Askeptosauridae Explained

Askeptosauridae is a family of thalattosaurs within the superfamily Askeptosauroidea. Fossils have been found from Italy, Switzerland, and China. Askeptosaurids are distinguished from other thalattosaurs by their long necks and narrow skulls.[1]

Classification

Askeptosauridae was named in 1952 to include the genus Askeptosaurus.[2] In 2000, the genus Anshunsaurus, which includes two species, was added to the family.[3] In a 2005 phylogenetic analysis, Endennasaurus was included within Askeptosauridae.[4] Later that year a new study placed Endennasaurus outside Askeptosauridae as a basal member of Askeptosauroidea.[1] More recent studies have placed the genus Miodentosaurus from China in the family as well. Below is a cladogram modified from Wu et al. (2009) showing the phylogenetic relationships of askeptosaurids:[5]

Chart Found on PBDB[6] !Time Interval !Ma!Country or State!Original ID and collection number !Purpose of Collection
Anisian - Ladinian247.2 - 237.0SwitzerlandAskeptosaurus italicus (174993) Taxonomic Analysis
Illyrian - Fassanian247.2 - 235.0SwitzerlandAskeptosaurus italicus (122057) [7] Taxonomic Analysis
Longobardian242.0 - 235.0China (Yunnan)Askeptosaurus sp. (196166) [8] Taxonomic Analysis
Longobardian242.0 - 235.0China (Guizhou)Anshunsaurus wushaensis, Anshunsaurus huangnihensis (98907) [9] General Faunal/Floral Analysis
Carnian237.0 - 228.0China (Guizhou)Anshunsaurus huangguoshuensis, Miodentosaurus brevis (97906) General Faunal/Floral Analysis
Tuvalian232.0 - 221.5China (Guizhou)Anshunsaurus huangguoshuensis (85166) [10] General Faunal/Floral Analysis
It was assigned to Thalattosauria by Kuhn (1966)[11] and Carroll (1988);[12] and to Askeptosauroidea by Wu et al. (2009).

The Askeptosauridae is known to be from the Alpine Triassic and Southern China. The Endennasaurus is from the Norian age and is a sister taxon of Askeptosaurids. The Askeptoaurus which is the oldest known member of the Askeptosaurids derived from the Northern Tethyan Area.This information proposes that Edennasaurus and future askeptosaurids originated from that Northern Tethyan area.

When the two major thalattosaur assemblages split, the Edennasaurus and Askeptosaurids still kept some similar appendages to each other, such as a relatively well-ossified carpus and tarsus. These bone structures show that these animals still made trips onto the land around them. The development of the elongated neck was for these creatures to better catch their prey. As a longer and more mobile neck gives them more advantage to be able to catch their movable prey.

Notes and References

  1. Liu . J. . Rieppel, O. . 2005 . Restudy of Anshunsaurus huangguoshuensis (Reptilia: Thalattosauria) from the Middle Triassic of Guizhou, China . American Museum Novitates . 3488 . 1–34 . 0003-0082 . 10.1206/0003-0082(2005)488[0001:roahrt]2.0.co;2. 55642315 .
  2. Kuhn-Schnyder . E. . 1952 . Die Triasfauna der Tessiner Kalkalpen. XVII. Askeptosaurus italicus Nopcsa . Schweizerische Paläontologische Abhandlungen . 69 . 1–52.
  3. Rieppel . O. . Liu, J.. Bucher, H. . 2000 . The first record of a thalattosaur reptile from the Late Triassic of southern China (Guizhou Province, PR China) . Journal of Vertebrate Paleontology . 20 . 3 . 507–514 . 10.1671/0272-4634(2000)020[0507:TFROAT]2.0.CO;2. 140706921 .
  4. Müller . J. . 2005 . The anatomy of Askeptosaurus italicus from the Middle Triassic of Monte San Giorgio, and the interrelationships of thalattosaurs (Reptilia, Diapsida) . Canadian Journal of Earth Sciences . 42 . 7 . 1347–1367 . 10.1139/e05-030. 2005CaJES..42.1347M .
  5. Wu . X.-C. . Cheng, Y.-N. . Sato, T. . Shan, H.-Y. . 2009 . Miodentosaurus brevis Cheng et al., 2007 (Diapsida: Thalattosauria): its postcranial skeleton and phylogenetic relationships . Vertebrata PalAsiatica . 47 . 1 . 1–20 . 2011-04-23 . https://web.archive.org/web/20111122152559/http://www.ivpp.ac.cn/cbw/gjzdwxb/xbwzxz/200902/W020090813372748918302.pdf . 2011-11-22 . dead .
  6. Web site: PBDB . 2023-11-07 . paleobiodb.org.
  7. Rieber . H . 1970 . Phragmoteuthis ? ticinensis n. sp., ein Coleoidea-Rest aus der Grenzbitumenzone (Mittlere Trias) des Monte San Giorgio (Kt. Tessin, Schweiz) . Paläontologische Zeitschrift . 44 . 1–2. 32–40. 10.1007/BF02989793 . 1970PalZ...44...32R . 129041989 .
  8. Sun . Z . Maisch . M. W. . Hao . W.-C. . Jiang . D . 2005 . A Middle Triassic thalattosaur (Reptilia: Diapsida) from Yunnan (China) . Neues Jahrbuch für Geologie und Paläontologie - Monatshefte . 2005 . 4 . 193–206. 10.1127/njgpm/2005/2005/193 .
  9. Rieppel . O . Liu . J . Li . C . 2006 . A new species of the thalattosaur genus Anshunsaurus (Reptilia: Thalattosauria) from the Middle Triassic of Guizhou Province, southwestern China . Vertebrata PalAsiatica . 44 . 4 . 285–296.
  10. Li . C . Rieppel . O . 2002 . A new cyamodontid placodont from Triassic of Guizhou, China . Chinese Science Bulletin . 47 . 5 . 403–407. 10.1360/02tb9094 . 2002ChSBu..47..403L . 129796015 .
  11. Book: Kuhn, O. W. M. . Die Reptillien. System und Stammesgeschichte . 1966 . 1–154.
  12. R. L. Carroll. 1988. Vertebrate Paleontology and Evolution 1-698 [A. Behrensmeyer/A. Behrensmeyer/M. Uhen]

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