|
|
|
SET OF THREE LOOSE CRETACEOUS BELEMNITES - Hover (Hannover), Germany UPPER CRETACEOUS PERIOD: 83 - 71 million years ago From this world-class Cretaceous site comes these superbly preserved belemnite sets. Hover is a working cement mine that happens to be quarrying rock right through a rich Cretaceous deposit in North Germany. Two species of belemnites are found here at the quarry - Gonioteutis quadrata which has slightly ovate cross-section profile, and Belemnitella mucronata with its round cross-section profile. We hand-select only the finest and complete specimens of the two types of species to be used in our kits. Each kit will include one or both of these species, our choice. What we guarantee is that you will be getting the absolutely nicest quality and COMPLETE fossil shell of the belemnite, not broken partials as others offer. This is important as the complete specimens have the unique phragmocone anatomy visible at the end. The phragmocone is the open, thin-walled air chamber at the posterior of the shell. Each of the belemnites we use in our kits will have this delicate feature. Most 'bargain' specimens sold elsewhere possess a missing or damaged phragmocone.
Cephalopods evolved during the Late Cambrian Period. Their bodies were predominantly elongate with conical shells. Some of these creatures evolved into semi-coiled forms eventually giving rise to coiled cephalopods like ammonites and nautili. Another branch of straight-shelled cephalopods continued to coexist with the coiled forms on into the Pennsylvanian Period. These straight forms were much less diverse and abundant than the coiled cephalopods, as a whole. Straight cephalopods were among the most advanced invertebrates of their time having 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 also much like the 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. Belemnites were different than other straight cephalopods like Orthoceras in that they had internal shells called 'guards' which were covered with the soft, muscular tissues of their bodies. These shells were also chambered but much less complex than the straight varieties of nautiloids and ammonoids. The gas chamber by which the animal regulated its buoyancy is called the phragmocone. In finely preserved specimens, it is a conical, thin-walled opening at the posterior of the shell. Rare belemnite fossils complete with soft body parts have been found and provide us with a valuable glimpse of what these creatures looked like when alive. Belemnites possessed 10 tentacles and males had chitonous hooks which they used to grasp the females during mating. Straight cephalopods probably lived for one to six years, with the majority living two to four years. They fed on plankton (tiny free-floating organisms), sea lilies, and smaller orthoceras. Although many fed off the ocean floor, others may have caught plankton while floating or swimming via jet propulsion, expelling water through a funnel-like opening to propel themselves in the opposite direction. CHOICE EXAMPLES FROM THIS WORLD-CLASS CRETACEOUS SITE! Belemnites vary in each set from approximately 2.75" to 1.75" long $35 BE1 INCLUDES DISPLAY BOX |
|
35 |
|
|
Belemnites
are extinct straight-shell members of the Cephalopoda that died out at
the end of the Cretaceous along with ammonites and dinosaurs. 