Diplograptid and early monograptid fauna Ordovician-Silurian

A form genus - that is, a set of species that have a common shape rather than a common ancestry. These form genera are still usefUl for identifications in the field and at a preliminary level. Climacograptids have box-like thecae and are always biserial. They are typically 2-6 cm long.


Monograptid fauna Silurian

A spirally coiled graptoloid with unusual thecae, each with a spine at the aperture. These spines are capable of developing into branches, each made of the same type of thecae and capable of branching again. These species may have filled a niche left vacant by the extinction of large, many branched, horizontally arranged dichograptids. They are usually 5-60 cm

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Survival Basics

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