|Lower Cretaceous ( Valanginium to Aptium )|
|139.3 to 112.9 million years|
|Mantell , 1825|
Iguanodon ("iguana") is a typeof dinosaur belongingto the ornithopoda groupfrom the early Cretaceous and the largest and best-known representative of the Iguanodontidae . Due to the relative frequency of the finds and an assumed comparable way of life, the Iguanodon and its Hadrosauridae relatives are often referred to as the "cows of the dinosaur age".
Discovery and Description
Iguanodon fossil bones are the first safely identifiable dinosaur fossils ever found. As early as 1809, the geology pioneer William Smith collected, among other things, the fragment of a large shin bone (tibia) in the area of Cuckfield in Sussex while exploring the geology of Great Britain . For more than 150 years the piece remained largely unnoticed in the collection of the Natural History Museum in London and was only identified as a remnant of Iguanodon in 1970 .
In 1822, doctor Gideon Mantell discovered several of the animal's teeth in the same area. However, there is no evidence for the often-reported version that Mantell's wife found the pieces while she was waiting for her husband to return from a patient. Mantell may have heard of Smith's findings and specifically looked for fossil bones at Cuckfield. Mantell immediately recognized that it was the tooth of a large, extinct herbivorous reptile, but it was only after extensive research that published the first description in 1824 . Due to the similarity of the found teeth with those of today's iguanas , he named the animal Iguanosaurus ("iguana lizard"). In the following year he gave the genus its current name.
Back then, the animal was drawn on four legs, resembling an iguana. Today it is known that the animal mostly walked on both of its hind legs. The animal is also known for its pointed thumbs, which were shaped like a thorn and were probably used as a weapon. The pointed thumbbone was initially mistaken for a horn and was placed on the nose during the first reconstructions.
The 8 m long animal was erect, 5 m high and weighed up to 4.5 tons. The hands had 5 fingers each, the feet 3 toes each.
Iguanodon remains have been exposed in Western Europe, Central Europe, Romania, North America, North Africa and Mongolia. In Dorset , UK, 24 cm wide footprints have been found. The site in a coal mine near the Belgian municipality of Bernissart is very well known , where the fossils of a total of 31 individuals were recovered from 1877 to 1878 at a depth of 322 meters. At that time they were described and reconstructed by Louis Dollo . Iguanodon bones have also been discovered in Germany . During excavations in the Brilon district of Nehden , two skeletons of young animals came to light.
The nomenclatory type was initially I. anglicus , but the species was only covered with a single tooth. Since no complete skeleton was found later either, the ICZN redefined the nomenclature type in 2000 as I. bernissartensis , which is much better documented by the numerous well-preserved Belgian finds. I. bernissartensis is the only known representative of the genus Iguanodon , with all other species there is great doubt about the assignment to this genus.
Model of an Iguanodon with young animals in the "Dinopark" in Fürth (Bavaria)
- Dougal Dixon : The World Encyclopedia of Dinosaurs & Prehistoric Creatures. Lorenz Books, London 2008, ISBN 978-0-7548-1730-7 , p. 268.
- David Norman: Dinosaurs: A Very Short Introduction. Oxford University Press 2005, ISBN 0-19-280419-7 , pp. 19 ff.
- David AE Spalding, William, AS Sarjeant: Dinosaurs: The aerliest discoveries. Pp. 3-24 in: MK Brett-Surman, Thomas R. Holtz, James Orville Farlow (Eds.): The Complete Dinosaur. 2nd Edition. Indiana University Press 2012, ISBN 978-0-253-35701-4 , p. 12.