The Early Jurassic
Triassic-Jurassic extinction event, 201.3 Ma (million years ago), and ends at the start of the Middle Jurassic174.1 Ma.
Certain rocks of marine origin of this age in Europe are called "Lias" and that name was used for the period, as well, in 19th-century geology. In southern Germany rocks of this age are called Black Jurassic.
Origin of the name Lias
There are two possible origins for the name Lias: the first reason is it was taken by a
sloops from north Cornish ports such as Bude would sail across the Bristol Channel to the Vale of Glamorgan to load up with rock from coastal limestone quarries (lias limestone from South Wales was used throughout North Devon/North Cornwall as it contains calcium carbonate to fertilise the poor quality Devonian soils of the West Country); the Cornish would pronounce the layers of limestone as 'laiyers' or 'lias'; leac is Gaelic for "flat stone".
There has been some debate
There are extensive Liassic outcrops around the coast of the
siltstones, deposited under fully marine conditions.
Lias Group strata form imposing cliffs on the Vale of Glamorgan coast, in southern Wales. Stretching for around 14 miles (23 km) between Cardiff and Porthcawl, the remarkable layers of these cliffs, situated on the Bristol Channel are a rhythmic decimetre scale repetition of limestone and mudstone formed as a late Triassic desert was inundated by the sea.
During this period,
zone fossils. There were several distinct waves of ammonite evolution in Europe alone.
The Early Jurassic was an important time in the evolution of the marine reptiles. The Hettangian saw the already existing
Occitanosaurus, and the pliosaur Hauffiosaurus).
On land, a number of new types of dinosaurs—the
sphenodonts, and early lissamphibians.