Table 1. Phylogenetic nomenclature.

Clade	Nominal and definitional authors, and Regnum code	Definition	Composition and remarks
Azhdarchoidea	Unwin, 1995 [Andres, 2021], [355].	Min ∇ (Tapejara wellnhoferi Kellner 1989 & Quetzalcoatlus northropi Lawson, 1975).	Includes the sister-taxa Tapejaromorpha and Azhdarchomorpha.
Azhdarchomorpha	Pêgas et al., 2021 [Pêgas et al., 2021], [574].	Max ∇ (Azhdarcho lancicollis Nessov, 1984 ~ Thalassodromeus sethi Kellner & Campos 2002 & Tapejara wellnhoferi Kellner 1989).	Includes Keresdrakon, Chaoyangopteridae, and Azhdarchiformes.
Azhdarchiformes	Andres, 2021 [Andres, 2021], [771].	Max ∇ (Quetzalcoatlus northropi Lawson, 1975 ~ Chaoyangopterus zhangi Wang & Zhou 2003).	Includes Alanqidae and Azhdarchidae.
Alanqidae	Pêgas et al., 2021 [Pêgas et al., 2021], [576].	Max ∇ (Alanqa saharica Ibrahim et al., 2010 ~ Chaoyangopterus zhangi Wang & Zhou 2003 & Azhdarcho lancicollis Nessov, 1984).	Includes Alanqa, Argentinadraco, Leptostomia, and Xericeps.
Azhdarchidae (unrestricted emendation)	Padian, 1986 {this work}, {1043}	Min ∇ (Azhdarcho lancicollis Nessov, 1984, Phosphatodraco mauritanicus Suberbiola et al., 2003, Zhejiangopterus linhaiensis Cai & Wei, 1994, & Quetzalcoatlus northropi Lawson, 1975).	See main text for a detailed protologue including remarks on its composition and conceptualization.
Phosphatodraconia (new clade name)	This work [this work], [1044].	Max ∇ (Phosphatodraco mauritanicus Suberbiola et al., 2003 ~ Azhdarcho lancicollis Nessov, 1984, Zhejiangopterus linhaiensis Cai & Wei, 1994 & Quetzalcoatlus northropi Lawson, 1975).	Includes Aralazhdarcho, Eurazhdarcho, Phosphatodraco, and Wellnhopterus.
Quetzalcoatlida (new clade name)	This work [this work], [1045].	∇ apo piriform/clithridiate neural canal opening [Quetzalcoatlus lawsoni Andres & Langston, 2021].	Includes Hatzegopterygia and Quetzalcoatlini.
Hatzegopterygia (new clade name)	This work [this work], [1046].	Max ∇ (Hatzegopteryx thambema Buffetaut, Grigorescu & Csiki, 2002 ~ Quetzalcoatlus northropi Lawson, 1975, Azhdarcho lancicollis Nessov, 1984).	Includes Albadraco, Cryodrakon, Hatzegopteryx, the Pui azhdarchid, and Tsogtopteryx.
Quetzalcoatlini (new clade name)	This work [this work], [1047].	Max ∇ (Quetzalcoatlus northropi Lawson, 1975 ~ Hatzegopteryx thambema Buffetaut, Grigorescu & Csiki, 2002, Azhdarcho lancicollis Nessov, 1984).	Includes Arambourgiania, Gobiazhdarcho, Infernodrakon, Nipponopterus, Quetzalcoatlus, and Thanatosdrakon.

Note:

Reference phylogeny: this work. Original definitional authors and Regnum codes are given between square brackets. Authors and Regnum codes of unrestricted emended definitions are given between curly braces. See the main text for further comments on the diagnoses, compositions, and conceptualizations of azhdarchid clades.