Large Orthoceras Fossil Stone Panel (Auction 2026-06-05, Lot 141)

$514.00

Ancient Seas, Morocco, Devonian Period, ca. 419.2 to 358.9 million years ago. A large rectangular orthoceras fossil panel featuring numerous fragmentary shells set within a dark stone matrix, with several circular flat sections suggesting use as a support base or presentation stand. The composition displays elongated, conical forms arranged in dynamic alignment across the surface. Orthoceras, an early cephalopod, possessed long, straight shells that housed its soft body and tentacles. The stone has been polished to clearly reveal the fossils, with white segmented sections representing preserved shell material. These contrast against the darker ground and emphasize the linear structure of the shells. Some elongated forms illustrate the full tapering shape of the organism, offering a clear view of the internal segmentation and overall morphology of these ancient marine animals. (25″L x 18.5″H x 2″W — 63.5cm(L)x46.99cm(H)x5.08cm(W))

Prehistoric ‘straight’ cephalopods include straight ammonoids called orthoceras. Cephalopod evolution began during the Late Cambrian Period. Some of these creatures evolved into semi-coiled forms, eventually giving rise to coiled cephalopods like ammonites and nautili. Straight cephalopods were among the most advanced invertebrates of their time, with eyes, jaws, and a sophisticated nervous system. These creatures were predators that swam freely using a jet propulsion system by squirting water from their bodies. They had tentacles and ink sacs, much like present-day squid. Except for belemnites, cephalopods had external shells with hollow internal 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. Only the last and largest chamber was occupied by the living animal!

Provenance: private Colorado, USA collection

Condition: Good. Chips and abrasions to high pointed areas, but otherwise intact.