|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Pterobranchia - Bireclinata - Retiolitidae
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.
|A. C. Lenz and M. J. Melchin 1987||Prosicula well developed. Virgella distally forming 4-pronged ancora which develops into basket-shaped corona formed of 2-3 crude rows of cells. Lateral bar from near apex of sicula splits into 2 parietal lists to form theca l1. Virgula moves quickly to ventral side of rhabdosome, alternately giving off short branches to 'left' and 'right'. Branch divides into short ventral and long dorsal, branch to form aboral list; these in turn divide and project laterally to form parietal lists. Zig-zag line on dorsal side alternately joins 'left' and 'right' thecal lists. Thecae orthograptid in profile, bases marked by a single median thread joining centre of thecal lip and aboral list of previous theca. Thecal spines developed near margin of thecal lips, projecting proximally and laterally (pi. 1, fig. 1). Lacinia not seen. Reticulum of very irregular meshwork; meshes vary considerably in size and shape. Large irregular openings (stomata) present along medial line. Rhabdosome ovate in cross-section. Fine structure of lists comprises longitudinal striations only.|