JURASSIC SEA LIFE FOSSIL CLAMS AND AMMONITES IN MATRIX
JURASSIC PERIOD (LIAS): 200 - 176 million years ago
an Early Jurassic deposit in Germany, this
unusual fossil rock contains multiple remains of clams and ammonites -
preserved sea life from a classic period of prehistory. The
ammonites and clams have been wonderfully preserved in full three
One of the primary
clams is actually removable from the matrix
and both sides are beautifully fossilized with intact luster from the
original shell. The outer ornamentation of the ammonites can
be seen in one repaired partial example as well as embedded associated
examples. This is the only specimen of this material we collected
years ago. Perfect for any sea life exhibit from the past.
Bivalves, which include
clams and mussels, are made
up of two half shells. The valves are attached by a hinge ligament
and articulate open and close by two muscles attached on the inside of
the shells. Bivalves are filter-feeders and pump water inside
their bodies to strain out phytoplankton and other small organisms for
food. Bivalves generally have limited locomotion and possess a
foot but mainly live attached to some type of substrate or burrow in the
underwater sand. Bivalves move along the bottom by means
of jumping. The foot is extended then contracted violently, moving
backwards in the process acting like a spring always kicking the animal
are extinct members of the Cephalopod class.
Modern members include nautilus, squid and octopus.
They first appeared during the Silurian Period (435 million to
410 million years ago) and were abundant and widespread in the seas of
the Jurassic and Cretaceous periods (175 million to 65 million years
ago). Ammonites are important index
fossils—that is, they often link the rock layer in which they
are found to specific geological time periods.
Ammonites varied greatly in size.
as 2 cm (0.75 in) in diameter. During the Jurassic and Cretaceous
periods, ammonites evolved more streamlined shells for swimming and the
structure of the shell became stronger. Different shell shapes emerged
as well, such as snail-like or uncoiled.
The shells of
had hollow chambers separated by walls called septa. A tube called the siphuncle, connected the body with the
chambers allowing the animal to fill them with water or air, changing
its buoyancy in order to
rise or drop in the ocean.
the last and largest chamber was occupied by the living animal.
probably lived for one to six years, with the majority living two to
four years. They fed on plankton (tiny free-floating organisms), sea
lilies, and smaller
orthoceras. Although many fed off the ocean floor, others may have
caught plankton while floating or swimming via jet propulsion,
expelling water through a funnel-like opening to propel themselves in
the opposite direction.
Because ammonites lived
exclusively in marine environments, their presence also indicates the
location of prehistoric seas.
UNCOMMON TYPE OF FOSSIL SEA LIFE FROM
THE JURASSIC - PERFECTLY PRESERVED 3D CLAM IS REMOVABLE AS SEEN ABOVE
Item - One Only