Microsauria

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Microsauria
Temporal range:
Ma
Microsauria diversity. (Hyloplesion (A), Pantylus (B), Pelodosotis (C) & Rhynchonkos (D))
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Superclass: Tetrapoda
Order: †Microsauria
Dawson, 1863
Subgroups

Microsauria ("small lizards") is an extinct, possibly

paraphyletic, as several other non-microsaur lepospondyl groups such as Lysorophia seem to be nested in it.[2][4][5] Microsauria is now commonly used as a collective term for the grade of lepospondyls that were originally classified as members of Microsauria.[3]

Microbrachis

The microsaurs all had short tails and small legs, but were otherwise quite varied in form. The group included lizard-like animals that were relatively well-adapted to living on dry land, burrowing forms, and others that, like the modern axolotl, retained their gills into adult life, and so presumably never left the water.[6] Their skeleton was heavily ossified, and their development was likely gradual with no metamorphosis.[7]

Distribution

Microsaurs are known from Europe and North America.

Microsaur remains have been found from

Late Permian in age, near the Permo-Triassic boundary. The microsaur material at Vyazniki may be the youngest record of microsaurs, and would extend their range by around 20 million years. However, fossil remains from Gansu Province shows possible Triassic record of microsaur.[13]

Classification

Cladogram modified from Anderson (2001), with microsaur taxa marked with yellow highlight:[4]

  Lepospondyli      Microsaurs
Marjanovic & Laurin (2009) tree from SOM[14]

Cladogram from Ruta and Coates (2007):[5]

  "Microsauria"  

Cladistic analysis by Pardo et al. (2017) places

Amniota.[15]

References

  1. S2CID 218925814
    .
  2. ^
    S2CID 31298396
    .
  3. ^
    S2CID 128436286
    .
  4. ^
    PMID 12116927
    .
  5. ^
    S2CID 86479890
    .
  6. ISBN 978-1-84028-152-1
    .
  7. ^ Herpetology: An Introductory Biology of Amphibians and Reptiles
  8. ^ Thayer, D.W. (1985). "New Pennsylvanian lepospondyl amphibians from the Swisshelm Mountains, Arizona". Journal of Paleontology. 59 (3): 684–700.
  9. doi:10.1080/02724634.1986.10011609
    .
  10. ^ Huttenlocker, A. K.; Pardo, J. D.; Small, B. J.; Anderson, J. S. (2013). "Cranial morphology of recumbirostrans (Lepospondyli) from the Permian of Kansas and Nebraska, and early morphological evolution inferred by micro-computed tomography". Journal of Vertebrate Paleontology 33 (3): 540.
  11. doi:10.1111/j.1096-3642.1934.tb01644.x
    .
  12. S2CID 129507095
    .
  13. S2CID 85789838
    .
  14. S2CID 12023942
    .
  15. S2CID 2478132
    .

External links
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