Many vertebrates are limbless, limb-reduced, or apodous, with a body plan consisting of a head and vertebral column, but no adjoining limbs such as legs or fins. Jawless fish are limbless but may have preceded the evolution of vertebrate limbs, whereas numerous reptile and amphibian lineages – and some eels and eel-like fish – independently lost their limbs. Larval amphibians, tadpoles, are also often limbless. No mammals or birds are limbless, but some feature partial limb-loss or limb reduction.
Lizards have evolved limbless forms on a number of occasions. The legless lizard shown above is known as a slowworm (Anguis fragilis).Life restoration of Phlegethontia longissima, fossil amphibians belonging to the limbless aistopods.
The jawless fish (hagfish and lamprey) do not have appendage-like fins. They may not have lost them, but rather, simply retained the form that vertebrates had before the evolution of limbs.[1] There are also a number of fish with elongated bodies that have no fins or reduced appendage-like fins, for example eels and swamp eels.[2]
Reptiles have on a number of occasions evolved into limbless forms – snakes, amphisbaenians, and legless lizards (limb loss in lizards has evolved independently several times, examples include the families Pygopodidae and Dibamidae and species of Isopachys, Anguis, and Ophisaurus). Several species of legless lizards have tiny useless legs, such as pygopodids which retain rudimentary flaps.[3] Contrarily, the worm lizard Bipes as its scientific name suggests has two stubby forelimbs which actually assist in digging similar to a mole. All other amphisbaenians have reduced or absent forelimb girdles.[4]
Larval amphibians, tadpoles, are often limbless. Adult amphibians have also evolved limblessness multiple times – caecilians, Sirenidae (a clade of salamanders that are limbless except for atrophied front limbs), Amphiumidae (a clade of salamander with extremely atrophied limbs that appear non-functional) and at least three extinct groups (Aïstopoda, Lysorophia, and Adelospondyli).[5]
There are no known limbless species of mammal or bird, although partial limb-loss and reduction has occurred in several groups, including whales and dolphins, sirenians, kiwis, and the extinct moa and elephant birds. The moa in particular are notable for having completely lost their wings, without even vestigial wings remaining outside their bodies.[6] Despite its name, the finless porpoise has two fins.
Evolutionedit
Legless forms of reptiles and amphibians probably evolved so as to be able to move underground or in water more easily. Some analyses suggest that elongation and undulatory locomotion (slithering) evolved first, before limb loss.[7] The debate about the origin of limblessness led to a temporary hypothesis about a marine origin for snakes, which is no longer favored since the discovery of snake fossils with hindlimbs.[8]
In the case of limb loss during evolution, vestigial structures testify to this change (remains of the pelvis, rudimentary femur or spurs in boas, pythons and Typhlops). The evolutionary process of transforming quadrupedal lizards into legless forms results in three main characteristics: the regression of the limbs is carried out gradually, via the reduction in their size and the reduction in the number of phalanges or fingers; the multiplication of the vertebrae (up to 600 in some snakes) induces a lengthening and a gain in flexibility of the trunk; and the vertebral axis is homogenized from the neck to the cloaca, evoking an interminable ribcage.[9][10]
See alsoedit
Look up apodous in Wiktionary, the free dictionary.
^Shimeld, Sebastian M.; Donoghue, Phillip C. J. (2012-06-15). "Evolutionary crossroads in developmental biology: cyclostomes (lamprey and hagfish)". Development. 139 (12): 2091–2099. doi:10.1242/dev.074716. ISSN 0950-1991. PMID 22619386.
^Pfaff, Cathrin; Zorzin, Roberto; Kriwet, Jürgen (2016-08-11). "Evolution of the locomotory system in eels (Teleostei: Elopomorpha)". BMC Evolutionary Biology. 16 (1): 159. doi:10.1186/s12862-016-0728-7. ISSN 1471-2148. PMC4981956. PMID 27514517.
^Spinner, M.; Gorb, S. N.; Westhoff, G. (2013-12-07). "Diversity of functional microornamentation in slithering geckos Lialis (Pygopodidae)". Proceedings of the Royal Society B: Biological Sciences. 280 (1772): 20132160. doi:10.1098/rspb.2013.2160. PMC3813336. PMID 24107533.
^Westphal, Natascha; Mahlow, Kristin; Head, Jason James; Müller, Johannes (2019-01-10). "Pectoral myology of limb-reduced worm lizards (Squamata, Amphisbaenia) suggests decoupling of the musculoskeletal system during the evolution of body elongation". BMC Evolutionary Biology. 19 (1): 16. doi:10.1186/s12862-018-1303-1. ISSN 1471-2148. PMC6329177. PMID 30630409.
^Woltering, Joost M (2012). "From Lizard to Snake; Behind the Evolution of an Extreme Body Plan". Current Genomics. 13 (4): 289–299. doi:10.2174/138920212800793302. ISSN 1389-2029. PMC3394116. PMID 23204918.
^"Moa forelimb structure and forelimb initiation gene network. A. The moa..." ResearchGate. Retrieved 2020-08-25.
^Gans, Carl (1975-05-01). "Tetrapod Limblessness: Evolution and Functional Corollaries". Integrative and Comparative Biology. 15 (2): 455–467. doi:10.1093/icb/15.2.455. ISSN 1540-7063.
^Greene, Harry W.; Cundall, David (2000-03-17). "Limbless Tetrapods and Snakes with Legs". Science. 287 (5460): 1939–1941. doi:10.1126/science.287.5460.1939. ISSN 0036-8075. PMID 10755945. S2CID 82318997.
^Aurélien, Miralles (2015). "Serpents et lézards sans pattes : quand les Tétrapodes ne le sont plus vraiment". Espèces (in French): 21.
limbless, vertebrate, confused, with, apodidae, many, vertebrates, limbless, limb, reduced, apodous, with, body, plan, consisting, head, vertebral, column, adjoining, limbs, such, legs, fins, jawless, fish, limbless, have, preceded, evolution, vertebrate, limb. Not to be confused with Apodidae Many vertebrates are limbless limb reduced or apodous with a body plan consisting of a head and vertebral column but no adjoining limbs such as legs or fins Jawless fish are limbless but may have preceded the evolution of vertebrate limbs whereas numerous reptile and amphibian lineages and some eels and eel like fish independently lost their limbs Larval amphibians tadpoles are also often limbless No mammals or birds are limbless but some feature partial limb loss or limb reduction Contents 1 Examples 2 Evolution 3 See also 4 ReferencesExamples edit nbsp Lizards have evolved limbless forms on a number of occasions The legless lizard shown above is known as a slowworm Anguis fragilis nbsp Life restoration of Phlegethontia longissima fossil amphibians belonging to the limbless aistopods The jawless fish hagfish and lamprey do not have appendage like fins They may not have lost them but rather simply retained the form that vertebrates had before the evolution of limbs 1 There are also a number of fish with elongated bodies that have no fins or reduced appendage like fins for example eels and swamp eels 2 Reptiles have on a number of occasions evolved into limbless forms snakes amphisbaenians and legless lizards limb loss in lizards has evolved independently several times examples include the families Pygopodidae and Dibamidae and species of Isopachys Anguis and Ophisaurus Several species of legless lizards have tiny useless legs such as pygopodids which retain rudimentary flaps 3 Contrarily the worm lizard Bipes as its scientific name suggests has two stubby forelimbs which actually assist in digging similar to a mole All other amphisbaenians have reduced or absent forelimb girdles 4 Larval amphibians tadpoles are often limbless Adult amphibians have also evolved limblessness multiple times caecilians Sirenidae a clade of salamanders that are limbless except for atrophied front limbs Amphiumidae a clade of salamander with extremely atrophied limbs that appear non functional and at least three extinct groups Aistopoda Lysorophia and Adelospondyli 5 There are no known limbless species of mammal or bird although partial limb loss and reduction has occurred in several groups including whales and dolphins sirenians kiwis and the extinct moa and elephant birds The moa in particular are notable for having completely lost their wings without even vestigial wings remaining outside their bodies 6 Despite its name the finless porpoise has two fins Evolution editLegless forms of reptiles and amphibians probably evolved so as to be able to move underground or in water more easily Some analyses suggest that elongation and undulatory locomotion slithering evolved first before limb loss 7 The debate about the origin of limblessness led to a temporary hypothesis about a marine origin for snakes which is no longer favored since the discovery of snake fossils with hindlimbs 8 In the case of limb loss during evolution vestigial structures testify to this change remains of the pelvis rudimentary femur or spurs in boas pythons and Typhlops The evolutionary process of transforming quadrupedal lizards into legless forms results in three main characteristics the regression of the limbs is carried out gradually via the reduction in their size and the reduction in the number of phalanges or fingers the multiplication of the vertebrae up to 600 in some snakes induces a lengthening and a gain in flexibility of the trunk and the vertebral axis is homogenized from the neck to the cloaca evoking an interminable ribcage 9 10 See also edit nbsp Look up apodous in Wiktionary the free dictionary Anguilliformity Category Animals with only two limbs Larvae which describes many non vertebrate limbless forms Limb development discussion of the genetic and developmental processes affecting limb growth Macroevolution Limbloss in lizards and snakes Snake evolution Terrestrial locomotion Undulatory locomotionReferences edit Shimeld Sebastian M Donoghue Phillip C J 2012 06 15 Evolutionary crossroads in developmental biology cyclostomes lamprey and hagfish Development 139 12 2091 2099 doi 10 1242 dev 074716 ISSN 0950 1991 PMID 22619386 Pfaff Cathrin Zorzin Roberto Kriwet Jurgen 2016 08 11 Evolution of the locomotory system in eels Teleostei Elopomorpha BMC Evolutionary Biology 16 1 159 doi 10 1186 s12862 016 0728 7 ISSN 1471 2148 PMC 4981956 PMID 27514517 Spinner M Gorb S N Westhoff G 2013 12 07 Diversity of functional microornamentation in slithering geckos Lialis Pygopodidae Proceedings of the Royal Society B Biological Sciences 280 1772 20132160 doi 10 1098 rspb 2013 2160 PMC 3813336 PMID 24107533 Westphal Natascha Mahlow Kristin Head Jason James Muller Johannes 2019 01 10 Pectoral myology of limb reduced worm lizards Squamata Amphisbaenia suggests decoupling of the musculoskeletal system during the evolution of body elongation BMC Evolutionary Biology 19 1 16 doi 10 1186 s12862 018 1303 1 ISSN 1471 2148 PMC 6329177 PMID 30630409 Woltering Joost M 2012 From Lizard to Snake Behind the Evolution of an Extreme Body Plan Current Genomics 13 4 289 299 doi 10 2174 138920212800793302 ISSN 1389 2029 PMC 3394116 PMID 23204918 Moa forelimb structure and forelimb initiation gene network A The moa ResearchGate Retrieved 2020 08 25 Gans Carl 1975 05 01 Tetrapod Limblessness Evolution and Functional Corollaries Integrative and Comparative Biology 15 2 455 467 doi 10 1093 icb 15 2 455 ISSN 1540 7063 Greene Harry W Cundall David 2000 03 17 Limbless Tetrapods and Snakes with Legs Science 287 5460 1939 1941 doi 10 1126 science 287 5460 1939 ISSN 0036 8075 PMID 10755945 S2CID 82318997 Aurelien Miralles 2015 Serpents et lezards sans pattes quand les Tetrapodes ne le sont plus vraiment Especes in French 21 Miralles Aurelien Hipsley Christy A Erens Jesse Gehara Marcelo Rakotoarison Andolalao Glaw Frank Muller Johannes Vences Miguel 2015 06 04 Distinct Patterns of Desynchronized Limb Regression in Malagasy Scincine Lizards Squamata Scincidae PLOS ONE 10 6 e0126074 Bibcode 2015PLoSO 1026074M doi 10 1371 journal pone 0126074 ISSN 1932 6203 PMC 4456255 PMID 26042667 Retrieved from https en wikipedia org w index php title Limbless vertebrate amp oldid 1203115981, wikipedia, wiki, book, books, library,
