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.

[2] 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.

The Las Hoyas Unit 3 site was once a forest surrounding a lake; the climate was warm with a distinct dry season.

The shorter tail and the higher position of the shoulder indicated by the strut-like coracoid — allowing for a greater wing amplitude — improved manoeuvrability, turning and swooping at speed.

Flying speed may have been impaired due to the lack of a bony keel on the sternum as attachment for the flight muscles; it is uncertain whether a true foramen triosseum was present, through which a tendon could elevate and supinate the wing.

Well preserved specimens of Chinese species such as Sinornis and Confuciusornis have permitted scientists to better understand the birds' early fossil history.