2014-02-21 16:27:42
“London. The first term of the term just ended, and the Lord Chancellor in session in the Great Hall of Lincoln’s Inn. Unrelenting November weather. As much mud on the streets as if the waters had just receded from the face of the Earth, and it would not be surprising to find a megalosaur, about forty feet long, staggering like a mammoth lizard towards Holborn Hill…”
Thus begins the first chapter of Charles Dickens’ novel Bleak House, the first literary work in which the name of a dinosaur appeared, in March 1852.
the first dinosaur
Dinosaur fossils have been unearthed for thousands of years. In China they were considered dragon bones, and are still used in traditional medicine today. In Europe it was believed that they were the remains of giants. But the first academic descriptions of dinosaur fossils were not made until the end of the century. XVII. The English naturalist Robert Plot, professor of chemistry at Oxford and curator of the Ashmolean Museum of that university, published in 1677 a description of a fragment of the femur of a large animal; as it was too large to belong to any of the species inhabiting England, he attributed it first to a Roman war elephant, and later to one of the giants that the Bible says died in the Great Flood. In 1699, his successor at the Ashmolean Museum, the Welshman Edward Lhuyd, described a fossil tooth that we now know belonged to a dinosaur.
A century later, in 1800, several collections of fossil bones collected by amateur naturalists in the Normandy region arrived at the National Museum of Natural Sciences in Paris, at the hands of zoologist Georges Cuvier, considered the father of paleontology. Among those bones were dinosaur vertebrae, but Cuvier, who described them in 1808, mistakenly associated them with other bones belonging to prehistoric marine crocodiles.
Megalosaurus e Iguanodon
Since 1820, the English gynecologist Gideon Mantell, fond of geology, had been collecting large fossil bones and teeth in a quarry in Tilgate Forest, West Sussex. At first, Mantell believed that they belonged to a giant crocodile. Some herbivorous teeth found in 1821 made him consider the possibility that part of the fossils belonged to some type of large herbivorous reptile; in 1822 he presented his findings to the Geological Society of London, but its members, among whom was the Rev. William Buckland, professor of geology at Oxford, were of the opinion that the teeth belonged to a fish or a rhinoceros. Two years later, in 1824, Buckland himself identified some fossils that he had collected between 1815 and 1824 as the remains of a huge carnivorous reptile, which he named Megalosaurus (“great lizard”). It was the first dinosaur to receive a scientific name. That same year, Mantell invited Buckland to see his collection, and this time Buckland agreed with Mantell that the bones and teeth belonged to a large reptile, though still unconvinced that it was herbivorous. Mantell then sent several teeth to Cuvier, who determined that they belonged to a giant herbivorous reptile. With Cuvier’s support, Mantell visited the Hunterian Museum of the Royal College of Surgeons of England, where the anatomical collections assembled by the 19th-century Scottish surgeon were kept. XVIII John Hunter, in search of similarities between his fossils and some living reptile. Coincidentally, the museum’s assistant curator, naturalist and geologist Samuel Stutchbury, had dissected an iguana a short time before, and realized that the Mantell reptile’s teeth were very similar to the iguana’s, although twenty times larger. Finally, in 1825, Mantell published the scientific description of the second dinosaur, which he named Iguanodon (“iguana tooth”). Although for him, as for all his contemporaries, they were only giant reptiles; the term “dinosaur” had not yet been invented.
Archaeopteryx y Hylaeosaurus
A few years later, in 1832, the German paleontologist Christian Erich Hermann von Meyer, who decades later would discover the first Archeopteryx feather, correctly identified the dinosaur vertebrae that Cuvier had studied fourteen years earlier in Paris, and gave them the name Streptospondylus. which means “inverted vertebrae”, since, unlike crocodile vertebrae, these were convex in front and concave behind. Today we know that Streptospondylus was a medium-sized carnivorous bipedal dinosaur that lived in France in the Middle Jurassic, about 160 million years ago.
That same year, 1832, an explosion in the same quarry where Mantell had discovered the first remains of Iguanodon brought to light several rocks containing the bones of what appeared to be a large lizard. A local fossil dealer sold the pieces, about fifty, to Mantell, who managed to put them together like a puzzle, discovering that they all belonged to a single skeleton, which had been preserved almost completely. Until then, the remains that had been found of Megalosaurus and Iguanodon had been only loose bones and teeth. Mantell thought it was an Iguanodon, but naturalist William Clift, curator of the Hunterian Museum, drew his attention to what looked like plates and spikes that were probably part of armor protecting the animal. Mantell then named it Hylaeosaurus, which means “forest lizard.”
Hylaeosaurus was a herbivorous, quadrupedal armored dinosaur, about six feet long, that lived in England in the early Cretaceous period, about 140 million years ago. Few more Hylaeosaurus fossils have been found since then, all in Europe, and the membership of many of them in the species is doubtful. The original remains of this dinosaur, preserved in the Natural History Museum in London, have remained embedded in its rock matrix until the early years of this century, when they began to be released by mechanical and chemical means. But no new study on them has yet been published.
Thecodontosaurus
In 1834, Samuel Stutchbury, the same person who had discovered the similarity between the teeth of the Iguanodon and those of the iguanas, was curator of the Bristol Museum. Together with the surgeon Henry Riley, he was conducting excavations in a nearby quarry, where the two discovered the remains of a new lizard, which they named Thecodontosaurus, which means “lizard with teeth in alveoli”, because the roots of its teeth were not fused. with the jaw bone, as in modern lizards, but embedded in alveoli.
Thecodontosaurus was a small herbivorous dinosaur, between five and eight feet long, twelve inches tall, and about twenty pounds in weight, that lived in the late Triassic period, about two hundred million years ago. It was bipedal, with a large head and eyes, a short neck, and a very long tail. He had five fingers on each foot and on each hand; these were narrow and elongated, and were armed with a long claw. The original remains of Thecodontosaurus were lost in the Bristol bombing raid during World War II, although other remains have been found at various sites in southern England.
The origin of the name “dinosaur”
Interest in the study of these large fossil lizards grew rapidly among European and American scientists; English paleontologist Richard Owen, who years later would found the British Museum of Natural History, found similarities between the first three species discovered in England, Megalosaurus, Iguanodon and Hylaeosaurus, which indicated that they belonged to the same taxonomic group, and in 1842 coined for this group the term “dinosaur”, which means “terrible lizard”. Owen did not include Thecodontosaurus in the group, perhaps because of its small size. It took until 1870 for the biologist Thomas Huxley, famous for his staunch defense of Darwin’s theory of evolution, to classify this species as a dinosaur.
For Owen, dinosaurs weren’t just giant reptiles, but rather had mammalian features. Owen, one of the most influential scientists of his time, was in charge of advising the sculptor Benjamin Waterhouse Hawkins for the realization of the first dinosaur sculptures that were made in the world. These first reconstructions were inaugurated in 1854, and had a great impact on the idea that the nineteenth-century public had of dinosaurs. The sculptures, which can still be seen in Crystal Palace Park in south London, show dinosaurs as burly quadrupeds. It is an open-air ensemble representing fifteen genera of extinct animals from various geological eras, not all of them dinosaurs. They are figures sculpted in cement on a steel and brick frame. Among them are two iguanodons; inside one of them, before the sculpture was finished, Owen held a banquet for twenty people.
the megalosaur
Those early species of dinosaurs have suffered very different fates throughout history. The worst part is taken by Buckland’s megalosaur. In the early years, the name Megalosaurus was used as a catch-all and was assigned to a multitude of fossil remains of carnivorous dinosaurs, which have since been identified as belonging to different species. According to some researchers, even the bones used by Buckland for the scientific description of the megalosaur, found in different places, belong to several different species; Technically, only one jaw bone would remain to carry out the scientific description of the species, which is clearly insufficient.
The second dinosaur, Iguanodon, has fared better. But a lot has changed since its discovery. Although as early as 1849 Mantell realized that, with its slender front legs, smaller than the hind legs, Iguanodon was not the quadruped imagined by Owen, the reconstruction of it in the Crystal Palace sculptures was accepted until, in In 1878, more fossil remains of the species appeared in a Bernissart coal mine in Belgium. Several dozen skeletons were excavated and reconstructed in 1888 by French-Belgian engineer and paleontologist Louis Dollo, an assistant naturalist at the Royal Belgian Institute of Natural Sciences. Dollo has gone down in the history of paleontology for the law that bears his name, Dollo’s law, which states that evolution is irreversible.
According to Dollo’s reconstruction, Iguanodon was bipedal, more like a kangaroo than Owen’s mastodon. A bony spike, which Owen had attached to the end of the snout, like a horn, turned out to be an extension of the thumb that Iguanodon probably used for defense or to open seeds and fruit. Today we know that Dollo’s reconstruction was not correct either. The Iguanodon tail was covered by strong ossified tendons, and was quite rigid; to adopt the upright bipedal kangaroo posture given to him by Dollo, those tendons would have to be broken. In reality, Iguanodon kept its body horizontal, and could walk equally well on two or all four legs. It was a herbivorous dinosaur weighing about three tons, which could measure up to twelve or thirteen meters long. It lived in Europe at the beginning of the Cretaceous, about 125 million years ago.
Meanwhile, on the other side of the Atlantic, the discoveries of dinosaur bones were waiting. But this is another story that we will tell another time.
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