Mean sea level (MSL) is the average (mean) height of the sea, with reference to a suitable reference surface. Defining the reference level, however, involves complex measurement, and accurately ... > more
Paralititan stromeri was a giant titanosaurian sauropod dinosaur discovered in coastal deposits in the Upper Cretaceous Bahariya Formation of Egypt. The fossil represents the first tetrapod reported ... > more
The pelycosaurs were smallish to large (up to 3 meters or more) primitive Late Paleozoic synapsid reptiles. They appeared during the Late Carboniferous and reached their acme in the early part of the ... > more
The southern supercontinent Gondwana (originally Gondwanaland) included most of the landmasses which make up today's continents of the southern hemisphere, including Antarctica, South America, ... > more
In geology, a crust is the outermost layer of a planet.
The crust of the Earth is composed of a great variety of igneous, metamorphic, and sedimentary rocks. The crust is underlain by the mantle. ... > more
Limestone is a sedimentary rock composed largely of the mineral calcite (calcium carbonate: CaCO3). Limestones often contain variable amounts of silica in the form of chert or flint, as well as ... > more
The Permian-Triassic (P-T or PT) extinction event, sometimes informally called the Great Dying, was an extinction event that occurred approximately 251.0 million years ago (mya), forming the boundary ... > more