This has led some researchers to suggest that many azhdarchoids, such as the azhdarchids and dsungaripterids, may have been primarily terrestrial, while retaining the ability to fly when necessary.

A simplified cladogram illustrating the relationships between azhdarchoids and other pterosaurs based on the analysis of Brian Andres, James Clark, and Xu Xing in 2014 is shown below.

An early study presented by paleontologist Felipe Pinheiro and colleagues in 2011 considered the tapejarids to be a monophyletic clade including the thalassodromines and the chaoyangopterids (therein called "chaoyangopterines").

[8] Other earlier studies, such as that of paleontologists Darren Naish & David Martill in 2006, and that of Lü Junchang and colleagues in 2008, considered the traditional "tapejarids" to be a paraphyletic grade of primitive azhdarchoids, with true tapejarids more basal, and the thalassodromines (alternatively called thalassodromids) and chaoyangopterids being successively more closely related to azhdarchids.

The first of these is based on the work of Brian Andres and colleagues, who have published multiple papers on the taxa Kryptodrakon, Elanodactylus, and Quetzalcoatlus among others, in which they examined the phylogenetic relationships of these groups.

[7] Pteranodontoidea Dsungaripteridae Thalassodromidae Caupedactylia Tapejaridae Keresdrakon Chaoyangopteridae Alanqidae Azhdarchidae A wide variety of subclades have been defined within Azhdarchoidea in the last 15 years.

Many of these have contradictory or overlapping definitions, and so whether or not these clades represent true monophyletic groups remains hotly debated.