Pelycosaur (/ˈpɛlɪkəˌsɔːrz/PEL-ih-kə-sorz)[1] is an older term for basal or primitive Late Paleozoicsynapsids, excluding the therapsids and their descendants. Previously, the term mammal-like reptile had been used,[2] and pelycosaur was considered an order, but this is now thought to be incorrect, and seen as outdated.
Because it excludes the advanced synapsid group Therapsida, the term is paraphyletic and contrary to modern formal naming practice.[3] Thus the name pelycosaurs, similar to the term mammal-like reptiles, had fallen out of favor among scientists by the 21st century, and is only used informally, if at all, in the modern scientific literature.[4][5] The terms stem mammals, protomammals, and basal or primitive synapsids are used where needed, instead.
The term pelycosaur has been fairly well abandoned by paleontologists because it no longer matches the features that distinguish a clade.[5] The modern word was created from Greek pélyx meaning 'wooden bowl' or 'axe' and saûros meaning 'lizard'. The intended etymology presents a problem, since pelycosaur as created basically means 'basin lizard', but there is a ambiguity between several original Greek words in that pélix is 'wooden bowl' and pelíkē is 'basin', whereas pélyx is 'ax' (like pélekys 'double-edged ax').[citation needed]
Pelycosauria is a paraphyletic taxon because it excludes the therapsids. For that reason, the term is sometimes avoided by proponents of a strict cladistic approach. Eupelycosauria is used to designate the clade that includes most pelycosaurs, along with the Therapsida and Mammalia. In contrast to "pelycosaurs", Eupelycosauria is a proper monophyletic group. Caseasauria is a pelycosaur side-branch, or clade, that did not leave any descendants.[citation needed]
Comparison of "pelycosaurian" skulls: 1 sphenacodont, 2 ophiacodont, 3 caseid. The quadratojugale is green, squamosale is red, jugale is blue.
The pelycosaurs appear to have been a group of synapsids that have direct ancestral links with the mammals, having differentiated teeth and a developing hard palate. The pelycosaurs appeared during the LateCarboniferous and reached their apex in the early part of the Permian, remaining the dominant land animals for some 40 million years. A few continued into the Capitanian, but they experienced a sharp decline in diversity in the late Kungurian.[6] They were succeeded by the therapsids.
Some species were quite large, growing to a length of 3 metres (10 ft) or more, although most species were much smaller. Well-known pelycosaurs include the generaDimetrodon, Sphenacodon, Edaphosaurus, and Ophiacodon.[7]
Pelycosaur fossils have been found mainly in Europe and North America, although some small, late-surviving forms are known from Russia and South Africa.
Unlike lepidosaurian reptiles, pelycosaurs lacked reptilian epidermal scales.[disputed – discuss] Fossil evidence from some varanopids shows that parts of the skin were covered in rows of osteoderms, presumably overlain by horny scutes.[4] The belly was covered in rectangular scutes, looking like those present in crocodiles.[8] Parts of the skin not covered in scutes might have had naked, glandular skin like that found in some mammals. Dermal scutes are also found in a diverse number of extant mammals with conservative body types, such as in the tails of some rodents, sengis, moonrats, the opossums and other marsupials, and as regular dermal armour with underlying bone in the armadillo.
In phylogenetic nomenclature, "Pelycosauria" is not used formally, since it does not constitute a group of all organisms descended from some common ancestor (a clade), because the group specifically excludes the therapsids which are descended from pelycosaurs. Instead, it represents a paraphyletic "grade" of basal synapsids leading up to the clade Therapsida.[10]
In 1940, the group was reviewed in detail, and every species known at the time described, with many illustrated, in an important monograph by Alfred Sherwood Romer and Llewellyn Price.[11]
In traditional classification, the order Pelycosauria is paraphyletic in that the therapsids (the "higher" synapsids) have emerged from them. That means Pelycosauria is a grouping of animals that does not contain all descendants of its common ancestor, as is often required by phylogenetic nomenclature. In evolutionary taxonomy, Therapsida is a separated order from Pelycosauria, and mammals (having evolved from therapsids) are separated from both as their own class. This use has not been recommended by a majority of systematists since the 1990s,[5] but several paleontologists nevertheless continue using this word.[12][10]
The following classification was presented by Benton in 2004.[13]
^Cope, E. D. (1878). "Descriptions of extinct Batrachia and Reptilia from the Permian formation of Texas". Proceedings of the American Philosophical Society. 17 (101): 505–530. JSTOR 982652.
^Carroll, R.L. 1988. Vertebrate Paleontology and Evolution. WH Freeman and Company, New York ISBN 0-7167-1822-7
^Hennig, Willi (1981). Insect phylogeny. Chichester [England]: J. Wiley. pp. xi + 514. ISBN0471278483.
^ abBotha-Brink, J.; Modesto, S.P. (2007). "A mixed-age classed 'pelycosaur' aggregation from South Africa: Earliest evidence of parental care in amniotes?". Proceedings of the Royal Society B. 274 (1627): 2829–2834. doi:10.1098/rspb.2007.0803. PMC2288685. PMID 17848370.
^ abcLaurin, Michel (2010). How Vertebrates Left the Water. Berkeley, CA: University of California Press. pp. xv + 199. ISBN978-0-520-26647-6.
^Didier, Gilles; Laurin, Michel (2021). "Distributions of extinction times from fossil ages and tree topologies: the example of some mid-Permian synapsid extinctions". PeerJ. 9 (e12577): e12577. doi:10.7717/peerj.12577. PMC8667717. PMID 34966586.
^Cowen, Richard (2013). History of Life. John Wiley & Sons. pp. 91–92. ISBN978-1-11851-093-3.
^Carroll, R.L. (1969). "Problems of the origin of reptiles". Biological Reviews. 44 (3): 393–432. doi:10.1111/j.1469-185X.1969.tb01218.x. S2CID 84302993.
^Tracy, C.R.; Turner, J.S.; Huey, R.B. (1986). "A biophysical analysis of possible thermoregulatoryadaptations in pelycosaurs". In MacLean, P.D.; Roth, J.J.; Roth, E.C.; Hotton, N. (eds.). Ecology and Biology of Mammal-Like Reptiles. Washington, DC: Smithsonian Press. pp. 195–205.
^ abBrocklehurst, Neil; Fröbisch, Jörg (2018). "A reexamination of Milosaurus mccordi, and the evolution of large body size in Carboniferous synapsids". Journal of Vertebrate Paleontology. 35 (8): e1508026. doi:10.1080/02724634.2018.1508026. S2CID 91487577.
^Romer, A.S.; Price, L.I. (1940). "Review of the Pelycosauria". 28 : Review of the Pelycosauria. Geological Society of America Special Papers. Vol. 28. pp. 1–538. doi:10.1130/SPE28-p1.
^Amson, Eli; Laurin, Michel (2011). "On the affinities of Tetraceratops insignis, an Early Permian synapsid". Acta Palaeontologica Polonica. 56 (2): 301–312. doi:10.4202/app.2010.0063. S2CID 56425905.
^Benton, Michael J. (2004). Vertebrate palaeontology (3rd ed.). Oxford: Blackwell Science. ISBN978-0-632-05637-8.
References
Reisz, R.R. (1986). Handbuch der Paläoherpetologie [Encyclopedia of Paleoherpetology]. Verlag Dr. Friedrich Pfeil. Part 17A Pelycosauria. ISBN3-89937-032-5.
External links
Wikispecies has information related to Pelycosauria.
"Introduction to the Pelycosaurs". UCMP.
"Synapsida - Pelycosauria". Palaeos. Archived from the original on 2006-03-13.
February 23, 2023
pelycosaur, ɔːr, sorz, older, term, basal, primitive, late, paleozoic, synapsids, excluding, therapsids, their, descendants, previously, term, mammal, like, reptile, been, used, pelycosaur, considered, order, this, thought, incorrect, seen, outdated, stemporal. Pelycosaur ˈ p ɛ l ɪ k e ˌ s ɔːr z PEL ih ke sorz 1 is an older term for basal or primitive Late Paleozoic synapsids excluding the therapsids and their descendants Previously the term mammal like reptile had been used 2 and pelycosaur was considered an order but this is now thought to be incorrect and seen as outdated PelycosaursTemporal range Pennsylvanian Capitanian 308 260 4 Ma Descendant taxon Therapsida survives to present PreꞒ Ꞓ O S D C P T J K Pg NMounted skeleton of Dimetrodon mileri Harvard Museum of Natural HistoryScientific classificationKingdom AnimaliaPhylum ChordataSuperclass TetrapodaClade ReptiliomorphaClade AmniotaClade SynapsidaInformal group PelycosauriaCope 1878Groups included Caseidae Eothyrididae Varanopidae Ophiacodontidae Edaphosauridae Palaeohatteriidae SphenacodontidaeCladistically included but traditionally excluded taxaTherapsidaBecause it excludes the advanced synapsid group Therapsida the term is paraphyletic and contrary to modern formal naming practice 3 Thus the name pelycosaurs similar to the term mammal like reptiles had fallen out of favor among scientists by the 21st century and is only used informally if at all in the modern scientific literature 4 5 The terms stem mammals protomammals and basal or primitive synapsids are used where needed instead Contents 1 Etymology 2 Evolutionary history 3 Description 4 Taxonomy 5 See also 6 Notes 7 References 8 External linksEtymology EditThe term pelycosaur has been fairly well abandoned by paleontologists because it no longer matches the features that distinguish a clade 5 The modern word was created from Greek pelyx meaning wooden bowl or axe and sauros meaning lizard The intended etymology presents a problem since pelycosaur as created basically means basin lizard but there is a ambiguity between several original Greek words in that pelix is wooden bowl and pelike is basin whereas pelyx is ax like pelekys double edged ax citation needed Pelycosauria is a paraphyletic taxon because it excludes the therapsids For that reason the term is sometimes avoided by proponents of a strict cladistic approach Eupelycosauria is used to designate the clade that includes most pelycosaurs along with the Therapsida and Mammalia In contrast to pelycosaurs Eupelycosauria is a proper monophyletic group Caseasauria is a pelycosaur side branch or clade that did not leave any descendants citation needed Evolutionary history EditSee also Evolution of mammals Comparison of pelycosaurian skulls 1 sphenacodont 2 ophiacodont 3 caseid The quadratojugale is green squamosale is red jugale is blue The pelycosaurs appear to have been a group of synapsids that have direct ancestral links with the mammals having differentiated teeth and a developing hard palate The pelycosaurs appeared during the Late Carboniferous and reached their apex in the early part of the Permian remaining the dominant land animals for some 40 million years A few continued into the Capitanian but they experienced a sharp decline in diversity in the late Kungurian 6 They were succeeded by the therapsids Description Edit Cotylorhynchus background Ophiacodon and Varanops Some species were quite large growing to a length of 3 metres 10 ft or more although most species were much smaller Well known pelycosaurs include the genera Dimetrodon Sphenacodon Edaphosaurus and Ophiacodon 7 Pelycosaur fossils have been found mainly in Europe and North America although some small late surviving forms are known from Russia and South Africa Unlike lepidosaurian reptiles pelycosaurs lacked reptilian epidermal scales disputed discuss Fossil evidence from some varanopids shows that parts of the skin were covered in rows of osteoderms presumably overlain by horny scutes 4 The belly was covered in rectangular scutes looking like those present in crocodiles 8 Parts of the skin not covered in scutes might have had naked glandular skin like that found in some mammals Dermal scutes are also found in a diverse number of extant mammals with conservative body types such as in the tails of some rodents sengis moonrats the opossums and other marsupials and as regular dermal armour with underlying bone in the armadillo At least two pelycosaur clades independently evolved a tall sail consisting of elongated vertebral spines the edaphosaurids and the sphenacodontids In life this would have been covered by skin and likely functioned as a thermoregulatory device 9 or as a mating display Taxonomy Edit Eothyris Dimetrodon a sphenacodontid In phylogenetic nomenclature Pelycosauria is not used formally since it does not constitute a group of all organisms descended from some common ancestor a clade because the group specifically excludes the therapsids which are descended from pelycosaurs Instead it represents a paraphyletic grade of basal synapsids leading up to the clade Therapsida 10 In 1940 the group was reviewed in detail and every species known at the time described with many illustrated in an important monograph by Alfred Sherwood Romer and Llewellyn Price 11 In traditional classification the order Pelycosauria is paraphyletic in that the therapsids the higher synapsids have emerged from them That means Pelycosauria is a grouping of animals that does not contain all descendants of its common ancestor as is often required by phylogenetic nomenclature In evolutionary taxonomy Therapsida is a separated order from Pelycosauria and mammals having evolved from therapsids are separated from both as their own class This use has not been recommended by a majority of systematists since the 1990s 5 but several paleontologists nevertheless continue using this word 12 10 The following classification was presented by Benton in 2004 13 Order Pelycosauria Family Eothyrididae Family Caseidae Family Varanopidae Family Ophiacodontidae Family Edaphosauridae Family Sphenacodontidae Order TherapsidaSee also EditEvolution of mammals List of pelycosaurs Vertebrate paleontologyNotes Edit Cope E D 1878 Descriptions of extinct Batrachia and Reptilia from the Permian formation of Texas Proceedings of the American Philosophical Society 17 101 505 530 JSTOR 982652 Carroll R L 1988 Vertebrate Paleontology and Evolution WH Freeman and Company New York ISBN 0 7167 1822 7 Hennig Willi 1981 Insect phylogeny Chichester England J Wiley pp xi 514 ISBN 0471278483 a b Botha Brink J Modesto S P 2007 A mixed age classed pelycosaur aggregation from South Africa Earliest evidence of parental care in amniotes Proceedings of the Royal Society B 274 1627 2829 2834 doi 10 1098 rspb 2007 0803 PMC 2288685 PMID 17848370 a b c Laurin Michel 2010 How Vertebrates Left the Water Berkeley CA University of California Press pp xv 199 ISBN 978 0 520 26647 6 Didier Gilles Laurin Michel 2021 Distributions of extinction times from fossil ages and tree topologies the example of some mid Permian synapsid extinctions PeerJ 9 e12577 e12577 doi 10 7717 peerj 12577 PMC 8667717 PMID 34966586 Cowen Richard 2013 History of Life John Wiley amp Sons pp 91 92 ISBN 978 1 11851 093 3 Carroll R L 1969 Problems of the origin of reptiles Biological Reviews 44 3 393 432 doi 10 1111 j 1469 185X 1969 tb01218 x S2CID 84302993 Tracy C R Turner J S Huey R B 1986 A biophysical analysis of possible thermoregulatoryadaptations in pelycosaurs In MacLean P D Roth J J Roth E C Hotton N eds Ecology and Biology of Mammal Like Reptiles Washington DC Smithsonian Press pp 195 205 a b Brocklehurst Neil Frobisch Jorg 2018 A reexamination of Milosaurus mccordi and the evolution of large body size in Carboniferous synapsids Journal of Vertebrate Paleontology 35 8 e1508026 doi 10 1080 02724634 2018 1508026 S2CID 91487577 Romer A S Price L I 1940 Review of the Pelycosauria 28 Review of the Pelycosauria Geological Society of America Special Papers Vol 28 pp 1 538 doi 10 1130 SPE28 p1 Amson Eli Laurin Michel 2011 On the affinities of Tetraceratops insignis an Early Permian synapsid Acta Palaeontologica Polonica 56 2 301 312 doi 10 4202 app 2010 0063 S2CID 56425905 Benton Michael J 2004 Vertebrate palaeontology 3rd ed Oxford Blackwell Science ISBN 978 0 632 05637 8 References EditReisz R R 1986 Handbuch der Palaoherpetologie Encyclopedia of Paleoherpetology Verlag Dr Friedrich Pfeil Part 17A Pelycosauria ISBN 3 89937 032 5 External links Edit Wikispecies has information related to Pelycosauria Introduction to the Pelycosaurs UCMP Synapsida Pelycosauria Palaeos Archived from the original on 2006 03 13 Retrieved from https en wikipedia org w index php title Pelycosaur amp oldid 1138971882, wikipedia, wiki, book, books, library,
