Paleozoic bryozoans of Mongolia

Stratigraphic assemblages characteristic for the Ordovician, Silurian, Devonian, Carboniferous, and Permian are presented based on the analysis of newly refined and supplemented data on the composition and distribution of Paleozoic bryozoans in Mongolia. Thirty-four auxiliary biostratigraphic units ranked as beds with bryozoans are established in order to subdivide the Paleozoic strata of Mongolia.     

Cancrinella and Costatumulus (Brachiopoda) from the Permian of South Mongolia and South China: Their morphology,biostratigraphy and distribution

Two brachiopod genera, Cancrinella Fredericks and Costatumulus Waterhouse, are studied from the Permian of South Mongolia and South China. Many of the specimens previously described as Cancrinella are revised and assigned to Costatumulus. The new data presented in this paper indicate that these two genera are similar to each other, but are distinguishable by different features in relation to their morphology. Several species of both genera are described here, providing critical new information on the morphology and taxonomy of Cancrinella and Costatumulus. The reported biostratigraphical information reveals that species of Cancrinella are present from the Lower Carboniferous (Tournaisian) to Middle Permian (Capitanian), whereas species of Costatumulus are mostly restricted to the Lower Permian (Sakmarian) to Upper Permian (Changhsingian). An analysis of the palaeogeographical distribution of Cancrinella and Costatumulus reveals that Cancrinella was more commonly distributed in the Northern Transitional Zone and the Boreal Realm, in contrast to Costatumulus, which tended to be more common in the Southern Transitional Zone and Gondwanan Realm.     

Iraida Pavlovna Morozova (1919–2007)

Paleontological Journal -     

一个重要的蒙古二叠纪牙形刺种

在蒙古南部Lugiingol剖面卢金格尔(Lugiingol)组下部发现牙形刺Mesogondolell aidahoensis,该地层应归入下二叠统空谷阶,而不是像以前那样归入上二叠统。     

Stratigraphic and paleogeographic distribution of the Upper Ordovician bryozoans of Mongolia

The taxonomic diversity and distribution of the Upper Ordovician bryozoans of Mongolia are analyzed. Five heterochronous assemblages of bryozoans are established: Chigertei and Tsagaan del in the Sandbian Stage and Bairim Ovoo, Uuregnur, and Sairin in the Katian Stage. The bryozoans are shown to be important for solving complex problems of stratigraphy of the Ordovician of Mongolia and for paleogeographic reconstructions.     

The northern most Emsian crinoids known, a Devonian fauna from the Chuluun Formation, Shine Jinst area, Southern Mongolia

The most northerly known Emsian crinoids were located at approximately 45° to 50° N latitude. They are the first Devonian crinoid cups discovered in Mongolia. Specimens are reported from excellent exposures of the informally designated crinoidal beds in the upper part of the stratotype section of the Chuluun Formation, between N44° 22.119', E99° 27.130' and N44° 22.201', E99° 26.906', near the Tsakhir Well, in the foothills south of Tsagaan Khaalga Mountain, Shine Jinst area, southern Mongolia. All specimens are crushed, altered by low-grade metamorphism, and ossicles flake as they weather. Five genera are present including a new genus of the Periechocrinidae, two indeterminant camerates, an undesignated new species of Cyathocrinites, and one indeterminant crinoid. These genera agree with a middle Emsian age previously assigned to the upper part of the Chuluun Formation on the basis of brachiopods and conodonts. They show affinity to European and North American Emsian faunas.