Hettangian (English, name)
expansion: Hettangian
Senses:
topics: biology
geography
geology
history
human-sciences
natural-sciences
paleontology
sciences
glosses: The earliest age of the Jurassic period, from 199.3–201.3Ma
glosses: The corresponding lowest stage of the Jurassic system, marked by the lowest strata in which the neoammonite genus Psiloceras appears.
Forms: