Biology:Echinochimaera
| Echinochimaera | |
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_(Bear_Gulch_Limestone,_Upper_Mississippian;_Montana,_USA)_(33784748875).jpg)
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| Specimen of Echinochimaera meltoni | |
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| A diorama of Echinochimaera | |
| Scientific classification | |
| Kingdom: | |
| Phylum: | |
| Class: | Chondrichthyes
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| Subclass: | |
| Order: | Chimaeriformes
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| Suborder: | Echinochimaeroidei
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| Family: | Echinochimaeridae
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| Genus: | Echinochimaera Lund, 1977[1]
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| Species | |
Echinochimaera ("prickly chimera") is an extinct genus of chimaeriform fish, known from the Lower Carboniferous Bear Gulch Limestone in Montana, United States . It is one of the earliest Chimaeriformes known.
Taxonomy
The genus' name derives from the Greek εχινό (echino) meaning spiny, and chimaera. It is assigned to the order Chimaeriformes.[1] it a relitive of ratfish
Species
The two known Echinochimaera species lived in the Upper Mississippian (Serpukhovian).[3] Fossils of the species were found in the Bear Gulch Limestone in Montana, United States .
Both species have rounded bodies and paddle-like tails as well as large pectoral fins, two dorsal fins and a jaw fused to the braincase.[4] The paddle-like tails indicate that E. meltoni was likely not a predator nor a fast swimmer.[5][6]
Echinochimaera meltoni
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E. meltoni was first described by Richard Lund, an Adelphi University palaeontologist,[7] in 1977.[1][3] The fossils found of E. meltoni have shown a great deal of sexual dimorphism, males being found to have a maximum 150mm body length while the maximum body length found in females was only 70mm (juveniles were 13-20mm). In general, the females only grew to about half the size of the males.[5] Males also had four pairs of spikes which may have been used to defend against predators and to identify the fish as male.[6]
There was a relative abundance of immature male fossils found, and that together with the significant sexual dimorphism indicate there was extreme sexual selection among the species.[5]
Echinochimaera snyderi
E. snyderi was described, like E. meltoni, by Richard Lund. It was described in 1988 based on juvenile specimens, all with a body length under 90mm. E. snyderi differs from E. meltoni in fin detail as well as jaw shape and teeth near the front edge of the face rather than a tooth plate, in mature specimens later found its mature size was found to be larger than E. meltoni.[8]
References
- ↑ 1.0 1.1 1.2 "The Paleobiology Database". http://paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=34799&is_real_user=0. Retrieved 2009-09-25.
- ↑ 2.0 2.1 "The Taxonomican: Genus Echinochimaera". http://sn2000.taxonomy.nl/Taxonomicon/TaxonTree.aspx?id=987645. Retrieved 2009-09-25.
- ↑ 3.0 3.1 "University of Montana Paleontology Center". 2007-11-01. http://www.cas.umt.edu/paleontology/search/details.cfm?catalogno=5371&refer=browse. Retrieved 2009-09-26.
- ↑ "Search for Ancient Sharks". Discovery Education. http://school.discoveryeducation.com/schooladventures/prehistoricsharks/gallery2.html. Retrieved 2009-10-11.
- ↑ 5.0 5.1 5.2 Lund, Richard (1990). "Chondrichthyan life history styles as revealed by the 320 million years old Mississippian of Montana". Environmental Biology of Fishes (Springer Netherlands) 27 (1): 1–19. doi:10.1007/BF00004900. ISSN 1573-5133.
- ↑ 6.0 6.1 "Fossil Fishes of Bear Gulch - Echinochimaera meltoni". 2006-02-01. Archived from the original on 2012-02-12. https://web.archive.org/web/20120212145647/http://www.sju.edu/research/bear_gulch/pages_fish_species/Echinochimaera_meltoni.php. Retrieved 2015-12-09.
- ↑ "Bear Gulch - About Richard Lund". 2006-11-16. Archived from the original on 2010-01-08. https://web.archive.org/web/20100108080608/http://www.sju.edu/research/bear_gulch/pages_other/other_lund.php. Retrieved 2009-09-27.
- ↑ "Fossil Fishes of Bear Gulch - Echinochimaera snyderi". http://www.sju.edu/research/bear_gulch/pages_fish_species/Echinochimaera_snyderi.php. Retrieved 2009-09-26.
Wikidata ☰ Q3718511 entry
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