|Rides septales à organisation de type tétracoralliaire chez Trachypsammia (Tabulata, Permien)|
In: Lethaia. Wiley-Blackwell: Oslo. ISSN 0024-1164; e-ISSN 1502-3931
Geological time > Phanerozoic > Paleozoic > Palaeozoic > Permian
TRACHYPSAMMIA; TABULATA; SEPTAL RIDGES; PERMIAN
|Auteurs|| || Top |
- Plusquellec, Y.
- Tourneur, F.
A rugosan pattern of the septal ridges, formerly described in Kerforneidictyum and Palaeacis, is pointed out in Trachypsammia monoseptata (Permian of Timor) for which only the 'Medianseptum' had been observed. T. monoseptata exhibits a strong cardinal ridge in dorsal or internal position, just opposite a shorter counter ridge, thus creating a plane of bilateral symmetry. The ridges assumed to be alar can be identified by their proximal ends being in contact with the 'Medianseptum'. The major ridges (proto and metaridges) are obvious, the minor ones show only their very proximal ends. T. monoseptata could be a calicinal young stage of T. dendroides. T. dendroides (Permian of Timor) shows a plane of bilateral symmetry, the cardinal ridge is stronger and longer than the others, the counter shorter, the alar ridges can be identified in transverse section, major and minor ridges are well developed; the number of ridges is often 32. In T. xizangensis (Permian of Tibet) only the bilateral symmetry is known, while there are no data for T. mediterranea (Permian of Sicily). The systematic affinities between Palaeacis and Trachypsammia pointed out on the basis of microstructural data are also supported by the septal ridges pattern. Do Palaeacis, Trachypsammia and others form a special division of Tabulate corals? That is the question.