Featured in this lot is this rare Ammonite defined suture 5 1/4" fossil. The fossil is encased in stone with excellent Ammonite sutures present (these are the ribs shown that shows the shell on the Ammonite). Ammonoids are a group of extinct marine mollusc animals. Fossilized ammonites were discovered rather late in history due to their inclusion in rock formations. It was not until 1884 that the first findings were documented. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids - octopuses, squid, and cuttlefish - than they are to shelled nauoids such as the living nautilus species. These creatures varied in size, ranging from only a few millimetres to some fossils being found measuring a whopping 8 feet 96 inches. Ammonites are excellent index fossils in that they link the rock layer in which a particular species or genus is found to specific geologic time periods. The condition of this Ammonite fossil is preserved in stone with some fissure to the fossil and erosion to the ribs of the shell but otherwise shows preserved condition. The measurements of this fossil is 4 3/8" x 5 1/8" x 1 3/4". The collective weight of this Ammonite fossil is 1lb 12oz.