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Tatiana P. Malyshkina
added a research item
The study of the holotype of Striatolamia tchelkarnurensis Glickman, 1964 (Lamniformes: Odontaspididae), presumed to be an invalid species, in the Collection of the State Darwin Museum, described from the Chegan Formation of South Turgay (West Kazakhstan) and including more than 30 isolated teeth from one individual, showed that the species is valid. Morphological characters of the teeth of S. tchelkarnurensis, a terminal taxon of a genus that became extinct in the late Eocene, correspond to the evolutionary trend of the genus-an increase in the size of teeth and an increase in their cutting function due to a change in the shape of the crown and root. The article provides a redescription of the species in accordance with the requirements of the International Code of Zoological Nomenclature (1999).
Tatiana P. Malyshkina
added a research item
Teeth of 14 shark species belonging to ten genera are recorded in the Middle Eocene (Kuma Horizon, Bartonian) bony fish localities of the northern Caucasus (Pshekha River) and Crimea (vicinity of Bakhchisarai). Most of the taxa are typical for the tropical Tethys.
David John Ward
added a research item
A rich elasmobranch assemblage is reported from the Early Neogene marine sediments of the lower member of the Navidad Formation, Central Chile. The fauna comprise Squalus sp., Pristiophorus sp., Heterodontus sp., Megascyliorhinus trelewensis, Carcharias cuspi- data, Odontaspis ferox, Isurus oxyirinchus, Isurus hastalis, Cosmopolitodus hastalis, Carcharoides totuserratus, Myliobatis sp. and Cal- lorhinchus sp., all of which are reported for the first time in the Early Miocene of Chile. The presence of Carcharoides totuserratus sup- ports the Early Miocene age for the lower part of the basal Navidad Formation. The Chilean fossil elasmobranch fauna is represented by deep water and shallow water taxa, which probably were mixed in a submarine fan. Certain taxa suggest warm-temperate waters. The Early Miocene fauna from the Navidad Formation show affinities with other faunas previously reported from the Late Paleogene and Neogene of Argentina and New Zealand.
Tatiana P. Malyshkina
added 2 research items
ABSTRACT Geological fieldwork to investigate the stratigraphic context of Dzheroy-2, fossil shark and ray location in the Kyzylkum desert (Case et al. 1996), resulted at the discovery of the new location, Dzheroy-3, consisting of three fossiliferous horizons, at different stratigraphic levels: in the base of Suzak Formation, in the middle of the Alay and at the base of Turkestan Formation. A total of over 450 shark and ray teeth were collected by a combination of surface prospecting and bulk sampling. From the lithology and the faunal composition of the individual assemblages it was possible to deduce the age and depositional environments of the new fossil fish-bearing horizons. Faunal analysis indicated full marine conditions of the including sediments with bottom-anoxic conditions of the two lower levels and more oxygenated in the upper one. All sequence of beds with fossil elasmobranches including Dzheroy-2 demonstrates a succession of sea shallowing. The vertebrate locality Dzheroy-2 has been placed in a stratigraphic context with its maximum age as NP16 – Late Middle Eocene, upper Lutetian or Bartonian. Lithostratigraphic description of the Dzheroy Sand Member is given. Key words: Dzheroy, Elasmobranchii, Eocene, Kyzylkum, paleoenvironment, stratigraphy
Two new species of carcharhinid sharks from the Late Eocene deposits (Tavda Formation) of the southern Trans-Urals, Abdounia vassilyevae sp. nov., previously determined as A. aff. beaugei, and A. lata sp. nov., are described. To date, up to five Priabonian species of Abdounia have been recorded. New finds supplement the data on diversity, evolution, and paleobiogeography of Abdounia.
Tatiana P. Malyshkina
added 2 research items
Geological fieldwork to investigate the stratigraphic context of Dzheroy-2, fossil shark and ray location in the Kyzylkum desert (Case et al. 1996), resulted at the discovery of the new location, Dzheroy-3, consisting of three fossiliferous horizons, at different stratigraphic levels: in the base of Suzak Formation, in the middle of the Alay and at the base of Turkestan Formation. A total of over 450 shark and ray teeth were collected by a combination of surface prospecting and bulk sampling. From the lithology and the faunal composition of the individual assemblages it was possible to deduce the age and depositional environments of the new fossil fish-bearing horizons. Faunal analysis indicated full marine conditions of the including sediments with bottom-anoxic conditions of the two lower levels and more oxygenated in the upper one. All sequence of beds with fossil elasmobranches including Dzheroy-2 demonstrates a succession of sea shallowing. The vertebrate locality Dzheroy-2 has been placed in a stratigraphic context with its maximum age as NP16 – Late Middle Eocene, upper Lutetian or Bartonian. Lithostratigraphic description of the Dzheroy Sand Member is given.
An isolated upper anterior shark tooth from the Early Miocene Holmsk Formation, Sakhalin Island, Russia, is identified as an Alopias close to extant Alopias superciliosus Lowe, 1841. This is the first reliable record of a fossil shark from the S akhalin Neogene, and the most northern finding of a fossil thresher shark in Eastern Asia.
Tatiana P. Malyshkina
added 2 research items
Priabonian deposits from two localities, Kurgan and Derney, in the Trans-Urals (Western Siberia) have yielded numerous selachian teeth. The carcharhiniform family Scyliorhinidae is represented by three species, including two new: Premontreia uralica sp. nov., Foumtizia zhelezkoi sp. nov., and F. pattersoni (Cappetta, 1976). Both genera are recorded from the West-Siberian Basin for the first time. Presumably all three species (including the one morphologically mimicking F. pattersoni, a species recorded from Ypresian of England) are endemic for the Trans-Urals region (contrary to the cosmopolitan lamniforms recorded previously from the area. The known distribution pattern of extant scyliorhinids supports the probability of endemism of the cat sharks from the West-Siberian Basin, which has also been isolated geographically from the Peri-Tethys during the Late Eocene marine regression. The peculiar local environmental conditions due to the Priabonian climatic cooling in the Boreal realm might have also facilitated the speciation.