A diverse productid fauna from the Artinskian-Kungurian sequences of
the northern Tarim Basin (NW China) is described by CHEN & SHI (2006),
who provide a detailed systematic and biostratigraphic study of these
Lower Permian assemblages collected from six outcrop sections located
on the soutwestern and nortwestern sides of the basin.
In the first paragraphs, the biostratigraphical significance of the
Lower Permian brachiopod fauna from the Tarim basin is clearly
outlined, also in term of its utility for hydrocarbon prospection.
Seven brachiopod biozones are established and defined as acme biozones
[erroneously equated by the authors to the assemblage biozone of
SALVADOR (1994)]: the lower Artinskian Bruntonella tenuireticulatus
and Hystriculina sinica 696 Paläozoologie Biozones, the middle to
upper Artinskian Orbicoelia magna Biozone, the uppermost Artinskian
Liraplecta richthofeni Biozone, the lower Kungurian Chianella
chianensis Biozone, the upper Kungurian Tarimathyris postambigua
Biozone and the uppermost Kungurian Liraplecta aspera Biozone. Their
age is supported in part by associated conodonts and fusulinids and by
correlation with faunas from South China, North China, Thailand,
Urals, and the Russian Platform.
The core of the monograph is represented by the Systematic
Paleontology section where 34 brachiopod species from 30 genera are
described, of which five species, two subgenera and one genus are new
based on the study of about 200 specimens.
The new species are Dyschrestia takelamaganensis sp. nov., based on 15
specimens and characterized by a large size and rugae only on ears;
Marginifera (Arenaria) yinjishaensis sp. nov., based on 9 specimens
and characterized by an elongate outline, narrow umbo and absence of
ventral sulcus; Chaoiella ustritskyi sp. nov., based on 2 specimens,
described as a large, strongly geniculated species with fine but
distinct costellae and rugae; Coolkilella pseudovilliersi sp. nov.,
based on 9 specimens and characterized by large size, an elongate
suboval to trigonal outline, relatively coarse ribs and few spines;
Cancrinella quadrata sp. nov., based on 7 specimens, described as
having dense and strong rugae and coarse ventral spines.
Two new subgenera are proposed to include different groups of Asian
Permian species of Marginifera WAAGEN, 1884: Marginifera (Arenaria)
subgen. nov. for small to medium sized species with weak ribbing and
evenly distributed ventral spines, i.e. M. (A.) arenaria GRANT, 1976,
M. (A.) ovalis WAAGEN, 1884, M. (A.) excavata WAAGEN, 1884, M. (A.)
echinata WAAGEN, 1884, M. (A.) transversa WAAGEN, 1884, and M. (A.)
elongatus HUANG, 1932. The second new subgenus Marginifera (Nesiotia)
subgen. nov. has been erected for the small species with small ears
and few spines as in M. (N.) nesiotes GRANT, 1976.
The genus Bruntonella gen. nov. is proposed based on the species
Dictyoclostus tenuireticulatus USTRITSKY, 1960 and placed in the tribe
Reticulatiini LAZAREV, 2000. Bruntonella is described as closely
allied to Reticulatia MUIR-WOOD & COOPER, 1960, differing by a less
strong reticulation, absence of dorsal spines anda deeper corpus
cavity.
The genus Pseudoavonia WANG in ZHANG et al. 1983 is revised and its
internal characters, previously unknown, are described in more detail;
also it is cleared its relationship to Liosotella COOPER, 1953. Based
on its cardinal process, marginal ridges and the lack of dorsal spines
the genus is transferred from the Costispiniferini MUIR-WOOD&COOPER,
1960 to the Marginiferini STEHLI, 1954.
The poorly known genus Kepingia WANG & YANG, 1998 is also emended and
provided with a more detailed description; it is included in the Tribe
Liraplectini CHEN&SHI, 2001.
For what concerns the illustration of the brachiopod fauna, the
fifteen plates are of very good quality and they well display the
features and the significance of the Lower Permian productid fauna of
the Tarim Basin.
L. ANGIOLINI
Zentralblatt Geo. Pal. T. II Jg. 2008, H. 3/4
