Graptolithina

Classification
Phylum: Hemichordata
Class: Graptolithina (Bronn, 1846)
Cincinnatian Orders: Graptoloidea, Mastigograptida

Geologic Range
Middle Cambrian – Carboniferous

Common Paleoecology
Graptolithina is an extinct class of passively mobile planktonic suspension feeders

Characteristics of the Class

• Chitinous exoskeleton with characteristic growth bands and growth lines in periderm
• Thecae arranged in single or double row along stipes
• Rhabdosomes originating in a conical sicula
• Sessile or epiplanktonic
• Attached by nema (or virgula) from apex of sicula

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Treatise on Invertebrate Paleontology, Part V (1955):

• Colonial marine organisms that secrete a chitinous exoskeleton with characteristic growth bands and growth lines in periderm; thecae arranged in single or double row along stipes, or rarely in less regular aggregates, in some orders polymorphic and related to a chitinized stolon system; rhabdosomes originating in a conical sicula, sessile or epiplanktonic, attached by nema (or virgula) from apex of sicula; stipes free or rarely encrusting.

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