Paleobiologist from Moscow, Russia. Researcher in Geological Institute of RAS, Moscow. My main research interests are following: ancient cephalopods, mainly Jurassic and Cretaceous ammonites, ammonoid paleobiology, paleoecology, cephalopod jaw apparatus, muscular system and soft body of the ammonoids, ammonoid reproduction.
New finds of cephalopod jaw apparatuses from the upper part of the Niortense Zone and the lower part of the Parkinsoni Zone (Upper Bajocian) from the interfluve of the Kuban and Urup rivers (Northern Caucasus) are described. Two isolated valves of aptychi which are considered to be ammonoid lower jaws are assigned to the superfamilies Haploceratoidea and Stephanoceratoidea. Two upper jaws likely belonged to ammonites with aptychus-type jaw apparatus (Ammonitida). The seven anaptychus-type jaws are assigned to the orders Phylloceratida and Lytoceratida. A well-preserved upper jaw of coleoid affinity is described for the first time from the Mesozoic of the Northern Caucasus.More >>>
This is the first record of Late Jurassic (Volgian) otoliths from the boreal province of Russia. Two new species– Palealbula korchinskyi n. sp. and Palealbula moscoviensis n. sp. – are described representing otoliths of putative stem-albuliform affinities of unresolved familiar position. The phylogeny of Palealbula and the supposedly related genus Protalbula is discussed in the light of the new findings presented in this article. Both genera are shown to represent a common faunal element in the early evolutionary phase of teleosts during the Late Jurassic and Early Cretaceous.More >>>
The discovery of a hermit crab (superfamily Paguroidea) preserved in the likely immature shell of an ammonite, Craspedites nekrassovi is reported from the Upper Jurassic of Moscow, Russia. This is the oldest undoubtable symmetrical hermit crab to date which is known from non-reefal environments. This new occurrence combined with the documentation of numerous sublethal and lethal injuries on ammonite shells in the same beds (probably produced by such paguroids), all suggest that the hermit crabs not only lived in ammonite shells but also hunted these animals. The proportion of damaged shells (including healed ones) varies in different Upper Jurassic ammonite genera from 1.2% in Kachpurites up to 9.3% in Craspedites. Among damaged Kachpurites only 6.25% survived attacks whereas among Craspedites the percentage of survivors was 87.5%. These data imply that Craspedites likely lived near the sea bottom and often encountered hermit crabs, whereas Kachpurites likely lived in the water column.More >>>
For a long time all extinct cephalopods of the subclass Nautiloidea were considered as ecological analogues of the Recent Nautilus. Recently this view has been rejected: it is now known that among the nautiloids there were not only demersal predators but also epipelagic animals whose life-style and reproduction differed from those of the Nautilus. However, the habits of some nautiloid orders is still poorly understood. One of the most enigmatic cephalopods is the Early Paleozoic nautiloid order Endocerida. Endocerids differ from other nautiloids: they reached gigantic sizes (up to 9 meters), had a wide siphuncle tube and were widespread and numerous during the Ordovician. Since they were an important component of many Ordovician ecosystems, without the understanding of their habits and feeding strategies a correct reconstruction of these ecosystems is impossible. Until now, endocerids have been considered as dominant apex predators, however, this assumption is based on an analogy with the Nautilus mode of life, while the features of the structure of endocerid shells do not confirm this idea and furthermore contradict it. In this article, a new hypothesis is proposed and debated: according to it, the endocerids were planktotrophic cephalopods and the largest of them were giant suspension feeders.More >>>
Conellae, enigmatic cone-shaped structures which can be found on the surface of internal moulds of cephalopod shells (predominantly of ammonoids), are regarded herein as the product of remote (biologically induced) biomineralization formed in closed-off cavities during lifetime and might be primarily composed of vaterite, aragonite, or calcite. To date conellae have been interpreted in many different ways: (i) as organisms (gastropods, cirriped crustaceans, or disciniscid brachiopods), (ii) pre-diagenetic syn vivo features, i.e., biologically controlled or induced, the product of remote biomineralization, (iii) and diagenetic, i.e., abiogenic origin and post-mortem. The proposed processes of conellae formation seem insufficient to explain conellae related phenomena. Further, their assumed primary aragonitic or calcitic mineralogy are reviewed and based on new material critically assessed. The stratigraphic range of conellae extends from the Middle Ordovician and probably to modern Nautilus. Predominantly, conellae can be found on internal moulds along the keel, ribs or nodes, umbilical shoulder, at the transition between phragmocone and body chamber, and can be associated with repaired scars. However, conellae are also common on the smooth body chambers of large macroconchs of Jurassic ammonites. Conellae, which are located on ammonite body chambers, are filled with the same material found in the body chamber and can contain small burrows, sand grains, or coprolites. Some of these conellae are partially covered with nacreous shell material. Limonitic conellae were also found on the limonitic internal moulds of orthocone nautiloids. Moreover, disciniscid brachiopods found on inoceramid bivalves were re-identified herein as conellae. A short guide for conellae identification has been provided herein.More >>>