Ctenochasmatoidea

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Ctenochasmatoids
Temporal range: Late Jurassic - Early Cretaceous, 152–105 Ma
Ctenochasma elegans.jpg
Fossil specimen of Ctenochasma elegans
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Pterosauria
Clade: Caelidracones
Suborder: Pterodactyloidea
Infraorder: Archaeopterodactyloidea
Clade: Euctenochasmatia
Unwin, 2003
Subgroups
Synonyms

Pterodactylidae Bonaparte, 1838

Ctenochasmatoidea is a group of pterosaurs within the suborder Pterodactyloidea.

Evolutionary history[edit]

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,[1] though further examination suggested it actually belonged to a teleosaurid stem-crocodilian instead of a pterosaur.[2]

Ecology[edit]

Most ctenochasmatoids were aquatic or semi-aquatic pterosaurs, possessing large webbed hindfeet and long torsos - both adaptations for swimming and floating -, as well as a predominant occurrence in aquatic environments, the exception being the more slender-limbed and short-torsoed gallodactylids. They occupied a wide variety of ecological niches, from generalistic carnivores like Pterodactylus to filter-feeders like Pterodaustro and possible molluscivores like Cycnorhamphus. Most common, however, were straight-jawed, needle-toothed forms, some of the most notable being Ctenochasma and Gnathosaurus; these possibly occupied an ecological niche akin to that of modern spoonbills, their teeth forming spatula-like jaw profile extensions, allowing them a larger surface area to catch individual small prey. [3]

Flight[edit]

Most ctenochasmatoids have wing proportions akin to those of modern shorebirds and ducks, and probably possessed a similar frantic, powerful flight style. The exception is Ctenochasma, which appears to have had longer wings and was probably more comparable to modern skuas.[4]

Launching varied radically among ctenochasmatoids. In forms like Cycnorhamphus, long limbs and shorter torsos meant a level of relative ease. In forms like Pterodaustro, 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 as swans, even with the pterosaurian quadrupedal launching.[5]

Classification[edit]

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.[6]

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.[7] Knoll had defined Pterodactylidae as a clade containing "Pterodactylus antiquus, Ctenochasma elegans, their most recent common ancestor and all [its] descendants".[8] Using this definition with the analysis conducted by Pereda-Suberbiola et al. (2012) meant that Ctenochasmatoidea was actually nested inside Pterodactylidae.[7] Below is the majority-rule consensus tree found by Pereda-Suberbiola et al. (2012), showing their preferred definitions of Pterodactylidae and Ctenochasmatoidea.[7]

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.[6] 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.[2]

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.[9]

Pterodactyloidea

Pterodactylus antiquus




Pterodactylus kochi


Lophocratia

Ctenochasmatidae





Germanodactylus rhamphastinus


Aurorazhdarchidae


Aerodactylus scolopaciceps



Gladocephaloideus jingangshanensis





Cycnorhamphus suevicus




Aurorazhdarcho micronyx



Ardeadactylus longicollum







Eupterodactyloidea






References[edit]

  1. ^ Buffetaut, E. and Jeffrey, P. (2012). "A ctenochasmatid pterosaur from the Stonesfield Slate (Bathonian, Middle Jurassic) of Oxfordshire, England." Geological Magazine, (advance online publication) doi:10.1017/S0016756811001154
  2. ^ a b Andres, B.; Clark, J.; Xu, X. (2014). "The Earliest Pterodactyloid and the Origin of the Group". Current Biology. doi:10.1016/j.cub.2014.03.030. 
  3. ^ Witton, Mark P. (2013). Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press. ISBN 0691150613.
  4. ^ Witton, Mark P. (2013). Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press. ISBN 0691150613.
  5. ^ Witton, Mark P. (2013). Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press. ISBN 0691150613.
  6. ^ a b Unwin, D. M., (2003). "On the phylogeny and evolutionary history of pterosaurs." Pp. 139-190. in Buffetaut, E. & Mazin, J.-M., (eds.) (2003). Evolution and Palaeobiology of Pterosaurs. Geological Society of London, Special Publications 217, London, 1-347.
  7. ^ a b c Xabier Pereda-Suberbiola; Fabien Knoll; José Ignacio Ruiz-Omeñaca; Julio Company; Fidel Torcida Fernández-Baldor (2012). "Reassessment of Prejanopterus curvirostris, a Basal Pterodactyloid Pterosaur from the Early Cretaceous of Spain". Acta Geologica Sinica. 86 (6): 1389–1401. doi:10.1111/1755-6724.12008. 
  8. ^ Fabien Knoll (2000). "Pterosaurs from the Lower Cretaceous (?Berriasian) of Anoual, Morocco". Annales de Paléontologie. 86 (3): 157–164. doi:10.1016/S0753-3969(00)80006-3. 
  9. ^ Vidovic, S. U.; Martill, D. M. (2014). "Pterodactylus scolopaciceps Meyer, 1860 (Pterosauria, Pterodactyloidea) from the Upper Jurassic of Bavaria, Germany: The Problem of Cryptic Pterosaur Taxa in Early Ontogeny". PLoS ONE. 9 (10): e110646. doi:10.1371/journal.pone.0110646.