Caseasauria: Difference between revisions
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{{Automatic taxobox |
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| name = Caseasaurs |
| name = Caseasaurs |
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| fossil_range = {{fossilrange|302|260|[[Late Carboniferous]]<ref name=Eocasea>{{Cite journal|author=Robert R. Reisz and Jörg Fröbisch |year=2014 |title=The Oldest Caseid Synapsid from the Late Pennsylvanian of Kansas, and the Evolution of Herbivory in Terrestrial Vertebrates |journal=PLoS ONE |volume=9 |issue=4 |pages=e94518 |doi=10.1371/journal.pone.0094518 }}</ref> - [[Middle Permian]]}} |
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| fossil_range = {{fossilrange|299|260|[[Early Permian]] - [[Middle Permian]]}} |
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| image = Cotylorhynchus romeri.jpg |
| image = Cotylorhynchus romeri.jpg |
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{{extinct}}?''[[Phreatophasma]]'' |
{{extinct}}?''[[Phreatophasma]]'' |
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'''Caseasauria''' is one of the two main [[clade]]s of early [[synapsids]], the other being the [[Eupelycosauria]]. Caseasaurs are currently known only from the [[Permian]], and include two superficially different families, the small insectivorous or carnivorous [[Eothyrididae]], and the large herbivorous [[Caseidae]]. These two groups share a number of specialised features associated with the morphology of the snout and external [[nares|naris]]. |
'''Caseasauria''' is one of the two main [[clade]]s of early [[synapsids]], the other being the [[Eupelycosauria]]. Caseasaurs are currently known only from the [[Late Carboniferous]]<ref name=Eocasea /> and the [[Permian]], and include two superficially different families, the small insectivorous or carnivorous [[Eothyrididae]], and the large herbivorous [[Caseidae]]. These two groups share a number of specialised features associated with the morphology of the snout and external [[nares|naris]]. |
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The ancestor of caseasaurs can be traced back to an insect eating or an omnivorous [[reptile]]-like [[synapsid]] from the [[Pennsylvanian (geology)|Pennsylvanian]] time of the [[Carboniferous]], possibly resembling ''[[Archaeothyris]]'', the earliest known synapsid. The caseasaurs were abundant during the later part of the [[Early Permian]], but by the [[Middle Permian]] caseasaur diversity declined because the group was outcompeted by the more successful [[therapsid]]s. The last caseasaurs became extinct at the end of the Guadelupian (Middle Permian).<ref>Maddin, H.C., Sidor, C.A. & Reisz, R.R. 2008. Cranial anatomy of Ennatosaurus tecton (Synapsida: Caseidae) from the Middle Permian of Russia and the evolutionary relationships of Caseidae. Journal of Vertebrate Paleontology (28): 160-180</ref> |
The ancestor of caseasaurs can be traced back to an insect eating or an omnivorous [[reptile]]-like [[synapsid]] from the [[Pennsylvanian (geology)|Pennsylvanian]] time of the [[Carboniferous]], possibly resembling ''[[Archaeothyris]]'', the earliest known synapsid. The caseasaurs were abundant during the later part of the [[Early Permian]], but by the [[Middle Permian]] caseasaur diversity declined because the group was outcompeted by the more successful [[therapsid]]s. The last caseasaurs became extinct at the end of the Guadelupian (Middle Permian).<ref>Maddin, H.C., Sidor, C.A. & Reisz, R.R. 2008. Cranial anatomy of Ennatosaurus tecton (Synapsida: Caseidae) from the Middle Permian of Russia and the evolutionary relationships of Caseidae. Journal of Vertebrate Paleontology (28): 160-180</ref> |
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Revision as of 21:41, 12 February 2015
| Caseasaurs Temporal range:
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| Fossil skeleton of Cotylorhynchus romeri | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Clade: | †Caseasauria |
| Genera and Families | |
Caseasauria is one of the two main clades of early synapsids, the other being the Eupelycosauria. Caseasaurs are currently known only from the Late Carboniferous[1] and the Permian, and include two superficially different families, the small insectivorous or carnivorous Eothyrididae, and the large herbivorous Caseidae. These two groups share a number of specialised features associated with the morphology of the snout and external naris.
The ancestor of caseasaurs can be traced back to an insect eating or an omnivorous reptile-like synapsid from the Pennsylvanian time of the Carboniferous, possibly resembling Archaeothyris, the earliest known synapsid. The caseasaurs were abundant during the later part of the Early Permian, but by the Middle Permian caseasaur diversity declined because the group was outcompeted by the more successful therapsids. The last caseasaurs became extinct at the end of the Guadelupian (Middle Permian).[2]
Phylogeny
Most uncertainty in the phylogeny of synapsids lies among the earliest members of the group, including forms traditionally placed within Pelycosauria. As one of the earliest phylogenetic analyses, Brinkman & Eberth (1983) placed the family Varanopidae with Caseasauria as the most basal ofshoot of the synapsid lineage. Reisz (1986) removed Varanopidae from Caseasauria, placing it in a more derived position on the stem. While most analyses find Caseasauria to be the most basal synapsid clade, the analysis of Benson (2012) placed a clade containing Ophiacodontidae and Varanopidae as the most basal synapsids, with Caseasauria occupying a more derived position. Benson attributed this revised phylogeny to the inclusion of postcranial characteristics, or features of the skeleton other than the skull, in his analysis. When only cranial or skull features were included, Caseasauria remained the most basal synapsid clade. Below is a cladogram modified from the analysis of Benson (2012):[3]
See also
References
- ^ a b Robert R. Reisz and Jörg Fröbisch (2014). "The Oldest Caseid Synapsid from the Late Pennsylvanian of Kansas, and the Evolution of Herbivory in Terrestrial Vertebrates". PLoS ONE. 9 (4): e94518. doi:10.1371/journal.pone.0094518.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Maddin, H.C., Sidor, C.A. & Reisz, R.R. 2008. Cranial anatomy of Ennatosaurus tecton (Synapsida: Caseidae) from the Middle Permian of Russia and the evolutionary relationships of Caseidae. Journal of Vertebrate Paleontology (28): 160-180
- ^ Benson, R.J. (2012). "Interrelationships of basal synapsids: cranial and postcranial morphological partitions suggest different topologies". Journal of Systematic Paleontology. in press. doi:10.1080/14772019.2011.631042.
- Reisz, R. R., 1986, Handbuch der Paläoherpetologie – Encyclopedia of Paleoherpetology, Part 17A Pelycosauria Verlag Dr. Friedrich Pfeil, ISBN 3-89937-032-5
- Laurin, M. and Reisz, R. R., 1997, Autapomorphies of the main clades of synapsids
External links
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