The first Baryonyx fossil was discovered in 1983 by an amateur fossil hunter named William J. Walker in Surrey, England. Walker found a large claw that he brought to the attention of the Natural History Museum in London. Subsequent excavations at the site revealed more bones, including parts of the skull, spine, limbs, and tail, which led to the identification of a new dinosaur species.
In 1986, paleontologists Alan J. Charig and Angela C. Milner officially described and named the dinosaur Baryonyx walkeri, with the genus name meaning “”heavy claw”” in reference to its distinctive thumb claw, and the species name honoring its discoverer, William Walker.