Bullatimorphites aff. costatus

Lissajous 1923

Jurásico - Fortuna

101x90x51 mm

Código Inventario:ACPMJUR025

Descripción

The genus Bullatimorphites, (macroconchs Bullatimorphites, Kheraiceras, microconchs Bomburites, Schwandorfia, Sphaeroptychius, Treptoceras), is characterized by an ontogenesis with three morphologic phases: serpenticone, sphaerocone and ellipticone. Within the successive populations, the relative development of these morphologies allows the defined species to be placed in an evolutive and stratigraphic lineage. The history of the genus comprises five steps: 1) emergence (Early Middle Bathonian), 2) first gradual evolution (Middle-Upper Bathonian), 3) first morphological diversification (Uppermost Bathonian), 4) second gradual evolution, 5) second morphological diversification and extinction (Lower Callovian). Such events are biostratigraphic datum lines which coincide with the palaeogeographic evolution of the West Peri-Tethyan platforms during the Middle Jurassic.Le genre Bullatimorphites (macroconques Bullatimorphites, Kheraiceras ; microconques Bomburites, Schwandorfia, Sphaeroptychius, Treptoceras) presente une ontogenese individuelle a trois stades morphologiques : serpenticone, spherocone, ellipticone. Dans les populations successives, l'importance relative de ces stades permet de replacer les especes dans une lignee evolutive et stratigraphique. Cinq etapes majeures marquent l'histoire du genre : 1) apparition (base du Bathonien moyen), 2) premiere derive graduelle (Bathonien moyen et superieur), 3) premiere diversification morphologique (Bathonien terminal), 4) seconde derive graduelle, 5) seconde diversification morphologique, puis extinction (Callovien inferieur). Ces evenements sont des reperes biostratigraphiques correlables avec l'evolution paleogeographique des plates-formes ouest peri-tethysiennes au Jurassique moyen.

Authors: Courville P.; Thierry J.; Cariou E. - Evolutionary trends of the genus Bullatimorphites (Ammonitina) during the Bathonian-Callovian (Middle Jurassic) in Western Europe