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Stem chondrichthyan microfossils from the Lower Old Red Sandstone of the Welsh Borderland

Burrow C. J., Turner S.

Acta Geologica Polonica

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2018

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Vol. 68, no. 3

321--334

EN

Placoid and polyodontode scales of stem chondrichthyans have been found in the early Lochkovian “Ditton Group” of the Brown Clee Hill district, Shropshire, England and at Talgarth, south Wales. One of the forms is assigned to a new species of Altholepis Karatajūtė-Talimaa, 1997, a genus already recognised from Lochkovian shallow marine deposits in Celtiberia, Spain and the Northwest Territories, Canada as well as the type locality in Podolia, Ukraine. Altholepis salopensis sp. nov. is based on small polyodontode scales with typically three to eight high odontodes; the scale form was previously considered to belong to acanthodian “Nostolepis” robusta (Brotzen, 1934). The structure of other scales formerly assigned to “Nostolepis” robusta has led us to erect a new genus Jolepis for this scale form, which differs from Altholepis in lacking an ordered layout of odontodes. Jolepis robusta (Brotzen, 1934), originally (and possibly still) considered to be an acanthodian, is also known from the Baltic countries, Russia, and northern Germany (ex erratic limestones). Scales of acanthodian Parexus recurvus Agassiz, 1845, and/or possibly from the stem chondrichthyan Seretolepis elegans Karatajūtė-Talimaa, 1968 (scales of these two taxa are barely distinguishable), and of stem chondrichthyan Polymerolepis whitei Karatajūtė-Talimaa, 1968 are also present. Altholepis, Jolepis gen. nov., Seretolepis Karatajūtė-Talimaa, 1968 and Polymerolepis KaratajūtėTalimaa, 1968 are found in marine deposits elsewhere; the British occurrence of these taxa adds to the debate on the sedimentological origins of the Lower Old Red Sandstone deposits in the Welsh Borderland. The geographic range of several early sharks is now known to extend around the Old Red Sandstone continent and beyond.

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Middle Devonian thelodont Australolepis sp. (Thelodonti) from the Skały Formation, Holy Cross Mountains, Poland

Turner S., Ginter M.

Acta Geologica Polonica

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2018

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Vol. 68, no. 3

467--473

EN

Sparse fish microremains have been found in marine limestones from the Middle Devonian (Givetian) Skały Formation (Sitka Coral-Crinoid Limestone Member and Sierżawy Member), Świętomarz–Śniadka section, Bodzentyn Syncline, Łysogóry Region, northern Holy Cross Mountains, associated with conodonts of the hemiansatus to ansatus zones. Thelodont scales referred here to Australolepis sp. cf. A. seddoni come from near Śniadka village, from samples dated as hemiansatus to rhenanus/varcus zones. This increases the known range for the genus from its original find in Western Australia. The presence of a thelodont in the late Middle Devonian in Poland extends the known distribution of turiniids around the peri-Gondwana shorelines of Palaeotethys.

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Protodus jexi Woodward, 1892 (Chondrichthyes), from the Lower Devonian Campbellton Formation, New Brunswick, Canada

Turner S., Miller R.

Acta Geologica Polonica

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2008

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Vol. 58, no. 2

133-145

EN

Protodus jexi from the early Emsian 'Atholville beds', Campbellton Formation between Atholville and Campbellton, northern New Brunswick, Canada, is redescribed from material studied by R. H. Traquair and new specimens. Protodus is a valid monotypic genus with rows of shark-like serrated teeth. The taxon is based solely on teeth, some of which are associated. The teeth have monocuspid crowns with a thin enameloid layer and distinctive labial depressions or grooves, and large subrectangular to D-shaped cladodont-like bases some laterally and downwards extended. Crown histology is orthodentine merging down into the osteodentine of the base. A possible relationship with cladodont-bearing sharks is mooted and Protodus and other putative late Silurian to early Devonian chondrichthyan teeth are referred to a redefined family Protodontidae WOODWARD.

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New information on the Devonian shark Mcmurdodus, based on material from western Queensland, Australia

Burrow C., Hovestadt D., Hovestadt-Euler M., Turner S., Young G.

Acta Geologica Polonica

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2008

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Vol. 58, no. 2

155-163

EN

Histological structure of the type and newly collected teeth of the shark Mcmurdodus whitei TURNER &YOUNG, 1987, from a Devonian (?late Emsian-early Eifelian) limestone outcrop in the Cravens Peak Beds of western Queensland, was determined by immersion in anise oil, thin sectioning, and acid etching of fractured surfaces. The morphology and vascularization of the teeth are comparable to those of modern hexanchiform and echinorhinid squaliform sharks, being most similar to those of Echinorhinus. Amultilayered enameloid layer is not discernible in Mcmurdodus teeth, but a parallel-fibred layer is possibly present. Prismatic calcified cartilage, presumed to be from M. whitei, appears identical to that of all elasmobranchs. Scales and spines and distinctive ring like elements occur in the same horizon, the latter comparable with elements that encircle the lateral line in Echinorhinus, and which are found in no other Recent elasmobranchs.

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The Early Famennian recovery of phoebodont sharks

Ginter M., Turner S.

Acta Geologica Polonica

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1999

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Vol. 49, no. 2

105-117

EN

Early Famennia microvertebrates from the Cape Fortune Member, Parry Islands Formation, of the Beverley Inlet area of Melville Island, Arctic Canada, comprise the teeth and possible scales of a new phoebodontid shark, Phoebodus rayi sp.n., of a protacrodont shark, Protacrodus aequalis IVANOV, and rare teeth of other sharks. The new phoebodont from the early Famennian crepida Zone is closely related to the Lazarus taxon, Ph. typicus GINTER & IVANOV. Ph. typicus emerges in the early Famennian Late triangularis Zone following the phoebodont shark hiatus subsequent to the Kellwasser Event which apparently caused extinction of most earlier phoebodonts.