Disponible en ligne sur Geobios 41 (2008) Original article

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1 Disponible en ligne sur Geobios 41 (2008) Original article Two new species of Constrictoceras nov. gen. (Ammonoidea) from the Early Cretaceous (Aptian) of Hungary Deux nouvelles espèces de Constrictoceras nov. gen. (Ammonoidea) du Crétacé inférieur (Aptien) de la Hongrie Ottilia Szives Department of Palaeontology, Hungarian Natural History Museum, 1437 Budapest Pf. 35, Hungary Received 29 March 2006; accepted 15 December 2006 Available online 20 February Abstract The new genus Constrictoceras is described below, and is represented in Hungary by two new species: Constrictoceras foezyi sp. nov. and Constrictoceras steineri sp. nov. According to morphological similarities, they are provisionally assigned to Acanthohoplitinae, but the lack of sutures cannot keep us from the idea of a possible relationship with Puzosiinae or Silesitidae, therefore its phylogenetic position of Constrictoceras gen. nov. is uncertain. Morphologically similar forms are described from the Aptian of Madagascar (Collignon, M., 1962) and from the Middle Aptian of Colombia (Sharikadze et al., 2004). Stratigraphical and paleobiogeographical use is very limited for the new genus. # 2007 Elsevier Masson SAS. All rights reserved. Résumé Après l analyse d une douzaine de moules internes recueillis des couches de base du conglomérat calcaire de Tata, deux nouvelles espèces du nouveau genre Constrictoceras ont été décrites. En tenant compte des ressemblances morphologiques, ce nouveau genre fait partie du rang des Ammonoidea, de la famille des Parahoplitidae et de la sous-famille Acanthohoplitinae. Faute de ligne de lobe, l analogie avec la sous-famille Puzosiinae ainsi qu avec la famille des Silesitidae ne peut être exclue. Des échantillons semblables ont été mis à jour (dans les couches de l Aptien moyen) à Madagascar (Collignon, M., 1962) et en Colombie (Sharikadze et al., 2004), mais le classement univoque de ces exemples au genre Constrictoceras est discutable. L importance stratigraphique et paléobiogéographique du nouveau genre est restreinte, étant découvert dans des sédiments condensés de l Aptien moyen et supérieur, exclusivement en Hongrie. # 2007 Elsevier Masson SAS. All rights reserved. Összefoglalás A Tatai Mészkő Formáció bázisrétegéből, tatai lelőhelyekről gyűjtött, több tucatnyi kőbél alapján kerül leírásra a Constrictoceras nov. gen. két új faja. Morfológiai hasonlóságok alapján az új genus feltételezhetően az Ammonoidea rend Parahoplitidae családjának Acanthohoplitinae alcsaládjába sorolható. Lóbavonal egyetlen példányon sem vizsgálható, ennak hiányában azonban nem zárható ki a rokonság a Puzosiinae alcsaláddal illetve a Silesitidae családdal. Hasonló formák kerültek leírásra Madagszkár apti (Collignon, M., 1962) és Kolumbia középső-apti (Sharikadze et al., 2004) rétegeiből, ezek azonban nem sorolhatóak minden kétséget kizáróan a Constrictoceras genusba. Az új genus sztratigráfiai és paleobiogeográfiai jelentősége csekély, mivel kondenzált középső - felső-apti üledékből került elő, eddig csupán Magyarország területéről. # 2007 Elsevier Masson SAS. All rights reserved. Keywords: Constrictoceras gen. nov.; Ammonoidea; Middle Late Aptian; Hungary Mots clés : Constrictoceras gen. nov. ; Ammonoidea ; Aptien moyen supérieur ; Hongrie address: sziveso@nhmus.hu /$ see front matter # 2007 Elsevier Masson SAS. All rights reserved. doi: /j.geobios

2 298 O. Szives / Geobios 41 (2008) Introduction The Aptian Tata Collection of the late Prof. Fülöp contains almost 2000 ammonoid specimens besides dozens of echinoids, belemnite rostra, gastropods, fossil plant remains and some bivalves. The fossil assemblage was first studied and summarized by Fülöp (1976) without giving any paleontological evaluation apart from a list of fossils. After a long break, Szives (1996, 1999a, 1999b, 2001) revised the ammonoid fauna and placed its age between the Middle Aptian Cheloniceras (Epicheloniceras) nodosocostatum and Lower Albian Leymeriella tardefurcata standard (Hoedemaeker and Rebouletreporters, 2003) ammonite Zones. Further studies of the Aptian Early Albian ammonites of Tata have demonstrated that some of the non-heteromorph ammonites belong to a new genus. New forms of heteromorph ammonoids were already described (Szives and Monks, 2002). In the present paper the author prefers to use the standard ammonite zonal scheme of the Kilian Working Group (Hoedemaeker and Reboulet, reporters) for the Lower Middle Aptian. For the Upper Aptian, the ammonite zonal scheme proposed by Kennedy et al. (2000: p. 601, Fig. 7.b) is accepted, as it better reflects the ammonoid faunal succession of Hungary in particular around the Aptian/Albian boundary (Fig. 1). The section at Kálváriadomb (Calvary Hill) has enabled us to define the precise stratigraphic position of the fossiliferous condensed pockets shown in Fig. 3. Fossils were found in local hollows in the underlying red nodular Berriasian Szentivánhegyi Limestone with a hardground on its upper surface. The infillings of these hollows are called here pockets. On the contact between Berriasian hardground and the overlying massive crinoidal Uppermost Aptian (sensu Kennedy et al., 2000) Tata Limestone Formation there are numerous, pockets that contain rich fossil assemblages. Supposedly, fossils were removed by terrestrial and/or submarine erosion from their original strata during Late Aptian times. The younger limestone beds of the Tata Limestone Formation become more marly and fine grained until the 2. Geological setting A rich fauna is collected from the Aptian condensed deposits of the Transdanubian Central Range (NW Hungary) in the town of Tata. The greater part of the assemblage has been collected from four sites, called Vájáriskola (Miners School), Fazekas utca (Potter street), Kálváriadomb (Calvary Hill) and Kékkőbánya (Bluestone Quarry). All sections were excavated in the mid 1950s led by the Hungarian Geological Survey. Unfortunately, the original documentation is missing so that it can hardly be reconstructed how many fossiliferous pockets were found. Further collecting was limited, on one hand because of the heavy protection of the Kálváriadomb site, which currently runs as an open-air geological museum, on the other hand owing to the limited number of pockets. All localities are in the town of Tata, in the Gerecse Mountains (Fig. 2). By the end of the Early Cretaceous the area was a part of a small, terrigenous sedimentary basin along the northern shore of the former western Tethys (Császár and Árgyelán, 1994). The syncline structure of the Transdanubian Central Range was supposedly formed during the Austrian orogenic phase (Albian-Early Cenomanian) of the Alpine belt. Further collecting was done in the same condensed horizon near the village of Olaszfalu at the Eperkéshegy (Strawberry Hill) and Márványbánya (Marble quarry) at Zirc, both situated in the Bakony Mountains. From the present point of view the Bakony Mountains are left aside because Constrictoceras were never found here. Fig. 1. Major differences in the Aptian/Lower Albian ammonite biostratigraphy of the Western Tethyan Boreal and Mediterranean areas. This figure is not a correlation chart. Double horizontal line indicates Aptian/Albian boundary, bold horizontal lines indicates substage boundaries.

3 O. Szives / Geobios 41 (2008) Fig. 2. Sketch map of Hungary. Asterisk shows city of Tata. matrix changes into the aleurolite, of the Vértessomló Aleurolite Formation. This unit has also yielded ammonites such as Parasilesites sp., Neosilesites nepos (Douvillé, 1917), Leymeriella sp., and Brancoceras sp., among others, which clearly demonstrate an Early Albian age (sensu Kennedy et al., 2000) of the overlying aleurolite unit. This implies that during Late Aptian-Early Albian, a very thick body of clastic sediment was deposited in the present Gerecse Mountains called Tata Limestone and Vértessomló Aleurolite Formations. 3. Characteristics of the fauna Fossils are preserved as reworked, phosphatised and glauconitised internal moulds state of preservation may vary according to the localities (Szives, 1999b), accompanied by well-sorted black (?coated), 1 2 cm large pebbles. These moulds consist of a marly sediment, which filled the shells or accumulated as matrix, and because subsequently covered by the crinoidal limestone. Marly intercalations and limestone Fig. 3. Schematized part of the section of Kálváriadomb at Tata. 1. Underlying Berriasian limestones hardground. 2. Fossiliferous pockets. 3. Tata Limestone Formation starting with marly layers overlain by massive crinoidal limestone banks.

4 300 O. Szives / Geobios 41 (2008) beds constitute a kind of rhythmic sedimentary unit, referred to as Tata Limestone Formation with a maximum thickness of 100 m in the southern Bakony Mountains. This unit contains no ammonites. Macrofossils are also rare apart from crinoid fragments and some brachiopods. Based on the mixed and reworked ammonite assemblage found in the Tata Limestone Formation, its age ranges from the late Middle Aptian Parahoplites melchiori Zone to the Late Aptian Leymeriella germanica Zone (sensu Kennedy et al., 2000), being condensed to a large extent (Szives, 1999b, 2001; Szives and Monks, 2002). For more details on the stratigraphy and the fauna see Szives (1999a). The sedimentological description of the Tata Limestone Formation is fully given by Lelkes (1990). Ammonites are sorted by size, sometimes flattened and deformed, mostly broken. Szives (1999a, 2001) fully described various species of Jauberticeras Jacob, 1908, Gabbioceras Hyatt, 1900, Melchiorites Spath, 1923, Puzosia Bayle, 1878, Silesitoides Spath, 1925, Beudanticeras Hitzel, 1902, Uhligella Jacob (1907),?Leymeriella Jacob (1907), Hamites Parkinson, 1811, Ptychoceras d Orbigny, 1842, Procheloniceras Spath, 1923, Cheloniceras Hyatt, 1902, Diadochoceras Hyatt, 1900, Eodouvilleiceras Casey, 1961a, Mathoceras Casey, 1964, Acanthohoplites Sinzow, 1907, Nolaniceras Casey, 1961b, Hypacanthoplites Spath, 1923, Parahoplites Anthula, 1899 among other Aptian-Early Albian forms. Further investigations are now in process on the exact age of the ammonite assemblage. Species as Jauberticeras jaubertianum (d Orbigny, 1851), Silesitoides escragnollensis (Jacob, 1908), Uhligella balmensis (Jacob, 1908), Uhligella rebouli (Jacob, 1908),?Leymeriella recticostata Saveliev, 1973, Neosilesites sp.,?ancyloceras matheroni (d Orbigny, 1842), Ephamulina arcuata Collignon, 1962; numerous species of Cheloniceras, Procheloniceras albrechti-austriae (Uhlig, 1883), Nolaniceras nolani (Seunes, 1887) and hundreds of Acanthohoplites and Hypacanthoplites are common in the assemblage. Exactly 57 fragments and specimens of a new species are presented and were described previously as cf.?neosilesites sp. nov. (Szives, 1999a) and?callizoniceras sp. nov. (Szives, 2001, unpublished PhD thesis). These species are here assigned to a new genus Constrictoceras Location of collection A part of the collection is temporarily housed in the Palaeontological Department of the Hungarian Natural History Museum for further investigations. All the published material is property of the Geological Museum of Hungary (Hungarian Geological Survey). Repository numbers are from K15275 to K15308, abbreviated as RN. 4. Systematic paleontology All dimensions are in millimetres. D = diameter, Wb = whorl width, Wh = whorl height, U = umbilical diameter. The author follows the classification of Wright et al. (1996). Class CEPHALOPODA Zittel, 1884 Order AMMONITIDA Zittel, 1884 Suborder ANCYLOCERATINA Wiedmann, 1966 Superfamily DESHAYESITACEAE Stoyanow, 1949 Family PARAHOPLITIDAE Spath, 1922 Subfamily ACANTHOHOPLITINAE Stoyanow, 1949 Genus Constrictoceras gen. nov. 1999a.?Neosilesites sp. nov. - Szives, Pl. 1, Fig ?Callizoniceras sp. - Szives, p. 75, Pl. II, Figs. 6 10, 13. Derivation of name: Named after the constrictions that characterizes the genus. Type species: Constrictoceras foezyi nov. sp., from the Middle to Upper Aptian condensed fossiliferous basal deposits of Tata Limestone Formation, Hungary. Type locality: Hungary, Gerecse Mountains, Tata, Kálváriadomb (Fig. 2). Type horizon: Middle - Upper Aptian basal fossiliferous pockets of the Tata Limestone Formation, Hungary. Diagnosis: Evolute conchs with strong ornamentation at all stages of growth. Deep, heavily collared constrictions characterize the genus, 7-9 per whorl. Between the constrictions 2-5 broad but not very high, slightly rectiradiate or straight ribs pass over the lateral flank and cross the venter without interruption. Ribs rarely bifurcate, but occasionally an intercalated rib appears, generally alongside the collars. Venter rounded, whorl section rounded to slightly depressed. Discussion: There are some morphological similarities between Constrictoceras and, on the one hand, some species of Desmocerataceae Puzosiinae and Silesitidae on the other hand to Acanthohoplitinae. On first sight the evolute conch and the constrictions suggest a resemblance to those taxa, but the shape of the whorl section and the style of ribbing made it questionable. Callizoniceras Spath, 1923 is much more involute, the ribs are branching and tend to be slightly sinuous and convex on the venter, in the same manner as the constrictions. In Neosilesites Breistroffer, 1951, constrictions are also straight on the venter, but main ribs tend to weaken on the outer part of the flank and only weak intercalatories arise on the outer side and pass over the rounded venter. On the nuclei of Neosilesites, ribs split on the venter, which is absent on Constrictoceras at any visible stage of growth: the type of ribbing is very different from that of Neosilesites. Silesitoides Spath, 1925 is more evolute with much more rigid ribbing and the shape of the conch is planulate, which is not a characteristic of Constrictoceras. Notwithstanding the constrictions mentioned and visible in the original description of the type species of the genus (Silesitoides escragnollensis Jacob, 1908) and in all other species of Silesitoides, the overall impression is different from Constrictoceras. The overall morphology of Constrictoceras is more like Acanthohoplitinae than any other options. The mode of coiling, the rounded to slightly depressed whorl section are also features

5 O. Szives / Geobios 41 (2008) of the Acanthohoplitinae. The stratigraphic position of the specimens from Colombia (Protacanthohoplites? originalis Sharikadze et al., 2004: p. 393, Fig. 5. [non Fig. 4]) here not referred to the new genus of Constrictoceras because of the need of further investigation also suggest Middle Aptian age. According to Wright et al. (1996), genus Protacanthohoplites Tovbina, 1970 is a synonym of Acanthohoplites Sinzow, The author of this paper shares the opinion of Wright et al. (1996) neither on Tovbina s (loc. cit.) species P. monilis (Tovbina, 1970) and P. mirus (Tovbina, 1970) nor on Acanthohoplites Sinzow, 1907 the constrictions were never observed or mentioned. Even more, P. mirus Tovbina, 1970 has distinct rounded tubercles on the flanks this in contrast to Constrictoceras, which completely lacks rounded tubercles at any visible stage of growth. The specimen described and figured from Madagascar by Collignon (1962, p. 61, Fig. 1028) as Colombiceras sp. aff. caucasicum Luppov in Luppov and Drushchits, 1958 also shows good resemblance to Constrictoceras but lack of further discussion did not permit us to put it in the new genus. The questionable position of the specimen is fully discussed at C. foezyi gen. and sp. nov. As for the mode of ribbing, there is a good resemblance to the genus Colombiceras Spath, BothColombiceras and Constrictoceras are characterized by flat-topped ribs in the later ontogenetic stages but constrictions characterize just Constrictoceras. While most Colombiceras species have a flat venter and flat flanks with a tubercle on the umbilical shoulder, these characteristics are absent in Constrictoceras. The sutures are not known; nevertheless the author cannot reject the idea that this new genus of Constrictoceras might be an early representative of Puzosiinae or Silesitoidae, therefore the systematic position remains uncertain. Distribution: The new genus is known from the condensed Middle Upper Aptian basal beds of Tata Limestone Formation of Hungary. (Constrictoceras foezyi gen. and sp. nov). Fig. 4 (1a, b 5a, b, 6, 7a, b 9a, b, 11, 12a, b, 14a, b 17a, b, 20, 21, 22a, b 28a, b, 30, 31a, b, c, 34a, b, c, 35a, b). 1999a. cf.?neosilesites sp. nov. Szives, Pl. 1, Fig. 3. Derivation of name: To the honour of a colleague, a Hungarian Cretaceous ammonite worker, István Főzy. Holotype: Constrictoceras foezyi gen. and sp. nov. by original designation, RN: K Paratypes: Constrictoceras foezyi gen. and sp. nov. by original designation, RN: K15282, K15283, K Type locality: Hungary, Gerecse Mountains, Tata, Kálváriadomb (Fig. 2). Type horizon: Middle Upper Aptian basal fossiliferous pockets of the Tata Limestone Formation. Type specimens: The holotype (K15281), three paratypes (K ) and additional specimens are deposited in the Geological Museum of Hungary (Hungarian Geological Survey), Budapest, Hungary. Dimensions: D Wb Wh Wb: Wh U Holotype K Paratypes K K K Diagnosis: Evolute conch with medium deep umbilicus. Ornamentation dominated by ribs and constrictions. Whorl section rounded, becoming subcircular and slightly depressed during ontogeny. Umbilical wall very well rounded. Both ribs and constrictions present on the early whorls. Ribs strong, narrow, sometimes having elongated tubercles at midflank, no bifurcation visible. Constrictions also narrow, moderately collared by broad ribs. At greater diameters (up to a diameter of 10 mm) ribs and constrictions broaden. Usually 4-5 ribs between two constrictions, totally ribs and 8-9 constrictions per whorl. Intercalated rib appears at midflank, directly apical of the collar of a constriction. Elongated tubercle appears on the collar at the beginning of the intercalated rib, sometimes on the neighbouring rib as well. Slightly broadened ribs and constrictions pass straight over the venter without interruption. No suture visible. Discussion: The holotype of?protacanthoplites originalis described and figured by Sharikadze et al. (2004: Pl. 81, Fig. 3) shows morphological affinities (in the mode of coiling, ribbing and the subcircular whorl section, as well as the large size) to the Early Albian genus Silesitoides Spath, However, Sharikadze et al. (loc. cit.) also didn t provide a suture to solve the problem whether the species is an early representative of the poorly known Early Albian genus Silesitoides Spath, 1925,ora Middle Aptian homeomorph, or something else. Sharikadze et al. (loc. cit.) chose a third option, are referred the species to Acanthohoplitinae, which is also a reasonable solution. In accordance with the morphological features and published measurements, the author of this paper concluded that the holotype and the paratypes of?protacanthoplites originalis Sharikadze et al., 2004 are not representatives of the same genus. Two paratypes of?protacanthoplites originalis Sharikadze et al., 2004 could better be incorporated to Constrictoceras foezyi gen. and sp. nov. This new species is also found in Hungary in great abundance. Collignon (1962: p. 61, Fig. 1028) figured and described a specimen of Colombiceras sp. aff. caucasicum Luppov in Luppov and Drushchits, 1958 from Madagascar which also shows morphological similarities to C. foezyi. On Collignon s specimen deep constrictions are visible. According to the original description of the genus Colombiceras (type species: Ammonites crassicostatus d Orbigny, 1841: p. 197), constrictions do not characterise this genus. The different whorl section, mode of coiling and ribbing also makes the latter generic identification questionable. Unfortunately the suture was not given neither in the original description nor in Collignon s (and not even in the description of genus Constrictoceras). For those

6 302 O. Szives / Geobios 41 (2008) Fig Constrictoceras foezyi gen. and sp. nov., K15281, holotype, (a) lateral view, (b) ventral view. 2. Constrictoceras foezyi gen. and sp. nov., K15283, paratype, (a) lateral view, (b) view of the cross-section. 3. Constrictoceras foezyi gen. and sp. nov., K15282, paratype, (a) lateral view, (b) ventral view. 4. Constrictoceras foezyi gen. and sp. nov., K15289, (a) lateral view, (b) ventral view. 5. Constrictoceras foezyi gen. and sp. nov., K15284, paratype, (a) lateral view, (b) ventral view. 6. Constrictoceras foezyi gen. and sp. nov., K15278, lateral view. 7. Constrictoceras foezyi gen. and sp. nov., K15292, (a) lateral view, (b) ventral view. 8. Constrictoceras foezyi gen. and sp. nov., K15294, (a) lateral view, (b) ventral view. 9. Constrictoceras foezyi gen. and sp. nov., K15285, (a) lateral view, (b) view of the

7 O. Szives / Geobios 41 (2008) morphological characters it is likely that Collignon s specimen is a member of the new genus and species of Constrictoceras foezyi gen. and sp. nov. but lack of further discussion makes the problem unsolvable at the moment. Distribution: Known from condensed Middle Upper Aptian basal beds of Tata Limestone Formation of Hungary. Constrictoceras steineri gen. and sp. nov. Fig. 4(10, 13a, b, 18, 19a, b, 29a, b, 32, 33a, b) Derivation of name: After Tibor Steiner, the leading collector of the Aptian Fülöp Collection. Type specimens: The holotype K15275, three paratypes K15276, K15277, K15280 and additional specimens are deposited in the Geological Museum of Hungary (Hungarian Geological Survey), Budapest, Hungary. Type locality: Hungary, Gerecse Mountains, Tata, Kálváriadomb (Fig. 2). Type horizon: Middle - Upper Aptian basal fossiliferous pockets of the Tata Limestone Formation. Dimensions: D Wb Wh Wb:Wh U Holotype K Paratypes K K K Diagnosis: The holotype shows the coiling to be rather evolute with a medium deep umbilicus, a rounded umbilical wall, and a broadly rounded whorl section becoming subcircular and slightly depressed during ontogeny. Coiling shows the same measure of evolution in all growths stages. Ornamentation dominated by rigid ribs and deep constrictions. Both ribs and constrictions are present on early whorls. Ribs strong, narrow, sometimes having elongated tubercles at midflank, no bifurcation visible. Number of ribs (2-3) between two constrictions is one of the characteristics of the species. Ornamentation changes with increasing size. Collars become blunter, ribs weaken and on the venter seem to disappear. At larger size (up to a diameter of 10 mm) ribs and constrictions become wider. Usually two to three primary ribs are present between two constrictions, totally ribs and seven to nine constrictions per whorl. The main, strong ribs start at the umbilical seam, sometimes an intercalated rib appears in the outer part of the flanks or next to the collar of a constriction at the same height as the beginning of the intercalated rib. Both ribs weaken when crossing the venter or may be interrupted on siphonal line. Strong ribs and collars very rarely bifurcate. The small number of ribs (two to three) between the constrictions is characteristic for the species. Ribs always weaken at mid-venter. Constrictions are present in all growth stages. They start at the umbilical seam, are usually deep, wide and strongly collared. Sometimes collars form bullae on the lateral side. Constrictions are straight, pass across the venter without any diminution in depth. Suture cannot be observed. Discussion: Ribbing is stronger, and more rigid than in Constrictoceras foezyi gen. and sp. nov. which make the difference clear between the two species. Distribution: Specimens from the condensed, basal Middle - Upper Aptian Tata Limestone Formation of Hungary. 5. Conclusion Species belonging to Constrictoceras gen. nov. were previously identified as?neosilesites sp. (Szives, 1999a) and?callizoniceras sp. (Szives, 2001). Unfortunately only five whole specimens were found, most of the material is fragmented. Ammonites are preserved as heavily phosphatized and glauconitized internal moulds but owing to reworking they exhibit no sutural details or sutures are preserved in unexamineable state. As to the generic characters, the new genus shows resemblance to genera of Puzosiinae, Silesitidae and Acanthohoplitinae. The evolute coiling, the flat-topped ribs and the presence of strong, collared constrictions made the new taxa quite distinguishable from other acanthohoplitinid genera. Provisionally, Constrictoceras foezyi gen. and sp. nov. and Constrictoceras steineri gen. and sp. nov. are regarded as representatives of the Aptian Lower Albian ammonite subfamily Acanthohoplitinae on the basis of morphological similarities. However, absence of sutures makes the phylogenetic position of both species uncertain. Dozens of specimens of the new species occur in the Hungarian condensed Middle to Upper Aptian deposits. The cross-section. 10. Constrictoceras steineri gen. and sp. nov., K15277, paratype, lateral view. 11. Constrictoceras foezyi gen. and sp. nov., K15298, paratype, lateral view. 12. Constrictoceras foezyi gen. and sp. nov., K15297, (a) lateral view, (b) ventral view. 13. Constrictoceras steineri gen. and sp. nov., holotype, K15275, (a) lateral view, (b) ventral view. 14. Constrictoceras foezyi gen. and sp. nov., K15291, (a) lateral view, (b) ventral view. 15. Constrictoceras foezyi gen. and sp. nov., K15296, (a) lateral view, (b) ventral view. 16. Constrictoceras foezyi gen. and sp. nov., K15287, (a) lateral view, (b) ventral view. 17. Constrictoceras foezyi gen. and sp. nov., K15286, (a) lateral view, (b) ventral view. 18. Constrictoceras steineri gen. and sp. nov., paratype, K15280, lateral view. 19. Constrictoceras steineri gen. and sp. nov., paratype, K15276, (a) lateral view, (b) ventral view. 20. Constrictoceras foezyi gen. and sp. nov., K15299, lateral view. 21. Constrictoceras foezyi gen. and sp. nov., K15303, lateral view. 22. Constrictoceras foezyi gen. and sp. nov., K15288, (a) lateral view, (b) ventral view. 23. Constrictoceras foezyi gen. and sp. nov., K153290, (a) lateral view, (b) ventral view. 24. Constrictoceras foezyi gen. and sp. nov., K15301, (a) lateral view, (b) ventral view. 25. Constrictoceras foezyi gen. and sp. nov., K15305, (a) lateral view, (b) ventral view. 26. Constrictoceras foezyi gen. and sp. nov., K15304, (a) lateral view, (b) ventral view. 27. Constrictoceras foezyi gen. and sp. nov., K15300, (a) lateral view, (b) ventral view. 28. Constrictoceras foezyi gen. and sp. nov., K15293, (a) lateral view, (b) ventral view. 29. Constrictoceras steineri gen. and sp. nov., K15279, (a) lateral view, (b) ventral view. 30. Constrictoceras foezyi gen. and sp. nov., K15306, (a) lateral view, (b), ventral view. 31. Constrictoceras foezyi gen. and sp. nov., K15295, (a) lateral view, (b) dorsal view, (c) ventral view. 32. Constrictoceras steineri gen. and sp. nov., K15302, lateral view. 33. Constrictoceras steineri gen. and sp. nov., K15307, (a) lateral view, (b) ventral view. 34. Constrictoceras foezyi gen. and sp. nov., K15308, (a) lateral view, (b) dorsal view, (c) ventral view. 35. Constrictoceras foezyi gen. and sp. nov., K15309, (a) lateral view, (b) ventral view. All specimens from the base of the Tata Limestone Formation from Tata localities, Middle Upper Aptian. All figures are in natural size.

8 304 O. Szives / Geobios 41 (2008) presence of Constrictoceras gen. and sp. nov. in Hungary make the paleogeographic distribution unique. Morphologically similar specimens are known from the Middle? Aptian deposits of Colombia (Sharikadze et al., 2004) and from the Middle? Aptian of Madagascar (Collignon, 1962); but the absence of suture lines makes the taxonomic position questionable in both cases. The exact stratigraphic position is uncertain for the Hungarian species, therefore the stratigraphic significance of the new taxa is low. Acknowledgements The author is grateful to Prof. W.J. Kennedy (Oxford University Museum), Dr. G. Delanoy (University of Nice) and Dr. Latil (Université de Bourgogne) for their significant consultation and to Dr. I. Főzy (Hungarian Natural History Museum) for his enthusiastic help. Prof. A. Galácz (Eötvös University of Budapest) and Dr. W.M.W. Jagt (Museum of Maastricht) are thanked for their valuable advices. The author is thankful the reviewers comments of Dr. Ph. Hoedemaeker and Dr. J. Schlögl, and of one anonymous reviewer. Studies on Cretaceous ammonites of Hungary were supported by the Hungarian Research Fund project no. OTKA T References Anthula, D.J., Über die Kreidefossilien des Kaukasus. In: Neumayr, M., Mojsisivics, I. (Eds.), Beitrage zur Paläontologie und Geologie Österreich Ungarns und des Orients, Wien B. 12, Bayle, E., Fossiles principaux des Terrains. Explication de la Carte Géologique de France. Volume 4, part 1 (atlas), Paris, Breistroffer, M., Sur quelques Ammonites de l Albien inférieur de Madagascar. Compte Rendu Sommaire des Séances de la Société géologique de France Casey, R., 1961a. A monograph of the Ammonoidea of the Lower Greensand. Part 3. Palaeontographical Society Casey, R., 1961b. The stratigraphical palaeontology of the Lower Greensand. Palaeontology 3, Casey, R., A monograph of the Ammonoidea of the Lower Greensand. Part 5. 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