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THE NATURE AND MODE OF LIFE OF THE GRAPTOLITE ZOOID
WITH REFERENCE TO SECRETION OF THE CORTEX
P.R. Crowther
Acta Palaeontologica Polonica 1978, 23, 4, 473-479
 
 
ABSTRACT:

Scanning electron microscope studies of well preserved, isolated graptolites have revealed a radically new and
unexpected structure to both normal cortex and endocortex, termed here "cortical bandaging". Bandage structure is
described and illustrated for several species and the collagenous nature of the component fibrils confirmed. The evidence
presented sheds new light on the nature of the graptolite zooid and how it functioned, in particular on the mode of
skeletal secretion. A model involving a more pterobranch-like zooid is preferred to the recent ideas of Urbanek (1976)
and Kirk (1972) for secretion beneath a perithecal membrane.
                                                        
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  "If the evidence is accepted the our view of the mode of life of a graptolite zooid is radically altered. In contrast to
the very close connection between zooid and theca envisaged by
Kozlowski, Kirk and Urbanek, we must now give it the
ability to leave its tube to secrete bandages at least in the vicinity of its aperture, and also within the theca itself"
(Crowther, p. 476).
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---------Related pages:

Collagen in pterobranchs   |  Cortical bandages in Orthograptus gracilis
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