesting facts which the researches of modern geologists have brought to light, there is none more extraordinary and imposing than the discovery that there was a period when the earth was peopled by oviparous quadrupeds of a most appalling magnitude and that reptiles were the Lords of Creation, before the existence of the human race!’

Much of the earliest scientific work on dinosaurs was done in Britain, so I will focus on a few key players from these early days.

William Buckland and the Megalosaurus

Although there are a number of examples of dinosaur fossils being found prior to this event, the first scientific description of a dinosaur is that of Megalosaurus in 1824 by William Buckland.

M0012517 Portrait of William Buckland
A portrait of William Buckland (‘M0012517’ from Wellcome Images is licensed under CC BY 4.0)

Reverend William Buckland (1784-1856) was a reader of Mineralogy (and later a reader of Geology) at the University of Oxford. He researched and lectured on what he called ‘undergroundology’ (an excellent name which sadly didn’t catch on…). Amongst his various duties, he curated the Ashmolean Museum and this is where he came across the Megalosaurus fossils he would later describe.

Various bones in the museum (attributed to an unknown animal) had been acquired from quarries around Oxford, in particular from Stonesfield. In 1818, Georges Cuvier (1769-1832) visited the Ashmolean museum and was shown these mysterious bones. Cuvier, famous for his work on comparative anatomy (among many other achievements), later corresponded with Buckland about these specimens and helped to come to some broad conclusions about their origin.

Key to these was an understanding of the rocks these bones were found in. The bones from Stonesfield were found well below ground in a quarry.  From analysis of the sequence of rock types across the country (some early work on stratigraphy – see my other post on stratigraphy) – they could be quite sure these rocks were far older than those in which various fossil mammals had been found. This suggested that these fossils belonged to something entirely different. On top of this, observations of the jaw pointed towards a reptile origin. Along the jaw were seen various smaller teeth beside the larger adult ones; this suggested a replacement cycle whereby older teeth are continually replaced by new ones. This is a feature found in reptiles.

Megalosaurus
Engraving of the jaw of Megalosaurus from William Buckland’s ‘Notice on the Megalosaurus or great Fossil Lizard of Stonesfield’, 1824 (via Wikimedia Commons)

As to what kind of reptile it was – that was a lot more difficult! Buckland finally read his paper on Megalosaurus to the Geological Society at its London Headquarters on February 20, 1824. He described the fragmentary nature of the fossils and the conclusions that could be drawn from them. Clearly, this ‘lizard’ had reached a very large size – as he described ‘we may with certainty ascribe to it a magnitude very far exceeding that of any living lacerta’. Megalosaurus aptly means ‘Great Lizard’.

The Marine Reptiles of Lyme Regis

Buckland’s announcement of Megalosaurus came at the same meeting as the announcement of the first example of the bizarre marine reptile – Plesiosaurus. This was one of many discoveries made around Lyme Regis at this time period. Although not dinosaurs, the marine reptiles were another important example of extinct reptiles that were starting to be described around this time. It was in the context of this growing interest in marine reptiles, that the first scientific descriptions of dinosaurs occurred.

So, to digress from dinosaurs for a moment, I’ll dip briefly into some of the early finds of marine reptiles from Lyme Regis. In 1811, Joseph Anning discovered the skull of a large creature he thought to be some sort of crocodile while walking the beaches. This skull now resides at the London Natural History Museum and, looking at it, you can understand what an impression it must have made – its large size and curious features made quite a stir at the time. Mary Anning, Joseph Anning’s sister, later helped with the extraction of more of the creature around a year later.

CIMG5298 - Copy
Standing next to the first Icthyosaur to be scientifically described (skull bottom left) – at the Natural History Museum in London

This was the first skeleton of its kind to be examined by the scientific community, leading to the first description of the marine reptile Icthyosaurus (meaning ‘fish-lizard’). The first detailed paper that recognised its reptile affinities was published by Reverend Conybeare and Henry de la Beche in 1821.

In later years Mary Anning continued to search the beaches around Lyme Regis and uncovered many more examples of Icthyosaurs. In 1823, however, she came across something entirely new. This skeleton revealed another marine reptile – this one with a tiny head, extremely long neck and four ‘paddles’ for swimming. Its bizarre form sparked some rumours that it may be a fake, but these were later resolved. In the same meeting that Megalosaurus was announced, Conybeare spoke of the first Plesiosaurus emaphsising its bizarre blend of features – ‘To the head of the Lizard, it united the teeth of the Crocodile; a neck of enormous length, resembling the body of a Serpent; a trunk and tail having the proportions of an ordinary quadraped; the ribs of a Chameleon and the paddles of a Whale’.

Plesiosaurs
Left – the first Plesiosaur skeleton to be described (Natural History Museum, London). Right – a letter concerning the discovery of Plesiosaurus from Mary Anning (‘L0022370’ from Wellcome Images is licensed under CC BY 4.0)

Gideon Mantell and the Iguanodon

Gideon Mantell (1790 – 1852) completed the second scientific description of a dinosaur – that of Iguanodon – in 1825, just one year after the publication on Megalosaurus.

L0006461 Portrait of G.A. Mantell by Davey after Sentier
Portrait of Gideon Mantell (‘L0006461‘ from Wellcome Images is licensed under CC BY 4.0)

Mantell worked as a doctor but devoted his spare time to descriptions of the geology of Sussex. In his travels, he came cross a quarry at Whiteman’s Green that contained large fossil bones. As more work was published on marine reptiles, it became clear to Mantell that these bones belonged to something very different (this was all before the publication on Megalosaurus).

Interestingly, the site also yielded a variety of fossil plants that were similar in appearance to those from tropical areas. The site seemed to represent a tropical environment, populated by large unknown creatures.

In addition, Mantell started to acquire large, unusual teeth from the quarry. These teeth resembled those of herbivorous mammals having broad, flat grinding surfaces. However, it was known that the rocks these fossils were found in were much older than those from which fossil mammals had been discovered previously. This suggested they may belong to something else – possibly a large, herbivorous reptile. It’s worth considering that while we are very familiar with images of large herbivorous dinosaurs roaming the land, the idea of a large, herbivorous reptile was bizarre for the time.

Lingering questions over the age of the rocks and the novel nature of these finds, led to repeated interpretation by others of these teeth as more recent mammal teeth or as the teeth of some kind of large fish. Perhaps most famously, Cuvier initially interpreted the tooth as the upper incisor of a rhinoceros.

Iguanodon teeth
Illustration of Iguanodon teeth (via Wikimedia Commons)

It was only later when the sequence of rocks in the area was better understood and many more of these teeth were collected that, on sending them to Cuvier again in 1824, he suggested that they may actually be those of a herbivorous reptile.

By this time Buckland had finally published on Megalosaurus (and Mantell will have been aware of his material some time beforehand). This added weight to Mantell’s idea of a large reptile.

But what sort of reptile? In late 1824, he took some of these teeth to the Hunterian Museum at the Royal College of Surgeons to compare them to the various specimens stored there. Fortuitously, Samuel Stutchbury demonstrated that they were similar to that of the modern Iguana. This similarity in shape (although the size was clearly very different, at around 20 times larger!) led to the name Iguanodon (meaning ‘Iguana-tooth’).

Soon after, in 1825, Mantell published his description of Iguanodon based on the material from Sussex. This was the first herbivorous dinosaur to be described.

The Age of Reptiles

In the years following these announcements, more and more ancient reptiles were described. In Britain and other areas of Europe, a variety of marine reptiles were coming to light. In addition, pterosaurs began to be described (a flying reptile). New dinosaurs were also added to the mix e.g. Mantell discovered Hylaeosaurus, the first ankylosaur in 1832.

Together these findings made popular the idea of an ‘Age of Reptiles’ that preceded the time period of the various fossil mammals that had been described (although we now know that there were also mammals that lived in this time period).

Yet, coming back to the dinosaurs, this was all in a time before the word ‘dinosaur’ had been created! The various dinosaurs that had been described were yet to be grouped together under this umbrella. This next step came from Richard Owen.

Richard Owen and the Dinosauria

L0018202 Engraving: portrait of R. Owen,
Portrait of Richard Owen (‘L0018202’ from Wellcome Images is licensed under CC BY 4.0)

Richard Owen (1804-1892) was an anatomist who worked as Hunterian Professor at the Royal College of Surgeons in London, and later as superintendent of the natural history department of the British Museum. Among many other areas of study, Owen worked on the various new finds of fossil reptiles.

Christian Erich Hermann von Meyer (1801-1869) in 1832 published the first attempt at classifying these fossil reptiles. It was based on different kinds of locomotion and therefore grouped Megalosaurus and Iguanodon together under ‘Saurians with Limbs similar to those of the heavy land Mammalia’. Mantell later commented that Hylaeosaurus should also be added to this grouping.

Building on this work and using observations of many fossil reptiles from various collections, Owen worked to publish his ‘Report on British Fossil Reptiles’. A key characteristic that Owen recognised was the fusing of vertebrae in the sacrum of Megalosaurus and Iguanodon. This had long been recognised for Megalosaurus, but only very recently had specimens of Iguanodon come to light that also showed this feature. Owen described this in terms of an adaptation to strengthen the backbone and help support these large animals upon the land.

Iguanodon sacrum
Engraving of the fossil sacrum of Iguanodon (via Wikimedia Commons)

In 1842, the report was published and Megalosaurus, Iguanodon and Hylaeosaurus became grouped under the name ‘Dinosauria’ (meaning ‘terrible lizard’).

As he describes in his report – “The combination of such characters, some, as the sacral ones, altogether peculiar among Reptiles, others borrowed, as it were, from groups now distinct from each other, and all manifested by creatures far surpassing in size the largest of existing reptiles, will, it is presumed, be deemed sufficient ground for establishing a distinct tribe or sub-order of Saurian Reptiles for which I propose the name of ‘Dinosauria’.


Since this time, our understanding of dinosaurs has advanced massively. Hundreds of dinosaur species have now been described from all over the world, and more are regularly added to this growing list. Our understanding of their morphology and how they lived also grows day by day. As a final note, it is interesting to look back on the first reconstructions of dinosaurs – those of the famous Crystal Palace Dinosaurs. Opening in 1854, just 12 years after the term ‘Dinosauria’ was first used by Richard Owen, these sculptures represent a fascinating snapshot of the views of these creatures at the time. Dinosaurs (along with other extinct forms of life) were starting to enter the public view not as old rocks, but as diverse communities, as real living creatures that roamed the Earth long before the first human being. Visiting these sculptures in the modern day, you can’t help but feel some of the excitement of these early days, from the times when dinosaurs were entirely new.

V0013783 The "Crystal Palace" from the Great Exhibition, installed at
Painting of the Crystal Palace dinosaurs. From left to right – Megalosaurus, Hylaeosaurus then two Iguanodon. (‘V0013783′ from Wellcome Images is licensed under CC BY 4.0)

References / suggestions for further reading

The Dinosaur Hunters by Deborah Cadbury – a popular science book focusing on Mary Anning, Buckland, Mantell and Owen

The Complete Dinosaur by Brett-Surman, Holtz and Farlow (chapters 1 and 2) – has a number of introductory chapters at the start on the history of research into dinosaurs

The Meaning of Fossils: Episodes in the History of Palaeontology by Martin J. S. Rudwick – an excellent book covering a wide range of events in the history of palaeontology

Oxford Museum of Natural History – http://www.oum.ox.ac.uk/learning/pdfs/buckland.pdf – a brief overview of the life of William Buckland

Friends of the Crystal Palace Dinosaurs – http://cpdinosaurs.org/ – many resources about the Crystal Palace Dinosaurs

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