Glossary

The **Morrison Formation** is an extensive sequence of Upper Jurassic sedimentary rocks distributed across the western United States, spanning approximately 1.5 million km² from Montana to New Mexico and from Idaho to Kansas. Radiometric dating of interbedded volcanic ash beds constrains its age to approximately 155–148 Ma (Britannica) or 154–145 Ma (NHM), corresponding to the Kimmeridgian through early Tithonian ages, and possibly extending into the latest Oxfordian. The formation is composed of multicoloured mudstones, sandstones, siltstones, conglomerates, and minor limestones, deposited predominantly in non-marine environments including rivers, floodplains, lakes, swamps, and alluvial plains, with some marine sediments at its base. Clastic material was sourced mainly from mountain ranges to the west, such as the Sierra Nevada, that were actively uplifting during the Late Jurassic, while numerous volcanic ash beds within the formation provided the basis for radiometric age determinations. The Morrison Formation is the most prolific source of dinosaur fossils in North America, with approximately 50 or more genera of dinosaurs described from its outcrops. Iconic taxa including *Allosaurus*, *Diplodocus*, *Apatosaurus*, *Stegosaurus*, *Brachiosaurus*, and *Camarasaurus* were all first described from this unit. The formation became the principal arena of the Bone Wars between Edward Drinker Cope and Othniel Charles Marsh beginning in 1877, an episode that catalysed the growth of vertebrate palaeontology as a scientific discipline and brought dinosaurs to widespread public attention.

The **Solnhofen Limestone** is a Late Jurassic geological formation located near the town of Solnhofen in southern Bavaria, Germany, formally designated as the **Altmühltal Formation**. Dated to the Tithonian Age (approximately 150.8–145.5 million years ago), it is one of the world's most celebrated **Konservat-Lagerstätten**—sedimentary deposits characterized by exceptional fossil preservation—including detailed impressions of soft-bodied organisms such as jellyfish, squid, and insects. The formation consists of thin beds of extremely fine-grained lithographic limestone (Plattenkalk) interbedded with thin shaly layers, deposited as calcium carbonate mud (micrite) in shallow tropical lagoons that were isolated by sponge and coral reefs along the northern margin of the Tethys Sea. Elevated salinity and anoxic bottom-water conditions in these confined lagoons suppressed scavenging and bacterial decomposition, enabling the preservation of feathers, skin impressions, and even internal organs. Over 750 plant and animal species have been described from the formation, most famously *Archaeopteryx*, the iconic transitional fossil linking theropod dinosaurs to birds. The Solnhofen Limestone also holds significance in the history of printing technology: its homogeneous, fine-grained texture made it the ideal medium for Alois Senefelder's invention of lithography in the late 1790s, and subsequent large-scale quarrying for lithographic stones led directly to many of the formation's most important fossil discoveries.