A 5.50 m thick interval of fossiliferous intensely bioturbated heterogenous glauconiferous sand of the upper Miocene Diest Formation is documented from a very large temporary outcrop just southeast of Antwerp International Airport (northern Belgium), allowing to observe lateral variations over several hundreds of meters and to collect many vertebrate and invertebrate fossils. This paper documents observations on lithology, sedimentary and post-sedimentary structures, and discusses the results of the multi-proxy analyses of the sediment (granulometry, glauconite content, clay mineralogy, Fe content and Fe3+/Fe2+ ratios), the interpretation of the trace fossil assemblage and the sedimentary structures as well as of the large-scale samplings of micro-, meso- and macrofossils. We evidence that the Diest Formation in the Antwerp area consists of two different lithological entities, and that this twofold character can be extrapolated to all previously recorded Deurne Member outcrops. A revised lithostratigraphic scheme for the Diest Formation in the Antwerp area is proposed, with the new Borsbeek member at the base and a redefined Deurne Member at the top.
Age and growth of the basking shark Cetorhinus maximus (Gunnerus) was examined using vertebral samples from 13 females (261 to 856 cm total length [TL]), 16 males (311 to 840 cm TL) and 11 specimens of unknown sex (376 to 853 cm TL). Vertebral samples were obtained worldwide from museums and institutional and private collections. Examination of multiple vertebrae from along the vertebral column of 10 specimens indicated that vertebral morphology and band pair (alternating opaque and translucent bands) counts changed dramatically along an individual column. Smaller sharks had similar band pair counts along the length of the vertebral column while large sharks had a difference of up to 24 band pairs between the highest and lowest count along the column. Our evidence indicates that band pair deposition may be related to growth and not time in this species and thus the basking shark cannot be directly aged using vertebral band pair counts.
Understanding the population structure of a species and the barriers that disrupt dispersal is important to accurately assess the global conservation status and manage the risk of local extinction. This is especially true for species of commercial importance (Begg et al., 1999) or conservation concern (Moritz, 1994), which are impacted disproportionally by anthropogenic or environmental pressures. Dispersal
Le squale bouclé, Echinorhinus brucus (Bonnaterre, 1788), a été décrit pour la première fois par Broussonet en 1780 à partir d'un type aujourd'hui perdu et de son illustration inédite. Dans sa description de l'espèce Broussonet dit : « M. de Jussieu a bien voulu nous en communiquer un dessin fait par Mrs. de l'Académie, envoyés par ordre du Roi, vers la fi n du dernier siècle, pour faire des observations anatomiques sur les bords de l'Océan ; il est désigné sous le nom de Brucus. Nous avons vu au Cabinet du Roi l'individu d'après lequel cette fi gure avoit été faite ». L'exploitation des indices contenus dans cette citation a permis de retrouver dans les archives du Muséum national d'Histoire naturelle le recueil contenant l'illustration du type, réalisée en 1680 sur la côte de Bayonne, ainsi que leurs auteurs anonymisés après la Révolution française, l'anatomiste Joseph-Guichard Du Verney et l'astronome Philippe de La Hire, membres de l'Académie royale des Sciences. Les magnifi ques planches anatomiques du recueil devaient servir à Claude Perrault pour illustrer le quatrième volume des Mémoires pour servir à l'histoire naturelle des animaux consacré à l'ichtyologie mais dont le projet avorta. Au début du XIX e siècle, Blainville fut lui le dernier zoologiste à examiner le type et à en donner une seconde illustration manuscrite inédite. Ce requin emblématique, anciennement exploité, a été extirpé des eaux européennes et est au bord d'une extinction globale. L'ignorance de sa disparition précoce dès le début de l'industrialisation de la pêche s'explique par l'absence de synthèses historiques le concernant. L'histoire révélée de sa description en constitue la première étape.
Palaeoichthyologist G. Guinot and colleagues (Guinot et al., 2018) are correct to request that new species descriptions of extant sharks, skates and rays include information on tooth morphology. But, even if their request is heeded, it will not address the broader issue associated with taxa that have been poorly described or incompletely illustrated in the past.
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