Archaeopterodactyloids Temporal range: Late Jurassic –Early Cretaceous,152–105 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Restored skull of thectenochasmatidPterodaustro guinazui
Cast of the sub-adulttype specimen ofPterodactylus antiquus, an archaeopterodactyloid.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	†Pterosauria
Suborder:	†Pterodactyloidea
Infraorder:	†Archaeopterodactyloidea Kellner,1996
Subgroups
†Prejanopterus? †Germanodactylidae? †EuctenochasmatiaUnwin, 2003 †Diopecephalus? †Pterodactylus †CtenochasmatoideaNopcsa, 1928 †Ardeadactylus †Aurorazhdarcho †Petrodactyle †Ctenochasmatidae †Gallodactylidae

Archaeopterodactyloidea (meaning "ancientPterodactyloidea") is anextinctclade ofpterodactyloidpterosaurs that lived from the middleLate Jurassic to the latestEarly Cretaceous periods (Kimmeridgian toAlbian stages) ofAfrica,Asia,Europe andNorth America.^[1] It was named byAlexander Wilhelm Armin Kellner in1996 as the group that containsGermanodactylus,Pterodactylus, theCtenochasmatidae and theGallodactylidae.^[2] Some researchers dispute the relationship ofGermanodactylus to other members of the group, and instead use the termsEuctenochasmatia orCtenochasmatoidea to describe the lineage ofPterodactylus, gallodactylids, and ctenochasmatids.

The earliest known archaeopterodactyloid remains date to the Late JurassicKimmeridgian age. Previously, a fossil jaw recovered from the Middle JurassicStonesfield Slate formation in theUnited Kingdom, was considered the oldest known. This specimen supposedly represented a member of the familyCtenochasmatidae,^[3] though further examination suggested it belonged to ateleosauridcrocodylomorph instead of a pterosaur.^[4]

Many archaeopterodactyloids had very distinctive features in comparison to other pterosaurs, including the shape of their jaws, as well as their highly specialized teeth. These teeth are thought to have been used forfilter-feeding, the genusPterodaustro for example, had a long snout and its lower jaws curve strongly upwards, and thetangent at the point of the snout was perpendicular to that of the jaw joint.Pterodaustro has around a thousandbaleen-like teeth in its lower jaws that might have been used to straincrustaceans,plankton,algae, and other small creatures from the water. The teeth ofPterodaustro are unique within pterosaurs, and no other discovered genera had this type of teeth.^[5][6]

A peculiar family within this group is theCtenochasmatidae, which most of the members had very distinguishing teeth that were lined within their elongated snouts.^[7] A genus calledPterofiltrus only had 112 teeth, but these teeth cover about 55.8% of the total skull, and the skull itself measured about 208 millimeters (8.2 in) in length.^[8]

Other members of this group, such as thegallodactylids, differ from other euctenochasmatians in several distinct features, including having fewer than 50 teeth, and were only present in the jaw tips; rounded crests were also present on the rear portion of the skull and jaws but not near the ends of their snouts.^[9] Similarly, thectenochasmatidFeilongus also had its teeth confined within its jaw tips, as well as having crests on the rear portion of the skull and jaws, but differedFeilongus from the gallodactylids by having a possible pronouncedoverbite, and 76 teeth, which wereneedle-like.^[10]

One of the largest toothed pterosaurs wasMoganopterus, it was, yet again, a ctenochasmatid, and was similar in build toFeilongus. What madeMoganopterus distinct was its size; whileFeilongus had a wingspan of about 2.4 meters (7.9 ft),Moganopterus had an impressive wingspan of more than 7 meters (23 ft), making it more than three times larger thanFeilongus.^[11]

Most archaeopterodactyloids have wing proportions akin to those of modernshorebirds andducks, and probably possessed a similar frantic, powerful flight style. The exception isCtenochasma, which appears to have had longer wings and was probably more comparable to modernskuas.^[12]

Launching varied radically among members of this clade. In forms likeCycnorhamphus, long limbs and shorter torsos meant a level of relative ease. In forms likePterodaustro, however, which possessed long torsos and short limbs, launching might have been a more taxing and prolonged affair, only possible in large open areas, just like modern heavy-bodied aquatic birds such asswans, even with the pterosaurian quadrupedal launching.^[12]

Many archaeopterodactyloids were aquatic or semi-aquatic pterosaurs; their remains are usually found in what were once coastal or lake environments. Some of them possessed large webbed hindfeet and long torsos, which were both adaptations for swimming and floating.^[13] The exception to their occurrence in coastal settings are thegallodactylids, which generally possessed more slender limbs and shorter torsos. They occupied a wide variety of ecological niches, from generalistic carnivores likePterodactylus tofilter-feeders likePterodaustro and possible molluscivores likeCycnorhamphus. Most common, however, were straight-jawed, needle-toothed forms, some of the most notable beingCtenochasma andGnathosaurus; these possibly occupied an ecological niche akin to that of modernspoonbills, their teeth formingspatula-like jaw profile extensions, allowing them a larger surface area to catch individual small prey.^[12]

In 2003, Kellner defined Archaeopterodactyloidea as anode-based taxon consisting of the last common ancestor ofPterodactylus,Ctenochasma andGallodactylus and all its descendants. Althoughphylogenetic analyses that based on David Unwin's 2003 analysis do not recover monophyletic Archaeopterodactyloidea, phylogenetic analyses that based on Kellner's analyses, or the analyses of Brian Andres (2008, 2010, 2018) recover monophyletic Archaeopterodactyloidea at the base of the Pterodactyloidea.^[2]

The largest subgroup of archaeopterodactyloids is the groupEuctenochasmatia. This group was named by David Unwin in 2003 as the group that contains the most recent common ancestor ofPterodactylus andCtenochasma, and all their descendants.^[13] Researchers like Unwin, have traditionally defined the dubious familyPterodactylidae in such a way to ensure it is nested within the clade Ctenochasmatoidea. In 2003, Unwin defined the same clade (Pterodactylus +Pterodaustro), but erected the name Euctenochasmatia instead of Pterodactylidae for his conclusion.^[14]

Another subgroup within Archaeopterodactyloidea isCtenochasmatoidea. Ctenochasmatoidea was first named as thesubfamily Ctenochasmatinae byFranz Nopcsa.^[15] Under theInternational Code of Zoological Nomenclature, this makes Nopcsa the author of Ctenochasmatidae and Ctenochasmatoidea as well.^[16] The modern clade Ctenochasmatoidea was defined by David Unwin in 2003 as the clade containingCycnorhamphus suevicus,Pterodaustro guinazui, their most recent common ancestor, and all its descendants.^[17] Below is acladogram showing the results of aphylogenetic analysis presented by Steven Vidovic and David Martill, using the earliest available definitions for each clade name.^[13] Unwin had considered Euctenochasmatia to be a subgroup within Ctenochasmatoidea, similar to his former conclusion of Pterodactylidae, but most analyses have since found the genusPterodactylus to be more primitive than previously thought, making the clade Euctenochasmatia the more inclusive group containing bothPterodactylus and Ctenochasmatoidea.^[18]

In 2017, Steven Vidovic and David Martill recovered a significantly different set of relationships for early pterodactyloids in their own analysis. They recovered Archaeopterodactyloidea, as it is traditionally conceived of, as aparaphyletic group. Under a strictly cladistical framework, this would imply that the majority of pterodactyloids are part of Archaeopterodactyloidea, includingazhdarchoids,pteranodontians, andornithocheiromorphs.^[13]

Below iscladogram following a topology recovered by Brian Andres, using the most recent iteration of his data set (Andres, 2021). Andres' analysis foundPterodactylus to be a close relative of the ctenochasmatoids. Andre's analysis found the "aurorazhdarchian" group recovered by the analysis of Vidovic and Martill to mostly be members of the Ctenochasmatidae, with only a small group of gallodactylids falling outside that group.^[19]

Summary of the given phylogenetic definitions of clades inArchaeopterodactyloidea.

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