Mesozoic era lasted c. 250 million years and consisted of Triassic (trias = triad) 51 million years inc. Lower,
Middle and Upper Triassic. Then 54 million years long Jurassic (Jura Mountains) consisting of Early, Lower,
Middle and Upper Jurassic ). Then
Cretaceous (Latin creta = chalk) 80 million Lower and Upper Cretaceous