A thousand ages underground
His skeleton has lain;
But now his body’s big and round,
And he’s himself again!
His bones, like Adam’s, wrapped in clay,
His ribs of iron stout,
Where is the brute alive today
That dares to turn him out?
Beneath his hide he’s got inside
The souls of living men;
Who dare our saurian now deride
With life in him again?
(Chorus)
The jolly old beast
Is not deceased
There’s life in him again (ROAR)
—SONG BY EDWARD FORBES, 1852, SUNG INSIDE THE IGUANODON MODEL IN THE “DINNER IN A DINOSAUR”
THE WEALDEN
If you drive southeast from the suburbs of London, you soon leave behind the dense housing and crowded streets and find yourself in the quiet countryside of Sussex (from the Old English “South Saxony”). The landscape is truly pastoral, with quiet country fields full of sheep and horses, and quaint villages here and there that have changed very little in 400 or 500 years or more. The roads were built to deal with one slow-moving single carriage or oxcart at a time and are extremely narrow; modern cars have a challenge squeezing through the tight spots and blind corners at high speed. Don’t even think about trying to park!
Thanks to the abundant rainfall typical of all the British Isles, the countryside is green and well watered without visible outcrops except in an occasional roadcut or beach cliff. These exposures are nothing like the famous desert landscapes of the Rocky Mountains that yield most of North America’s dinosaurs, nor are they like the spectacular cliffs and buttes of the Gobi Desert or the dry Argentinian Pampas and Andean foothills that are famous for their dinosaurs. Rest assured that dinosaurs are underfoot, but only luck and a rare good exposure provides any chance of collecting them.
Even a good geologist is hard-pressed to recognize the formations beneath the landscape until he or she acquires a more discerning eye. Geologists soon realize that the high ridges (perversely, they are called the “Downs” or “downlands”) are held up with the famous Cretaceous Chalk beds, which are exposed along the southern coast of England from the White Cliffs of Dover to the Isle of Wight. The Chalk was the first geologic unit recognized in the area and gave the Cretaceous its name (creta is the Latin word for “chalk”). The Chalk is made up of trillions of tiny shells of plankton (especially phytoplankton, or golden-brown algae known as coccolithophorids), which are only a few tens of microns across. Such plankton once bloomed in the shallow warm seas that drowned most of Europe. Similar chalk beds are found across the English Channel in Belgium and northeastern France, in Denmark, and even in Austin, Texas, and western Kansas.
Figure 2.1
The Wealden anticline and the Jurassic and Cretaceous rocks that make it up: (A) geologic map of Sussex and Kent, showing the outcrop pattern with the large parabola of the beds of a plunging anticline, with the older Jurassic and Lower Cretaceous Wealden beds in the middle and the Upper Cretaceous Chalk on the flanks (North and South Downs); (B) cross section showing the relations of the strata. (Redrawn from several sources)
Across Sussex and Kent, the Chalk crops out in a big parabola opening to the east (figure 2.1), which developed due to an upward fold that geologists call a plunging anticline. In the center of the parabola is a lowland area, once heavily forested, known as the Weald (Old English for “woodland” and related to the German word for “forest,” Wald). The bedrock beneath the Weald is made of Lower Cretaceous rocks that once lay beneath the Chalk but are now exposed as the chalk beds were folded upward and eroded away (figure 2.1B). A dome of layered Lower Cretaceous rocks has been cut by weathering to expose the layers as sandstone ridges and clay valleys. The oldest rocks exposed at the center of the anticline are correlated with the Purbeck Beds of the Upper Jurassic. Above these, the Cretaceous rocks include the Wealden Group of alternating sands and clays: the Ashdown Sand Formation, Wadhurst Clay Formation, Tunbridge Wells Sand Formation (collectively known as the Hastings Group), and the Weald Clay. The Wealden Group is overlain by the Lower Greensand and the Gault Formation, consisting of the Gault and the Upper Greensand. These in turn are capped by the Chalk.
The rocks of the central part of the anticline include hard sandstones, and these form hills now called the High Weald. The peripheral areas are mostly softer sandstones and clays and form a gentler rolling landscape, the Low Weald. The Weald-Artois Anticline continues some 64 kilometers (40 miles) further southeastward under the Straits of Dover and includes the Boulonnais region of France.
THE COUNTRY DOCTOR AND THE GIANT TEETH
In the middle of the Lower Cretaceous beds of the Weald lies the tiny village of Cuckfield. Today it is just a quiet country town with Tudor-style white buildings with dark timber beams that date back 500 years or more. In 1822, however, it was the starting point for the first extensive discoveries not only of dinosaurs but of entire dinosaurian faunas. That year Gideon Mantell, a local doctor (figure 2.2) from the nearby town of Lewes, was working in the area, visiting his patients and collecting fossils on the side. Although most people pronounce the name with the accent on the second syllable, in Lewes and throughout Kent and Sussex it is pronounced MAN-tle (like the name for the cloak, or the layer in the earth’s interior).
Figure 2.2
Portrait of Gideon Mantell. (Courtesy of Wikimedia Commons)
Mantell is an interesting example of how paleontology first blossomed; it was not solely due to the work of the educated scholars of Oxford and Cambridge (such as Buckland) but also due to the people of many walks of life who were interested in natural history. Some were dedicated field collectors with limited education, such as the famous Mary Anning. Her discoveries of marine reptiles and other fossils from Lyme Regis began the entire field of vertebrate paleontology in England. Others were dedicated amateurs with limited specialized education who studied fossils as a hobby. Many, such as Mantell (or James Hutton, the founder of modern geology), were trained as doctors and had as much scientific education as could be obtained in those days.
Mantell was typical of the naturalist doctors of his time. Born in Lewes in 1790, he was one of five children of a humble shoemaker. At an early age, he showed an interest in collecting fossils and understanding the geology of the Weald, discovering ammonites, sea urchins, fish bones, corals, and other typical fossils of the region (especially the Chalk). A family of Methodists, the Mantells were forbidden from attending any of the local schools (which were only open to Anglicans), so young Gideon was tutored by local women who operated their own small schools at home. At age 15, he was apprenticed to the local doctor, James Moore, for five years. Originally his job was cleaning tools and vials and separating and arranging drugs and doing the doctor’s billing and bookkeeping, but eventually he learned to make pills himself and to extract teeth from patients. When his father died in 1807, Gideon began to study medical anatomy texts closely and subsequently wrote his own book based on what he had learned. By 1811, he had received a medical education in London and was admitted to the Royal College of Surgeons. There he did an internship as an obstetrician in a women’s hospital delivering babies. Once he had finished his London duty, he returned to Lewes and became a partner of Dr. Moore, his former master and mentor. He soon became very busy, typically seeing 50 patients a day, traveling to see each one at home. He workload was staggering. He helped deliver about 300 babies a year. He often stayed up six or seven nights in a row when delivering babies all over Sussex.
Despite this exhausting schedule, Gideon took time when he could to search for fossils and other interesting natural objects on his trips around Sussex. By 1813, he was corresponding with fossil collector James Sowerby about his finds and sent some of his best specimens to Sowerby. A species that Gideon had collected was named after him by Sowerby, Ammonites mantelli. By December 1813, Mantell had published his first paper on the fossils of the Lewes area and had been elected as a Fellow of the Linnean Society of London.
During those years of grueling work, Mantell and Dr. Moore dealt with epidemics of cholera, typhoid, and even plague, which killed hundreds of his patients. The daughter of one of those victims was Mary Ann Woodhouse, and she and Gideon fell in love when he was treating her father. They married in 1816 when he was 26 and she was 20 years old (still technically underage). She had to obtain special permission to marry because her father was dead. That same year Gideon set up his own medical practice, and his wife often went with him to help with patients. She also spent time collecting fossils while Mantell was busy with work.
Inspired by Mary Anning’s sensational discovery of ichthyosaurs and plesiosaurs at Lyme Regis in Dorset, Mantell became passionately interested in the study of the fossil animals and plants found in his area. By 1819, Mantell had begun acquiring fossils from a quarry near Cuckfield (figure 2.3). These included the first remains of terrestrial and freshwater ecosystems at a time when all the known fossil remains from the Cretaceous of England were marine fossils. As Mantell began to map and understand the geologic sequence of the rocks of the Weald, he called the new beds the Strata of Tilgate Forest, after a historical wooded area. Today that same Tilgate Quarry is covered by a park and soccer field called Whiteman’s Green. Standing there today watching kids playing soccer, it is difficult to visualize the steep rock quarry, which has been filled in, but if you stand in the right spot, you can still see the church steeple in the background and determine that you are in the right place. The tiny Cuckfield Museum in town exhibits quite a few small fossils of dinosaurs that were found there.
Figure 2.3
The frontispiece of Mantell’s 1827 book showing workers in the quarry in the Wealden rocks of the Tilgate Forest, where the first Iguanodon fossils were found. (From Gideon Mantell, The Geology of Sussex, 1827)
By 1820, Mantell had acquired some very large bones from the quarry men at Cuckfield. They were as large as those discovered and named Megalosaurus by William Buckland at Stonesfield Slate Quarry north of Oxford. In 1822, Gideon was finishing his first book (The Fossils of South Downs) and was on the lookout for more fossils. Legend has it that while waiting for Gideon to come back from his rounds, Mary Ann found several large teeth in the roadside that looked like nothing anyone had ever seen before (figure 2.4). (Other scholars say that Gideon rarely took his wife along and found the fossils himself, which is what he claims in his own books.) By 1821 Gideon had written and published his next book on the geology of Sussex. It was an immediate success, with 200 subscribers. One of these was none other than King George IV himself. The letter the king wrote at Carlton House Palace read: “His majesty is pleased to command that his name should be placed at the head of the subscription list for four copies.”
Figure 2.4
Illustration of Iguanodon teeth and the jaw of a modern iguana for comparison. (From Gideon Mantell, “Notice on the Iguanodon, a newly discovered fossil reptile, from the sandstone of Tilgate forest, in Sussex,” Philosophical Transactions of the Royal Society, no. 115 [1825]:179–186)
The king probably heard about Mantell’s work when he spent summers at the nearby beach resort town of Brighton. We definitely know how Gideon responded. Now realizing he was onto something important, Mantell showed the teeth to other scientists, but none of them could identify them. Buckland and some others called them teeth of a huge fish or teeth from a large mammal. Others doubted that they were that old, suggesting they might have come from a younger deposit. There were many instances of Ice Age beds deposited on top of the older Mesozoic bedrock that sometimes yielded rhinoceroses, hippos, and mammoths, whose teeth are also large; these were clearly much younger than the ancient Tilgate Forest fossils. No one could imagine that such huge, flat, grinding teeth could have come from a reptile because most reptilian teeth are pointed and cone-shaped for grabbing prey. They are not grinding teeth for eating vegetation—and not even the largest crocodile had teeth this big.
On a trip to Paris, Charles Lyell (author of Principles of Geology in 1830, which helped found modern geology) brought some of Mantell’s teeth to the famous Baron Georges Cuvier, founder of comparative anatomy. During his weekly salon with friends and admirers, Cuvier examined the teeth and told Lyell that they were rhinoceros teeth. According to Lyell, “the next morning he told me that he was confident that it was something quite different.” Unfortunately, Lyell never told Mantell about Cuvier’s retraction in Paris, and Mantell felt hurt by having been rejected by the great Cuvier. In 1824, Mantell sent some more teeth to Cuvier, who then admitted he was wrong and that the teeth were from some gigantic herbivorous reptiles. Cuvier even printed a retraction in his Recherches sur les Ossemens Fossiles later that year.
Convinced he was right, Mantell looked harder and found more bones and teeth that were unquestionably from the Mesozoic rocks of the Wealden Group. Meanwhile, other people looked among living animals for something with similar teeth. Samuel Stutchbury, then an assistant curator at the Hunterian Museum, discovered that they resembled the teeth of an iguana (which he had just been working on) but were 20 times larger (figure 2.4). From these isolated teeth and a few broken chunks of limb bones, Mantell estimated that the creature must be at least 18 meters (60 feet) long.
Mantell’s ideas were finally confirmed in 1825 when publication of the formal description of Megalosaurus opened the possibility of gigantic extinct reptiles. Most scholars soon agreed with Mantell that the teeth looked like those of an immense iguana. But what should he call this new creature? In his original presentation Mantell named it “Iguana-saurus,” but he then received a letter from William Daniel Conybeare objecting to that name: “Your discovery of the analogy between the Iguana and the fossil teeth is very interesting but the name you propose will hardly do, because it is equally applicable to the recent iguana. Iguanoides or Iguanodon would be better.” Of those two names, Iguanodon (“iguana tooth”) made the most sense, and thus it got its name.
As the years progressed, the Mantells collected enough fossil limb bones to demonstrate that the forelimbs of Iguanodon were much shorter than its hind legs. Their best find was a slab from the Lower Greensand found in 1824 that contained a partial skeleton of an iguanodontid (now considered a distinct genus named in his honor, Mantellisaurus). This helped improve Mantell’s coverage of the bones and enabled him to make a more accurate reconstruction. Newer specimens showed that it was not built like a rhinoceros or elephant, as Sir Richard Owen and others claimed. Even more discoveries showed that fossil vertebrae found in the Tilgate Quarry were from Iguanodon. Unfortunately, Mantell also made mistakes. Among the fossils found in Tilgate Quarry was a large spike-like object, which Mantell thought was a nose horn, making Iguanodon look even more rhinoceros-like.
But Mantell went further than Buckland or the others: he found not just a single dinosaur but a complete fauna of dinosaurs and other animals that had lived in the area in the Early Cretaceous. Some of the fossils came not from Iguanodon but from something with a very different build. In 1833, Mantell gave a partial skeleton the new generic name Hylaeosaurus. This name was based on limited material, but Hylaeosaurus is now known to be a small nodosaurid ankylosaur (see chapter 21). He found and named two other local dinosaurs, Pelorosaurus (an enormous sauropod known from an enormous upper arm bone and a few vertebrae) and Regnosaurus (later found to be a stegosaur, only known from a partial jaw), along with fish fossils and crocodiles. Together with his other discoveries, Mantell had found and named four of the first five known dinosaurs and was the world’s leading authority on prehistoric reptiles.
Mantell did something even more groundbreaking: he documented not only the fossils but also their geological context and provided the first paleoecological speculation about the environment inhabited by Iguanodon, Hylaeosaurus, Pelorosaurus, Regnosaurus, and other Wealden creatures. From the fish fossils, fossilized mud cracks, and even dinosaur tracks, he demonstrated that the beds were of freshwater origin—not marine rocks like the Chalk and much of the Cretaceous sequence in southeastern England.
Over the rest of his life, Mantell wrote more and more about Sussex fossils. Given his busy medical practice, he was amazingly prolific. He published 67 books and 40 scientific papers over his lifetime. In 1833, he moved his medical practice south from Lewes to the fashionable coastal resort town of Brighton, the favorite summer holiday spot for King George IV, and set up his own museum in addition to his medical duties. His medical practice suffered, however, because he spent most of his time collecting fossils and doing geology instead of attending to patients. In his darkest hour, the Brighton town council supported him by turning his house into a museum. There he gave a very successful lecture series titled “The Wonders of Geology, or A Familiar Exposition of Geological Phenomena: Being the Substance of a Course of Lectures Delivered at Brighton.” This lecture was published as a book in 1838, which helped his finances somewhat. Unfortunately, Gideon’s home museum failed because he neglected to charge admission to people who wanted to see his spectacular collection. Hitting rock bottom financially, he offered his entire collection to the British Museum for £5,000; they lowballed him and paid him only £4,000. There his collection still resides.
By 1839, Mantell had fallen on hard times. His wife left him with their four surviving children, his son emigrated to New Zealand (where he acquired and sent his father the first fossils of extinct giant birds known as moas), and then a year later his daughter died. Seeking new patients, Mantell moved to Clapham Commons in southern London and spent the rest of his life treating patients. In 1841, he had a terrible carriage accident; he fell from his seat, was entangled in the reins, and was dragged along the ground for some distance, severely injuring his back. He suffered ever-increasing pain and severe scoliosis throughout the remainder of his life. He used chloroform and later became addicted to opium to alleviate the extreme pain. (After his death, Richard Owen had Mantell’s severely deformed and fused spine dissected and preserved at the Royal College of Surgeons as an example of scoliosis. It was destroyed during the bombing of London in World War II.)
During his last few years, Mantell tried to maintain his medical practice while publishing books about fossils and geology, but he felt abandoned and neglected because others had stolen his thunder and built on his research. Crippled and sickly, he frequently visited the Great Crystal Palace Exhibition in Hyde Park in 1851. Mantell gave a lecture on November 10, 1852, and died of an opium overdose later that night in his home (possibly a deliberate suicide, or possibly an accidental overdose after falling on the stairs in his home).
Today his home on 166 High Street in Lewes is a historic landmark maintained by the National Trust. It is marked by a rectangular blue plaque that reads:
Dr. Gideon A. Mantell, F.R.S.
Surgeon and Geologist
Born in Lewes 1790. Died in London 1852
Lived here
He discovered the fossil bones
Of the prehistoric Iguanodon
In the Sussex Weald.
Tilgate Quarry is covered by an athletic field, but there is a monument at Whiteman’s Green where the first Iguanodon was discovered, and the tiny town museum in Cuckfield commemorates Mantell and his fossils. Mantell’s work was truly pioneering; his 1849 description of Iguanodon won the Royal Medal of the Royal Society, the second-highest award in science at that time. More important, Mantell holds a prime place in the history of paleontology: the first to discover a nearly complete dinosaur skeleton (Megalosaurus was very incomplete) from a locality we still can locate (the position of the type locality of Megalosaurus is unknown), and the first to describe a dinosaur fauna.
The following was written as a memorial to him by a member of the Council of the Clapham in 1853:
Living in the midst of a most interesting geological district, his quick appreciation could not fail to be struck with its interesting characteristics. As on his professional visits, he rode or drove over the South Downs and Weald of Sussex, he was continually searching for the organic treasures imbedded in the quarries or lying by the roadside, which afforded him an inexhaustible source of delight and instruction; and he thus accumulated materials which eventually enabled him to establish the fresh-water character of the Wealden,—a discovery which alone will hand down his name to the latest posterity as one of the great founders of the science of Geology,—and brought together the fragments of fossil bones which afterwards gave him the power of building up the skeletons of those gigantic reptiles, the hyleosaurus, iguanodon, pelorosaurus, others, with which he astonished and delighted, not only the public generally, but the scientific world. The number of specimens so collected amounted to upwards of 1,200, and with these he founded the Mantellian Museum, which was visited, while he lived at Lewes, by the most eminent men of the day; among others by Baron Cuvier, and by the Royal Princes. This collection he afterwards removed to Brighton, when he went to reside there, and he made great efforts to have it established in the county from the strata of which it had been gathered, as the nucleus of a local geological museum, but the requisite funds were not forthcoming, and it was ultimately sold to the British Museum.
DINNER IN A DINOSAUR
Meanwhile Mantell’s archrival, Richard Owen, was up to his usual tricks. Throughout his career, Owen did everything he could to dismiss or to minimize Mantell’s discoveries, even stealing credit for some of them. Mantell was too ill to work on the fossils that were now in the British Museum, so Owen took charge of them, publishing several papers between 1849 and 1884 that were later collected in a huge four-volume History of British Fossil Reptiles. In that book, Owen redescribed and reinterpreted Mantell’s specimens.
Owen saw an opportunity for great publicity in the upcoming Great Crystal Palace Exhibition and commissioned Benjamin Waterhouse Hawkins to build huge concrete reconstructions of nearly all the prehistoric beasts then known (see chapter 1). These 33 sculptures included Buckland’s Megalosaurus and Mantell’s Iguanodon and Hylaeosaurus, as well as nearly every other extinct creature: the plesiosaurs and ichthyosaurs that Mary Anning had found; the pterodactyls, mosasaurs, and marine crocodiles; the giant amphibians then known as labyrinthodonts; some of the Eocene mammals reported from the Paris and London basins; and even some Ice Age mammals. The reconstructions of ichthyosaurs, plesiosaurs, the giant ground sloths, and Irish elk were reasonably accurate by today’s standards because they were based on nearly complete fossils. But the Megalosaurus was rendered as a giant quadrupedal lizard because so little was known of it at that time (see figure 1.6).
Even worse was Owen’s version of Iguanodon. Although as early as 1849 Mantell had published illustrations of the smaller, delicate front limb bones to show that it could walk on two legs, Owen had it reconstructed in a quadrupedal pose like an elephantine lizard (see figure 1.5 and figure 2.5). Being the largest creatures there, the two Iguanodon reconstructions dominated the exhibit (figure 2.5A). They were so large and spectacular that Hawkins organized a famous 1853 New Year’s Eve party for Owen and 20 other leading paleontologists with a table set inside the mold of the larger Iguanodon (figure 2.5B). Sadly, Mantell had died just a few months earlier, and although his name was commemorated on the walls, he was no longer around to take his rightful place among the other giants of paleontology.
Figure 2.5
Benjamin Waterhouse Hawkins’ reconstruction of Iguanodon (guided by Richard Owen) in the Crystal Palace Exhibition, now in Crystal Palace Park in Sydenham: (A) the sculptures as they appear today; (B) image from the Illustrated London News in 1853 of Owen hosting a dinner in the hollow shell of Iguanodon (before it was completed) for the leading scientists of the day; the tent pavilion around them has the names of Owen, Mantell, Buckland, and Cuvier displayed prominently. ([A] Photo by the author; [B] Courtesy of Wikimedia Commons)
When the Great Exhibition closed, the sculptures and the giant Crystal Palace made of iron and glass were moved from Hyde Park in central London to Sydenham Park in southeastern London, which became known as Crystal Palace Park. They were placed in a corner of the park on a series of islands, and the water protected them from being climbed on by overcurious visitors. Over the years, they suffered much damaged through weathering as the elements broke down the concrete. The Crystal Palace itself burned down in 1936, and by the end of the twentieth century, the dinosaur sculptures were decaying and badly overgrown. In 2002, money was raised to restore them to their original glory, and they remain available for inspection by anyone visiting London’s Sydenham Park during daylight hours. They are amazing monuments of where paleontology was more than 160 years ago and provide a benchmark for how much has been learned since then.
DINOSAURS IN THE COAL MINE
Despite Mantell’s suggestion that Iguanodon might have walked on two legs, Owen’s quadrupedal reconstruction dominated for a few more decades. With such incomplete and fragmentary fossils, it was impossible to know what these extinct creatures looked like. All of this changed on February 28, 1878, when two coal miners, Jules Créture and Alphone Blanchard, accidentally hit fossil bones at a depth of 322 meters (1,056 feet) in a coal mine near Bernissart, Belgium. By May, the mine workers began to excavate the skeletons from the depths of the mine under supervision of a technician from the museum in Brussels, and they were brought to the surface. By 1882, there were no less that 38 fossil skeletons in the Belgian collections. Most of them were complete, articulated skeletons of adult Iguanodon.
Their study fell to the Belgian paleontologist Louis Dollo, later famous for “Dollo’s Law,” which said that evolution is not reversible. Dollo published a few short notes on the fossils, but it was almost a century later, in 1980, before David Norman finally completed the work and published a lengthy monograph on them. In 1881, the famous herpetologist George Albert Boulenger formally gave them a new species name, Iguanodon bernissartensis. The type specimen was mounted on a scaffold with adjustable ropes holding it in place, which was the first time any dinosaur had been mounted in a life-like pose for public display (figure 2.6). It was opened for public viewing in the Palace of Charles of Lorraine in July 1883, and in 1891 the fossils were moved to the Royal Museum of Natural History (now the Royal Belgian Institute of Natural Sciences, where they still stand today). This row of nine huge standing mounts made a very impressive display, and 19 more sit in the museum basement because there was not room to display all of them. Casts of the Belgian specimens were eventually sent to the museums in Cambridge and Oxford, where they are still on display.
Figure 2.6
The Bernissart Iguanodon specimens: (A) shown as originally mounted using wooden scaffolds and ropes to suspend the bones in place; (B) shown as they are currently mounted in the Royal Belgium Institute of Natural Sciences in Brussels; (C) mounted Iguanodon in the Oxford Natural History Museum in the outdated “kangaroo” pose. ([A–B] Courtesy of Wikimedia Commons; [C] photograph by the author)
Such complete articulated skeletons allowed scientists to put Iguanodon together correctly for the first time (figure 2.7). Not only were they capable of bipedal walking, but the front limbs were only of limited use for locomotion. The “nose horn” that Mantell and Owen had put on the snout of the models turned out to be a thumb spike.
Figure 2.7
Modern reconstruction of Iguanodon as it looked in life, with a long straight tail and spikes on the thumbs rather than on the nose. (Courtesy of N. Tamura)
Dollo also made some mistakes that have been corrected by more recent work. In the 1970s, paleontologists began to realize that most of the bipedal dinosaurs, from the large predatory theropods to the duck-billed dinosaurs and many others, must have held their bodies horizontal to the ground, balanced on their hip joint, and held their tails out straight behind them as a counterbalance. This was established by dinosaur trackways, which seldom show any tail drag marks, and also by the presence of a network of tendons to hold the tail rigid in many dinosaurs, especially duck-billed dinosaurs and long-necked sauropods. Even the Bernissart specimens were discovered with straight tails and ossified tendons. Yet the bias of nearly all paleontologists of that time was that dinosaurs were stupid, slow, sluggish monsters living in swamps, dragging their heavy bodies and tails around. Nearly all the original Belgian mounts (and their copies in England) posed the skeleton like a kangaroo, leaning back on a curved tail braced against the ground. (Dollo had to break the straight row of tail vertebrae in the mount to make it curve in the kangaroo pose.) Many museums (such as those in Belgium) have remounted some of their Iguanodon skeletons in the modern balance-beam stance (figure 2.6B), but others (such as those in Cambridge and Oxford) do not have the money or staff to completely tear down their century-old replicas and remount them in the modern fashion (figure 2.6C). Thus they remain as a relict of an earlier way of thinking about dinosaurs.
Iguanodont material has been found in numerous other places, from the Isle of Wight in England to Mongolia to Africa to South Dakota to Utah. Most of it was originally assigned to the genus Iguanodon, which once had dozens of different species, but these finds have since been redescribed and renamed in new genera. The huge herd at Bernissart is not the only place where a large numbers of specimens have been found. In Nehden, in North Rhein-Westphalien in northwestern Germany, a quarry yielded another assemblage killed in a flash flood. At least 15 individuals, from 2 meters (6.6 feet) to 8 meters (26 feet) in length, were preserved there.
Today we know Iguanodon was a bulky bipedal herbivore that could occasionally shift to a quadrupedal posture. The Bernissart specimens show that they reached 10 meters (33 feet) to 13 meters (43 feet) as adults and weighed about 3 metric tonnes (3.3 U.S. tons). This range is much smaller than estimates given by Mantell or Owen, who thought Iguanodon was the largest creature that had ever lived on land (before much larger dinosaurs were found). Iguanodonts had long narrow skulls with a toothless beak, and those distinctive iguana-like teeth are arranged in dense rows in the jaw.
The long slender forearms had three robust middle fingers to bear the weight when they leaned forward in a quadrupedal posture, plus the thumb spike projecting forward and inward. The function of the thumb spike is debated. They could have been used for defense against predators or fighting other members of their herd, or possibly for foraging for food. Their “pinky” finger was long and flexible and may have been able to manipulate the plant fronds on which they fed. They had powerful hind legs, but their proportions and size do not suggest that they were very fast runners. As mentioned previously, the backbone and tail were stiffened by ossified tendons, which held them rigid in a straight line, but these were often left off the skeletal mounts because they didn’t fit when they were posed like kangaroos (although they are preserved intact on the vertebrae of the Brussels mounts).
Thus Iguanodon is not only one of the earliest dinosaurs to be discovered but today is also one of the best studied and represented, with dozens of specimens from many continents, including two large quarry samples. We have come a long way from Mantell’s or Owen’s early notions of a giant saurian pachyderm to the more delicately built biped and quadruped we know today.
FOR FURTHER READING
Cadbury, Deborah. The Dinosaur Hunters: A True Story of Scientific Rivalry and the Discovery of the Prehistoric World. New York: Harper Collins, 2000.
——. Terrible Lizard: The First Dinosaur Hunters and the Birth of a New Science. New York: Henry Holt, 2001.
Colbert, Edwin. Men and Dinosaurs: The Search in the Field and in the Laboratory. New York: Dutton, 1968.
Maddox, Brenda. Reading the Rocks: How Victorian Geologists Discovered the Secret of Life. New York: Bloomsbury, 2017.
McGowan, Christopher. The Dragon Seekers: How an Extraordinary Circle of Fossilists Discovered the Dinosaurs and Paved the Way for Darwin. New York: Perseus, 2001.
Naish, Darren. The Great Dinosaur Discoveries. Berkeley: University of California Press, 2009.
Rudwick, Martin. Bursting the Limits of Time: Reconstructing Geohistory in the Age of Revolution. Chicago: University of Chicago Press, 2007.
——. The Meaning of Fossils: Episodes in the History of Paleontology. New York: Science History, 1976.
——. Worlds Before Adam: Reconstructing Geohistory in the Age of Reform. Chicago: University of Chicago Press, 2010.
Spaulding, David A. E. Dinosaur Hunters: Eccentric Amateurs and Obsessed Professionals. Rocklin, Calif.: Prima, 1993.