Pachydendron microthallos Cuif, 1975

Roniewicz, Ewa, 2011, Early Norian (Triassic) corals from the Northern Calcareous Alps, Austria, and the intra-Norian faunal turnover, Acta Palaeontologica Polonica 56 (2), pp. 401-428 : 408

Pachydendron microthallos Cuif, 1975

Fig. 2C, D .

1975 Pachydendron microthallos Cuif, 1975 ; Cuif 1975b: 169, text−figs 5–7, pl. 14: 2.

1986 Pachydendron microthallos Cuif, 1975 ; Melnikova 1986: 88, pl. 20: 3, 4.

1987 Pachydendron microthallos Cuif, 1975 ; Turnšek and Ramovš 1987: 37, pl. 7: 3, 4.

2007 Pachydendron microthallos Cuif, 1975 ; Roniewicz et al. 2007: 590, pl. 4: 1.

Material.—Two fragments of large phaceloid coralla with numerous corallites: GBA 2007/152/2 and 2009/019/1, single corallites in thin sections from the specimens GBA 2009/ 019/2, 2009/019/3, 2009/019/4, and 2009/019/5.

Measurements (in mm): Remarks.—The indication of the Upper Norian/Rhaetian as the stratigraphical position of this species in the Northern Julian Alps ( Turnšek and Ramovš 1987) needs verification, because none of the well identified early Norian species are known in the late Norian; early Norian genera related to Pachydendron ( Pachythecalis , Pachysolenia ) are restricted to the early Norian.

Stratigraphic and geographic range.— Austria: Northern Calcareous Alps, Dachstein Plateau, north of Feisterscharte, lower Norian, Epigondolella quadrata Conodont Zone. Turkey: Taurus Mts, Alakir Çay: Stikinoceras kerri Ammonoid Zone. Tajikistan: SE Pamirs, Shindy Say Valley and Djilgakochusu Valley, Shaimak svite, upper Carnian–lower Norian. Slovenia: Northern Julian Alps: upper Norian/Rhaetian.

Figures

Fig. 2. Hexanthiniarian corals from vicinity of Feisterscharte, Austria, early Norian, Triassic. A. Pachysolenia cylindrica Cuif, 1975; GBA 2007/152/1. A fragment of phaceloid corallum in upper view (A1); transverse section (A2); a corallite with septa thickened by a cover of fine crystals (A3); a tube−like, distal part of the calice with a thick pachythecal wall (A4); a magnified fragment showing modular structure of the pachythecal wall with internal wall surface longitudinally sculptured with minute ridges at left (A5); a corallite in longitudinal section showing a thick wall and thin, rare tabulae (A6). B. Pachysolenia cf. cylindrica Cuif, 1975; GBA 2007/152/3. Transverse section of the corallite with abundant septa. C, D. Pachydendron microthallos Cuif, 1975. C. GBA 2007/152/2. Corallum in transverse section (C1); corallite with rare tabulae in longitudinal section (C2); and a corallite (C3) with traces of microstructure in the wall with lumen filled by coarse calcite crystals. D. GBA 2009/019/3. Corallite with recrystallised wall, transverse section. E. Indetermined solitary hexanthiniarian coral?; GBA 2009/019/12. Thick−walled pachythecal−like coral in transverse section (E1), and its fragment (E2) showing septa with sharp ornamentation.