Ammonites from the Maastrichtian (Upper Cretaceous) Quiriquina Formation in central Chile
Abstract:The Quiriquina Formation in central Chile is famous for its abundant and diverse ammonite assemblages of Maastrichtian age. In the type locality around the Concepción Bay in the Bío-Bío Region of central Chile we have identified a total of 30 species referred to 17 genera. Hypophylloceras (Neophylloceras) ramosum, H. (N.) hetonaiense, H. (N.) inflatum, H. (N.) surya, Anagaudryceras politissimum, Gaudryceras kayei, Zelandites varuna, Pseudophyllites indra, Kitchinites darwini, Kossmaticeras (Natalites) erbeni, Grossouvrites gemmatus, Gunnarites spinosissimus, Maorites densicostatus, Pachydiscus (P.) jacquoti chilensis, Menuites fresvillensis, Diplomoceras cylindraceum, Phylloptychoceras sp., Baculites huenickeni, Baculites vicentei and Eubaculites carinatus have been recorded previously from the Quiriquina Formation. Hoploscaphites constrictus quiriquiniensis sensu Wilckens (1904). Phyllopachyceras forbesianum, Anagaudryceras subtilineatum, Gunnarites cf. bhavaniformis and Baculites anceps are new records for the Quiriquina Formation added here. Kitchinites vicentensis n. sp., Kitchinites ifrimae n. sp., Grossouvrites joharae n. sp., Pachydiscus (P.) gutierrezi n. sp. and Menuites gerardoi n. sp. are new. Gaudryceras kayei specimens are recorded with diameters in excess of 200 mm and present marked changes during growth. Anagaudryceras politissimum and Zelandites varuna also show strong ontogenetic changes. Kitchinites darwini of the Quiriquina Formation differs from material from Antarctica; we propose that the latter should by separated. The presence of Hypophylloceras (Neophylloceras) surya, Zelandites varuna, Pachydiscus (P.) jacquoti, Diplomoceras cylindraceum, Baculites anceps, Eubaculites carinatus and Hoploscaphites constrictus quiriquiniensis indicates a Maastrichtian age for the Quiriquina Formation. Menuites fresvillensis confirms the late Maastrichtian age for most of the Quiriquina Formation. The assemblage presented shows cosmopolitan and Indo-Pacific affinities with a few European and Tethyan links.
Document Type: Research Article
Publication date: August 1, 2010
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