metasicula. They attached themselves to the substratum by a wide basal surface or basal disc.The sicula
of Epigraptus represent a primitive condition, strongly resembling the 'embryonal vesicle' of
Rhabdopleura. A more advance stage is represented by the sicula of Kozlowskitubus.
boulder, Ordovician, Baltic Coast.
d - dorsal apertural process (fragmental), m - marginal
membrane, ms - metasicula, ps - prosicula, v - ventral process.
sicula (attachment surface damaged). B.
diagrammatic illustration of central part of
thecorhiza. Glacial boulder, Ordovician, Poland,
Vistula Valley.
d - diaphragms, h - trace of helicoidal line, ps -
prostolon, si - base of prosicula, st - thecal stolon, ss
-stolothecal stolon, t - thecae.
Kozlowski, R. 1971. Early development stages and the mode of
life of graptolites. - Acta Palaeontologica Polonica 16, 4,
313-343.
2003-2004
