Pleurodira

{{Short description|Suborder of turtles}} {{Automatic taxobox | fossil_range = Late Jurassic to present, {{fossilrange|163|0}} | image = Eastern long neck tortoise - chelodina longicollis03.jpg | image_caption = Eastern long-necked turtle ''Chelodina longicollis'' | taxon = Pleurodira | authority = Cope, 1865<ref name="cope1865">{{Cite journal |jstor=4624040 |title=Third Contribution to the Herpetology of Tropical America|last1=Cope|first1=E. D.|journal=Proceedings of the Academy of Natural Sciences of Philadelphia|year=1865|volume=17|issue=4|pages=185–198}}</ref> | subdivision_ranks = Superfamilies | subdivision = | synonyms = * Pleuroderes - Duméril and Bibron 1834:354<ref name="dum&bib1834">{{Cite book|last1=Duméril|first1=C.|last2=Baird|first2=Spencer Fullerton|last3=Bibron|first3=Gabriel|last4=Duméril|first4=Auguste Henri André |title=Erpétologie générale, ou, Histoire naturelle complète des reptiles / Par A.M.C. Duméril et par G. Bibron |year=1834 |url=https://www.biodiversitylibrary.org/item/100088 |location=Paris |publisher=Roret, 1834-54 |doi=10.5962/bhl.title.45973 |doi-access=free |lccn=06014283 |oclc=5718160}} [http://catalog.hathitrust.org/Record/001501045 At] HathiTrust.</ref> * Pleurodera - Lichtenstein 1856:2<ref name="lich1865">{{Cite book |last1=Lichtenstein |first1=Heinrich |year=1856 |title=Nomenclator reptilium et amphibiorum musei zoologici Berolinensis: Namenverzeichnis der in der zoologischen Sammlung der Koeniglichen Universität zu Berlin aufgestellten Arten von Reptilien und Amphibien nach ihren Ordnungen, Familien und Gattungen |publisher=Berlin |url=https://archive.org/details/nomenclatorrepti00lich |url-access=registration |doi=10.5962/bhl.title.45245 |doi-access=free |oclc=249533370}}</ref> * Pleurodera - Cope 1864:181<ref name="cope1864">{{Cite journal |jstor=4623931|title=On the Limits and Relations of the Raniformes|last1=Cope|first1=E. D.|journal=Proceedings of the Academy of Natural Sciences of Philadelphia|year=1864|volume=16|issue=4|pages=181–183}}</ref> | synonyms_ref =<ref name="ttwg">{{Cite book |doi=10.3854/crm.5.000.checklist.v5.2012|chapter=Turtles of the World, 2012 Update: Annotated Checklist of Taxonomy, Synonymy, Distribution, and Conservation Status|title=Conservation Biology of Freshwater Turtles and Tortoises|year=2012|last1=Van Dijk|first1=Peter Paul|last2=Iverson|first2=John|last3=Shaffer|first3=H. Bradley|last4=Bour|first4=Roger|last5=Rhodin|first5=Anders|isbn=978-0-9653540-9-7}}</ref> }}

The '''Pleurodira''' are one of the two living suborders of turtles, the other being the Cryptodira. The division between these two suborders represents a very deep evolutionary divide between two very different types of turtles. The physical differences between them, although anatomical and largely internal, are nonetheless significant, and the zoogeographic implications are substantial. The Pleurodira are known more commonly as the '''side-necked turtles''' and the name Pleurodira quite literally translates to side neck, whereas the Cryptodira are known as hidden-necked turtles.<ref name="Prit84">{{Cite book |isbn=978-0-916984-11-3 |pages=403|title=The Turtles of Venezuela|last1=Pritchard|first1=Peter Charles Howard|last2=Trebbau|first2=Pedro|year=1984|publisher=Society for the Study of Amphibians and Reptiles }}</ref> Pleurodiran turtles are currently restricted to the freshwater ecosystems of former Gondwanan landmasses, including in Australia, South America, Arabia, Madagascar and Africa. Within the Pleurodira, three living families are represented: Chelidae, also known as the Austro-South American side-necked turtles, the Pelomedusidae, also known as the African mud terrapins, and the Podocnemididae, also known as the American side-neck river turtles.<ref name=Prit84 /><ref name=":0">{{Cite book|vauthors=Vitt L, Caldwell J|title=Herpetology: An Introductory Biology of Amphibians and Reptiles.|publisher=Academic Press|year=2014|pages=523–543}}</ref> However, they were a cosmopolitan clade during the Cretaceous and most of the Cenozoic, and even occurred in marine environments around the world.<ref>{{Cite journal |doi=10.1206/0003-0090(2006)300[1:EOTSTT]2.0.CO;2|issn=0003-0090|year=2006|volume=300|pages=1–698|title=Evolution of the Side-Necked Turtles: The Families Bothremydidae, Euraxemydidae, and Araripemydidae|last1=Gaffney|first1=Eugene S.|last2=Tong|first2=Haiyan|last3=Meylan|first3=Peter A.|journal=Bulletin of the American Museum of Natural History|s2cid=85790134 |url=http://doc.rero.ch/record/15686/files/PAL_E2036.pdf }}</ref><ref>{{Cite journal |last1=Pérez-García |first1=Adán |date=4 June 2016 |title=A New Turtle Confirms the Presence of Bothremydidae (Pleurodira) in the Cenozoic of Europe and Expands the Biostratigraphic Range of Foxemydina |journal=The Science of Nature |volume=103 |issue=7–8 (article 50) |page=50 |bibcode=2016SciNa.103...50P |doi=10.1007/s00114-016-1375-y |pmid=27262289 |s2cid=15652309}}</ref>

== Definition and description ==

[[Image:Pelomedusa subrufa (cropped).JPG|thumb|right|''Pelomedusa subrufa'' showing typical pleurodiran neck retraction, under the shell and towards the side.]]

The Pleurodira are identified by the method with which they withdraw their heads into their shells. In these turtles, the neck is bent in the horizontal plane, drawing the head into a space in front of one of the front legs. A larger overhang of the carapace helps to protect the neck, which remains partially exposed after retraction. This differs from the method employed by a cryptodiran, which tucks its head and neck between its forelegs, within the shell.

thumb|right|Differences in neck retraction between cryptodirans and pleurodirans.

The different methods of bending the neck require completely different anatomies of the cervical vertebrae. All extant turtles studied so far have eight vertebrae in the neck.<ref name="Romer56">{{Cite book |last=Romer |first=Alfred |title=Osteology of the Reptiles |publisher=University of Chicago Press |year=1956 |location=Chicago |page=772}}</ref> In the Pleurodira, these vertebrae are narrow in cross-section and spool-shaped with biconvex centra on one or more of the cervicals.<ref name=Romer56 /> These centra act as a double joint, allowing a large degree of sideways movement and providing a means of folding the neck onto itself in the lateral plane. Conversely, in the Cryptodira, the neck bones are wide and flat. The biconvex centra in some of the cryptodiran cervicals allow the neck to fold onto itself in the vertical plane.<ref name=Romer56 />

Pleurodirans also differ from cryptodirans in the emarginations of their skulls. Skull emargination provides room and anchorage for the jaw muscles. The connection points and the position of the emarginations relate to different bones of the skull.

Another difference is in the arrangement of the bones of the shell and the scutes overlaying them. Pleurodiran turtles have 13 scutes on the plastron of the shell, whereas cryptodiran turtles have only 12. The extra scute is called the intergular and is at the front of the plastron between the gular scutes. Pelomedusid turtles also possess mesoplastra, further differentiating this group.

The jaw closure mechanism has articulation on trochlear surfaces of the pterygoid.

==Suction feeding== One of the three extant families in this suborder is the family Chelidae, which have a specially adapted strategy for catching prey. While the majority of the family Chelidae are omnivores, 17 species are carnivorous:<ref name=":0" /> ''Chelus fimbriatus'' and species of the ''Chelodina'' genus.<ref name=":0" /> This special strategy is referred to as a gape-suck mechanism.<ref name=":0" /><ref name=":1">{{Cite journal|last=Lemell, P., Lemell, C., Snelderwaard, P., Gumpenberger, M., Wocheslander, R., and Weisgram, J.|title=Feeding patterns of ''Chelus fimbriatus'' (Pleurodira: Childae)|journal=The Journal of Experimental Biology|year=2002|volume=205|issue=Pt 10|pages=1495–1506|doi=10.1242/jeb.205.10.1495|pmid=11976360|bibcode=2002JExpB.205.1495L }}</ref> The turtle first opens its mouth little by little. Then, when the turtle is within striking range of the prey, it will open its mouth completely, sucking in water at such a rate that the current into its mouth is too strong for prey to escape and it engulfs the prey within 0.004 seconds.<ref name=":1" /> This strategy also circumvents issues to quick capture of underwater prey, such as resistance to rapid movement in water, pressure waves due to a rapid strike, and rapid water intake when feeding.<ref name=":1" />

==Taxonomy== '''References:'''<ref>{{cite web|url=https://www.paleodb.org |title=The Paleobiology Database |publisher=Paleodb.org |access-date=2012-09-24}}</ref><ref>{{Cite journal|last1=Joyce|first1=Walter G.|last2=Anquetin|first2=Jérémy|last3=Cadena|first3=Edwin-Alberto|last4=Claude|first4=Julien|last5=Danilov|first5=Igor G.|last6=Evers|first6=Serjoscha W.|last7=Ferreira|first7=Gabriel S.|last8=Gentry|first8=Andrew D.|last9=Georgalis|first9=Georgios L.|last10=Lyson|first10=Tyler R.|last11=Pérez-García|first11=Adán|date=2021-02-09|title=A nomenclature for fossil and living turtles using phylogenetically defined clade names|journal=Swiss Journal of Palaeontology|volume=140|issue=1|page=5|doi=10.1186/s13358-020-00211-x|issn=1664-2384|doi-access=free|bibcode=2021SwJP..140....5J |hdl=11336/155192|hdl-access=free}}</ref><ref>{{Cite journal|last1=Joyce|first1=Walter G.|last2=Rollot|first2=Yann|last3=Evers|first3=Serjoscha W.|last4=Lyson|first4=Tyler R.|last5=Rahantarisoa|first5=Lydia J.|last6=Krause|first6=David W.|title=A new pelomedusoid turtle, Sahonachelys mailakavava, from the Late Cretaceous of Madagascar provides evidence for convergent evolution of specialized suction feeding among pleurodires|journal=Royal Society Open Science|year=2021|volume=8|issue=5|article-number=210098|doi=10.1098/rsos.210098|pmid=34035950|pmc=8097199 |bibcode=2021RSOS....810098J|doi-access=free}}</ref>

After Ferreria, et al. 2018.<ref>{{Cite journal|last1=Ferreira|first1=Gabriel S.|last2=Bronzati|first2=Mario|last3=Langer|first3=Max C.|last4=Sterli|first4=Juliana|title=Phylogeny, biogeography and diversification patterns of side-necked turtles (Testudines: Pleurodira)|journal=Royal Society Open Science|year=2018|volume=5|issue=3|article-number=171773|doi=10.1098/rsos.171773|doi-access=free|pmc=5882704|pmid=29657780|bibcode=2018RSOS....571773F}}</ref>

* '''Panpleurodira''' ** †Dortokidae (extinct) (Early Cretaceous–Paleocene) ** †Platychelyidae (extinct) (Late Jurassic–Early Cretaceous) ** '''Pleurodira''' *** Chelidae (20 genera) *** Pan-Pelomedusoides **** †Araripemydidae (extinct) (Early Cretaceous) **** †Euraxemydidae (extinct) **** Pelomedusoides ***** Pelomedusidae (two genera) ***** †''Francemys'' (extinct) (Early Cretaceous) ***** †Sahonachelyidae (extinct) (Late Cretaceous) ***** †Bothremydidae (extinct) (Early Cretaceous–Miocene) ***** Podocnemidoidae ****** †Peiropemydidae (extinct) ****** Podocnemididae (three extant, many extinct genera)

==References== {{Reflist|2}}

Category:Pleurodira Category:Taxa named by Edward Drinker Cope Category:Tetrapod suborders