Lapillopsis
| Lapillopsis Temporal range:Early Triassic,
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| Restoration ofLapillopsis nana | |
Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Order: | †Temnospondyli |
| Suborder: | †Stereospondyli |
| Family: | †Lapillopsidae |
| Genus: | †Lapillopsis Warren and Hutchinson, 1990 |
| Type species | |
| †Lapillopsis nana Warren and Hutchinson, 1990
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Lapillopsisis an extinctgenusofstereospondyltemnospondylwithin thefamilyLapillopsidae.Fossilsbelonging to the genus have been found in theArcadia Formation(Rewan Group) ofQueensland,Australia.
History of study
[edit]Thetype speciesand only known species isLapillopsis nana,named in 1990 by Australian scientists Anne Warren and Mark Hutchinson.[1]The name is derived from the Latinlapillus(pebble) and Greek -opsis(appearance) in reference to the material of this species being collected from within small rocky nodules. There are two known specimens, both nearly complete skulls with associated mandibles and associated postcranial elements. An additional fourteen specimens from the same locality were described by Australian paleontologist Adam Yates in 1999.[2]
Anatomy
[edit]
Lapillopsiswas differentiated from the closely relatedRotaurisaurusfrom Australia by several features: (1) a deep, semi-elliptical otic notch; (2) an abbreviated posterior skull table; (3) a broad shallow sulcus extending from the posterolateral corner of the quadratojugal to the posterior orbital margin; (4) a broadly flared anterior end of the cultriform process; (5) pterygoid-palatine separation, resulting in an ectopterygoid framing the interpterygoid vacuity; (6) jugal terminating at anterior orbital margin.[2]The skull and mandible are particularly well-known, permitting a more or less complete reconstruction. Postcranial material consists largely of the pectoral and forelimb regions and a few vertebrae.
Phylogenetic relationships
[edit]When it was named,Lapillopsiswas identified as amicropholiddissorophoid;dissorophoids are almost exclusivelyPaleozoicin occurrence with the exception ofMicropholisfrom theEarly TriassicKaroo BasinofSouth Africa.Because computer-assisted phylogenetics were not widely available at the time, the authors made comparisons of distinctive features with those known in other clades and found many similarities with dissorophoids. At the time, dissorophoid systematics remained partially in flux, particularly as it related to several small-bodied terrestrial forms, and Warren and Hutchinson revived Micropholidae, originally created by Watson (1919), to encompass bothMicropholisandLapillopsis,[3]while noting that the latter lacked several apomorphies of Dissorophoidea.
Yates' (1999) description of additional material ofLapillopsisand the new taxonRotaurisaurusled him to create the family Lapillopsidae for this unusual group of small-bodied stereospondyls. Yates' phylogenetic analysis, as well as that of Yates & Warren (2000),[4]recovered lapillopsids at the base of Stereospondyli. A supertree analysis by Ruta et al. (2003)[5]recovered them in a vastly different position, as the sister group to eryopoids, dissorophoids (inclusive of modern amphibians), and zatracheidids.
Lapillopsiswas found as the sister toRotaurisaurusin a 1999 analysis that found theLapillopsidaeas basal stereospondyls.[2]The most recent analysis of stereospondylomorphs by Eltink et al. (2019)[6]recoveredLapillopsiswithinLydekkerinidae,another small-bodied Early Triassic group, as the sister taxon ofLydekkerina,somewhat similar to the results of McHugh's 2012 dissertation.[7]This is in contradiction to previous studies in whichLapillopsishas been recovered: outside of Lydekkerinidae but as its sister group,[8]with dissorophoids,[9][10]as the sister taxon of short-snouted stereospondyl clades like lydekkerinids and metoposaurids,[11]or closely related to brachyopoids.[12]There is a general consensus that lapillopsids are at least stereospondylomorphs if not stereospondyls proper, but there is no clear agreement beyond that. Previous workers have highlighted the potential that specimens may not represent adults[2]or that diminished body size may cause attraction with other small-bodied taxa, like lydekkerinids, in an analysis.[6]
See also
[edit]
References
[edit]- ^Warren, A. A.; Hutchinson, M. N. (1990). "Lapillopsis,a new genus of temnospondyl amphibians from the Early Triassic of Queensland ".Alcheringa.14(2): 149–158.doi:10.1080/03115519008527816.
- ^abcdYates, A. M. 1999. The Lapillopsidae: a new family of small temnospondyls from the Early Triassic of Australia. Journal of Vertebrate Paleontology 19: 302-320.https://doi.org/10.1080/02724634.1999.10011143
- ^"I. The structure, evolution and origin of the amphibia. - The" orders' rachitomi and stereospondyli ".Philosophical Transactions of the Royal Society of London. Series B, Containing Papers of a Biological Character.209(360–371): 1–73. 1920-01-01.doi:10.1098/rstb.1920.0001.ISSN0264-3960.
- ^Yates, Adam M.; Warren, A. Anne (January 2000)."The phylogeny of the 'higher' temnospondyls (Vertebrata: Choanata) and its implications for the monophyly and origins of the Stereospondyli".Zoological Journal of the Linnean Society.128(1): 77–121.doi:10.1111/j.1096-3642.2000.tb00650.x.ISSN0024-4082.
- ^Ruta, Marcello; Jeffery, Jonathan E.; Coates, Michael I. (2003-12-07)."A supertree of early tetrapods".Proceedings of the Royal Society of London. Series B: Biological Sciences.270(1532): 2507–2516.doi:10.1098/rspb.2003.2524.ISSN0962-8452.PMC1691537.PMID14667343.
- ^abEltink, Estevan; Schoch, Rainer R.; Langer, Max C. (2019-04-16). "Interrelationships, palaeobiogeography and early evolution of Stereospondylomorpha (Tetrapoda: Temnospondyli)".Journal of Iberian Geology.45(2): 251–267.doi:10.1007/s41513-019-00105-z.ISSN1698-6180.S2CID146595773.
- ^McHugh, Julia (2012).Temnospondyl ontogeny and phylogeny, a window into terrestrial ecosystems during the Permian-Triassic mass extinction.University of Iowa. Archived fromthe originalon October 1, 2017.
- ^Dias-da-Silva, Sergio; Hewison, Robin H. (2013). "Phylogenetic Analysis and Palaeobiogeography of the Pangaean Lower Triassic Lydekkerinidae (Temnospondyli, Stereospondyli)".73rd Meeting of the Society of Vertebrate Paleontology Abstracts:116.
- ^Schoch, Rainer R. (2013). "The evolution of major temnospondyl clades: an inclusive phylogenetic analysis".Journal of Systematic Palaeontology.11(6): 673–705.doi:10.1080/14772019.2012.699006.ISSN1477-2019.S2CID83906628.
- ^Pardo, J. D., Small, B. J., Huttenlocker, A. K. 2017. Stem caecilian from the Triassic of Colorado sheds light on the origins of Lissamphibia. PNAS.https://doi.org/10.1073/pnas.1706752114
- ^Maganuco, Simone; Pasini, Giovanni (2009). "A new specimen of trematosaurian temnospondyl from the Lower Triassic of NW Madagascar, with remarks on palatal anatomy and taxonomic affinities".Atti Soc. It. Sci. Nat. Museo Civ. Stor. Nat. Milano.150:91–112.
- ^Marsicano, Claudia A.; Latimer, Elizabeth; Rubidge, Bruce; Smith, Roger M.H. (2017-05-29). "The Rhinesuchidae and early history of the Stereospondyli (Amphibia: Temnospondyli) at the end of the Palaeozoic".Zoological Journal of the Linnean Society.doi:10.1093/zoolinnean/zlw032.hdl:11336/105150.ISSN0024-4082.
