Parajuresania tastubensis (Tschernyshev)

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Discussion:

This specimen clearly shows an abrupt change in spine ornamentation
from a simple juvenile pattern to a complex pattern on the mature
portion of the shell. The juvenile has larger spines that are spaced
farther apart, whereas the mature shell has strong wide growth bands
with many small spines in quincunx arrangement and only a few larger
spines in a row along the edge of the growth bands. This major change
in ornamentation is quite different from the pattern present on the
type species of the genus, although the juveniles of both species are
very similar.

Tom Yancey

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Phylum Brachiopoda (brachiopods)
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