Delware State Fossil
Delaware State Fossil, The Belemnite
Belemnite is
the common name applied to an extinct order (Belemnoida) of mollusks belonging
to the cephalopod class. Modern cephalopods include the squid, octopus,
and pearly Nautilus. The belemnoid animal was most closely related to
the squid as it had an internal shell covered by a leathery skin, tentacles
that pointed forward, and a siphon that expelled water forward thus moving
the animal backward by jet propulsion. The internal shell of the belemnoid
was cone-shaped and divided into chambers that were gas-filled for maintaining
buoyancy in the sea. The chambered shell had a blade-like forward extension
that is seldom preserved as a fossil. The most common fossilized part
of the internal shell is called the "guard" or "cigar" consisting of a
massive, generally brown-colored, subcylindrical structure called the
rostrum that encloses the chambered shell and extends to the rear where
it tapers to a conical apex. The rostrum served as a counter-weight to
the buoyancy provided by the chambered shell and also for protection of
that delicate shell. Belemnoids reached their greatest abundance and diversity
during the Jurassic and Cretaceous periods.
After Moore, Lalicker, and Fisher, 1952, Invertebrate
Fossils: New York, McGraw-Hill Book Company.
On July 2, 1996, belemnite was named as the official fossil of Delaware. The Martin Luther King, Jr. Elementary School(Wilmington) third grade Quest students of Kathy Tidball suggested honoring the ancient and noble belemnite as our State fossil.(Delaware Code Title 29 ยง 314)
Belemnites
have been found abundantly in the exposures of the Mount Laurel Formation
along the banks of the Chesapeake and Delaware Canal in Delaware, east
of St. Georges. The fine-grained sands and silts of the Mount Laurel were
deposited in a shallow sea during the Late Cretaceous time around 70 million
years ago. The fossil belemnite species found here is Belemnitella americana.
Sometimes, almost complete belemnite guards can be found, similar in size
and shape to a pencil, pointed at one end, but flaring at the other end
(if preserved) and partly hollow in the center where the chambered shell
was located. Often, only rod-like broken sections of the brown rostrum
are found.
In Delaware,
the best place to look for Belemnitella americana is in the dredge
spoil piles on the north side of the Chesapeake and Delaware Canal, just
west of St. Georges and also just east of the north side of the Reedy
Point Bridge.
