Pterodactyloidea is traditionally considered to be the group of short-tailed pterosaurs with long wrists (metacarpus), compared with the relatively long tails and short wrist bones of basal pterosaurs ("rhamphorhynchoids"). In 2004, Kevin Padian formally defined Pterodactyloidea as an
apomorphy-based
clade containing those species possessing a metacarpal at least 80% of the length of the
humerus,
homologous with that of
Pterodactylus. This definition was adopted by the
PhyloCode in 2020.
Subgroups '', a
ctenochasmatoid A subgroup of pterodactyloids, called the
Lophocratia, was named by David Unwin in 2003. Unwin defined the group as the most recent common ancestor of
Pterodaustro guinazui and
Quetzalcoatlus northropi, and all its descendants. This group was named for the presence of a head crest in most known species, though this feature has since been found in more primitive pterosaurs and was probably an ancestral feature for all pterodactyloids. Another subgroup within Lophocratia is
Eupterodactyloidea (meaning "true Pterodactyloidea"). Eupterodactyloidea was named by S. Christopher Bennett in
1994 as an infraorder of the suborder Pterodactyloidea. Bennett defined it as an
apomorphy-based
clade. However, in 2010, Brian Andres re-defined the group as a
stem-based taxon in his dissertation, and then formalized the definition in 2014 as all pterosaurs more closely related to
Pteranodon longiceps than to
Pterodactylus antiquus. Later that year, David Unwin suggested a more restrictive definition, in which the clade only contains
Pteranodon longiceps,
Istiodactylus latidens, and their descentants. Brian Andres (2008, 2010, 2014) in his analyses, defined Ornithocheiroidea using the definition of Kellner (2003) to avoid confusion with similarly defined groups, like
Pteranodontoidea. In 2019, a phylogenetic analysis conducted by Kellner and colleagues had recovered Ornithocheiroidea as the sister taxon of the
Archaeopterodactyloidea, and consisting of the clades
Tapejaroidea and
Pteranodontoidea. Several recent studies have followed this or a similar concept. '', a terrestrial
azhdarchoid However, not all of the subgroups of pterodactyloids are universally accepted. One controversial taxon is
Tapejaroidea. Tapejaroidea was named by paleontologist
Alexander Kellner from Brazil in 1996, and in 2003 it was given a
phylogenetic definition by Kellner himself as the most recent common ancestor of
Dsungaripterus,
Tapejara and
Quetzalcoatlus, and all their descendants. Tapejaroidea, in Kellner's 2003 study, was recovered as the sister taxon of the
Pteranodontoidea, both within the group
Ornithocheiroidea, and consisting of the groups
Dsungaripteridae and
Azhdarchoidea. However, in a phylogenetic analysis made by
Jaime Headden and
Hebert Bruno Nascimento Campos in 2014, Tapejaroidea was recovered within the Azhdarchoidea, as a clade comprising the families
Tapejaridae and
Thalassodromidae. More recently, the original definition of Tapejaroidea has been used in a number of phylogenetic analyses conducted in 2019 and 2020, meaning that Tapejaroidea and Pteranodontoidea were once again recovered as the sister taxa and within the larger Ornithocheiroidea. The
cladogram below represents the phylogenetic analysis conducted by Kellner and colleagues in 2019, where they recovered Tapejaroidea as the more inclusive group containing both the Dsungaripteridae and the Azhdarchoidea.
Taxonomy '', a marine
pteranodontoid There are competing theories of pterodactyloid phylogeny. Below is
cladogram following a topology recovered by Brian Andres, using the most recent iteration of his data set (Andres, 2021). This study found the two traditional groupings of ctenochasmatoids and kin as an early branching group, with all other pterodactyloids grouped into the
Eupterodactyloidea. A simplified version of the cladogram included in that publication is shown below. }} }} Some studies based on a different type of analysis have found that this basic division into primitive (archaeopterodactyloid) and advanced (eupterodactyloid) species may not be correct. Beginning in 2014, Steven Vidovic and David Martill constructed an analysis in which several pterosaurs traditionally thought of as archaeopterodactyloids closely related to the ctenochasmatoids may have been more closely related to
ornithocheiroids, or in some cases, fall outside both groups. The results of their updated 2017 analysis are shown below. }} ==References==