Ctenochasmatoidea

Ctenochasmatoids Temporal range: Late Jurassic - Early Cretaceous, 152–105 Ma PreЄ Є O S D C P T J K Pg N
200 px
Fossil specimen of Ctenochasma elegans
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Order:	†Pterosauria
Suborder:	†Pterodactyloidea
Infraorder:	†Archaeopterodactyloidea
Clade:	†Euctenochasmatia Unwin, 2003
Subgroups
†Ardeadactylus †Pterodactylus †Ctenochasmatoidea †Ctenochasmatidae †Gallodactylidae
Synonyms
Pterodactylidae Bonaparte, 1838

Ctenochasmatoidea is a group of pterosaurs within the suborder Pterodactyloidea.

Evolutionary history

The earliest known ctenochasmatoid remains date to the Late Jurassic Kimmeridgian age. Previously, a fossil jaw recovered from the Middle Jurassic Stonesfield Slate formation in the United Kingdom, was considered the oldest known. This specimen supposedly represented a member of the family Ctenochasmatidae, though further examination suggested it actually belonged to a teleosaurid stem-crocodilian instead of a pterosaur.

Classification

Ctenochasmatoidea was first defined by David Unwin in 2003 as the clade containing Cycnorhamphus suevicus, Pterodaustro guinazui, their most recent common ancestor, and all its descendants.

During the 2000s and 2010s, several competing definitions for the various ctenochasmatoid groups were proposed. Pereda-Suberbiola et al. (2012) used Fabien Knoll's (2000) definition of the family-level name Pterodactylidae. Knoll had defined Pterodactylidae as a clade containing "Pterodactylus antiquus, Ctenochasma elegans, their most recent common ancestor and all [its] descendants". Using this definition with the analysis conducted by Pereda-Suberbiola et al. (2012) meant that Ctenochasmatoidea was actually nested inside Pterodactylidae. Below is the majority-rule consensus tree found by Pereda-Suberbiola et al. (2012), showing their preferred definitions of Pterodactylidae and Ctenochasmatoidea.

Pterodactylidae	Pterodactylus Prejanopterus Ctenochasmatoidea Cycnorhamphus Cearadactylus Gnathosaurus Ardeadactylus Pterodaustro Ctenochasma Gegepterus Eosipterus

Other researchers, such as David Unwin, have traditionally defined Pterodactylidae in such a way to ensure it is nested within Ctenochasmatoidea instead. In 2003, Unwin defined the same clade (Pterodactylus + Pterodaustro) with the name Euctenochasmatia. Unwin considered this to be a subgroup within Ctenochasmatoidea, but most analyses since have found Pterodactylus to be more primitive than he thought, making Euctenochasmatia the more inclusive group. Below is a cladogram showing the results of a phylogenetic analysis presented by Andres, Clark & Xu (2014) illustrating this view.

Archaeopterodactyloidea

Germanodactylidae  Normannognathus wellnhoferi Germanodactylus cristatus Germanodactylus rhamphastinus  Euctenochasmatia  Pterodactylus antiquus Pterodactylus kochi Ardeadactylus longicollum  Ctenochasmatoidea   Gallodactylidae  Cycnorhamphus suevicus Gallodactylus canjuersensis  Ctenochasmatidae   Gnathosaurinae  Kepodactylus insperatus Elanodactylus prolatus Feilongus youngi Moganopterus zhuiana Huanhepterus quingyangensis Plataleorhynchus streptophorodon Gnathosaurus subulatus Gnathosaurus macrurus  Ctenochasmatinae  Ctenochasma elegans Ctenochasma roemeri Pterodaustro guinazui Eosipterus yangi Beipiaopterus chenianus Gegepterus changi

Some studies based on a different type of analysis have found that Ctenochasmatoidea, as usually thought of, is not a natural group (making it paraphyletic). In 2014, Steven Vidovic and David Martill concluded that several pterosaurs traditionally thought of as ctenochasmatoids, specifically Gladocephaloideus, Cycnorhamphus, Aurorazhdarcho, Aerodactylus, and Ardeadactylus, may actually have been more closely related to ornthocheiroids. They found that Pterodactylus itself was actually more primitive than both this new group, the Aurorazhdarchidae, and the classic ctenochasmatids. The results of their analysis are shown below.

Pterodactyloidea	Pterodactylus antiquus Pterodactylus kochi Lophocratia Ctenochasmatidae Germanodactylus rhamphastinus Aurorazhdarchidae Aerodactylus scolopaciceps Gladocephaloideus jingangshanensis Cycnorhamphus suevicus Aurorazhdarcho micronyx Ardeadactylus longicollum Eupterodactyloidea