Mesadactylus ornithosphyos
(Jensen and Padian 1989, Oxfordian/ Kimmeridgian, Late Jurassic, BYU 2024) described the bits and pieces of the Mesadactylus holotype The type specimen is the synsacrum. The IVPP embryo is a sister. The only other anurognathid known from North America is the related, Dimorphodon? weintraubi.

Jensen and Padian (1989) considered Mesadactylus a basal pterodactyloid pterosaur. Bennett (2007) considered the synsacrum anurognathid even though no other anurognathid had such a sacrum.

Smith et al. (2004) reported on new Mesadactylus material, but it is unrelated, nesting closer to the flightless pterosaur, Sos 2428.

Enough is known of these few parts to label this anurognathid, otherwise it was considered a pterosaur incerta sedis.