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A complete ichthyosaur rostrum, with 124 associated teeth, was recently discovered in Laux-Montaux locality, department of Drôme, southeastern France. The associated belemnites and ammonites indicate a late Valanginian age (Neocomites peregrinus Zone, Olcostephanus nicklesi Subzone) for this fossil, which consequently represents the first diagnostic ichthyosaur ever reported from Valanginian strata. This specimen also represents the first occurrence of Aegirosaurus outside the Tithonian (Upper Jurassic) lithographic limestones of Bavaria (southern Germany). Tooth morphology and wear pattern suggest that Aegirosaurus belonged to the “Pierce II/ Generalist” feeding guild, which was hitherto not represented in post-Liassic ichthyosaurs. Most Late Jurassic ichthyosaurs actually crossed the Jurassic-Cretaceous boundary. 相似文献
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Matthieu Moreau Christopher J. Duffin Claudia Hildebrandt Deborah Hutchinson Adam Parker Simon Carpenter Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2021,132(2):174-187
The famous Rhaetian bone bed (Late Triassic, 205 Ma) is well known because it marks a major switch in depositional environment from terrestrial red beds to fully marine conditions throughout the UK and much of Europe. The bone bed is generally cemented and less than 10 cm thick. However, we report here an unusual case from Saltford, near Bath, S.W. England where the bone bed is unconsolidated and up to nearly 1 m thick. The exposure of the basal beds of the Westbury Formation, Penarth Group includes a bone bed containing a diverse Rhaetian marine microvertebrate fauna dominated by sharks, actinopterygian fishes and reptiles. Despite the unusual sedimentary character of the bone bed, we find similar proportions of taxa as in other basal Rhaetian bone beds (55–59 % Lissodus teeth, 13–16 % Rhomphaiodon teeth, 12–14 % Severnichthys teeth, 6–9% Gyrolepis teeth, 3–4% undetermined sharks’ teeth, 1–3% undetermined bony fish teeth, and < 1% of each of Hybodus, Parascylloides, and Sargodon), the only differences being in the proportions of Rhomphaiodon teeth, which can represent 30–40 % of specimens elsewhere. This suggests that taphonomic bias of varying Rhaetian bone beds may be comparable despite different sedimentary settings, and that the proportions of taxa say something about their original proportions in the ecosystem. 相似文献
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根据采自贵州关岭上三叠统小凹组一件近乎完整的鱼龙骨架标本和一件压扁的头骨标本,笔者建立并系统描述了卡洛维龙的一个新种Callawayia wolonggangensis sp.nov.。分析和讨论了新种与Callawayia属其他种及其在关岭生物群中共生的各鱼龙属种之间的异同点,指出新种以具有发育的上颌骨上升支,窄的额骨及其与鼻骨之间宽缓的U-形接缝与该属模式种C.neoscapularis相区别。新种与关岭生物群中的Panjiangsaurus分子在头骨和四肢的一般形态特征上较为接近,但新种的鼻骨向后延伸与后额骨接触;额骨呈槽状向上颞孔方向延伸,并直接参与上颞孔前边缘的形成,以及后部顶骨脊之下具有发育的顶骨架而易于区别。另外,新种桡骨和桡侧腕骨前边缘直的特点也与Panjiangsaurus明显不同。 相似文献
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An incomplete rostrum of a platypterygiine ichthyosaur (IGVR 94574) has recently been found near Tregnago (Verona, Italy), in the Lessini Mts. This is the first Cretaceous ichthyosaurian fossil found in Italy outside the northern Apennines, where fragmentary remains have been recovered since the 19th century.IGVR 94574 is a mid-distal rostral fragment infilled by a white, fine-grained limestone matrix. It consists of the premaxilla, nasal, vomer, dentary, and splenial, together with 20 teeth.Even if the exact horizon of provenance is unknown, analysis of the microfossil content of the matrix (planktonic foraminifera and calcareous nannofossils) allowed us to assign it to the lower part of the upper Albian. This is also the first Cretaceous ichthyosaur in Italy with a precise age: all previously reported fossils from the Apennines could not be dated due to the complete absence of microfossils in the surrounding matrix.We assign IGVR 94572 to Platypterygiinae; generic specification is not possible pending the taxonomic revision of the genus Platypterygius.Finally, the Tregnago rostrum is strikingly similar to the specimen IPUM 30139 from Gombola (Modena, Italy), stored in the collections of the Paleontological Museum of Modena and Reggio Emilia University and also attributable to a platypterygiine ichthyosaur. The comparison between these two fossils reveals the teeth are very similar both in shape and size. 相似文献
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Dean R. Lomax Judy A. Massare 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(6):770-773
An incomplete forefin in the collections of the National Museum of Wales, Cardiff, is herein assigned to the rare leptonectid species, Leptonectes solei, known only from the west Dorset coast. It is only the third specimen of the species and is smaller than both the holotype and referred specimen. The new specimen is from the Lower Jurassic (lower Pliensbachian, Charmouth Mudstone Formation, Tragophylloceras ibex Ammonite Zone, Acanthopleuroceras valdani Ammonite Subzone) of Seatown, Dorset, UK. It confirms that all three species of Leptonectes were present in the Pliensbachian and expands the known diversity of ichthyosaurs for that time period. We show that isolated forefins of Leptonectes can be assigned to a species with a high degree of confidence. 相似文献
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