The plains inland from Berbera, and the maritime margins between the coast and foot of the plateau, consist of limestones of Lower Oolitic age with Belemnites subhastatus.
Striolaris, Belemnites Panderianus, B.
Their fossils include belemnites, ammonites, scaphites and marine saurians, such as Cimoliosaurus.
Westward of and above these strata, the Middle and Upper Jurassic formations are found (Lias, Lower Oolite, Oxfordian, &c.), with well-marked and numerous fossils (Ammonites, Nerinaea, Natica, Astarte, Rhynchonella, Echinodermata, &c.); then the Cretaceous rocks, both these and the Jurassic series being largely developed, the Cretaceous fossils including Nautilus, Belemnites, Ostrea, Gryphaea, &c., and some very large Ammonites (Pachydiscus).
In the seas, bony fish and crab-like decapods increased in numbers and variety, while pelecypods and gasteropods took the prominent place previously occupied by ammonites and belemnites, and, leaving behind such forms as Rudistes, Inoceramus, &c., they gradually developed in the direction of the modern regional groups.
Few or no extinct types are to be found in these older strata - there is nothing among the plants equivalent to the unmistakably extinct Ammonites, Belemnites, and a hundred other groups, and we only meet with constant variations in the same genus or family, these variations having seldom any obvious relation to phylogeny.