New and poorly known Valanginian ammonites from South-West ...

More documents

Recommendations

Info

108 Evgenij J. BARABOSHKIN & Irina A. MIKHAILOVAp. 531, pi. I, fig. 1, reproduced in VASICEK., 1994:p. 180. pi. 1, fig. 1). is distinguished from Campylotoxiacampylotoxa by more frequent ribbing, weakenedin the middle of whorls and is similar toTeschenites neocomiensefortnis HQHENEGGER in UHLIG,1902.Busnardoites campylotoxus (COMPANY, 1987: p. 145,pi. 11, fig. 12, 13; pi, 19, fig, 13) is referred by us tothe new subspecies Campylotoxia densocostata, describedbelow.Neocomites sp. (KEMPER, 1976: pi. 30. fig. 10), redefinedlater as Thurmanniceras cf. campylotoxum (KEMPER et ah1981: p. 279), has bidichotomic ribs with high branchingas in Teschenites.Hoplites ambligonium (TZANKOV, 1946: pi. XI, fig. 10) isclose to Campylotoxia campylotoxa by the type of cyclicityof its ribs, but its poor preservation does not allow acomplete identification.It seems that only one sample of Busnardoites campylotoxusfigured by FARAONI et al. (1997: pi. 6, tig. 3) hasribbing close to the real Campylotoxia campylotoxa.The other specimens (pi, 6. fig. 1 and 2) are closer toThurmanniceras, because they have a very high pointof rib-branching. The record of C. campylotoxa fromthe Saynoceras verrucosum Zone, is doubtful in theabsence of that species in the lower Upper Valanginian.We think that the sections, described by FARAONI et al.(1997) are characterised by the earliest appearance ofSaynoceras verrucosum and thus of early Late Valanginianage.Neocomites teschenensis, figured by ETTACHFINI et al.(1998: fig. 2G) is very similar to Campylotoxia campylotoxa,having the same style of ribbing, bipartite in theinner whorls. Unfortunately the other parts of the sampleare not well-preserved and complete identification isdifficult.Similar to Campylotoxia campylotoxa is C. brasseuri(COLLIGNON). which differs by the prevalence ofsingle ribs and by bifurcate tripartite ribs at the end ofeach cycle of ribbing. Its cycles of ribbing consist oftwo to four single, one bipartite, and one bifurcatetripartite rib, as is apparent in the type of Sarasinellabrasseuri, COLLIGNON, 1962: p. 26, fig. 832). The presenceof bipartite ribs with a high point of branchingindicates similarity of this species with the genus Thurmanniceras.Distribution. Lower Valanginian, Campylotoxia campylotoxaZone of Crimea, France, Slovakia, Bulgaria, Pakistan,Morocco; Haploceras (Neolissoceras) salinariumZone of Spain, (?) Upper Valanginian Saynoceras verrucosumZone of Italy.Campylotoxia campylotoxa densocostata subsp. nov,PI. 2, Fig. 7; PI. 3, Figs, la-b, Text-fig. 9, 111934 - Hoplites amblygonimn: STEFANOV, p. 218, pi. VII,fig. I (only).1987 - Busnardoites campylotoxus: COMPANY, p. 145.pi. 11. fig. 12, 13; pi. 19. fig. 13.Subspecies name: from Latin densuscostatus - ribbed.- frequent andHolotype: MSU 95/12 a complete specimen of goodpreservation from bed Kp23/I5, condensed horizon onthe Lower/Upper Valanginian boundary, Campylotoxiacampylotoxa Zone (?) of Verkhorechie Village, base ofRezanaya Mt.Paratypes: several fragments of satisfactory preservationfrom the same locality collected by students of the GeologicalFaculty. Moscow State University.Description: Moderate, with high trapezoidal whorl-sectionand weakly keeled venter. Umbilicus relatively narrow,shallow; umbilical wall is vertical to projected,narrow.Sculpture consists of rare simple ribs, 3-4 - partiteand bidichotomic rib, branching at an umbilical tubercle.Ribs terminate by ventro-latcral tubercles, whichbecome subparallel to the plane of symmetry of theshell in adult. Cycles of ribbing are separated byweak constrictions and not very typical for the genus,because single ribs are presented in internal whorlsonly. Cycles of internal whorls (lX20mm) begin by asimple or bifurcate rib and include also 2-3 bifurcateribs and a tripartite rib terminating the cycle. Cyclesof the external whorls (D=20-40mm) each consist ofa bifurcate rib and tripartite rib. There are up to 9cycles per whorl. The cyclicity disappears later(D>50mm) and the ribbing then consists of tripartitebidichotomic ribs with additional branching on one ofthe branches.Measurements:No. D H W Du Wu ai 0.2 P y95/12 52 21,5 15,5 16 3 30 -10 10-15 15 -5; 9095/13 - 20 14 3 30 -15 15 15 90Suture line (Figure 9): Ventral lobe (V) is narrow, deepand bifurcate: umbilical lobe (U) is tripartite, somewhatasymmetric, strongly deviating inside umbilicus; the firstumbilical lobe (U ) is twice shorter than the umbilicallobe (U).External (V/U) and first lateral (U/U 1 ) saddles areasymmetric, but the former is broader and somewhatshallower than the latter.
New and poorly known Valanginian ammonites from South-West Crimea 109Remarks: The new subspecies is distinguished from C.campylotoxa campylotoxa by denser ribbing, nearly completeabsence of single ribs in cycles and development oftripartite ribs on the outer whorls.The holotype has a weak original damage on theshell of the body-chamber, which is not a change of styleof ribbing. All samples came from the horizon of condensationat the Lower/Upper Valanginian boundary.They were met in reworked condition together withCampylotoxia campylotoxa. This allows us to expectthat their primary distribution was in the campylotoxaZone.Distribution: Lower Valanginian, Campylotoxia campylotoxaZone (?) of Crimea, Lower Valanginian of Bulgaria,Haploceras (Neoiissoceras) sallnarrum Zone ofSouthern Spain.Campylotoxiaevoluta sp. nov.PL 3, Figs. 5a-b1907 - Hoplites cfr. amblygonius: KARAKASCH, p. 86,pi. XI, fig. 6a-b.Species name: from Latin evolutus - unrolled.Holotype: MSU 95/14, complete specimen of good preservationfrom bed Kp23/15, horizon of condensation onthe Lower/Upper Valanginian boundary, Campylotoxiacampylotoxa Zone (?), Verkhorechie Village, base ofRezanaya Ml., collected by students of the GeologicalFaculty, Moscow State University.Description: Moderately evolute with rounded-rectangular(on the early whorls) and trapezoidal (on the latewhorls) whorl-section and weakly keeled venter. Umbilicusrelatively narrow, shallow; umbilical wall is verticalto overhanging, narrow.Sculpture is formed by single, 2-3 - partite and rarebidichotomic ribs, branching in the umbilical tubercle.Ribs are terminated by ventro-lateral tubercles, perpendicularto the plane of symmetry of the shell on earlywhorls and subparallel on later whorls. Ventral and umbilicaltubercles of terminal bunches are sometimes moreprominent. Cycles of ribbing in the internalwhorls (D
Page 1 and 2: BULLETIN DE L'INSTITUT ROYAL DES SC
Page 3: New and poorly known Valanginian am
Page 6 and 7: 94 Evgenij J. BARABOSHKIN & Irina A
Page 8 and 9: 96 Evgenij J. BARABOSHKIN & Irina A
Page 10: 98 Evgenij J. BARABOSHKIN & Iriua A
Page 14 and 15: 102 Evgenij J. BARABOSHKIN & Irina
Page 16 and 17: KMEvgenij J. BARABOSHKIN & Irina A.
Page 18 and 19: SaynocerasCampylotoxiacampylotoxaTh
Page 22 and 23: noEvgenij J. BARABOSHKIN & Irina A.
Page 26 and 27: Evgenij J. BARABOSHKIN & lrina A. M
Page 28 and 29: PLATE 2Fig. 1 — Bodrakiceras disc
Page 32 and 33: li SEvgenij J. BARABOSHKJN & Irina
Page 34: 120 Evgenij J. BARABOSl-]K IN & Iri

New and poorly known Valanginian ammonites from South-West ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?