Claire Derycke

Palaeozoic vertebrates ofnorthern France and Belgium: Part II. Chondrichthyes; Acanthodii; Actinopterygii (uppermost Silurian to Carboniferous)

Abstract More than 61 chondrichthyan genera belonging to six families of Holocephali and 13 families of Elasmobranchi have been reported from the Frasnian to Westphalian D. Although very rare; acanthodians represent the oldest vertebrates reported from northern France and Belgium (uppermost Silurian). Actinopterygian taxa are relatively diversed in the studied area (more than 20 nominal species); they include mimiids (Famennian); stegotrachelids (Frasnian-Namurian A); osorioichthyids (Famennian); kentuckiids (Namurian A); acrolepidids (Namurian A; Westphalian A); rhadinichthyids (Visean; Namurian C-Westphalian D); gonatodids (Visean; Westphalian C-D); styracopterids (Visean); canobiids (Famennian); platysomiids (Visean; Westphalian A-B); amphicentrids (Westphalian B); and palaeoniscids (Famennian-Westphalian D).

Microremains of vertebrate near the devonian-carboniferous boundary of Southern China (Hunan province) and their biostratigraphical significance

Abstract Microvertebrate remains of chondrichthyans, acanthodians, actinopterygians and sarcopterygians have been collected in three sections of Central Hunan, China. The investigated sections show Upper Devonian formations of which one, the Malanbian Formation, bears localy the Devonian-Carboniferous boundary. The other sections having yielded microremains of vertebrates belong to the Tuzitang and to the top of the Magunao Formations respectively dated as crepida and marginifera conodont zones. A new species of Orodus, O. aramisi nov. sp. is erected and based on a tooth. The significance of these microremains, specially that of chondrichthyans, is analysed. They do not appear to have more importance than other higher taxa for the discussion of the Devonian-Carboniferous boundary in China, elsewhere their importance is questionable. In the Hunan and Guizhou Provinces mainly two taxa, Protacrodus orientalis and Acanthodes guizhouensis could provide pertinent information on the Devonian-Carboniferous boundary and biostratigraphy. Although our present knowledge remains poor, comparisons with Belgian microvertebrate faunas of the same age are tentatively drawn.

Famennian Chondrichthyan Microremains from Morocco and Sardinia

Abstract New material from the Famennian of Morocco in the southern Maider comprises chondrichthyan teeth (Thrinacodus, Cobelodus, Denaea, Stethacanthus), actinopterygian remains (scales, teeth and hemilepidotrichium) and one acanthodian scale. The absence of crushing teeth suggests deeper water environments for the Maider Basin than the Tafilalt Basin. Vertebrate microremains from the Famennian of Sardinia, including Siamodus and Jalodus teeth, are illustrated and described. Ichthyofaunal relationships of the North Gondwanan platform during the Famennian are examined.

Histological discovery onacanthodian scales from the Famennian of Belgium

Abstract Microscopic tubercles have been discovered on the acanthodian scale surface. Up to now described on actinopterygianscales only, these tubercles have been considered to be symptomatic of ganoin. So two hypotheses may be proposed: either such tubercles are not characteristic of ganoin, or the hypermineralized tissue which covers acanthodian scale corresponds to ganoin. Then the presence of ganoin might be a common character of acanthodians and actinopterygians.

Multicuspidate shark teeth associated with chondrichthyan and acanthodian scales from the Emsian (Devonian) of southern Algeria

ABSTRACT Previously undescribed Emsian vertebrates from southern Algeria (southern Ahaggar) include a new chondrichthyan Tassiliodus lessardi n. gen., n. sp. with multicuspidate teeth and scales with a distinctive histology. This is the first Emsian chondrichthyan taxon reported from the north-western margin of Gondwana. Rare acanthodian scales are assigned to Milesacanthus cf. ancestralis Burrow, Lelièvre & Janjou, 2006, an Emsian species also known from Saudi Arabia, reinforcing the Gondwanan faunal affinity.