Lower Cretaceous

Subdivision of the Cretaceous system according to the IUGS, as of July 2012.

The Early Cretaceous (geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 146 Ma to 100 Ma.
During this time many new types of dinosaurs appeared or came into prominence, including Psittacosaurus, spinosaurids, carcharodontosaurids and coelurosaurs, while survivors from the Late Jurassic continued.

In the seas, the ichthyosaurs declined and eventually died out at the start of the Late Cretaceous. Angiosperms (flowering plants) appear for the first time.

Note : The above story is based on materials provided by Wikipedia