0000000000049739
AUTHOR
Christian C. Emig
Brachiopodes et Mollusques Bivalves: Concurrence ou indifférence?
Resume Dans le debat entre les tenants d'une concurrence directe entre les Brachiopodes et les Mollusques Bivalves, et ceux pour lesquels la substitution des Bivalves aux Brachiopodes dans les communautes benthiques a partir du Mesozoique n'est que la consequence de potentialites evolutives differentes, nous proposons une analyse critique et objective des donnees disponibles et de leur interpretation. L'etude quantitative des informations (celles du Treatise) associees a l'analyse des donnees ecologiques nous conduisent a opter en faveur d'une indifference globale des deux groupes dans leurs processus evolutifs respectifs; ces processus ont ete acceleres et/ou gravement perturbes lors des g…
δ18O values of coexisting brachiopods and fish: Temperature differences and estimates of paleo–water depths
To estimate vertical thermal gradients and paleo–water depths to marine platforms we present a new method based on the difference between δ 18 O values of contemporaneous brachiopod carbonate and fish phosphate. Present-day marine fauna of well-known ecology from the surface to the sea floor record isotopic temperatures that agree with measured temperatures. We predict distributions of isotopic data that result from sampling strategy, basin morphology, and fauna ecology and discuss limitations. Application of the method to the Jurassic Paris-London basin gives vertical thermal variations of up to 14 °C associated with depths varying from a few meters to 170 ± 30 m. The estimated depths are …
Drilling predation on Gryphus vitreus (Brachiopoda) off the French Mediterranean coasts
Abstract A total of 145 valves of Gryphus vitreus with naticid drillholes have been recorded from samples during 21 cruises in the Northwestern Mediterranean, out of about 30,000 empty valves. Drilling was lower than 1% in all stations, except in one station where it reached up to 25.5%. Selectivity of drillhole site by the naticid Euspirella pulchella seems to apply in G. vitreus as drillholes are mainly concentrated in the relatively meaty distal half of the shell, which is also the thickest part of the valve (about 0.6–2 mm). Attacks occur generally on the ventral valve (86.2%) according to the life position of Gryphus. The predation pressure on G. vitreus by drilling appears exceptional…
Triassic lingulide brachiopods from the Iberian Range (Spain)
Abstract During the Middle Triassic marine transgression in Spain, several lingulide populations were fossilized in the Iberian Range (western part of Sephardic Province) and the recorded specimens have been described previously under several specific names. The paleontological aspects of the Jalance (Valencia province) section have been studied for the first time. Its exceptionally large population was fossilized in situ as flat-lying valves and can be interpreted as an autochthonous association related to a very shallow marine environment. The lingulide specimens belong to the genus Lingularia Biernat & Emig , 1993 , but the species name remains under debate, probably Lingularia smirnovae…