Leedsichthys: Perbedaan antara revisi
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{{italic title}}{{Taxobox |
{{italic title}}{{Taxobox |
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|name = ''Leedsichthys'' |
|name = ''Leedsichthys'' |
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| image_caption = Restorasi berdasarkan interpretasi modern dari fosil |
| image_caption = Restorasi berdasarkan interpretasi modern dari fosil |
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|fossil_range = {{Fossil range|Middle Jurassic}} |
|fossil_range = {{Fossil range|Middle Jurassic}} |
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|regnum = [[ |
|regnum = [[Animalia]] |
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|phylum = [[Chordata]] |
|phylum = [[Chordata]] |
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|classis = [[Actinopterygii]] |
|classis = [[Actinopterygii]] |
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'''''Leedsichthys''''' |
'''''Leedsichthys''''' adalah suatu [[genus]] besar yang merupakan anggota [[familia]] [[Pachycormidae]], sebuah kelompok [[:en:Osteichthyes|ikan bertulang]] dari zaman [[Mesozoikum]] bony fish]] yang pernah hidup di samudera pada periode [[Jura (periode)|Middle Jurassic]] dan sekarang sudah punah.<ref name="Liston4">Liston, 2004</ref> |
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The first remains of ''Leedsichthys'' were identified in the nineteenth century. Especially important were the finds by the British collector Alfred Nicholson Leeds, after whom the genus was named "Leeds' fish" in 1889. The type species is ''Leedsichthys problematicus''. ''Leedsichthys'' fossils have been found in England, France, Germany and Chile. In 1999, based on the Chilean discoveries, a second species was named ''Leedsichthys notocetes'', but this was later shown to be indistinguishable from ''L. problematicus''. |
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Peninggalan ''Leedsichthys'' pertama kali diidentifikasi pada abad ke-19. Penemuan terpenting dilakukan oleh kolektor [[Britania Raya]], Alfred Nicholson Leeds, sehingga namanya menjadi nama genus, yang bermakna "ikan Leeds" pada tahun 1889. Spesies utama adalah ''Leedsichthys problematicus''. Fosil ''Leedsichthys'' ditemukan di [[Inggris]], [[Perancis]], [[Jerman]] dan [[Chili]]. Pada tahun [[1999]], berdasarkan penemuan di Chili, spesies kedua dinamakan ''Leedsichthys notocetes'', tetapi kemudian ternyata tidak dapat dibedakan dari ''L. problematicus''. |
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''Leedsichthys'' fossils have been difficult to interpret because the skeletons were not completely made of bone. Large parts consisted of [[Tulang rawan|cartilage]] that did not fossilize. On several occasions the enigmatic large partial remains have been mistaken for stegosaurian [[Dinosaurus|dinosaur]] bones. As the vertebrae are among the parts that have not been preserved, it is hard to determine the total body length. Estimates have varied wildly. At the beginning of the twentieth century a length of nine metres was seen as plausible, but by its end ''Leedsichthys'' was sometimes claimed to have been over thirty metres long. Recent research has lowered this to about sixteen meters for the largest individuals. Skull bones have been found indicating that ''Leedsichthys'' had a large head with bosses on the skull roof. Fossilised bony fin rays show large elongated pectoral fins and a tall vertical tail fin. The gill arches were lined by gill rakers, equipped by a unique system of delicate bone plates, that filtered [[plankton]] from the sea water, the main food source. |
''Leedsichthys'' fossils have been difficult to interpret because the skeletons were not completely made of bone. Large parts consisted of [[Tulang rawan|cartilage]] that did not fossilize. On several occasions the enigmatic large partial remains have been mistaken for stegosaurian [[Dinosaurus|dinosaur]] bones. As the vertebrae are among the parts that have not been preserved, it is hard to determine the total body length. Estimates have varied wildly. At the beginning of the twentieth century a length of nine metres was seen as plausible, but by its end ''Leedsichthys'' was sometimes claimed to have been over thirty metres long. Recent research has lowered this to about sixteen meters for the largest individuals. Skull bones have been found indicating that ''Leedsichthys'' had a large head with bosses on the skull roof. Fossilised bony fin rays show large elongated pectoral fins and a tall vertical tail fin. The gill arches were lined by gill rakers, equipped by a unique system of delicate bone plates, that filtered [[plankton]] from the sea water, the main food source. |
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In 1999 Martill suggested that a [[Perubahan iklim|climate change]] at the end of the Callovian led to the extinction of ''Leedsichthys'' in the northern seas, the southern Ocean offering a last refuge during the Oxfordian.<ref name="Martill1999">Martill, D.M., Frey, E., Caceras, R.P. & Diaz, G.C., 1999, "The giant pachycormid ''Leedsichthys'' (Actinopterygii) in the southern hemisphere: further evidence for a Jurassic Atlanto-Pacific marine faunal province", ''Neues Jahrbuch für Geologie und Paläontologie'', Monatshefte 1999: 243-256</ref> However, in 2010 Liston pointed out that ''Leedsichthys'' during the later Kimmeridgian was still present in the north, as testified by Normandian finds.<ref name="Liston2010Oryctos">Liston, J.J., 2010, "The occurrence of the Middle Jurassic pachycormid fish ''Leedsichthys''", ''Oryctos'' '''9''': 1-36</ref> Liston did nevertheless consider in 2007 that the lack of any vertebrate suspension feeders as large as 0.5 metres prior to the Callovian stage of the [[Mesozoikum|Mesozoicum]] might indicate that the Callovian had seen a marked change in productivity as regarded [[zooplankton]] populations. Indeed, further studies supported this, viewing ''Leedsichthys'' as the beginning of a long line of large (>2 metres in length) pachycormid suspension feeders that continued to flourish well into the Late Cretaceous, such as ''Bonnerichthys'' and ''Rhinconichthys'',<ref>Friedman, M., K. Shimada, L.D. Martin, M.J. Everhart, J. Liston, A. Maltese and M. Triebold, 2010, "100-million-year dynasty of giant planktivorous bony fishes in the Mesozoic seas", ''Science'' '''327''': 990–993</ref> and emphasising the [[Evolusi konvergen|convergent evolutionary]] paths taken by pachycormids and [[Paus balin|baleen whales]].<ref>Friedman, M., 2011, "Parallel evolutionary trajectories underlie the origin of giant suspension-feeding whales and bony fishes", ''Proceedings of the Royal Society B'', '''279''': 944-951</ref> |
In 1999 Martill suggested that a [[Perubahan iklim|climate change]] at the end of the Callovian led to the extinction of ''Leedsichthys'' in the northern seas, the southern Ocean offering a last refuge during the Oxfordian.<ref name="Martill1999">Martill, D.M., Frey, E., Caceras, R.P. & Diaz, G.C., 1999, "The giant pachycormid ''Leedsichthys'' (Actinopterygii) in the southern hemisphere: further evidence for a Jurassic Atlanto-Pacific marine faunal province", ''Neues Jahrbuch für Geologie und Paläontologie'', Monatshefte 1999: 243-256</ref> However, in 2010 Liston pointed out that ''Leedsichthys'' during the later Kimmeridgian was still present in the north, as testified by Normandian finds.<ref name="Liston2010Oryctos">Liston, J.J., 2010, "The occurrence of the Middle Jurassic pachycormid fish ''Leedsichthys''", ''Oryctos'' '''9''': 1-36</ref> Liston did nevertheless consider in 2007 that the lack of any vertebrate suspension feeders as large as 0.5 metres prior to the Callovian stage of the [[Mesozoikum|Mesozoicum]] might indicate that the Callovian had seen a marked change in productivity as regarded [[zooplankton]] populations. Indeed, further studies supported this, viewing ''Leedsichthys'' as the beginning of a long line of large (>2 metres in length) pachycormid suspension feeders that continued to flourish well into the Late Cretaceous, such as ''Bonnerichthys'' and ''Rhinconichthys'',<ref>Friedman, M., K. Shimada, L.D. Martin, M.J. Everhart, J. Liston, A. Maltese and M. Triebold, 2010, "100-million-year dynasty of giant planktivorous bony fishes in the Mesozoic seas", ''Science'' '''327''': 990–993</ref> and emphasising the [[Evolusi konvergen|convergent evolutionary]] paths taken by pachycormids and [[Paus balin|baleen whales]].<ref>Friedman, M., 2011, "Parallel evolutionary trajectories underlie the origin of giant suspension-feeding whales and bony fishes", ''Proceedings of the Royal Society B'', '''279''': 944-951</ref> |
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== Referensi == |
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{{Reflist}} |
{{Reflist}} |
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[[Kategori:Actinopterygii]] |
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Revisi per 3 Desember 2015 21.54
| Leedsichthys | |
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| Restorasi berdasarkan interpretasi modern dari fosil | |
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| Genus: | †Leedsichthys
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| Spesies: | †L. problematicus
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| Nama binomial | |
| Leedsichthys problematicus Woodward, 1889
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Leedsichthys adalah suatu genus besar yang merupakan anggota familia Pachycormidae, sebuah kelompok ikan bertulang dari zaman Mesozoikum bony fish]] yang pernah hidup di samudera pada periode Middle Jurassic dan sekarang sudah punah.[2]
Peninggalan Leedsichthys pertama kali diidentifikasi pada abad ke-19. Penemuan terpenting dilakukan oleh kolektor Britania Raya, Alfred Nicholson Leeds, sehingga namanya menjadi nama genus, yang bermakna "ikan Leeds" pada tahun 1889. Spesies utama adalah Leedsichthys problematicus. Fosil Leedsichthys ditemukan di Inggris, Perancis, Jerman dan Chili. Pada tahun 1999, berdasarkan penemuan di Chili, spesies kedua dinamakan Leedsichthys notocetes, tetapi kemudian ternyata tidak dapat dibedakan dari L. problematicus.
Referensi
- ^ Wiley. "Phylum Chordata" (PDF). hlm. 100. Diakses tanggal 2009-04-11.
- ^ Liston, 2004