Castillo Formation, Venezuela

The Castillo Formation crops out cover a wide semicircular area that extends through the northwestern Venezuelan states of Falcón and Lara. During Oligocene to Miocene times, the formation formed the northwest to southeast edge of the Falcón Basin. The formation, with a minimum thickness of , has formerly been regarded as Late Oligocene in age (Wheeler, 1960), but more recent workers, regard it to be Early Miocene. The Castillo Formation at Cerro La Cruz comprises of clayey marls, interbedded with numerous thin (less than ) hardground units. The strata are underlain and overlain by sandstones, and the upper are gypsiferous. The formation was deposited in a calm near-shore marine to brackish lagoonal environment with possibly fluvial influence. Elements of the fauna are consistent with the hypothesis that a tributary and/or delta of the Orinoco existed in this area of northwestern Venezuela during Early Miocene times. == Fossil content ==

In the formation, apart from corals, fossils of the giant sloth Baraguatherium takumara, the turtle Chelus colombiana, the crocodylians Siquisiquesuchus venezuelensis, Purussaurus, Caiman, Gryposuchus, and indeterminate other crocodylians, and the pelican-like Pelagornis sp. have been found. The pelican-like fossil is the oldest of South America. Other fossils reported from the formation are: • silky shark (Carcharhinus falciformis) • wahoo (Acanthocybium sp.) • barracuda (Sphyraena sp.) • Carcharhinus cf. obscurus • Carcharhinus cf. perezi • Hemipristis serra • aff. Prosqualodon australis • Bairdemys sp. • Rhinoptera sp. • Scirrotherium sp. • Arecaceae indet. • Astrapotheriidae indet. • Iniidae indet. • Litopterna indet. • Mylodontidae indet. • Platanistoidea indet. • Squalidae indet. • Tardigrada indet. • Trionychoidea indet. == See also ==