Multiple specimens of jaw bones were discovered by Samuel Beckles high on a cliff in Durdlestone Bay on the Isle of Purbeck in southern England.
These fossils, including many teeth as well as maxilla and dentary bones of the upper and lower jaws, were found alongside shells and plant fossils in the Purbeck Beds.
These were first described in a monograph published in 1861 written by Sir Richard Owen, a British palaeontologist who also described fossils of Iguanodon and Megalosaurus.
Owen gave the name Echinodon becklesii for the fossils, which he considered to be part of the lizard clade Lacertilia.
While the specific name honoured Beckles for his discovery of the fossils and allowing Owen to study his collection of Purbeck fossils, the generic name was derived from the Ancient Greek εχινος, 'hedgehog', and ὀδών, 'tooth', which Owen combined as "prickly tooth" to describe the anatomy of the serrations along the sides of the teeth.
Owen had corresponded with British palaeontologist Hugh Falconer, who had suggested the name "Sauraechinodon", but as the shortened form Echinodon was not preoccupied, Owen chose to use the abbreviated form as the name for his new animal.
Falconer issued a correction in 1861, specifying that he proposed the name "Sauraechmodon" instead of "Sauraechinodon".

Although originally described as a lacertilian by Owen, he revised his classification in 1874 to group Echinodon with Scelidosaurus and Iguanodon in a clade he called Prionodontia, which was within the larger clade Dinosauria.
In 1888 British palaeontologist Richard Lydekker followed previous classification of Echinodon as a dinosaur based on the anatomy of its teeth, describing them as similar to Scelidosaurus although not referring them to a more specific clade than Dinosauria indeterminate.
The series of specimens designated as types by Owen were purchased by the British Museum of Natural History (BMNH now NHMUK) in 1876 and form part of the Beckles Collection, bearing specimen numbers NHMUK 48209 to 48215.
Lydekker also specified that Echinodon was found in to the Middle Purbeck Beds, an informal unit of the modern Purbeck Limestone Group, the formal name for the historic Purbeck Beds.
British palaeontologist Peter Galton narrowed down the depositional locality of Echinodon further in 1978 to the freshwater "Dirt Bed", also known as the "Mammal Pit" that was excavated by Beckles in 1857.
However, no evidence exists to link Echinodon to any specific bed in the Lulworth Formation of the Purbeck Group.
Galton also referred the specimen NHMUK 48229 to Echinodon, a fragmentary dentary with teeth, and the only further referrals to the genus includes isolated teeth also from the Purbeck beds.

In the late 1970s and early 1980s, excavations of the Natural History Museum of Los Angeles County uncovered many small ornithischian fossils in the Fruita Paleontological Area of Colorado.
These remains, collected from sandstones at the base of the Brushy Basin Member of the Morrison Formation, were approximately 150.2-150.3 million years old, and were initially described as intermediate fabrosaur remains by their collector George Calliston in 1984.
Three years later Calliston revised his description and referred the material, including jaw bones, vertebrae and most of the hindlimb, to Echinodon sp.,
an assignment supported by Galton in 2002, although in 2006 he reconsidered the material and noticed differences in tooth anatomy from Echinodon proper.
In 2009, these fossils were given their own genus, Fruitadens haagarorum, a related but distinct taxon from Echinodon.
Multiple specimens of jaw bones were discovered by Samuel Beckles high on a cliff in Durdlestone Bay on the Isle of Purbeck in southern England. These fossils, including many teeth as well as maxilla and dentary bones of the upper and lower jaws, were found alongside shells and plant fossils in the Purbeck Beds. These were first described in a monograph published in 1861 written by Sir Richard Owen, a British palaeontologist who also described fossils of Iguanodon and Megalosaurus. Owen gave the name Echinodon becklesii for the fossils, which he considered to be part of the lizard clade Lacertilia. While the specific name honoured Beckles for his discovery of the fossils and allowing Owen to study his collection of Purbeck fossils, the generic name was derived from the Ancient Greek εχινος, 'hedgehog', and ὀδών, 'tooth', which Owen combined as "prickly tooth" to describe the anatomy of the serrations along the sides of the teeth. Owen had corresponded with British palaeontologist Hugh Falconer, who had suggested the name "Sauraechinodon", but as the shortened form Echinodon was not preoccupied, Owen chose to use the abbreviated form as the name for his new animal. Falconer issued a correction in 1861, specifying that he proposed the name "Sauraechmodon" instead of "Sauraechinodon".
Although originally described as a lacertilian by Owen, he revised his classification in 1874 to group Echinodon with Scelidosaurus and Iguanodon in a clade he called Prionodontia, which was within the larger clade Dinosauria. In 1888 British palaeontologist Richard Lydekker followed previous classification of Echinodon as a dinosaur based on the anatomy of its teeth, describing them as similar to Scelidosaurus although not referring them to a more specific clade than Dinosauria indeterminate. The series of specimens designated as types by Owen were purchased by the British Museum of Natural History (BMNH now NHMUK) in 1876 and form part of the Beckles Collection, bearing specimen numbers NHMUK 48209 to 48215. Lydekker also specified that Echinodon was found in to the Middle Purbeck Beds, an informal unit of the modern Purbeck Limestone Group, the formal name for the historic Purbeck Beds. British palaeontologist Peter Galton narrowed down the depositional locality of Echinodon further in 1978 to the freshwater "Dirt Bed", also known as the "Mammal Pit" that was excavated by Beckles in 1857. However, no evidence exists to link Echinodon to any specific bed in the Lulworth Formation of the Purbeck Group. Galton also referred the specimen NHMUK 48229 to Echinodon, a fragmentary dentary with teeth, and the only further referrals to the genus includes isolated teeth also from the Purbeck beds.
In the late 1970s and early 1980s, excavations of the Natural History Museum of Los Angeles County uncovered many small ornithischian fossils in the Fruita Paleontological Area of Colorado. These remains, collected from sandstones at the base of the Brushy Basin Member of the Morrison Formation, were approximately 150.2-150.3 million years old, and were initially described as intermediate fabrosaur remains by their collector George Calliston in 1984. Three years later Calliston revised his description and referred the material, including jaw bones, vertebrae and most of the hindlimb, to Echinodon sp., an assignment supported by Galton in 2002, although in 2006 he reconsidered the material and noticed differences in tooth anatomy from Echinodon proper. In 2009, these fossils were given their own genus, Fruitadens haagarorum, a related but distinct taxon from Echinodon.
Echinodon