The Lautaro Formation is sedimentary and fossiliferous geological formation that largely crops out near Copiapó (Atacama Region), Chile. It is dated back to the Jurassic period (Toarcian through Aalenian stages). The lithology of the formation comprises limestone and sandstone, formed in marine settings. The Lautaro Formation preserves a marine fossil record, representing molluscs (bivalves, gastropods) and marine reptiles (metriorhynchids, plesiosaurs).
The strata of the Lautaro Formation and its basin of deposition (the Lautaro Basin) have been subject to intense tectonic movement during the Mesozoic, producing large-scale stratigraphic discontinuity and tectonic inversion.
Paleobiota of the Lautaro Formation
Ammonites Genus Species Material Locality Unit Notes Images Arieticeras Indeterminate Not specified. Tranque Lautaro A hildoceratid ammonite. Oxynoticeras O. oxynotum Not specified. Tranque Lautaro An oxynoticeratid ammonite.
Bivalves Genus Species Material Locality Unit Notes Images Gryphaea G. darwini Partial and complete shells. La Puerta, Tranque Lautaro A gryphaeid bivalve. Weyla W. alata Partial and complete shells. La Puerta, Tranque Lautaro A pectinid bivalve.
Brachiopods Genus Species Material Locality Unit Notes Images Rhynchonella R. variabilis Not specified. Tranque Lautaro A rhynchonellid brachiopod.
Crocodyliformes Genus Species Material Locality Unit Notes Images Metriorhynchus Indeterminate Partial skull. Quebrada La Iglesia Upper part A metriorhynchid.
Gastropods Genus Species Material Locality Unit Notes Images Lithotrochus L. humboldtii Partial and complete shells. La Puerta, Tranque Lautaro A trochid gastropod.
Plesiosaurs Genus Species Material Locality Unit Notes Images Plesiosauria indet. Indeterminate Three vertebrae. Quebrada La Iglesia Upper part A plesiosaur.
See also Pan de Azúcar Formation
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