The Guasasa Formation is a geologic formation in Cuba dating to the Late Jurassic to Early Cretaceous (Tithonian to early Valanginian ages). It is primarily composed of limestone. Fossils from the formation include ammonitesGuasasa Formation at Fossilworks.org and a partially articulated skeleton of an unnamed possible ophthalmosaurid.
See also List of fossiliferous stratigraphic units in Cuba
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