Examples of abnormalities and regeneration in Wenlock Monograptidae are described and illustrated. The
sicula displays deformations of the dorsal processes, swellings of virgula or extremely numerous internal
rings. Some thecae reveal deformed apertures various excrescences and shortenings. Excessive growth
and reduction of lateral apertures are very common. Specimens with split of virgulae have also been found.
These phenomena seem to be common among graptolites but their origin is not very clear, each case
requiring a separate interpretation. The only exception is regeneration whose mechanism is the best studied
so far.

Lech Teller, Institute of Palaeobiology, Polish Academy of Sciences, Twarda 51/55, PL-00-818 Warszawa,
Poland; e-mail: l.teller@twarda.pan.pl
GRAPTOLITE NET
was established in 2002 by Zakład Paleobiologii
It is edited and periodically updated by
Piotr Mierzejewski, Count of Calmont
ABNORMALITIES IN THE DEVELOPMENT OF MONOGRAPTID COLONIES
Lech TELLER
Geological Quaterly 1999, 347-352