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See detailA new placoderm fish (Acanthothoraci) from the Early Devonian Jauf Formation (Saudi Arabia)
Olive, Sébastien ULg; Goujet, Daniel; Lelièvre, Hervé et al

in Geodiversitas (2011), 33(3), 393-409

An exceptionally well-preserved new acanthothoracid (placoderm fish) presenting complete endocranium and skull roof, from Saudi Arabia (Qasr Limestone Member, Jauf Formation), Early Devonian in age, is ... [more ▼]

An exceptionally well-preserved new acanthothoracid (placoderm fish) presenting complete endocranium and skull roof, from Saudi Arabia (Qasr Limestone Member, Jauf Formation), Early Devonian in age, is described as Arabosteus variabilis n. gen. n. sp. Compared to other Acanthothoraci, the new taxon exhibits a skull roof variable in its dermal plate distribution (e.g. a supernumerary plate: the posterior central plate) and sensory line pattern. Even the different specimens of this taxon show such variability between them. Arabosteus variabilis enlarges the scope of our knowledge of Acanthothoraci and Placodermi in general. Traditionally, the Arthrodira, one of the historically earliest described groups, provide the standard reference model for the placoderm skull roof pattern. The interpretation of the acanthothoracid skull roof pattern of the Saudi taxon from an arthrodiran model and the establishment of homologies is impossible to resolve unless based on prior assumptions (e.g. hypothesis of fragmentation or fusion for the paranuchal plate complex). The lateral line system of A. variabilis is unstable (e.g. presence or absence of the postmarginal sensory line canal) making it ambiguous to define bone homology and terminology. Consequently spatial distribution of skull roof plates has been retained for such a task with a minimal reference to the instable features of the sensory line groove distribution. [less ▲]

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See detailNew observations on some Upper Devonian brachiopods from the Namur-Dinant Basin (Belgium)
Mottequin, Bernard ULg

in Geodiversitas (2008), 30

Brachiopods (Productida [except Chonetidina], Orthida, Athyridida, Spiriferida [Adolfiidae, Reticulariidae, Ambocoeliidae, Thomasariidae], and Spiriferinida) recovered in the interval, in terms of the ... [more ▼]

Brachiopods (Productida [except Chonetidina], Orthida, Athyridida, Spiriferida [Adolfiidae, Reticulariidae, Ambocoeliidae, Thomasariidae], and Spiriferinida) recovered in the interval, in terms of the standard conodont zonation, between the Palmatolepis hassi and P. triangularis zones (Late Middle Frasnian to Early Famennian) in the Namur-Dinant Basin (Belgium) are described. The orders and suborders investigated include 32 species: 21 are described in open nomenclature, seven are previously known, four are new of which three are assigned to previously known genera: Aulacella aggeris n. sp., Dicamara plutonis n. sp., and Warrenella (Warrenella) aquaealbae n. sp. Th e fourth species belonging to a newly defined genus: Neptunathyris buxi n. gen., n. sp. A major brachiopod faunal change occurs at the top of the P. rhenana Zone in southern Belgium, with the disappearance of most existing species in parallel with the deterioration of the oxygenation conditions preceding the Upper Kelwasser Event. Only an impoverished fauna (Lingulida, Chonetidina, Rhynchonellida) has been collected in the P. linguiformis Zone. The recovery of the Famennian brachiopods after the end-Frasnian biotic crisis was rapid in the basal Famennian but, despite their great abundance, their diversity was relatively low. New cosmopolitan genera appeared at this time especially among the rhynchonellids, athyridids and spiriferids with new species of pre-existing orthid and orthotetid genera. [less ▲]

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