T. N. Smirnova

Early Cretaceous rhynchonellids of Dagestan: System, morphology, stratigraphic and paleobiogeographic significance

A comprehensive report on Early Cretaceous Dagestan rhynchonellids is provided for the first time. It includes the rhynchonellid system based on detail morphofunctional studies, recognition of the boundary in the evolutionary development of Late Mesozoic rhynchonelloids at the Barremian-Aptian boundary, analysis of changes in shell matter structure during successive time periods of the Early Cretaceous, elucidation of stratigraphic importance of species assemblages allocated stratigraphically by layers to six sections of the Lower Cretaceous deposits described by the author, and revelation of possibilities of using this group in paleobiogeographic reconstructions. The study describes 37 species, 7 genera, and 2 families; 16 species and 2 genera are new. This paper is useful for a wide range of paleontologists, experts on the Mesozoic fauna, biostratigraphers, and geologists dealing with Mesozoic deposits. The study provides 8 plates, 58 figures, 71 references.

Shell structure of the Early Cretaceous (Berriasian-Barremian) Rhynchonellids from Dagestan

The shell structure of five rhynchonellid species from the Lower Cretaceous of Dagestan was studied for the first time. The primary layer is rarely preserved in fossil rhynchonellids. Most of the species studied have a primary layer composed of prismatic calcite, one species has a finely granulated primary layer. The secondary fibrous layer consists of crossing bundles of fibers the (throughout shell thickness) and parallel bundles of fibers on the valve bottom.

First data on the shell structure of the Early Cretaceous (Berriasian) rhynchonellids from Crimea

The shell structure of the Early Cretaceous rhynchonellids from Crimea has not been previously studied. First data on the shell structure of Berriasian rhynchonellids from the family Praecyclothyrididae Makridin, 1964 from southwestern and central Crimea are presented. Sulcirhynchia semenovi (Moisseev, 1939), S. berriasensis (Lobacheva, 1980), S. gracilis (Lobacheva, 1977), Belbekella airgulensis Moisseev, 1939, B. mutabilis Lobacheva, 1983, B. minor Lobacheva, 1983 and partly Lamellaerhynchia rectimarginata (Smirnova, 1972) are studied. The shell wall of most species consists of three layers: external (finely or coarsely crystalline), fibrous, and prismatic layers. The layers are usually strongly recrystallized, especially external and prismatic layers. New fibers were formed by repeated dichotomy of ridges in different areas of the fibrous layer independently of the distance from the anterior margin.

Ontophylogenetic Studies of the Brachiopods of the Order Terebratulida

The patterns of ontophylogenetic change of the brachidium in Late Paleozoic, Mesozoic, and Cenozoic terebratulids are analyzed. The work of Russian specialists in establishing new evolutionary trends and working out terebratulid taxonomy on the basis of ontophylogenetic studies is discussed.

Permian Terebratulids of Eurasia: Morphology, Systematics, and Phylogeny

The Permian terebratulids of Eurasia are revised. The taxonomic composition of the Permian terebratulids of the Russian Platform, Northern Caucasus, Transcaucasia, northern and southeastern Pamirs, and northern China (Inner Mongolia) is elucidated. Fifty-one species (13 described here as new), 21 genera (3 described here as new), 7 families, and 6 superfamilies are described. During the progress of the study, the author (Smirnova, 2004a, 2004b, 2006a, 2006b) and Smirnova and Grunt (2002, 2003a, 2003b) described for the first time 19 species, nine genera, two families, and one superfamily. Morphofunctional analysis reveals a great diversity of internal structures, of the time of their appearance in the ontogeny, and of their taxonomic significance. Ontogenetic study reveals phylogenetic relationships between the Permian and Meso-Cenozoic terebratulids, the presence of the superfamilies Terebratuloidea and Loboidothyroidea in the Permian, and a new type of brachidium ontogeny characterizing the superfamily Compositelasmatoidea. This book is intended for paleontologists and biologists interested in problems of taxonomy and phylogeny, and includes 5 plates, 80 figures, and 75 bibliographic references.

New upper permian superfamily compositelasmatoidea (Brachiopoda, Terebratulida) from the east of the Russian platform: The specificity of ontogenetic transformations

A previously unknown type of ontogeny is discussed that unites features of two different types of loop development: the ancient dielasmoid type, which is typical of Upper Paleozoic terebratulids, and the angustothyridid type, which is typical of the Lower Mesozoic terebratulids. A new superfamily, Compositelasmatoidea, and a new family, Compositelasmatidae, with its type genus Compositelasma gen. nov., are established based on their unique ontogenetic changes.

Shell microstructure and variability of cell imprints of the mantle outer epithelium in the genus Suiaella Moisseev (Brachiopoda, Rhynchonellida) from the Lower Cretaceous of Crimea

The shell microstructure of the Lower Cretaceous Suiaella weberi Moisseev, 1949 (superfamily Norelloidea) from the Lower Barremian of Crimea is studied for the first time. The fibers of Suiaella are shown to differ strongly in size and outline of cross section from the fibers of the superfamily Rhynchonelloidea. Suiaella is shown to differ from rhynchonellids of the superfamily Basilioloidea in the presence of straight or slightly curved fibers and absence of twisted fibers and overlapping adjacent fibers within one and the same bundle, it also differs in the presence of capillation and fine ribbing. Numerous cell imprints of the mantle outer epithelium have been found in fossil Norelloidea for the first time.

Lingularia Biernat et Emig, 1993 from the Upper Jurassic of western Siberia: Larval and embryonic shells and shell microstructure

Remains of organophosphatic brachiopods of the order Lingulida have been found in the Upper Jurassic of Central West Siberian basin in the Shirotnoe Priob’e area (latitudinally extended Ob River region), in the 15-m-thick boundary deposits between the Bazhenov and Abalak formations. A new species, Lingularia salymica Smirnova, sp. nov., is established; its embryonic and larval shells, impressions of the bundles of setae on the larval shell, and shell microstructure are described. Impressions of the cuboidal cells of the mantle outer epithelium were found on the inner surface of the dorsal valve.

Shell microstructure of Lacunosella Wiśniewska (Brachiopoda, Rhynchonellida) from the Lower Cretaceous of Crimea; First finds of casts of outer epithelial cells of the mantle in rhynchonellids

First study of the shell microstructure of Lacunosella Wiśniewska, 1932 revealed bilayered shell wall and peculiarities in the structure of fibrous layer and separate fibers. Casts of cuboidal cells of the outer epithelium of the mantle on the inner valve surfaces are described for the first time for the Mesozoic rhynchonellids. The comparative characterization of the shell microstructure of the family Basiliolidae (superfamily Pugnacioidea) and families Praecyclothyrididae and Cyclothyrididae (superfamily Rhynchonelloidea) is refined.

The ontogeny of the Late Permian terebratulids (Brachiopoda) Gruntelasma Smirnova, Grigorjevaelasma Smirnova, and Campbellelasma Smirnova and their taxonomic position

A specific type of ontogenetic change combining elements of dielasmoid and angustothyridid stages of brachidium development is established for the Late Permian genera Gruntelasma Smirnova, 2004, Grigorjevaelasma Smirnova, 2004, and Campbellelasma Smirnova, 2004 from the Russian Platform. On this basis, these genera are assigned to the superfamily Compositelasmatoidea Smirnova, family Compositelasmatidae.