Abstract
Fishes from Turonian deposits at Lac des Bois, Northwest Territories, Canada, have previously been described based on material from calcareous mudstone concretions collected in 1969. A more recent collecting trip to the locality in 2010 led to the discovery of fossil fishes in a shale layer. These fishes, preserved in a different manner from the earlier collections, provide new information and allow reinterpretations on two previously described fishes, Aquilopiscis wilsoni (Pachyrhizodontidae) and Avitosmerus canadensis (Euteleostei). Although the new material allows a better understanding of these two fishes, it does not change our ideas about their relationships. Avitosmerus canadensis remains in the Euteleostei with relationships uncertain, and Aquilopiscis wilsoni is confirmed as a member of the Pachyrhizodontidae.
Highlights
Fossil fishes have been known from Turonian deposits at Lac des Bois, Northwest Territories since 1968 when geologists studied the area and found fossil remains
The fossils collected by Bardack and his team were almost exclusively recovered from calcareous concretions, collected in situ and where tumbled down along the base of a kilometre-long shale outcrop
We discovered that vertebrate and invertebrate fossils were recoverable in situ from shales along the shore of the lake, 15 to 20 metres away from the base of the cliff, from just above water level to the practical limit of our quarrying, about 15 to 20 cm below the water table
Summary
Fossil fishes have been known from Turonian deposits at Lac des Bois, Northwest Territories since 1968 when geologists studied the area and found fossil remains. The fossils collected by Bardack and his team were almost exclusively recovered from calcareous concretions, collected in situ and where tumbled down along the base of a kilometre-long shale outcrop From this collection, several fishes were named including Avitosmerus canadensis Fielitz, 2002, a small euteleost, Aquilopiscis wilsoni Cumbaa and Murray, 2008, a pachyrhizodontid, and Ornatipholis sahtu Cumbaa and Murray, 2008, an enchodontoid. The locality was again visited by our field party in 2010 During this trip, we discovered that vertebrate and invertebrate fossils were recoverable in situ from shales along the shore of the lake, 15 to 20 metres away from the base of the cliff, from just above water level to the practical limit of our quarrying, about 15 to 20 cm below the water table. Anatomical Abbreviations: ach, anterior ceratohyal; ang, anguloarticular; ao, antorbital; brst, branchiostegal rays; cl, cleithrum; cor, coracoid; den, dentary; dfin pt, dorsal fin pterygiophores; ect, ectopterygoid; end, endopterygoid; epi, epioccipital; ex, extrascapular; fr, frontal; hy, hypurals 1-6; hyo, hyomandibula; io, infraorbitals 2-3; iop, interopercle; lac, lacrimal; le, lateral ethmoid; meth, mesethmoid; mx, maxilla; met, metapterygoid; npu, neural spine of first preural centrum; op, opercle; pa, parietal; pal, palatine; pch, posterior ceratohyal; pfin, pectoral fin; phy, parhypural; pmx, premaxilla; pop, preopercle; psph, parasphenoid; ptf, posttemporal fossa; pto, pterotic; ptt, posttemporal; pu, preural centra 1-2; qu, quadrate; ret, retroarticular; sa, sesamoid articular; scl, supracleithrum; sm, supramaxilla; sn, supraneural bones; so, supraorbital; soc, supraoccipital; sop, subopercle; sph, sphenoid; sym, symplectic; u1-2, ural centra 1-2 (diural terminology); un, uroneurals 1-3; vo, vomer; ?vo tth, possible vomerine teeth
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