Indoscaphites pavana 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 . |
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Species Indoscaphites pavana Forbes 1846 |
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Diagnosis / Definition: |
Kennedy & Henderson (1992):
DESCRIPTION.-
The holotype is only 12.2 mm in diameter, with half a whorl of body chamber, and retains much of the original shell material. Coiling is moderatly involute, ammonitic rather than scaphitoid. The earliest whorls visible are compressed and rounded, but as diameter increases they become even more compressed and flat-sided. Ornament is present from the smallest diameters visible. It conists of approximately sixteen low, broad, flexuous, prorsiradiate primary ribs on the outer whorl. Initially single, they branch on the inner flank as size increases, and are accompanied by similarly flexuous growth striae. At the largest diameters preserved, these are almost falcoid; feebly concave and prorsiradiate ont hte inner flank, convex at mid-flank, and concave on the ventrolateral shoulder, where they bear small ventral clavi. The clavi are connected across the venter by a low convex rib or ribs, striae and growth lines, which also occur between ribs. The suture, which is imperfectly exposed, is little incised and of Hoploscaphites type. |
Discussion / Comments: |
Kennedy & Henderson (1992):
TYPE.-
Holotype, by monotypy, is BMNH C51092, the original of Fprbes 1846 (p. 110, pl. 7, fig. 5), GSC R10480, from the Valudavur Formation of Pondicherry, south India (ex Kaye and Cunliffe Collection).
DISCUSSION.-
The holotype of Indoscaphites pavana is easily seperated from Indoscaphites cunliffei of similar size (Pl. 5, figs. 2, 6-9), where the whorl section is broader, tubercles stronger, and ribs distant and straight, rather than crowed and flexuous. The style of ventral ornament is of the same basic type, as in the coiling, and two species are certainly congeneric. Some authors (e.g. Pervinquiere 1907) have regarded them as conspecific, but we have studied all the available specimens, including those from Tunisia; there are no intermediate forms.
OCCURRENCE.-
Maastrichtian of south India and Tunisia. |
Systematics: |
41 Subordo Ancyloceratina
Superfamilia Scaphitaceae
Familia Scaphitidae
Subfamilia Scaphitinae
Genus Indoscaphites
Species Indoscaphites pavana
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Synonym list: |
Kennedy & Henderson (1992):
p 1907 Scaphites Cunliffei Forbes. - PERVINQUIERE : p.124 pl. 4, fig. 41-42 only;
text-fig. 45 only
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Stratigraphy - relative ages: |
Maastrichtian: Kennedy & Henderson (1992)
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References: |
Forbes,E.. (1846): Report on the Cretaceous fossil invertebrates from southern India, collected by Mr. Kaye and Mr. Cunliffe . Transactions of the Geological Society of London Vol. 2(7) p. 97–174
d'Orbigny,A. (1850): Prodrome de Paléontologie. Stratigraphique universelle des animaux mollusques & rayonnés faisant suitre au cours élémentaire de paléontologie et de géologie stratigraphique. , Cours Élémentaire de Paléontologie et de Géologie Stratigraphiques Vol. 2
Stoliczka,F.. (1865): The fossil Cephalopoda of the Cretaceous rocks of southern India. Ammonitidae with revision of the Nautilidae etc. . Memoirs of the Geological Survey of India, (1), Palaeontologica Indica6-9 p. 107-154
Kossmat,F.. (1898): Untersuchungen über die Südindische Kreideformation. Dritter Theil. . Beiträge zur Paläontologie Österreich-Ungarns und des Orient Vol. 11 p. 89-152
PERVINQUIERE,L.. (1907): Etudes de paleontologie tunisienne I: Cephalopodes des terrains secondaires. In: Carte Geologique de Tunisie p. 438 pp
Spath,L.F.. (1953): The upper Cretaceous cephalopod fauna of Graham Land . Scientific Reports of the Falkland Islands Survey Department Vol. 3 p. 60
Phillips,D.. (1977): Catalogue of the type andjigured specimens of Mesozoic Ammonoidea in the British Museum (Natural History). , Trustees of the British Museum (Natural History) p. 220 pp.
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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