A partial rostrum of the Porbeagle shark <i>Lamna nasus</i> (Lamniformes, Lamnidae) from the Miocene of the North Sea basin and the taxonomic importance of rostral morphology in extinct sharks

A fragmentary rostrum of a lamnid shark is recorded from the upper Miocene Breda Formation at Liessel (Noord-Brabant, The Netherlands); it constitutes the first elasmobranch rostral process to be described from Neogene strata in the North Sea Basin. Based on key features of extant lamniform rostra and CT scans of chondrocrania of modern Lamnidae, the Liessel specimen is assigned to the porbeagle shark, Lamna nasus (Bonnaterre, 1788). In addition, the taxonomic significance of rostral morphology in extinct sharks is discussed and a preliminary list of elasmobranch taxa from Liessel is presented

A new species of <i>Abdounia</i> (Elasmobranchii, Carcharhinidae) from the base of the Boom Clay Formation (Oligocene) in northwest Belgium

On the basis of isolated teeth, collected from the base of the Boom Clay Formation (Rupelian, Oligocene) at the SVK clay pit (Sint-Niklaas, NW Belgium), a new species of requiem shark, Abdounia belselensis sp. nov., is described. Affinities and heterodonty are discussed

The taxonomic value of rostral nodes of extinct sharks, with comments on previous records of the genus <i>Lamna</i> (Lamniformes, Lamnidae) from the Pliocene of Lee Creek Mine, North Carolina (USA)

Shark rostral nodes from the Yorktown Formation (Zanclean, early Pliocene) of Lee Creek Mine, North Carolina (USA), previously assigned to the genus Lamna Cuvier, 1816, have been reinterpreted using a preliminary identification key for extant Lamniformes based on rostral morphology. In addition, the fossil rostral nodes have been compared in detail with Recent material of both the porbeagle, Lamna nasus (Bonnaterre, 1788) and the salmon shark, Lamna ditropis Hubbs and Follet, 1947. Despite the fact that the rostra compared relatively well with those of Recent Lamna, the Lee Creek Mine specimens proved to differ significantly in having near-parallel lateral rostral cartilages that join the rostral node individually, instead of abutting ones. Based on this observation, we here propose to strike the genus Lamna from the Lee Creek Mine faunal list, so long as no other diagnostic material is forthcoming. These partially preserved rostra are likely to have belonged to extinct taxa within the families Lamnidae or Otodontidae, both of which have been documented from the Yorktown Formation on the basis of isolated teeth of at least three species, Cosmopolitodus hastalis (Agassiz, 1838), Megaselachus megalodon (Agassiz, 1835) and Parotodus benedenii (Le Hon, 1871)

Cold case: The early disappearance of the Bramble shark (<i>Echinorhinus brucus</i>) in European and adjacent waters

Surveys of marine resources suffer from the lack of long time series, particularly concerning targeted species currently not of high value. The disappearance of a marine species, even of large size, can go completely unnoticed. Large shark species are among the most affected by depletion because of their life history traits. In European and adjacent waters, the rare Bramble shark (Echinorhinus brucus; formerly known as the Spinous shark) is suspected of being threatened, but the lack of population data precludes its evaluation. As a result, the species is currently unregulated and listed as "Data Deficient" by the International Union for Conservation of Nature (IUCN)

A new partial skeleton of a palaeospinacid shark (Neoselachii, Synechodontiformes) from the Albian of northern France, with a review of the taxonomic history of Early Cretaceous species of <i>Synechodus</i> Woodward, 1888

An articulated skeleton of a palaeospinacid shark from the Saint-Pô Formation (Albian, upper Lower Cretaceous) of the Boulonnais (northern France) is described and illustrated for the first time, inclusive of tooth vascularisation and histology. The specimen comprises portions of the neurocanium, splanchnocranium, pectoral girdle, vertebrae, numerous teeth and about 12 000 dermal denticles, but no dorsal fin spines. Its dental morphology is unique in combining relatively smooth crown surfaces in anterior teeth, a strongly reticulated ornamentation in latero-posterior teeth and an intermediate ornamentation in larger antero-lateral teeth. The differential diagnoses of three nominal species of Synechodus Woodward, 1888 that have often been recorded from Albian strata (i.e., S. dubrisiensis (Mackie, 1863), S. nitidus Woodward, 1911 and S. tenuis Woodward, 1889) were based mainly on tooth ornamentation. This observation would favour the conspecificity of these three forms, as has been suggested previously by several authors. However, it does not rule out the possibility of more than one species of Synechodus in the Albian of the Anglo-Paris Basin. Such divergent ornamentation might be characteristic of more than one species, meaning that differentiation would be more complex. Awaiting a thorough revision of these taxa, a review of their taxonomic history is presented here. For the time being, the specimen from the Boulonnais is left in open nomenclature and referred to as Synechodus sp

A new axiid (Crustacea: Decapoda: Axiidea) from the Neogene of Belgium and the Netherlands

From small phosphatic nodules in sandy deposits of Neogene age, previously excavated at Emblem (northwest Belgium) and currently suction dredged at Langenboom (southeast Netherlands), several chelipeds as well as fragments of carapace and abdomen of an axiid shrimp have been collected. These remains are here described as a new genus and species, which constitute the first record of the family Axiidae from Neogene strata in the North Sea Basin and the second species to be reported from Pliocene strata worldwide

Comparative morphology of rostral cartilages in extant mackerel sharks (Chondrichthyes, Lamniformes, Lamnidae) using CT scanning

A comparative study of rostral morphology of extant mackerel sharks (Lamniformes, Lamnidae) is presented. Based on computed tomography (CT) scans of fresh specimens, 3D reconstructions, dried museum chondrocrania and the available literature, detailed morphological descriptions of the rostral cartilages are provided for the type species of all three extant lamnid genera, namely Carcharodon carcharias (Linnaeus, 1758), Isurus oxyrinchus Rafinesque, 1810 and Lamna nasus (Bonnaterre, 1788), and compared with those of I. paucus Guitart Manday, 1966 and L. ditropis Hubbs & Follett, 1947. Despite intraspecific variation, the rostral cartilages of all extant lamnids present significant differences that allow genusand species-level identification, which is especially of use to identify fossil rostral nodes of these particular taxa. The main differences were found to be in overall calcification of the rostrum (Lamna > Isurus > Carcharodon), general configuration of the rostral open space, position of the base of the lateral rostral cartilages, (non-)abutting lateral cartilages, (absent) rostral keels and shape of the rostral node. In cross section, the base of the rostral node is rounded in Lamna, Y-shaped in Isurus and uncalcified in juvenile and subadult Carcharodo (tesserae absent)

A partial braincase and other skeletal remains of Oligocene angel sharks (Chondrichthyes, Squatiniformes) from northwest Belgium, with comments on squatinoid taxonomy

A detailed redescription of a chondrocranium from the basal Boom Clay Formation (Rupelian, Upper Oligocene) at the SVK clay pit, Sint-Niklaas (province of Oost-Vlaanderen, Belgium), previously assigned to the sawshark Pristiophorus rupeliensis, is presented. The chondrocranium is re-identified as that of an angel shark (Squatinidae), based on comparative anatomy of extant Squatina, inclusive of CT scans of Squatina africana, S. australis, S. dumeril, S. guggenheim and S. squatina, with different geographic distributions and representing all four angel shark clades as defined in a previous molecular study. Differential characters for chondrocrania listed in earlier accounts to discriminate angel shark species from the southwest Atlantic proved to be even more revealing when comparing angel sharks from different regions/clades. Despite this wide interspecific variation, the fossil chondrocranium compares well with modern Squatina, but differs in having a UUU-shaped ventral margin of the occipital region and rounded margins of the upper postorbital processes. The distal expansion of the upper postorbital processes present in modern species has not yet been observed in extinct squatinoids and might constitute a derived character for modern representatives only. Angel shark teeth and vertebrae are well known from the same basal deposit at the SVK clay pit, but Cenozoic squatinid taxonomy remains problematic. It is here discussed in detail for the Oligocene taxa S. angeloides, S. rupeliensis and S. beyrichi. For the time being, all SVK material is left in open nomenclature and referred to as Squatina sp

Ontogenetic vertebral growth patterns in the basking shark <i>Cetorhinus maximus</i>

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

South Africa preliminary investigation of vertebral growth rings in the basking shark Cetorhinus maximus(Gunnerus)

Conference Abstracts AES/ASIH , Norman , Oklahoma , May 26-31 200