Aurorazhdarchia
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Ctenochasmatoidea is a group of early
pterosaurs Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to ...
within the suborder Pterodactyloidea. Their remains are usually found in what were once coastal or lake environments. They generally had long wings, long necks, and highly specialized teeth.


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 Stonesfield is a village and civil parish about north of Witney in Oxfordshire, and about 10 miles (17 km) north-west of Oxford. The village is on the crest of an escarpment. The parish extends mostly north and north-east of the village, ...
formation in the United Kingdom, was considered the oldest known. This specimen supposedly represented a member of the family Ctenochasmatidae,Buffetaut, E. and Jeffrey, P. (2012). "A ctenochasmatid pterosaur from the Stonesfield Slate (Bathonian, Middle Jurassic) of Oxfordshire, England." ''Geological Magazine'', (advance online publication) though further examination suggested it belonged to a
teleosaurid Teleosauridae is a family of extinct typically marine crocodylomorphs similar to the modern gharial that lived during the Jurassic period. Teleosaurids were thalattosuchians closely related to the fully aquatic metriorhynchoids, but were less ad ...
stem-crocodilian instead of a pterosaur.


Ecology

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
spoonbill Spoonbills are a genus, ''Platalea'', of large, long-legged wading birds. The spoonbills have a global distribution, being found on every continent except Antarctica. The genus name ''Platalea'' derives from Ancient Greek and means "broad", refe ...
s, their teeth forming spatula-like jaw profile extensions, allowing them a larger surface area to catch individual small prey.Witton, Mark P. (2013). Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press. .


Flight

Most ctenochasmatoids have wing proportions akin to those of modern
shorebirds 245px, A flock of Dunlins and Red knots">Red_knot.html" ;"title="Dunlins and Red knot">Dunlins and Red knots Waders or shorebirds are birds of the order Charadriiformes commonly found wikt:wade#Etymology 1, wading along shorelines and mudflat ...
and
ducks Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form t ...
, 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. 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
swan Swans are birds of the family (biology), family Anatidae within the genus ''Cygnus''. The swans' closest relatives include the goose, geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form t ...
s, even with the pterosaurian quadrupedal launching.


Classification

Ctenochasmatoidea was first defined by David Unwin in 2003 as the clade containing ''
Cycnorhamphus suevicus ''Cycnorhamphus'' (meaning "swan beak") is a genus of gallodactylid ctenochasmatoid pterosaur from the Late Jurassic period of France and Germany, about 152 million years ago. It is probably synonymous with the genus ''Gallodactylus''. History I ...
'', '' Pterodaustro guinazui'', their most recent common ancestor, and all its descendants.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. Below is a cladogram showing the results of a phylogenetic analysis presented by Steven Vidovic and David Martill, using the earliest available definitions for each clade name. Below is cladogram following a topology recovered by Brian Andres, using the most recent iteration of his data set (Andres, 2021). 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.Andres, B. (2021) Phylogenetic systematics of ''Quetzalcoatlus'' Lawson 1975 (Pterodactyloidea: Azhdarchoidea). ''Journal of Vertebrate Paleontology'', 41:sup1, 203-217. DOI: 10.1080/02724634.2020.1801703 https://www.tandfonline.com/doi/full/10.1080/02724634.2020.1801703


References

{{Taxonbar, from=Q139216 Ctenochasmatoids Tithonian first appearances Early Cretaceous extinctions