Parajuresania tastubensis (Tschernyshev)

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Discussion:

This brachiopod is highly inflated and has a strongly curved shell,
with concentric rows of spines covering semi-regular growth bands.
The adult shell is elongate and has the greatest width at mid-length
on the shell, not on the hingeline. The interior of the dorsal valve
(lower right image) has a long median septum and scattered endospines.

Viewer comments:

The type species of Parajuresania is P. nebrascensis (Owen), a
common species of the late Pennsylvanian and earliest Permian of
midcontinent North America (Dunbar & Condra, 1932). The species
at Gzhel differs from the type species in having a great difference
between the juvenile and mature portions of the shell. The mature shell
on P. tastubensis has wide concentric bands with closely spaced spines
of different sizes, typical of the echinoconchids, whereas the juvenile
portion of the shell lacks banding and has more widely spaced spines
of a single size. Placement of this brachiopod in the Echinoconchidae is
indicated by the presence of growth bands on both valves, concentric
rows of spines and by the change in spine arrangement from juvenile
to mature shell.

Tom Yancey

References
Dunbar, C.O. and Condra, G.E., 1932, Brachiopoda of the Pennsylvanian
System in Nebraska; Nebraska Geological Survey, Bull. 5, p. 195-198,
pl. 32, figs. 1-9,13

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