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GRAPTOLITE NET
is edited and periodically updated by
Piotr Mierzejewski, the Count of Calmont DRG, FRC
Established 2002
GRAPTOLITHOIDEA: Order Crustoidea
Urbanekicrusta reversa Mierzejewski, 1985
Urbanekicrusta is an interesting form
since it combines features of three
non-dendroid orders of sessile
graptolites: Crustoidea, Tuboidea and
Camaroidea. Each autotheca of
Urbanekicrusta, like numerous genera
of these three orders, is sharply
differentiated into a distinct proximal
creeping portion and a distal erect
portion. Generally, autothecal shape is of
camaroid or tuboid type rather than a
crustoid type. The tubular erect part of
each autotheca is provided with one
linguiform process, and distinctly
resembles  resembles the autothecae of
some tuboids (Epigraptus Eisenack =
Idiotubus Kozlowski) and camaroids
(Graptocamara Kozlowski). In all other
known encrusting graptolites, when the
apertural apparatus consists of only one
process, it is always ventral. But, in
Urbanekicrusta this situation is
reversed, its apertural apparatus is
made of only a dorsal process.

It is possible that Urbanekicrusta
represents an unknown line of crustoid
graptolite evolution.
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Mierzejewski, P. 1985. New aberrant sessile graptolites from glacial
boulders. - Acta Palaeontologica Polonica 30, 3/4, 191-199.
   Urbanekicrusta reversa Mierzejewski, 1985.
Holotype.Silurian (Wenclock-Pridoli) glacial boulder No.
ZPAL )326 (Mochty). 1. General view of holotype. 2. Fusellar
structure of the autothecal venral wall. 3. Trifurcation of the
stolon system, infrared micrograph. 4. Details of the autothecal
stolon.