Beginning of the April was marked by 3-days Cephalopod conference held in Paleontological Institute, Moscow
Leonova T.B., Barskov I.S., Mitta V.V. (Eds.) (2009) Contributions to current Cephalopod research: morphology, systematics, evolution, ecology and biostratigraphy. Moscow: PIN RAS. 142 pp. [in Russian with English summary]
Among the other topics there are some papers devoted to Jurassic and Lower Cretaceous cephalopods:
1. Ippolitov A.P., Bizikov V.A., Rogov M.A. A functional morphological interpretation of some Mesozoic belemnites. P.27-30.
Features of the soft body of belemnites are discussed based on functional morphological relationships known to exist in recent groups of coleoids. The position and articulation of the mantle and fins, the number and armature of arms, body shape and orientation are discussed. The ability to change skin color is suggested for belemnites based on similarity analogy with recent coleoids. Apparently this ability was already present in ancient ectocochleate cephalopods (Bactritoidea) and was the key preadaptation for the parallel development of partly or completely internal shell in different Mesozoic cephalopod lineages (Ammonoidea, Coleoidea).
2. Baraboshkin E.Yu., Mikhailova I.A. The genus Paraspiticeras (Ammonoidea) distribution and evolution . P.38-40.
The heteromorph genus Paraspiticeras was revised based on an ammonoid collection from the Upper Hauterivian-Lower Barremian of the Southwest Crimea. The results indicate that this genus evolved from the Hauterivian heteromorphy Crioceratites by the spiral coiling of the shell. The absence of descendants of Paraspiticeras in the Late Barremian contradicts the assumption that this genus was ancestral to the Aptian Douvilleicerataceae.
3. Kiselev D.N. Parallel evolution of the Arctic and Central-Russian Paracadoceras (Cadoceratinae, Ammonoidea)
At the beginning of the Early Callovian (Elatmae Phase) the territory of European Russia and the Arctic Basin were independent centers of the Cadoceras (Paracadoceras) speciation. Two Paracadoceras lineages evolved independently in these places, and developed the same shell morphotype. The final members of both lineages (C. (P.) elatmae and C. (P) anabarense) are considered as stratigraphic analogues.
4. Rogov M.A., Perminov V.A. The first record of Kimmeridgian and Berriasian ammonites with traces of color pattern. P.47-49.
The first occurrence of Kimmeridgian and Berriassian Haploceratid ammonites with preserved color patters are studied. The Upper Kimmeridgian Neochetoceras from the Middle reaches of the Volga River shows a color pattern caused by schemochromy. Lower Berriasian ammonites from the Crimea (Haploceras (Hypolissoceras) cf. carachteis and Haploceratinae indet.) show traces of supposed color patterns, a longitudinal band on the upper flank, which probably reflects true shell coloration.
5. Seltzer V.B. Anomalous phragmocones of the Late Callovian Cardioceratidae (Ammonoidea). P.50-51.
Some anomalous phragmocones of the species of Quenstedtoceras Hyatt show distorted symmetry around the coiling axis. These distortions are caused by the encrustation by shell epibionts (bivalves, polychaetes). All cases of distorted symmetry are recorded in adults. In early whorls such anomalies are probably not found because of a change in habitat. As the mollusc grew its life-style approached nektobenthic, and the probability of the encrustation by larval epibionts increased.
6. Repin Yu.S. Internal structure of the shells of the Early Toarcian ammonites of the genera Tiltoniceras and Eleganticeras. P.59-60.
The shell interior of Tiltoniceras and Eleganticeras (Lower Toarcian) is discussed, and the five-lobed primary suture of Tiltoniceras is demonstrated.
7. Ippolitov A.P., Zibrov I.A., Tishchenko A.I. New finds of aulacoceratid phragmocones (Coleoidea) in the Lower Jurassic of the Crimea. P.61-65.
New finds of aulacoceratid pharagmocones, from the Upper Toarcian (6 samples) and Lower-Middle Liassic (1 sample) of the two localities, Petropavlovsky and Lozovoje quarries, are described and illustrated. Provisional study has shown them to represent at least two separate species. These are the youngest occurrences of aulacoceratids from the territory of the former USSR. Some issues of the modern systematics of aulacoceratids are discussed.
8. Mitta V.V. On the discovery of aptychi in the Upper Bathonian of the Russian Platform . P.66-68.
Aptychi are recorded for the first time in the Upper Bathonian Paracadoceras keuppi Zone in the Middle Volga Reaches (Mordovia, Alatyr II Section) in association with Kepplerites ex gr. inflatus Callomon. Their comparison with an aptychus of the Early Callovian Kepplerites galilaeii (Oppel) and published records from the Upper Callovian show that the Late Bathonian aptychi belong to the same parataxon (Granulaptychus), which is apparently typical of the family Kosmoceratidae [in opinion by M.Rogov these aptychy should be assigned to Praestriaptychus].
9. Mitta V.V., Bogomolov Yu.I. New data on Delphinites from the Lower Valanginian of the Russian Platform. P.69-71
The distribution of the Central Russian representatives of the genus Delphinites is discussed. Apart from the Lower Valanginian Delphinites undulatoplicatilis Zone in the type region (Menya River, Chuvashia, Middle reaches of the Volga River), they are found in the Kostroma Region, in the basin of the Unzha River, together with Euryptychites ex gr. astieriptychus, Siberites cf. ramulicosta and Buchia keyserlingi varkeyserlingi var. sibirica. This assemblage indicates the Lower Valanginian, most likely the upper part of the Hoplitoides Zone to the lower part of the Michalskii Zone.
10. Gulyaev D.B., Rogov M.A. Macrocephalitids (Sphaeroceratidae, Ammonoidea) in the Early Callovian of the East-European Subboreal sea. P.72-74.
Macrocephalitid ammonites which inhabited the Early Callovian Central Russian Sea are studied. These ammonites mostly belong to an eudemic lineage of descendants of Macrocephalites jacquoti. Their evolutionary trend was directed towards further reduction of ribbing and compression of whorls leading to the appearance of oxycones. Ammonites of this lineage became extinct during the early part of the Subpatruus Chron, when morphologically similar shells with reduced ornamentation appeared within the Boreal Cadoceratinae.
11. Arkadiev V.V. Ammonites of the genera Euthymiceras and Neocosmoceras (Neocomitidae) from the Berriasian of the Mountainous Crimea. P.77-79.
The diagnosis of the genus Neocosmoceras is discussed. The similarity in the shell morphology and sutural development allows the genus Euthymiceras to be considered as a junior synonym of the genus Neocosmoceras.
12. Igolnikov A.E. Problems in the systematics of the Berriasian Craspeditidae Spath (Ammonoidea). P.80-82.
Problems in the systematics of the Berriasian Craspeditidae Spath (Ammonoidea), an important group in the biostratigraphy of the Berriasian of Siberia, are discussed. The genera Hectoroceras Spath and Schulginites Casey are substantiated. Uncertainty in the interpretation of the species Surites analogus Bogosl. leads to difficulties in using it as an index zonal species. It is concluded that Peregrinoceras Sason. is a typical representative of the Boreal-Atlantic Region, which did not enter the Arctic. Marked similarity between the genera Pachypraetollia Alekseev and Praesurites Mesezhn. et Alekseev is noted, and their synonymy is suggested.
13. Kasumzade A.A., Akhmedova S.A. Patterns of the spatial-temporal distribution of the Lower Cretaceous aptychi in the Greater Caucasus (Azerbaijan). p.83-84.
The study of aptychi from the Lower Cretaceous of the Azerbaĳani regions of the Greater Caucasus revealed 56 parataxa of the species group assigned to six genera. Specific assemblages of aptychi for the Berriasian, Upper Valanginian, Lower and Upper Hauterivian are established. The majority of the species identified are not endemic and are found beyond Azerbaĳan in the Northern and Western Tethys.
14. Repin Yu.S. On Boreal Phylloceratida. P.85.
The superfamily Boreophylloceratacea, including the two families, Boreophylloceratidae and Yukagiritidae, is substantiated based on the study of the shell interior of these ammonites.
15. Ruban D.A. Diversity dynamics of Triassic-Jurassic ammonoids in the Caucasus and transgressive-regressive cycles. P.105-106.
In the Triassic and Jurassic, the dynamics of ammonoid diversity in the Caucasus corresponded generally to the regional transgressive-regressive cycles, although some deviations are also documented. The responses of species diversity to shifts of the shoreline were stronger than those of generic diversity. Despite a widespread transgression, the Permian/Triassic mass extinction precluded ammonoid radiation in the Early Triassic.
16. Gulyaev D.B. The evolution and stratigraphic significance of the Middle Jurassic Boreal genus Paracadoceras (Cardioceratidae, Ammonoidea). P.107-109.
The evolution, classification, stratigraphic and geographical distribution of Paracadoceras Crickmay is discussed. The genus Paracadoceras is divided into three subgenera, the Late Bathonian Arctic Catacadoceras Bodylevsкy, the Early Callovian Western-Boreal “Subgen. nov.” and the Early Callovian Eastern-Boreal – Paracadoceras s.s. The infra-zonal scale of near-boundary Bathonian-Callovian deposits of the European Russia based on Paracadoceras phylogeny is considered.
17. Knyazev V.G., Kutygin R.V., Meledina S.V. Cadoceratinae and zonal biostratigraphy of the Lower Callovian of Northern Siberia. P.110-117.
A Lower Callovian chart is proposed based on the studies of the most complete sections of the Callovian of the northern Siberia, on the western and eastern coasts of the Anabar Bay and Bolshoi Begichev Island, and the revision of the representative ammonite collections belonging to the genus Cadoceras. This chart includes five subdivisions, which are directly correlated with the standard scale. The Cadoceras elatmae Zone (subdivided into the C. frearsi and C. elatmae Zones) is proposed as the basal zone of the Callovian Stage. It is overlain by the C. tschernyschewi Zone, which is established for the first time in this region and is correlated with the Eastern European Cadochaumoussetia subpatruus Zone. In total, all the above subdivisions correspond to the standard Macrocephalites herveyi Zone. The succession of the above subdivisions correspond to the Proplanulites koenigi Zone. The C. tolype Zone, recognized for the first time in northern Siberia also corresponds to the Proplanulites koenigi Zone. The equivalents of the uppermost Lower Callovian Sigaloceras calloviense standard Zone are reliably established on Bolshoi Begichev Island in a rank of Beds with Cadoceras cf. sublaeve.
18. Alifirov A.S. Taxonomic identification of ammonites from the borehole cores and biostratigraphy of the Volgian Stage in Western Siberia. P.118-120.
The analysis of the material from the boreholes of Western Siberia allowed the re-identification of ammonites from the Jurassic terminal stage and the refinement of the nomenclature of the zonal scheme of the Volgian Stage in this region.
19. Berezin A.Yu. Ammonites from the Volgian and Ryazanian boundary beds in the basin of the Sura river. P.121-123.
Ammonites from the Jurassic-Cretaceous boundary beds from a new locality on the Menya River are studied. The Upper Volgian beds contain typical representatives of Craspedites (C.) okensis (d’Orb.) in association with Garniericersas subclypeiforme (Mil.) and ammonites resembling the lost holotype of Ammonites okensis d’Orb., 1845. The latter are similar to ammonites of the genus Chuvacshites Berezin, 2008, frequently occurring in the same beds.
20. Rogov M.A., Igolnikov A.E. Bochianites (Ammonoidea) in the Lower Cretaceous of the Panboreal Superrealm and their significance for paleobiogeographical reconstructions. P.124-126.
Heteromorph ammonites of the genus Bochianites are widely distributed in the Valanginian and more restricted in the Berriasian of the Arctic. These ammonites are represented by two clades which differ in their ribbing, stratigraphic range and geographical distribution. The Berriasian-Valanginian Boahianites from the northern Siberia resemble Californian representatives, whereas B. ex gr. Neocomiensis from the western part of the Arctic are similar to the West-European Bochianites. Shortterm but mass immigration of Bochianites in the Late Valanginian to Northwestern Europe coincided with a major climate change and with a turnover of oceanic currents. Their Western Arctic records are probably dated as Early Valanginian.
21. Kiselev D.N. Evaluation of sutural complexity and functional aspects of septal shape in ammonoids. P.131-136.
Changes in the sutural complexity in some Jurassic Cardioceratidae and two Cretaceous ammonites are studied using the Westermann index (sinuosity). It is show that the sutural complexity does not always correlate with the morphological and bathymetric parameters of the shell and often simply reflects a phylogenetic trend. This suggests that the intricately shaped ammonitic septum was multi-functional.