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Palaeoecological implications of neoselachian shark teeth from the Bathonian (Middle Jurassic) ore-bearing clays at Gnaszyn, Kraków-Silesia Homocline, Poland

Rees J.

Acta Geologica Polonica

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2012

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Vol. 62, no. 3

397-402

EN

Systematic sampling through the Middle and Upper Bathonian strata at Gnaszyn has resulted in the discovery of 13 neoselachian teeth. Systematically, the teeth represent five taxa including Sphenodus sp., Protospinax sp. 1, Protospinax sp. 2, Palaeobrachaelurus sp. and another, indeterminate orectolobiform. The presence of two species of the flattened and bottom-dwelling Protospinax and two different orectolobiforms that are likely to have lived near the bottom, is a strong indication of oxygenated bottom conditions at the time of deposition. The dietary preferences of these taxa included a wide variety of benthic invertebrates. The synechodontiform Sphenodus may have been the first pelagic predatory neoselachian in the Jurassic, equipped with high and slender piercing teeth that formed a tearing-type dentition. The diet of Sphenodus probably included bony fish, smaller sharks and cephalopods.

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The Late Jurassic neoselachian Macrourogaleus FOWLER, 1947 is a palaeospinacid shark (Elasmobranchii; Synechodontiformes)

Klug S.

Acta Geologica Polonica

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2008

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Vol. 58, no. 2

229-234

EN

The taxonomy of palaeospinacid sharks (Chondrichthyes, Neoselachii) is reviewed. New skeletal material from the famous Late Jurassic lithographic limestones of southern Germany (Solnhofen area and Nusplingen) enables identification of the morphological and dental differences between Synechodus and Paraorthacodus. These taxa were hitherto known mainly by isolated teeth or a few mostly fragmentary skeletal remains from the Early and Late Jurassic and Late Cretaceous. Differences not only include dental features but also the presence of a single dorsal fin in Paraorthacodus compared to two in Synechodus. Fin spines are restricted to Early Jurassic specimens. A detailed examination of the small neoselachian shark, Macrourogaleus hassei, from the lithographic limestones of the Solnhofen area revealed that this taxon displays the characteristic synechodontiform tooth root morphology (pseudopolyaulacorhize) and a single dorsal fin as seen in Paraorthacodus. Consequently, Macrourogaleus is assigned to the Palaeospinacidae. It differs from Paraorthacodus, however, in the presence of a single row of enlarged placoid scales on the caudal crest.

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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.