lingulate

As the shells were poorly preserved, but differed from the lingulate species formerly known in the region, they were referred to as Ungula sp.

Stem leaves straight, concave, ovate, elongate-ovate or lingulate; [+ or -] erect and imbricate, sometimes spreading; margin plane, slightly recurved at base, entire; apex rounded or obtuse, cucullate; costa long and single (up to 80% of length leaf); median lamina cells linear, slightly incrassate, porose; marginal cells similar or narrower than adjacent median lamina cells; alar cells rectangular, shortly rectangular or quadrate, hyaline, [+ or -] inflated, [+ or -] thick-walled, forming a well delimited ovate or rectangular group along basal leaf margin, decurrent; initial cells of rhizoids abundant near apex or beside nerve in upper part of leaves, rhomboidal and hyaline.

The lower boundary of the Kallavere Formation is marked by the lingulate coquina containing numerous valves of linguloid brachiopods Ungula ingrica, Schmidtites celatus, rare Keyserlingia buchii and Oepikites obtusus.

Lingulate tip of supra-anal plate narrow and strap like.

Leaf blades lingulate, acute to attenuate, 15-24 mm wide, subdensely brown punctate-lepidote throughout, light or bright green.

The rate of this process is determined by the primary organic matter content of the mineralized tissue: the most rapid changes take place in tissues with a high organic matter content (e.g., among Recent organisms, lingulate brachiopod shells; Nemliher & Kallaste 2002).

Inarticulated lingulate brachiopods Bicarinatina, Laima and Orbiculoidea occur in the Rezekne-Gauja interval, whereas Bicarinatina is most common (for comparison see Zabini et al.

Supra-anal plate elongate-triangular, with smoothly rounded lingulate tip.

Petals lingulate, obtuse, 17-19 mm long, each with a pair of fimbriate basal appendages, pale yellow tipped with white.

Lingulate brachiopods represent a class of marine invertebrates (Lingulata Gorjansky & Popov) existing from the Lower Cambrian to the present (Holmer & Popov 2000).

The lingulate brachiopod faunas documented from the Paltodus deltifer Biozone of the Eastern Alborz Mountains and Poland (Biernat 1973; Holmer & Biernat 2002) show clear signs of the beginning of recovery.

Leaves 12 to 18 in number, laxly spreading, thin coriaceous, 30-45 cm long, dark punctate-lepidote throughout; sheaths elliptic, 3-5 x 2-4 cm, dark castaneous especially abaxially, slightly nerved; blades lingulate, acute to attenuate, pungent, 1-3 cm wide, thin coriaceous, green tinged purple or reddish striate.

This level coincides with a lithological boundary which is marked by a 2-3 cm thick layer of the black shale and numerous fragments of lingulate brachiopods.

Phosphorus is bound in apatite of lingulate brachiopods Paterina and Mickwitzia (Gorjansky 1969) and phosphatic pebbles (Mens & Pirrus 1977).