Oreochima

Oreochima ellioti is an archaeomaenid pachycormiform fish from Lower Jurassic-aged freshwater strata of Antarctica.[1] Fossils come from the Lower Jurassic Carapace Formation(Pliensbachian-Toarcian) of Storm Peak, Antarctica, where a freshwater lake system once existed.[2] O. ellioti is also notable for being one of three archaeomaenid genera found outside of Australia.[2]

Oreochima
Temporal range: 183 Ma
↓
[1]
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Actinopterygii
Order:
†Pachycormiformes
Family:
†Archaeomaenidae
Genus:
†Oreochima
Species:
†O. ellioti
Binomial name
Oreochima ellioti
Schaeffer & Elliot 1972

Description

Two nearly complete specimens of Oreochima ellioti (specimens AMNH 9910 and AMNH 9916) have an average total length of about 60 mm, with incomplete specimens represent individuals of similar size.[2] The frontals taper anteriorly and were slightly notched where they were in contact with the nasals. The opercular bone was about twice as high as the subopercular.[2]

Paleoenvironment


The interbeds of the Kirkpatrick Basalt record sedimentary and biotic processes in relatively shallow lakes and ponds, and in surrounding wetlands to upland areas, with the biota of the lakes having access to magmatic sources. Hydrothermal activity help the development of microbes (Archaea) and helping the fauna on cooler events. Alongside Oreochima lived the spinicaudatan Carapacestheria disgregaris, notostracan branchiopods, ostracoda, insect nymphs and wings (mayflies, the stonefly nymph Uralonympha sehopfi and the dragonfly Caraphlebia antartica,[3] and a Coleopteran[4]), and plant leaves (Zamites).[5][6]

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See also
  • Prehistoric fish
  • List of prehistoric bony fish

References
  1. Sepkoski, Jack (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology. 364: 560. Archived from the original on July 23, 2011. Retrieved 2009-02-27.
  2. Schaeffer, Bobb. "A Jurassic Fish from Antarctica". American Museum of Natural History, 1972.
  3. F. M. Carpenter. 1969. Fossil insects from Antarctica. 76:418–425
  4. P. Tasch. 1973. Jurassic beetle from southern Victoria Land, Antarctica. 47:590-592
  5. . Babcock LE, Leslie SA, Elliot DH, Stigall AL, et al. 2006. The “Preservation Paradox”: microbes as a key to exceptional fossil preservation in the Kirkpatrick Basalt (Jurassic), Antarctica. The Sedimentary Record 4: 4–8
  6. Stigall, A. L., Babcock, L. E., Briggs, D. E. G., & Leslie, S. A. (2008). Taphonomy of Lacustrine Interbeds in the Kirkpatrick Basalt (Jurassic), Antarctica. PALAIOS, 23(6), 344–355. doi:10.2110/palo.2007.p07-029r.


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