Alphachoristites condoriformis (Einor, 1939)

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Discussion:

A large thick-shelled brachiopod with sub-rounded sides and many
mid-sized ribs. The fold and sulcus also contain ribs of a size
similar to ribs on the flanks.

Viewer comments:

This brachiopod is typical of species traditionally assigned to the
genus Trautscholdia by Russian workers (including Kalasnikov, 1998).
However, the genus name has been synonomized with Alphachoristites
in the new Treatise on Invertebrate Paleontology (Carter, 2006) and
furthermorethe features of this species are unlike features of the holotype
specimen of Trautscholdia trautscholdi (Stuckenberg). The holotype of
T. trautscholdi is well illustrated in the Treatise volume, showing that
the species has a wide well defined fold and sulcus with little radial
ribbing. That suggests that species like the one illustrated here belong
in a different genus than Trautscholdia or its senior synomym
Alphachoristites. Determining a genus for this and closely related
species requires further study.

Note the boreholes present in valves of this brachiopod and the
presence of several encrusters of the genus Spirorbis. The boreholes
are steep sided and may be produced by organisms excavating a
burrow, not by a predator.

The white-colored circular spots present on most areas of the shell
are surface expressions of beekite rings. These are concentric
shells of silica that have replaced the original calcite of the shell.
This shell has been extensively silicified.

Tom Yancey

The genus name Trautscholdia was erected by Cox and Arkell in 1948
for a Mesozoic venerid bivalve, so the name Trautscholdia Ustritsky,
1967, proposed for spiriferid brachiopods is invalid.

Gera Mironcev

References:
Likharev B.K. and Einor O.L., 1939, Additions to the knowledge of the
fauna of the Upper Paleozoic of Novaya Zemlya, Brachiopoda; Arctic
Institute, Trudy, v. 127, p. 79, pl. 14, fig. 8-9 (" Materialy k poznaniu
verchnepaleozoyskoy fauny Novoy Zemly ")

Kalashnikov, N.V., 1998, Permian spiriferids from the north of
European Russia; Moscow, Geos, 139 p.

Carter, J.L., 2006, Spiriferoidea, in Williams, A., and others,
Treatise on Invertebrate Paleontology, Brachiopoda; Geological
Society of America and University of Kansas, v. 5, p. 1785

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