The proximal development in Anisograptis (Graptoloidea, Anisograptidae)

model for the proximal development of anisograptids is proposed. The complex proximal development types of tri- and quadriradiate rhabdosomes are constructed by repetition of simple isograptid branching. The simple structures involved in the proximal developments indicate possibly a polyphyletic origin of biradiate graptolites.