Dogs are great optimists. They are also, by nature, empiricists. Experience has taught them that if they wait long enough, and with sufficient faith (manifest in a particular look which, while not resembling any human equivalent, nevertheless communicates itself to us across the species divide with absolute certainty) that which is believed in will come to pass: the ball will be thrown; the sausage will fall from the table. Dogs are also rarely disappointed. On the few occasions when the above does not work, something more interesting will inevitably turn up that then becomes of crucial importance. In this way, existential crisis is averted. The pigeon may not be caught, but look, there is another!

Of course, it may be that dogs have no intention of catching pigeons or, for that matter, car wheels. It is enough that the pigeon flies away, the car retreats. These too are results.

I spent several years of my childhood living in a bungalow. Down its center ran a hallway, at one end of which was the front door. This was panelled with two moderately sized sheets of patterned glass, one above, one below the letterbox. These panes, while offering privacy, nevertheless allowed us to see visitors approaching the door. Every morning one such visitor was the postman. You could set your watch by the regularity of his appearance, something our small and perky terrier knew only too well, and, as the time approached, Patch would skulk at the kitchen end of the corridor, with eager anticipation badly disguised as nonchalance. At the sound of the postman’s approaching steps the dog would fly down the hallway barking furiously and, a few feet before the door, leap forwards, hitting the glass with a satisfying clang. Equally satisfying would be the sound of the entire family shouting ‘Patch! Stop it!’ accompanied on the other side of the door by muttered curses occasionally augmented with a backwards stumble. It mattered not to Patch that the door prevented any chance of apprehending the intruder. Clearly the defensive manoeuvre had worked and the postman had, once again, been seen off. Happy with his work, our faithful guardian would then trot off and lie on the sofa.

However, over time the glass must have weakened so that, one day, the morning ritual did not culminate in the usual clang but with a great shattering explosion as the glass gave way and Patch, for the first time, found himself in actual physical contact with the postman. Perhaps contact is too strong a word? Bouncing off the postman’s legs Patch ended up seated on the lawn, surrounded by glass, while the postman ran up the garden path shouting ‘you want to watch that bloody dog’. It didn’t occur to Patch to chase the intruder because hitting the glass door had always worked, and now, with this obstacle removed, he found himself in unfamiliar territory. Instead, slightly bemused, he got up and found some very interesting things to sniff around the garden.

In 1821 a fossil tooth was discovered by a labourer while quarrying at Cuckfield in Sussex. The tooth came to the attention of Gideon Mantell, the Victorian palaeontologist. Mantell excited by what he believed to be the uniqueness of the find consulted a French comparative anatomist, a certain Baron Cuvier, but Cuvier pronounced it to be merely that of an ancient rhinoceros. Mantell cannot have been entirely convinced by this dismissal because, upon acquiring several more similar remains, he began to search for a living descendant whose teeth might resemble his own growing collection more closely. In his quest he came upon a specimen of iguana from the Galapagos islands. The Galapagos iguana is a herbivorous lizard whose staple diet is seaweed. While its teeth would have been substantially smaller than the petrified equivalents in Mantell’s possession; in every other respect the physical similarities, even down to the patterns of wear, were too similar to be ignored. In 1824 Mantell published these findings in a paper, pronouncing the discovery of a ‘new’ species and naming it Iguanadon, meaning Iguana tooth.

The study of palaeontology in Sussex during the 19th century was fraught with problems. Discoveries were rare and almost invariably incomplete; moreover, not enough was known within this emerging science to provide a framework within which to fit new examples as they came to light. What kind of animal could the teeth have belonged to? From the similar patterns of wear displayed in Mantell’s growing collection, Iguanadon could be established as being a herbivore, but biped or quadruped? Furthermore, of all the other bones that were from time to time dug up, which ones belonged to which? The physical attributes of the tooth collection’s original owners persisted as an enigma for years. Then in 1834 a quarryman in Maidstone found a more complete example of Iguanadon which, while still only partial and scattered, included a similar tooth. Mantell recognised the importance of this find and purchased it. He then set to reconstructing the pieces.

From his knowledge of other ancient and modern skeletons there were few difficulties in the putting together of this strange monster: hip bones, ribs and vertebrae were easily recognisable despite the novelty of the species and a team of technicians and assistants assembled these disparate elements into a semblance of what the creature may have looked like. There was one problem, no one could fathom the placement of a long sharp bone found with the others. Perhaps the earlier meeting with Baron Cuvier had an influence because it was finally decided that this fossil fragment should go on the end of the creatures nose thus giving it a somewhat rhinoceros like appearance.

Illustrations were prepared and the resulting pictures of this exotic beast, when published, stirred the imaginations of the contemporary scientific community. In the great inaugural exhibition of Crystal Palace in London it is recorded that a full sized model of iguanadon was shown, proudly displaying it’s horn.

Several years later in 1878, nineteen more or less complete examples of the dinosaur were exhumed by coal miners in a pit at Benissart in Belgium. In the ensuing excavation organised by Louis Dollo it was discovered that each came with not one but two of the aforementioned pointed bones. In all of the remains their position, when found, corresponded to the places where we might find thumbs on other animals. The illustrations and skeletal reconstructions were subsequently changed.