The Jagua Formation is a

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

(middle to late Oxfordian) geologic

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

in the Sierra de los Órganos and Sierra del Rosario mountain ranges in

Pinar del Río Province Pinar del Río is one of the provinces of Cuba. It is at the western end of the island of Cuba. Geography The Pinar del Río province is Cuba's westernmost province and contains one of Cuba's three main mountain ranges, the Cordillera de Guanig ...

, western Cuba. Plesiosaur,

pliosaur Pliosauroidea is an extinct clade of plesiosaurs, known from the earliest Jurassic to early Late Cretaceous. They are best known for the subclade Thalassophonea, which contained crocodile-like short-necked forms with large heads and massive toot ...

pterosaur Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 ...

,Barrett et al., 2008 metriorhynchid,

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...

and

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

remains are among the

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s that have been recovered from its strata.

Description

The formation comprises marine shales and

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

s. The thick Jagua Vieja Member consists of

black shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...

s and horizontally laminated marly micritic to biomicritic limestones. The latter contains

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an ad ...

concretion A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular ...

s which the fossils are found in. The formation overlies the San Cayetano Formation and is overlain by the

Guasasa Formation The Guasasa Formation is a geologic formation in Cuba. It is Tithonian to Early Valanginian In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 139.8 ± 3.0 Ma and 132.9 ± 2.0 Ma ...

. The bedding direction is steeply dipping towards the northwest.

Fossil content

Vertebrate paleofauna

Other fossils

*'' Favreina'' *'' Globochaete'' * '' Gryphaea mexicana'' - Pan de Azúcar Mb. * '' Lepidotes gloriae'' * '' Liostrea mairei'' * '' L. sandalina'' - Zacarías Mb. * '' Nanogyra (Nanogyra) nana'' - Zacarías Mb. * '' Ostrea broughtoni'' - Zacarías Mb.Mogote La Mina
at Fossilworks.org * '' Plicatula cf. weymouthiana'' - Zacarías Mb. * '' Voltzia palmeri'' * '' Perisphinctes sp.''Viñales
at Fossilworks.org

References

Bibliography

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