This spiral-shaped fossil is a Goniatite from the Devonian era and is 251 to 390 million years old. These cephalopods lived in shallow seas in tropical to sub-tropical climates. Their spiraled shell had internal compartments which would have been filled with gas to provide buoyancy. The open front chamber acted as the goniatite’s living space.
Goniatites have been found in every continent except Antarctica and in almost every state of the USA. They survived the Late Devonian extinction, allowing them to thrive for a period before eventually going extinct during the Great Dying of the P-T extinction event.
This order of creatures survived for 139 million years and paleontologists use Goniatite fossils to reliably date the rock formations in which they are discovered.
Goniatids, informally goniatites, are ammonoid cephalopods that form the order Goniatitida, derived from the more primitive Agoniatitida during the Middle Devonian some 390 million years ago (around Eifelian stage). Goniatites (goniatitids) survived the Late Devonian extinction to flourish during the Carboniferous and Permian only to become extinct at the end of the Permian some 139 million years later.
All goniatites possessed an external shell, which is divided internally into chambers filled with gas giving it buoyancy during the life of the animal. An open chamber at the front of the shell provided living space for the goniatitid animal, with access to open water through a ventral siphuncle. The general morphology and habit of goniatites was probably similar to that of their later relatives the ammonites, being free swimming and possessing a head with two well developed eyes and arms (or tentacles).
Goniatite shells are small to medium in size, almost always less than 15 centimeters (5.9 inches) in diameter and often smaller than 5 centimeters (2.0 inches) in diameter. The shell is always planispirally coiled, unlike those of Mesozoic ammonites in which some are trochoidal and even aberrant (called heteromorphs). Goniatitid shells vary in form from thinly discoidal to broadly globular and may be smooth or distinctly ornamented. Their shape suggests many were poor swimmers.
The typical goniatitid has a suture with smooth saddles and lobes, which gives the name "goniatitic" to this particular suture pattern. In some the sutures have a distinctive "zigzag" pattern. Not all goniatitid ammonoides have goniatitic sutures. In some the sutures are ceratitic, in others, even ammonitic. Nor are goniatitic sutures limited to the Goniatidia. The sutures of nautiloids are by comparison somewhat simpler, being either straight or slightly curved, whereas later ammonoids showed suture patterns of increasing complexity. One explanation for this increasing extravagancy in suture pattern is that it leads to a higher strength of the shell.
Nice addition to my office, beautiful little piece.
Gleena1613 rated this 5 stars on Etsy
Really gorgeous piece. Mostly intact and a good size. My son really loved it
Beautiful fossil. Would recommend.