Indoscaphites cunliffei Forbes 1846 from: Kennedy, W.J..Henderson, R.A.. (1992): Heteromorph ammonites from the Upper Maastrichtian of Pondicherry, south India . Palaeontology Vol. 35 p. 693-731
|Notice: This catalogue page may contain unedited data.
Species Indoscaphites cunliffei Forbes 1846
|Diagnosis / Definition:
Kennedy & Henderson (1992):
The lectotype is a complete adult, the paralectotypes are juveniles. All retain traces of original shell material. The early growth stages are moderately involute, with a rounded whorl section and faint constrictions, plus an ornament of low, irregular ribs and growth striae only. By a diameter of 6.5 mm, the distinctive ornament of the species has appeared. This consists of weak, distant umbilical bullae (six or seven per half whorl at a diameter of 10.5 mm in BMNH C51089) connected by a low, rounded, straight to feebly concave prorsiradiate ribs to stronger conical ventrolateral horns, the ribs broading as they cross the flanks. The ventrolateral horns are linked across the venter by a low, broad convex rib or ribs, while there are low, variable and irregular intercalated ribs, growth lines and grooves between tuberculate groups; some ribs show a trace of an outer ventrolateral node. By this ontogenetic stage the whorl section has become progressively more compressed, the sides flattened, with greatest breadth at the umbilical tubercle, the venter very broad and rounded. The somewhat larger paralectotype, BMNH C 51089 (Pl. 5, fig. 7-9) shows a comparable ornament at a maximum preserved diameter of 15 mm, although there are low intercalated ribs extending to mid-flank, and distinct looping of ventral ribs and striae between the ventrolateral tubercles.
The lectotype (Pl. 6, figs. 4-6) is septate to a diameter of approximately 21 mm, with two-thirds of a whorl of body chamber. The ornament of the phragmocone is as described above. The body chamber shows markedly eccentric, scaphitoid coiling, although the whorls remain in contact. The umbilical seam becomes distinctly undercut, with a sharp umbilical shoulder. The umbilical bullae become sharper and more pronounced and are progressively deflected forwards as size increases. The broad, simple ribs of the phragmocone give way to groups of much finer, sharper, irregularly developed strongly flexed prorsiradiate ribs and striae which occasionally bifurcate around mid-flank where intercalatories are inserted. They link in groups to the ventral tubercles, which are irregularly developed and disappear before the adult aperture is reached. The ribs are convex across the venter and variably developed, both linking tubercles and intercalating.
On the last sixth of a whorl before the aperture, beyond the last ventral tubercle, the ventral and ventrolateral ribbing strengthens markedly, with many ribs branching. The aperture itself is simple and entire.
The suture line (Text-fig. 2A) is relatively simple, with asymmetrically bifid E/L and L/U:L is deep and asymmetrically trifid.
|Discussion / Comments:
Kennedy & Henderson (1992):
Lectotype, here designated, is BMNH C51090, the original of Forbes (1846, pl. 8, fig. 2a-b, d), GSC R10477. Paralectotypes are BMNH C51089, the original of Forbes (1846, pl. 8, fig. 2c), GSC R10478, and BMNH C51091, all from the Valudavur Formation of Pondicherry, south India (ex Kaye and Cunliffe Collection).
D Wb Wh Wb:Wh U
BMNH C51090 35.0(100) 12.2(34.9) 12.9(36.9) 0.95 10.0(28.6)
at c 23.8(100) 9.0(37.8) 11.4(47.9) 0.79 5.8(24.4)
BMNH C51091 10.2(100) 6.1(59.8) 4.3(42.1) 1.4 3.3(32.4)
The coarseness of flank ribs and development of strong ventrolateral horns immediately distinguishes this species from I. pavana (Forbes, 1846), discussed further below. Spath (1953, p. 14) thought there were morphological transistions between Indoscaphites and Hoploscaphites of the quadrangularis group, but these are much larger US Western Interior scaphitid stock, referred to Jeletzkytes Riccardi, 1983, and bear no assemblages to the present form.
Maastrichtian, south India and Tunisia.
Species Indoscaphites cunliffei
|Kennedy & Henderson (1992):
p 1907 Scaphites Cunliffei Forbes. - PERVINQUIERE
: p.124 pl. 4, fig. 36-40;
fig. A-C on the explanation of pl. 4;
text-fig. 42-44 [non pl. 4, fig. 41-42 (= I. pavana);
non text-fig. 45 (= I. pavana)]
1989 Indoscaphites Spath. - Kennedy : text-fig. 17e
1992 Indoscaphites cunliffei Forbes. - Kennedy & Henderson
: p. 715, 719, 703 pl. 5, fig. 2, 6-9;
pl. 6, fig. 4-6;
|Stratigraphy - relative ages:
| Maastrichtian: Kennedy & Henderson (1992)
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Kennedy,W.J.. and Henderson,R.A.. (1992):
Heteromorph ammonites from the Upper Maastrichtian of Pondicherry, south India . Palaeontology Vol. 35 p. 693-731
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