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Species Fresvillia teres Forbes 1846 | ||||||||||||||
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[1] text-fig. 12g Ifrim et al. (2004) [2] text-fig. 13a-c, f Ifrim et al. (2004) | ||||||||||||||
Diagnosis / Definition: | ||||||||||||||
Ifrim et al. (2004): Description: The straight shell is perfectly circu1ar in cross section and expands slow1y with a low apical angle of 3-4 degrees. Ornament consists of faint, broad, annu1ar ribs that are weakest on the dorsum. They strengthen across the dorso1ateral area. The rib index is c. 1·5. The bacu1itid suture is composed of triangular elements of equal height, which are moderate1y incised. The ventral sadd1e is incised centrally, the dorsal sadd1e is slightly narrower than the others. Kennedy & Henderson (1992): DESCRIPTION.- The holotype is a fragment 46.5 mm long, septate throughout, and retaining partially exfoliated shell material. The shell is straight, slowly expanding, with a circular whorl section. Ornament is of low, broad ribs. These are weakest on the dorsum, which they cross in a broad convexity. They strengthen on the dorsolateral area, sweep back and are markedly concave across the middle of the flank, sweeping forwards and straight on the ventral flanks, strengthening and crossing the venter in a broad convexity, where they are scale-like, and separated by narrow interspaces. Both ribs and interspaces are ornamented by delicate growth lines and striae, and fine riblets are developed in outer flank. The course of the ornament thus defines a short, blunt, dorsal rostrum, and a longer blunt ventral one. Suture (Text-fig. 2C) baculitid, with triangular, moderately incised bifid lobes and saddles. |
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Discussion / Comments: | ||||||||||||||
Ifrim et al. (2004): Remarks: Whorl section and suture line are comparable to that of F. constricta. Ribs of F. aff. F. teres are not as pronounced as described by Kennedy and Henderson (l992a) although this may be an artefact of weathering and/or abrasion. The Cerralvo specimens are here related to F. teres because of the similar rib index, although they lack the conspicuous backward sweeping towards the venter of the otherwise annular ribs. This absence could result from juvenile specimens. Occurrence: Fresvillia teres (Forbes) is restricted to the Maastrichtian, with records from India (Kennedy and Henderson 1992a), western Austra1ia (Brunnschwei1er 1966; Henderson et al. 1992), A1aska (Jones 1963) and California (Matsumoto 1959a). Kennedy & Henderson (1992): TYPES.- The holotype, by monotypy, is BMNH C51152, the original of Forbes (1846, pl. 10, fig. 5), GSC R10490, from the Valudavur Formation of Pondicherry, south India (ex Kaye and Cunliffe Collection). Topotypes are BMNH C2586, and C41504-41505, removed by L.F. Spath from the type series of Phylloptychoceras siphon. DISCUSSION.- F. teres differs from the type species, F. constricta Kennedy, 1986b (p. 62, pl. 14, figs. 39-42; text-fig. 10a) from the Upper Maastrichtian Calcaire a Baculites of Manche, France, which lacks the well-differentiated ribbing of F. teres, and has constrictions. Baculites lechides Brunnschweiler, 1966 (p. 23, pl. 1, figs. 1-3; text-fig. 8) may be a Fresvillia, but the (worn) suture is simple in Brunnschweiler’s figure. It differs from F. teres in having a compressed whorl section and widely separated, narrow ribs; it is perhaps closer to “Baculites” columna Morton, 1834 (p. 44, pl. 19, fig. 8), first described from the Maastrichtian Prairie Bluff Chalk of Alabama (see also Stephenson 1941, p. 405, pl. 76, figs. 1-4; and Matsumoto 1959b, p. 161, pl. 30, fig. 1; pl. 34, fig. 4; pl. 43, fig. 4: text-figs. 80-81), which also has narrow, distant ribs and a much simpler suture than F. teres. So too does “Baculites” vincenti Stinnisbeck, 1986 (p. 203, pl. 9, fig. 4; pl. 10, figs. 3-6; text-fig. 23a-e), where the suture is even more simplified, and more polyptychoceratid than baculitid. OCCURRENCE.- Maastrichtian of south India and Carlifornia. |
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Systematics: | ||||||||||||||
36 Ordo Ammonoidea Subordo Ancyloceratina Superfamilia Turrilitaceae Familia Baculitidae Genus Fresvillia Species Fresvillia teres 41 Subordo Ancyloceratina Superfamilia Turrilitaceae Familia Diplomoceratidae Subfamilia Polyptychoceratinae Genus Cyrtoptychoceras Species Fresvillia teres |
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Synonym list: | ||||||||||||||
Ifrim et al. (2004): 1846 Baculites teres Forbes. - Forbes : p.115 pl. 10, fig. 5
1992 Fresvillia teres Forbes. - Kennedy & Henderson : p.718 pl. 5, figs. 14-17; text-fig. 2c (with full synonymy)
2004 Fresvillia aff. teres Forbes. - Ifrim et al. : 31, 34 text-figs. 12g, 13a-c, f
Kennedy & Henderson (1992): 1846 Baculites teres Forbes. - Forbes : p.115 pl. 10; fig. 5
1850 Baculites teres Forbes. - d'Orbigny : p.215
p 1866 Baculites teres Forbes. - Stoliczka : p.197 pl. 90; fig. 12 only [non fig. 13 (not a baculitid)]
1895 Baculites sp. teres Forbes. - Kossmat : 155(59)
1897 Baculites teres Forbes. - Kossmat : p.64
1953 "Baculites" teres Forbes. - Spath : p.16
1959 Baculites? aff. teres Forbes. - Matsumoto : p.163 pl. 45, fig. 5-6;
text-fig. 82a-c, 83
1986 Baculites teres Forbes. - Kennedy : p.62
1986 Baculites? teres Forbes. - Stinnesbeck : p.204
1992 Fresvillia teres Forbes. - Kennedy & Henderson : p. 715, 703 pl. 5, fig. 14-17;
text-fig. 2C
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Stratigraphy - relative ages: | ||||||||||||||
Maastrichtian: Ifrim et al. (2004) Maastrichtian: Kennedy & Henderson (1992) |
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References: | ||||||||||||||
Forbes,E.. (1846): d'Orbigny,A. (1850): Stoliczka,F.. (1866): Kossmat,F.. (1895): Kossmat,F.. (1897): Spath,L.F.. (1953): Matsumoto,T.. (1959): Stinnesbeck,W.. (1986): Kennedy,W.J.. (1986): Kennedy,W.J.. and Henderson,R.A.. (1992): Kennedy,W.J.. and Henderson,R.A.. (1992): Ifrim,C..; Stinnesbeck,W.. and López-Oliva,J.G.. (2004): |
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Anonymous: Unedited TaxonConcept data | ||||||||||||||
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