Diferencia entre revisiones de «Shastasaurus»
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{{Ficha de taxón |
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|image = Shastasaurus liangae.jpg |
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| status = Fósil |
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|image_caption = Ejemplar juvenil de ''S. liangae'', YGMIR SPCV03108 |
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|authority = Merriam, 1895 |
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| image = Shastasaurus2DB.jpg |
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| regnum = [[Animalia]] |
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* ''S. liangae'' <small>(Yin ''et al.'', 2000) <br/>[originalmente ''Guanlingsaurus''] </small> |
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| phylum = [[Chordata]] |
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* ''S. pacificus'' <small>Merriam, 1895 ([[especie tipo]])</small> |
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| classis = [[Sauropsida]] |
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* ''S. sikanniensis'' <small>(Nicholls & Manabe, 2004) <br/>[originalmente ''[[Shonisaurus]]'']</small> |
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| subclassis = [[Diapsida]] |
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| synonyms = |
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| superordo = [[Ichthyopterygia]] |
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* '''''Guanlingsaurus''''' <small>Yin ''et al.'', 2000 </small> |
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| ordo = [[Ichthyosauria]] |
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| familia = [[Shastasauridae]] |
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| genus_authorithy = Merriam, 1902 |
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* ''S. alexandrae''<br /> |
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* ''S. osmonti''<br /> |
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* ''S. altispinus''<br /> |
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* ''S. careyi''<br /> |
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* ''S. carinthiacus''<br /> |
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* ''S. carithiacus''<br /> |
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* ''S. merriami''<br /> |
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* ''S. neoscapularis''<br /> |
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* ''S. neubigi''<br /> |
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* ''S. polaris'' |
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'''''Shastasaurus''''' ("lagarto del [[Mt. Shasta]]") es un [[género]] extinto de [[ichthyosauria|ictiosaurio]] del Triásico Medio y Superior, y es el reptil marino más grande que se haya encontrado.<ref name = Hilton>Hilton, Richard P., ''Dinosaurs and Other Mesozoic Animals of California'', University of California Press, Berkeley 2003 ISBN 0-520-23315-8, at pages 90-91.</ref> Specimens have been reported from the [[United States]], [[Canada]], and [[China]].<ref name="Shang&Li">{{cite journal|authors=Shang Qing-Hua, Li Chun |year=2009 |title=[http://www.ivpp.cas.cn/cbw/gjzdwxb/xbwzxz/200909/P020090917531791680790.pdf On the occurrence of the ichthyosaur Shastasaurus in the Guanling Biota (Late Triassic), Guizhou, China] |journal=Vertebrate PalAsiatica |volume=47 |issue=3 |pages=178–193}}</ref> Este animal ha sido interpretado como un especializado devorador de peces y cefalópodos sin concha, a travès de la succión.<ref name=plosone2011/> |
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'''''Shastasaurus''''' es un [[género (biología)|género]] de [[ictiosaurio]]s que vivieron en el [[Triásico Superior]], en lo que hoy es [[Norteamérica]]. |
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==Description== |
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[[image:Shonisaurus scale mmartyniuk.png|thumb|left|Tamaños comparativos de ''[[Shonisaurus popularis]]'' (en verde) y ''S. sikanniensis'' (en rojo) junto a un ser humano]] |
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''Shastasaurus'' vivió durante el periodo [[Triásico]]. ''S. sikanniensis'' es conocido de la [[formación Pardonet]] [[Columbia Británica]], datando del periodo [[Noriano]] Medio (hace unos 210 millones de años).<ref name=giant>Nicholls, E.L. and Manabe, M. (2004). "Giant ichthyosaurs of the Triassic - a new species of ''Shonisaurus'' from the Pardonet Formation (Norian: Late Triassic) of British Columbia." ''Journal of Vertebrate Paleontology'', '''24'''(3): 838-849.</ref> Siendo la especie de mayores proporciones, ''S. sikkanniensis'' llegaba a medir 21 metros de largo. |
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''Shastasaurus'' estaba altamente especializado, y diferìa considerablemente de otros ictiosaurios. Era un animal de perfil bastante delgado. En los mayores especímenes la caja torácica medía menos de 2 metros de alto, a pesar de tener una distancia de cerca de 7 metros entre sus aletas<ref name=giant/> |
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Su cràneo ademàs era inusualmente corto, con un hocico trunco y desdentado, muy distinto a los hocicos alargados y dentados, similares a los de los delfines que tenía la práctica totalidad de los demás ictiosaurios. Parece probable entonces que este extraño hocico indique que el ''Shastasaurus'' era un devorador por succión, alimentándose sobretodo de [[cephalopoda|cefalópodos]] de cuerpo blando, que carecían de conchas para defenderse. En ''S. liangae'', la única especie con varios cráneos bien preservados, el cráneo solo contenía un 8.3% de la longitud corporal total (9.3% en un ejemplar juvenil). A diferencia de su pariente ''Shonisaurus'', incluso los jóvenes ''Shastasaurus'' carecían por completo de dientes. El hocico estaba altamente cmprimido a travès de una disposicon única de los huesos craneales. A diferencia de muchos otros reptiles, el hueso nasal, que usualmente forma la parte media del cráneo, se extendía hasta la punta del hocico, y todos los huesos del hocico se estrechaban abruptamente.<ref name=plosone2011/> |
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''Shastasaurus'' was also traditionally depicted with a dorsal fin, a feature found in more advanced ichthyosaurs. However, other shastasaurids likely lacked dorsal fins, and there is no evidence to support the presence of such a fin in any species. The upper fluke of the tail was probably also much less developed than the shark-like tails found in later species.<ref name=neptune>Wallace, D.R. (2008). ''Neptune's Ark: From Ichthyosaurs to Orcas''. University of California Press, 282pp.</ref> |
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==Species and synonyms== |
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[[File:Shastasaurus pacificus.jpg|thumb|left|Partial skull of ''S. pacificus'' (UCMP 9017) ]] |
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The [[type species]] of ''Shastasaurus'' is ''S. pacificus'', from the late [[Carnian]] of northern [[California]]. It is known only from fragmentary remains, which have led to the assumption that is was a 'normal' ichthyosaur in terms of proportions, especially skull proportions. Several species of long-snouted ichthyosaur were referred to ''Shastasaurus'' based on his misinterpretation, but are now placed in other genera (including ''[[Callawayia]]'' and ''[[Guizhouichthyosaurus]]'').<ref name=plosone2011>Sander, P.M., Chen X., Cheng L. and Wang X. (2011). "[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0019480 Short-Snouted Toothless Ichthyosaur from China Suggests Late Triassic Diversification of Suction Feeding Ichthyosaurs.]" ''PLoS ONE 6(5)'': e19480. {{doi|10.1371/journal.pone.0019480}}</ref> |
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''Shastasaurus liangae'' was the first species to definitively show the unusual short-snouted, toothless nature of ''Shastasaurus''. It is known from several good specimens, and was originally placed in the separate genus '''''Guanlingsaurus'''''. The largest specimen (YIGMR SPCV03109) measures {{convert|8.3|m|ft}} long. A juvenile specimen (YIGMR SPCV03108) has also been found, measuring {{convert|3.74|m|ft}} in length.<ref name=plosone2011/> |
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''S. sikkanniensis'' was originally described in 2004 as a large species of ''[[Shonisaurus]]''. However, this classification was not based on any phylogenetic analysis, and the authors also noted similarities with ''Shastasaurus''. The first study testing its relationships, in 2011, supported the hypothesis that it was indeed more closely related to ''Shastasaurus'' than to ''Shonisaurus'', and it was reclassified as ''Shastasaurus sikkanniensis''.<ref name=plosone2011/> Specimens belonging to ''S. sikanniensis'' have been found in the [[Pardonet Formation]] [[British Columbia]], dating to the middle [[Norian]] age (about 210 million years ago).<ref name=giant>Nicholls, E.L. and Manabe, M. (2004). "Giant ichthyosaurs of the Triassic - a new species of ''Shonisaurus'' from the Pardonet Formation (Norian: Late Triassic) of British Columbia." ''Journal of Vertebrate Paleontology'', '''24'''(3): 838-849.</ref> |
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In 2009, Shang & Li reclassified the species ''Guizhouichthyosaurus tangae'' as ''Shastasaurus tangae''. However, later analysis showed that ''Guizhouichthyosaurus'' was in fact closer to more advanced ichthyosaurs, and so cannot be considered a species of ''Shastasaurus''.<ref name=plosone2011/> |
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[[Nomen dubium|Dubious]] species that have been referred to this genus include ''S. carinthiacus'' (Huene, 1925) from the [[Austrian Alps]] and ''S. neubigi'' (Sander, 1997) from the German [[Muschelkalk]]<ref name="Shang&Li"/> |
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'''Synonyms of ''S. liangae'':''' |
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''Guanlingsaurus liangae'' <small>Yin ''et al.'', 2000</small><br/> |
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''Shastasaurus alexandrae'' <small>Merriam, 1902</small><br/> |
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''Shastasaurus osmonti'' <small>Merriam, 1902</small><br/> |
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[[Image:Royal Tyrell Shonisaurus.jpg|thumb|right|''S. sikanniensis'' specimen, [[Royal Tyrrell Museum]]]] |
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'''Synonyms of ''S. sikkanniensis'':'''<br/> |
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''Shonisaurus sikkanniensis'' <small>Nicholls & Manabe, 2004</small><br/> |
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==References== |
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{{reflist}} |
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{{portal|Paleontology}} |
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[[Category:Triassic ichthyosaurs]] |
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[[Category:Prehistoric reptiles of North America]] |
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{{ichthyosaur-stub}} |
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[[pl:Szastazaur]] |
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[[pt:Shastasaurus]] |
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[[zh:薩斯特魚龍]] |
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== Referencias == |
== Referencias == |
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Revisión del 00:44 27 may 2011
| Shastasaurus | ||
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| Rango temporal: Triásico Medio-Triásico Superior | ||
 Ejemplar juvenil de S. liangae, YGMIR SPCV03108 | ||
| Taxonomía | ||
| Especies | ||
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| Sinonimia | ||
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Shastasaurus ("lagarto del Mt. Shasta") es un género extinto de ictiosaurio del Triásico Medio y Superior, y es el reptil marino más grande que se haya encontrado.[1] Specimens have been reported from the United States, Canada, and China.[2] Este animal ha sido interpretado como un especializado devorador de peces y cefalópodos sin concha, a travès de la succión.[3]
Description
Shastasaurus vivió durante el periodo Triásico. S. sikanniensis es conocido de la formación Pardonet Columbia Británica, datando del periodo Noriano Medio (hace unos 210 millones de años).[4] Siendo la especie de mayores proporciones, S. sikkanniensis llegaba a medir 21 metros de largo.
Shastasaurus estaba altamente especializado, y diferìa considerablemente de otros ictiosaurios. Era un animal de perfil bastante delgado. En los mayores especímenes la caja torácica medía menos de 2 metros de alto, a pesar de tener una distancia de cerca de 7 metros entre sus aletas[4]
Su cràneo ademàs era inusualmente corto, con un hocico trunco y desdentado, muy distinto a los hocicos alargados y dentados, similares a los de los delfines que tenía la práctica totalidad de los demás ictiosaurios. Parece probable entonces que este extraño hocico indique que el Shastasaurus era un devorador por succión, alimentándose sobretodo de cefalópodos de cuerpo blando, que carecían de conchas para defenderse. En S. liangae, la única especie con varios cráneos bien preservados, el cráneo solo contenía un 8.3% de la longitud corporal total (9.3% en un ejemplar juvenil). A diferencia de su pariente Shonisaurus, incluso los jóvenes Shastasaurus carecían por completo de dientes. El hocico estaba altamente cmprimido a travès de una disposicon única de los huesos craneales. A diferencia de muchos otros reptiles, el hueso nasal, que usualmente forma la parte media del cráneo, se extendía hasta la punta del hocico, y todos los huesos del hocico se estrechaban abruptamente.[3]
Shastasaurus was also traditionally depicted with a dorsal fin, a feature found in more advanced ichthyosaurs. However, other shastasaurids likely lacked dorsal fins, and there is no evidence to support the presence of such a fin in any species. The upper fluke of the tail was probably also much less developed than the shark-like tails found in later species.[5]
Species and synonyms
The type species of Shastasaurus is S. pacificus, from the late Carnian of northern California. It is known only from fragmentary remains, which have led to the assumption that is was a 'normal' ichthyosaur in terms of proportions, especially skull proportions. Several species of long-snouted ichthyosaur were referred to Shastasaurus based on his misinterpretation, but are now placed in other genera (including Callawayia and Guizhouichthyosaurus).[3]
Shastasaurus liangae was the first species to definitively show the unusual short-snouted, toothless nature of Shastasaurus. It is known from several good specimens, and was originally placed in the separate genus Guanlingsaurus. The largest specimen (YIGMR SPCV03109) measures 8,3 metros (27,2 pies) long. A juvenile specimen (YIGMR SPCV03108) has also been found, measuring 3,74 metros (12,3 pies) in length.[3]
S. sikkanniensis was originally described in 2004 as a large species of Shonisaurus. However, this classification was not based on any phylogenetic analysis, and the authors also noted similarities with Shastasaurus. The first study testing its relationships, in 2011, supported the hypothesis that it was indeed more closely related to Shastasaurus than to Shonisaurus, and it was reclassified as Shastasaurus sikkanniensis.[3] Specimens belonging to S. sikanniensis have been found in the Pardonet Formation British Columbia, dating to the middle Norian age (about 210 million years ago).[4]
In 2009, Shang & Li reclassified the species Guizhouichthyosaurus tangae as Shastasaurus tangae. However, later analysis showed that Guizhouichthyosaurus was in fact closer to more advanced ichthyosaurs, and so cannot be considered a species of Shastasaurus.[3]
Dubious species that have been referred to this genus include S. carinthiacus (Huene, 1925) from the Austrian Alps and S. neubigi (Sander, 1997) from the German Muschelkalk[2]
Synonyms of S. liangae:
Guanlingsaurus liangae Yin et al., 2000
Synonyms of S. pacificus:
Shastasaurus alexandrae Merriam, 1902
Shastasaurus osmonti Merriam, 1902
Synonyms of S. sikkanniensis:
Shonisaurus sikkanniensis Nicholls & Manabe, 2004
References
- ↑ Hilton, Richard P., Dinosaurs and Other Mesozoic Animals of California, University of California Press, Berkeley 2003 ISBN 0-520-23315-8, at pages 90-91.
- ↑ a b Shang Qing-Hua, Li Chun (2009). «On the occurrence of the ichthyosaur Shastasaurus in the Guanling Biota (Late Triassic), Guizhou, China». Vertebrate PalAsiatica 47 (3): 178-193.
- ↑ a b c d e f Sander, P.M., Chen X., Cheng L. and Wang X. (2011). "Short-Snouted Toothless Ichthyosaur from China Suggests Late Triassic Diversification of Suction Feeding Ichthyosaurs." PLoS ONE 6(5): e19480. doi 10.1371/journal.pone.0019480
- ↑ a b c Nicholls, E.L. and Manabe, M. (2004). "Giant ichthyosaurs of the Triassic - a new species of Shonisaurus from the Pardonet Formation (Norian: Late Triassic) of British Columbia." Journal of Vertebrate Paleontology, 24(3): 838-849.
- ↑ Wallace, D.R. (2008). Neptune's Ark: From Ichthyosaurs to Orcas. University of California Press, 282pp.
Portal:Paleontology. Contenido relacionado con Paleontology.
Referencias
- Callaway, J. M. & Massare, J. A. 1989. Journal of Paleontology, Vol. 63, No. 6, pp. 930-939