Tithonian Age
The Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series within the geological timescale. This age spans from approximately 149.2 ±0.7 million years ago (Ma) to 143.1 ±0.6 Ma. It is chronologically preceded by the Kimmeridgian Age and succeeded by the Berriasian Age, marking the transition into the Cretaceous Period.
Geological Features
During the Tithonian, sedimentary rocks such as limestones were formed, particularly in the Tethys Ocean. These rocks are notable for containing fossilized remains of organisms like cephalopods. A prime example is the Solnhofen Limestone found in southern Germany, renowned for its exceptional fossil preservation, including the iconic Archaeopteryx.
The Tithonian can be subdivided into Lower/Early, Middle, and Upper/Late substages. The Late Tithonian is contemporaneous with the Portlandian Age according to British stratigraphy.
Paleobiology
The Tithonian was a dynamic period marked by diverse flora and fauna. Many notable dinosaur genera lived during this time, including the formidable Allosaurus and the armored Stegosaurus. These dinosaurs are discovered in formations such as the Morrison Formation in modern-day Colorado and the Isle of Portland in Dorset, UK.
Avialans such as Baminornis, an extinct genus from the Nanyuan Formation in China, also existed. The Tithonian age witnessed the presence of early birds and pterosaurs, including the genus Mesadactylus, discovered in the Morrison Formation.
The era also gave rise to various marine arthropods, such as the Porcelain Crab, first appearing in this age. These crustaceans adapted with large claws for maintaining territories within marine ecosystems.
Notable Formations
Several geological formations from the Tithonian age are significant for their fossil content. The Portland Stone Formation, quarried on the Isle of Portland, is one such example. It is a key source of building stone and a rich repository of ancient life forms.