Cretaceous Fossils of the Simsima Limestone Formation
of this ancient marine fauna of crabs, sea-urchins, bivalve shells,
corals and sea worms would be easily recognisable to us today. However,
there are also fossils from some groups of animals that have completely
disappeared, having become extinct at the end of the Cretaceous period.
These include the ammonites, free-swimming relatives of bivalves and
sea-snails that possessed a spirally-coiled chambered shell. Another
group of marine animals that no longer exists today are the rudists,
a highly specialised kind of bivalve with a large, horn-shaped lower
valve that rested on or in the sediment. A rudist found by Natural History
Museum palaeontologists from Jebel Rawdah has been given the new scientific
name of Glabrobournonia arabica .
Corals were common in these waters,
sometimes forming dense bush-like thickets or patch reefs and sometimes
occurring as button-like individuals (some rudists resemble these corals)
scattered across the ocean floor. On the edges of the shoals, massive
brain corals are to be found. Probably the most unusual of all the corals
is the fan-shaped and solitary Diploctenium , which attached
itself to the sea floor by a thin stalk. Rather delicate for potential
preservation as a fossil, it is only found in rocks deposited in the
more sheltered environments.
Of the 45 sea-urchins now known from the Simsima Formation, 14 species
are new to science and some of them have been named after places where
they were found or, in one instance, after a person who has helped the
Natural History Museum team - Codiopsis lehmannae . Specimens
named after places in the Emirates are Prionocidaris ?emiratus
, Heterodiadema buhaysensis, Goniopygus arabicus , Circopeltis
? emiratus , and Petalabrissus rawdahensis .