BIOSTRATINOMY AND PALAEOBIOLOGY OF ECHINODERMS IN THE LOWER DEVONIAN OF THE ARGENTINE PRECORDILLERA

HAUDE, R.; STERREN, A.F.

San Juan

Otro; Field Meeting of the IGCP 499 "Devonian land-sea interaction: evolution of ecosystems and climate" (DEVEC); 2007

IGCP 499. IUGS-UNESCO

Several small associations of echinoderms are recorded from a series of siltstone beds in the Lower Devonian Talacasto Formation, Argentinan Precordillera (e.g. Kayser 1897, Waisfeld 1989, Haude 1995, 2004). The siltstones probably represent tempestitic events mostly in the upper part of a monotonous succession of some 650 m highly bioturbated mudstones which are interpreted as background sedimentation on a broad shelf platform (Astini 1991). Altogether, the echinoderms show a rather high taxonomic diversity of mostly crinoids (about 15 species: 5 camerates, 7 cladids, 2 disparids, 1 flexibles), and ophiuroids (9 species); rarely carpoids (2 species), edrioasteroids (1 species), blastoids (1 species); asteroids (2 species), and holothurians (2 species). According to sedimentologic, biostratinomic, and functional-morphologic observations several of these forms are tentatively attributed to 2 hydrodynamically rather extreme types of echinoderm biotopes: