Porifera-microbialites of the Lower Liassic (Northern Calcareous ...

The Schnöll Formation (Spiculite Facies) 59
Family Tretodictyidae ? Schulze, 1886
Skeleton type 7
(Pl. 13C, D)
Habit: Cup-shaped to tubular species, attaining diameters of 3.5-4.5 cm and heights of 6 cm or
more. Distinct wall structures, 0.5-1cm in thickness, display a schizorhyse aquiferous system and
0.5-0.7 mm wide ostia.
Skeleton: Euretid type with mainly fused spicules. Dictyonal skeleton of hexactins that form
short tracks or bigger clusters of a basically cubic meshwork, that get often disturbed by
intercalated triangular or polygonal meshes thus eluding the canals of the aquiferous system.
Internodes measure 160-240 µm. The rays of the spicules are 25-30 µm thick.
Skeleton type 8
(Pl. 13B)
Habit: Several small tubes, 2-5 mm in diameter, either protruding from a common base or
growing side by side. Features of an aquiferous system were not detected.
Skeleton: Euretid type with predominantly fused spicules. The dictyonal skeleton consists of
fused hexactins that form a radial-concentric meshwork, according to the tubular growth.
Internodes measure 200-300 µm. The rays of the spicules are thin, about 25-30 µm in diameter.