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Roger Weller, geology instructor                     

Karen Murray
Physical Geology
Spring 2009



Dinosaur Valley State Park in Glen Rose, Texas, a wonderful experience for both children and adults.  Within this park is a plethora of tracks left by dinosaurs of all kinds, one such dinosaur which left its tracks behind was a large herbivore by the name of Iguanodon.  The tracks it left behind within this park are large enough to seat about 4 children inside comfortably, a hulking creature to say the least.


This physical attributes of the gargantuan reptile included a toothless beak and molars packed tightly into its cheeks.  The forelegs were relatively short, roughly comparable to an adult man in both length and thickness, and consisted of 4 toes and a thumb spike (conical spike).  The hind legs, on the other hand, were longer and bulkier and consisted of only 3 toes and hoof like claws.  The typical Iguanodon stood on all fours at a height of 16 ft and a length of 26 ft.  While proof has been found that the Iguanodon could stand on its hind legs, it is believed that it most commonly stood on all fours.


                It is believed that the first bones of Iguanodon were found in almost 200 years ago in 1822.  It is told that teeth of the first Iguanodon discovered were found by the wife of Doctor Gideon Mantell in the Tilgate Forest while her husband visited a patient.  In 1851, doctor Mantell confessed that he was actually the one who discovered them, and not his wife.  However, whether or not it was actually doctor Mantell or his wife who found them is still left to speculation.  It was also found through Mantell’s personal notebooks that in 1820 he had acquired a fossil specimen from the Whiteman’s Green quarry.  The fossil contained both herbivorous and carnivorous teeth, likely mixed together in a fight, which prompted him to attempt to combine the partial skeletal remains into a crocodile like form.  Later, when studying the teeth discovered, he noted that the teeth closely resembled that of an iguana, thus earning the creature the name ‘Iguanodon’.  In 1834, another Iguanodon fossil came to be discovered in a quarry in Maidstone, one of much higher quality than the previous.  From this fossil Mantell was able to put together a sketch of a far more accurate skeletal model than in 1820, although it was still not completely accurate.

As time passed, Mantell began to conflict with a man by the name of Richard Owen, an ambitious scientist with much better funding and connections to society.  Owen, a firm creationist, opposed the beliefs of evolution, a hot debate topic at the time, and used what he would soon coin as dinosaurs as a weapon in this conflict.  He scaled down dinosaurs from lengths of 200 ft and larger, determined to spread his belief they were not simply giant lizards, and put forward that they were mammal-like creatures, he believed that they were direct creations of God.  Like many other scientists at the time, he believed they could not have been transformed from reptiles to mammal-like creatures through time.

                While Owen believed Iguanodon to be more slender and small, Mantell realized that the Iguanodon was in truth more heavy and bulky like a pachyderm.  However, as a result of his passing, Mantell was unable to take part in the creation of the ‘Crystal Palace Sculptures’, a series of dinosaur sculptures which were commissioned in 1852 and unveiled in 1854.  Rather than using the proper Iguanodon structure and design, the Iguanodon sculptures were modeled in the likeness of Owen’s interpretation.  As a result, the public came to see Owen’s interpretation as proper for many decades.



Works Cited