Ctenochasmatoidea
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Ctenochasmatoidea is a group of early pterosaurs within the suborder
Pterodactyloidea Pterodactyloidea (derived from the Greek words ''πτερόν'' (''pterón'', for usual ''ptéryx'') "wing", and ''δάκτυλος'' (''dáktylos'') "finger" meaning "winged finger", "wing-finger" or "finger-wing") is one of the two traditional ...
. 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 In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxford ...
age. Previously, a fossil jaw recovered from the Middle Jurassic Stonesfield Slate formation in the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...
, 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 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
gallodactylid Gallodactylidae is a group of pterosaurs within the suborder Pterodactyloidea. Gallodactylids differed from other related pterosaurs in several distinct features, including fewer than 50 teeth present only in the jaw tips, and rounded crests pre ...
s. They occupied a wide variety of ecological niches, from generalistic carnivores like ''
Pterodactylus ''Pterodactylus'' (from Greek () meaning 'winged finger') is an extinct genus of pterosaurs. It is thought to contain only a single species, ''Pterodactylus antiquus'', which was the first pterosaur to be named and identified as a flying rept ...
'' to filter-feeders like ''
Pterodaustro ''Pterodaustro'' is a genus of ctenochasmatid pterodactyloid pterosaur from South America. Its fossil remains dated back to the Early Cretaceous period, about 105 million years ago. The most distinctive characteristic that separates ''Pterodaus ...
'' and possible molluscivores like ''
Cycnorhamphus ''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 ...
''. Most common, however, were straight-jawed, needle-toothed forms, some of the most notable being ''
Ctenochasma ''Ctenochasma'' (meaning "comb jaw") is a genus of Late Jurassic ctenochasmatid pterosaur belonging to the suborder Pterodactyloidea. Three species are currently recognized: ''C. roemeri'' (named after Friedrich Adolph Roemer), ''C. taqueti'', a ...
'' and ''
Gnathosaurus ''Gnathosaurus'' (meaning "jawed lizard") is a genus of ctenochasmatid pterosaur containing two species: ''G. subulatus'', named in 1833 from the Solnhofen Limestone of Germany, and ''G. macrurus'', known from the Purbeck Limestone of the UK. ...
''; these possibly occupied an ecological niche akin to that of modern spoonbills, their teeth forming
spatula A spatula is a broad, flat, flexible blade used to mix, spread and lift material including foods, drugs, plaster and paints. In medical applications, "spatula" may also be used synonymously with tongue depressor. The word ''spatula'' derives f ...
-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 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 The skuas are a group of predatory seabirds with seven species forming the genus ''Stercorarius'', the only genus in the family Stercorariidae. The three smaller skuas, the long-tailed skua, the Arctic skua, and the pomarine skua are called jae ...
. Launching varied radically among ctenochasmatoids. In forms like ''Cycnorhamphus'', long limbs and shorter torsos meant a level of relative ease. In forms like ''
Pterodaustro ''Pterodaustro'' is a genus of ctenochasmatid pterodactyloid pterosaur from South America. Its fossil remains dated back to the Early Cretaceous period, about 105 million years ago. The most distinctive characteristic that separates ''Pterodaus ...
'', 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.


Classification

Ctenochasmatoidea was first defined by David Unwin in 2003 as the clade containing '' Cycnorhamphus suevicus'', ''
Pterodaustro guinazui ''Pterodaustro'' is a genus of ctenochasmatid pterodactyloid pterosaur from South America. Its fossil remains dated back to the Early Cretaceous period, about 105 million years ago. The most distinctive characteristic that separates ''Pterodaus ...
'', 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 A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...
showing the results of a
phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
analysis presented by Steven Vidovic and David Martill, using the earliest available definitions for each clade name. Below is
cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...
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