In 1825 physician and amateur paleontologist Gideon Mantell described the dinosaur genus Iguanodon based on fossils collected in a quarry north of Cuckfield in the Tilgate Forest. Since then, he periodically visited the quarry in search of more fossils, and also persuaded quarry workers to contact him if they found any interesting fossils.
In the summer of 1832, he got word from the quarrymen that they had found a large chunk of rock containing bones. Mantell went to investigate and realized the remains represented a new type of reptile-like animal that he would name Hylaeosaurus.
Gideon Mantell Describes Hylaeosaurus
When Mantell arrived at the quarry to examine the fossil-bearing chunk of rock, he found that the workers had blasted the rock and broke it up into several pieces before realizing it contained fossils. Mantel, undeterred, gathered more than 50 pieces and had them shipped back to his home in Lewes.
Mantel spent several weeks reassembling the rock fragments to produce a large block 4 ½ feet long. He spent more time carefully removing rock matrix around bones, eventually revealing numerous vertebrae, ribs, and other bones.
Of particular interest was a series of bone plates and spines, the largest more than 17 inches long and seven inches wide at the base. Mantell believed these bones were originally positioned along the top of the animal’s back. Paleontologists later determined they projected from the side of the animal and were used for defense.
In 1933 Mantell named the beast Hylaeosaurus (“forest lizard”) armatus (“armored”). Ten years later, anatomist Richard Owen included Hylaeosaurus, along with Megalosaurus and Iguanodon, in his new classification of fossils he called Dinosauria, the dinosaurs.
Characteristics of Hylaosaurus
Today paleontologists classify Hylaeosaurus as a type of ankylosaur, an armored herbivourous dinosaur. It is a member of the family Nodosauridae, a type of ankylosaur lacking tail clubs.
Hylaosaurus lived during the early Cretaceous Period, about 135 million years ago. It had short legs, grew to a length of up to 20 feet, and weighed up to two tons. Except for its belly, it was covered with plates and spikes for defense.
H. armatus remains as the only valid species in the genus Hylaeosaurus, and Mantell’s fossils, still embedded in his reconstructed block, remain as the best examples of the taxon.
Sources
Cadbury, Deborah. 2000. Terrible Lizard. Henry Holt and Company.
Mantell, Gideon. 1833. The Geology of the South-East of England. Longman, Rees, Orme, Brown, Green & Longman.
Kevin Schindler - I have worked at scientific institutions for more than 20 years written more than 200 articles about science, history, and baseball.
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