In 1985 the fossil of Iberomesornis was discovered by Armando Díaz Romeral in the Early Cretaceous Calizas de La Huérguina Formation at Las Hoyas, Cuenca Province, east central Spain, which dates to the late Barremian, roughly 125 million years ago.
The holotype specimen, LH-22, part of the Las Hoyas Collection, consists of a compressed articulated partial skeleton of an adult individual lacking the skull, the anterior neck and most of the hands.