- Thalattosaur
Taxobox
name = Thalattosaurs
fossil_range =Triassic
image_width = 250px
image_caption = Life restoration of "Miodentosaurus "
regnum =Animal ia
phylum = Chordata
classis = Sauropsida
subclassis =Diapsid a
ordo = Thalattosauria
ordo_authority = Merriam, 1904
subdivision_ranks = Families
subdivision =Askeptosauridae Claraziidae Endennasauridae Thalattosauridae * (type)Thalattosaurs (meaning "ocean lizards") are a group of prehistoric
marine reptile s which lived during the mid-lateTriassic Period. Some species of thalattosaur grew to over 4 meters (13 feet) in length, including a long, flattened tail used in underwater propulsion. While they bore a superficial resemblance tolizard s, the exact relationships of thalattosaurs is unknown; most experts place them on the reptile family tree somewhere in between theichthyosaur s andarchosaur s.ystematics
The Thalattosauria (and family
Thalattosauridae ) were named byJohn C. Merriam in 1905 for a distinctive group of marine reptiles, at the time containing only the first known species, "Thalattosaurus ". The classification of thalattosaurs has varied from study to study, especially since some paleontologists began including the askeptosaurids as true thalattosaurs. While some authors have placed the traditional thalattosaurs and the askeptosaurids within an expanded Order Thalattosauria, somecladistic defintions (see Phylogeny below) reserve the name Thalattosauria for aclade comprising the traditional thalattosaurs, and name the larger thalattosaur-askeptosaurid group Thalattosauriformes. In studies that use a more inclusive Thalattosauria, the name Thalattosauroidea has been used for the more exclusive thalattosaur group.Rieppel, O., Liu, J., and Bucher, B. (2000). "The fist record of a thalattosaur reptile from the Late Triassic of Southern China (Guizhou Province, PR China)." "Journal of Vertebrate Paleontology", 20(3): 507-514.]Taxonomy
The taxonomy presented here includes genera listed in an online survey by Mikko Haaramo, with additional taxa added based on their referral in subsequent papers.Haaramo, M. (2004). "Thalattosauriformes," from "
Mikko's Phylogeny Archive ". Accessed 4-OCT-2007. http://www.fmnh.helsinki.fi/users/haaramo/Metazoa/Deuterostoma//Chordata/Reptilia/Sauropterygia/Thalattosauriformes.htm] Thalattosauria is used in its most inclusive sense after Cheng "et al.", 2007.Cheng, Y., Wu, X., Li, C., and Tamaki, S. (2007). "A new thalattosaurian (Reptilia: Diapsida) from the Upper Triassic of Guizhou, China." ] Note that the familyThalattosauridae isparaphyletic , as it includes the direct ancestors of the familyClaraziidae .* Order Thalattosauria
** SuperfamilyAskeptosauroidea
*** Genus "Miodentosaurus "
*** FamilyAskeptosauridae
**** Genus "Anshunsaurus "
**** Genus "Askeptosaurus "
*** FamilyEndennasauridae
**** Genus "Endennasaurus "
** Superfamily Thalattosauroidea
*** Genus "Nectosaurus "
*** Genus "Xinpusaurus "
*** FamilyClaraziidae
**** Genus "Clarazia "
**** Genus "Hescheleria "
*** FamilyThalattosauridae *
**** Genus "Agkistrognathus "
**** Genus "Paralonectes "
**** Genus "Thalattosaurus "Phylogeny
While Thalattosauria has traditionally been used for the largest group containing all families of "thalattosaurs", several authors have recently used this name for what would otherwise be known as Thalattosauroidea, and used the
clade Thalattosauriformes for the larger group.Müller, J., Renesto, S., and Evans, S.E. (2005). "The marine diapsid reptile "Endennasaurus" (Reptilia: Thalattosauriformes) from the Late Triassic of Italy." "Palaeont", 48: 15-30.] Thephylogeny presented here again follows Haaramo, 2004.clade| style=font-size:100%;line-height:80%
label1=Thalattosauriformes
1=clade
label1=Askeptosauroidea
1=clade
1="Endennasaurus "
label2=Askeptosauridae
2=clade
1="Askeptosaurus "
2="Anshunsaurus "
label2=Thalattosauria
2=clade
label1=unnamed
1=clade
1="Nectosaurus "
2="Xinpusaurus "
label2=Thalattosauridae
2=clade
1="Agkistrognathus "
label2=unnamed
2=clade
1="Paralonectes "
label2=unnamed
2=clade
1="Thalattosaurus "
label2=Claraziidae
2=clade
1="Clarazia "
2="Hescheleria "References
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