Omphalotrochus canaliculatus Trautschold

Click on pictures to magnify

1 2

3

4

5

Discussion:

Omphalotrochus is a large and conspicuous gastropod, having whorls
with a squared cross section on adult specimens and a large open
umbilicus. A ridge along the shoulder of the whorl is a common
feature, like the one present on this species. The left specimen in
#3 shows a well developed sinus in the shell margin on the upper part
of the whorl. Image #4 shows a juvenile shell that is a little higher
spired than the adult shell. The white areas in the shell are areas
of silicification.

Viewer Comments:

Omphalotrochus is a common gastropod that has often been used as an
indicator of Early Permian age of the sediments containing it. However,
the age of the Carboniferous-Permian boundary now occurs at a level
above the first appearance of Omphalotrochus, as indicated by
this occurrence at Gzhel. Omphalotrochus has a thick outer calcite
shell layer that results in good preservation in strata where other
gastropods of aragonite composition have been lost by dissolution
of their shells.

Tom Yancey

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