|Portal of Pterobranchs and Graptolites sponsored by M.M. plus M. Fahnen - Flags
|Graptolithoidea: Order Crustoidea
|Graptoblasti Kozłowski, 1949 or graptoblasts
|Graptoblasti were erected by Roman Kozlowski
(1949) on the basis of the material from the famous
exposure of late Tremadoc cherts near Wysoczki
(Gory Swietokrzyskie = Holy Cross Mts., Poland). He
treated them as an incertae sedis group related in
some way to the Pterobranchia or the Graptolithina,
because their upper surface exhibits the typical
fusellar pattern arranged along a distinctly zigzag
line. Later, Kozlowski (1962) found these obscure
fossils intimately associated with rhabdosomes of
various crustoid graptolites (Crustoidea). Finally,
Kozlowski (1971) expressed the opinion that
graptoblasts were produced by both crustoid and
camaroid (Camaroidea) graptolites, but this point of
view was overlooked by later researchers.
Kozlowski (1949) introduced a classification of
graptoblasts and erected two new 'genera', namely
Graptoblastoides Kozlowski, 1949 and Graptoblastus
Kozlowski, 1949, and twelve new species. Later,
Kozlowski (1962) was of the opinion that his 'taxa' and
classification should be regarded as a parataxonomic
system, independent of graptolite systematics,
because they were not intended to identify species in
any biological sense. This problem was discussed also
by Mierzejewski (2000).
Graptoblasts are known from the Upper Tremadocian
to the Upper Ludlow Series (Mierzejewski 1977).
Urbanek (1984) regarded graptoblasts as closed,
resting terminal portions of the stolothecae,
containing dormant buds, and he compared then to the
hibernaculae of ctenostomate bryozoans.
Fine structure of graptoblasts
Cephalodiscus-like fibrils in graptoblasts
Development of graptoblasts
Cellular tissue in graptoblasts
|Graptoblast from the Upper Tremadocian
of Wysoczki, Poland.
From Kozlowski 1949
|Inner cavity of the graptoblast.
SEM micrograph from Mierzejewski (2000)
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