Pachymylus is an extinctgenus of chimaera belonging to the family Callorhinchidae. The type species. P. leedsi was described by A. S. Woodward in 1892, and is known from the Middle-Late Jurassic (Callovian-Oxfordian) Oxford Clay of Peterborough, England. The type material consisted of a large mandibular tooth and two palatine teeth.[1][2] Indeterminate remains of the genus are also known from the Middle Jurassic (Bajocian) of France.[2]