|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Pterobranchia - Bireclinata
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|P. Storch et al. 2011||Rhabdosome consists of two slightly recli- ned stipes with one or more (max 4) lateral branches – me- tacladia – developed in mature specimens. Th11 and 12 slightly declined before subsequently becoming slightly reclined at which point stipes diverge at 140°–170°. The most mature rhabdosome (Figs 8F, 11C) exhibits broad ventral curvature of the stipe. Metacladia appear to extend from dorsal side of stipe but arise from the lateral part of the thecal aperture as in Nemagraptus (Finney 1985). Si- cula up to 1.7 mm long with apertural width of 0.12–0.2 mm in flattened material. One specimen possesses 0.4 mm long virgella. Slender, elongated thecae with gently inclined supragenicular ventral walls do not exceed much parallel-sided outline of stipe. Introverted thecal apertures partly overlap shallow excavations that occupy one-third to two-fifths of stipe width. Thecal geniculation varies accor- ding to preservation and mode of the rhabdosome flattening. Th11 and 12 with tiny subapertural spine. Primary stipes (procladia) 0.18–0.25 mm wide at th1 and 0.2–0.3 mm wide at th3; maximum distal width 0.22–0.42 mm, depending on preservation (e.g. Fig. 8L, M, O, P). Metacladia attain maxi- mum width of 0.22–0.45 mm. 2TRD: 1.45–1.9 mm at th2 of the primary stipe whereas distal thecae number ~10 in 10 mm (2TRDdist: 1.75–2.3 mm). Metacladia with similar thecal density; 2TRD: 1.75–2.6 mm.|