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This is not about the identification of a fossil (it's an Asineopps squamifrons) but about the identification of a quarry unknown to me. I received two Asineops squamifrons from a friend, unfortunately without a location (he received it as a gift, the fish themselves are not very well prepped). What irritates me is that the rock doesn't look like Green River Formation at all - at least not like the rocks I have encountered in the quarries around Kemmerer. The rock is relatively fine-grained and very dark, almost black, and probably has a high organic content. The two Asineops in it also look almost charred. I've only dug once at Lake Gosiute sites (Currant Creek Ranch), but I don't know of any dark rock like this from there either. And it doesn't look like Farson either. I am at a bit of a loss. Can anyone give me a hint as to where this slab could be from?
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Asineops (Greek for "donkey-faced") squamifrons was first described by Cope as having an affinity to the pirat perch family. Later, with more detailed study, this species was found to lack the diagnostic characters of that family. Thus it is not yet clearly assignable to order. Although this species is much rarer in the Fossil Lake sediments than in Lake Gosiute deposits, the specimens from Fossil Lake are much larger than those from Lake Gosiute. Line drawing from Grande 1984: Identified by oilshale using Grande 1984. References: Cope, Edward D. (1870). Observations on the Fishes of the Tertiary Shales of Green Nov. River, Wyoming Territory. Proc. Amer. Philos. Soc. Vol. 21 XI, pp. 380-384. Grande, L, (1984). Paleontology of the Green River Formation, with a Review of the Fish Fauna. Bulletin 63, the Geological Survey of Wyoming.
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The information on Asineops is scarce so I thought I'd do some research and make it publicly available. Asineops squamifrons is a Eocene fish and an incertae sedis. They are rare and are most commonly found in a fragile layer of the green river formation at smith hollow quarry. They can be found in fossil lake or lake gosiute. Fossil lake ones are bigger but rarer. I don't know the maximum size on these but I would guess 7-12 inches. Their scales a very distinctive in shape. According to Rosen and Patterson (1969) it may represent a intermediate between acanthopterygians and paracanthopterygians (which looking at a phylogenetic chart is confusing to me) , meaning their closest living relatives would be the troutperch and its allies (percopsiformes). Its relations to other fish are confusing and not understood but it bears some affinity to Nardoichthys (a Italian late Cretaceous fish which seems to be closely related to troutperchess) and prolates (couldn't find much info on this guy). Diagnostic features include the following: long premaxillary ascending process six branchiostegals unforked caudal fin with 14 principal rays (12 branched) cycloid scales full nueral spine on PU2 two epurals free second ural centrum two anal spines two supranuerals unserrated preopercular Pelvis girdle and cleithrum do not touch unfused lower hypurals sources: Wikipedia Enigmatic fish Oilshales topic @FossilDudeCO Fossil lake Specimens from top to bottom: @oilshale Fossil lake If you have anything to add, or a specimen to show off, I encourage you to do so! Thanks for reading!
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Asineops squamifrons was first described by Cope as having an affinity to the pirat perch family. Later, with more detailed study, this species was found to lack the diagnostic characters of that family. Thus it is not yet clearly assignable to order. Although this species is much rarer in the Fossil Lake sediments than in Lake Gosiute deposits, the specimens from Fossil Lake are much larger than those from Lake Gosiute.
