Charlotte's Stock Picks - Orthoceras



These are just some of the most attractive fossils for ornamental and sculptural interior design, with their very striking black and white colouring.


Orthoceras means ‘straight horn’ and refers to a genus of European and North African nautiloid which, though now extinct, lived from between 450-360 million years ago crossing from the mid-Ordovian age to the Devonian period.

Fossilised Orthoceras

Fossilised Orthoceras are distinct as they have an elongated cylindrical spear shape and they varied in size from less than a metre up three metres. They swam with a jet propulsion system. Their life cycle is believed to be from one to six years old, they fed on plankton, sea lillies and other smaller Orthoceras! They had tentacles and ink sacs much like the squid.

Orthoceras and Goniatite

They were amongst the most advanced vertibrates as they had eyes, jaws and a fairly sophisticated nervous system.

Orthoceras in Black Limestone Paque

Orthoceras deposits can be found in Morocco and their shells accumulated in great numbers on the sea bed  other areas include the Americas, Asia, Europe and the Baltic, the island of Oland off the Swedish coast where quarries yield such fossils.


© Copyright Charlotte M Bailey 2012


Orthoceras Fossils


Orthoceratid nautiloids.  Late Silurian / Early Devonian of Erfoud (Morocco).

Above: ideal reconstruction life position

Below: two specimen and a polished section of phragmocone (visible the endocameral deposits).

[ Source: Wikimedia Commons / Antonov ]



Orthoceras Fossil Details

Polished section of Late Silurian / Early Devonian Orthoceras limestone (Erfoud, Morocco).  The camerae of the shells are mostly infilled by spathic calcite.  Dimensions: 4×3 cm.

Internal characters of orthoceratid nautiloids;

a)  septa

b)  siphuncle

c)  connecting rings

d)  septal necks (short & othocoanitic)

e)  endocameral deposits

f)  sediment infillings.

[ Source: Wikimedia Commons / Antonov ]