Cameroceras-Jurassic Kratts preview

The Cameroceros is one of the creatures in Orthocone Attack, from Jurassic Kratts. Enjoy the preview!

## Facts:

***Cameroceras*** ("chambered horn") is a genus of extinct, large orthoconic cephalopod that lived mainly during the Ordovician period. It first appears during the middle Ordovician, around 470 million years ago, and was a fairly common component of the fauna in some places during the period, inhabiting the shallow seas of Laurentia, Baltica and Siberia. Its diversity and abundance became severely reduced following the Ordovician–Silurian extinction events, and the last remnants of the genus went extinct sometime during the Wenlock. *C. rowenaense* from Cincinnati had shell length about 70 centimeters (2.3 ft), and unnamed species had length about 1 metre (3.3 ft). In older literature *Cameroceras* was treated as the largest nautiloid with shell length about 6 metres (20 ft) or even 30 feet (9.1 m). However, the large-sized species no longer belongs to genus *Cameroceras* but *Endoceras giganteum*, and the 30 feet (9.1 m)-long specimen is highly doubtful.

## Description

*Cameroceras* is a cephalopod, a taxon of molluscs that includes the octopuses, squids and cuttlefish. From comparison with living cephalopods, particularly the shelled chambered nautilus, some inferences about the biology of *Cameroceras* can be made. The head of the animal would have been soft muscular tissue situated at the opening of the hard cone-like shell, with the mantle (main body) lying within the shell for protection. Tentacles would have grown from the base of the head like in a modern nautilus, and these tentacles would have been used to seize and manipulate prey. At the base of these tentacles within the buccal mass (analogous to the mouth) a hard keratinous beak would have bitten into the bodies of its prey, and is assumed to have been strong enough to breach the prey's exoskeleton or shell. Within the beaks of modern cephalopods a radula, or 'toothed' tongue is used to rasp out soft tissue from within the prey's shell.

## Taxonomic usage

*Cameroceras* has become a "wastebasket taxon" in which large orthoconic endocerids such as *Endoceras*, *Vaginoceras*, and *Meniscoceras* were originally placed. This makes it extremely difficult to describe *Cameroceras* as a distinct genus. Although the type species *Cameroceras trentonense* was first described by Conrad in 1842, since then the generic term has had variable meaning.

Hall, who named and described *Endoceras* in 1847 recognized *C. trentonense* specifically, but used *Endoceras* for other specimens of large endocerids from the Trenton Limestone of western New York state. *Cameroceras* and *Endoceras* have even been applied to different stages of the same species. Although *Cameroceras* takes precedence where the two refer to the same species, its vague application leaves *Endoceras* or other better-described genus the term of choice.

## Paleontology-biology

The lifestyle and habits of *Cameroceras* can only be surmised. They were almost certainly stalkers and ambush predators that moved across the sea floor or lay in wait. The large rigid shell would have made maneuvering difficult. The larger ones especially were probably not active swimmers. The very largest may have remained on the bottom without ever changing position.

As with all endoceratids *Cameroceras* was weighted so as to be horizontally stable. This would have been achieved by the endocones in the apical portion of the siphuncle that would have compensated for the visceral mass forward in the body chamber. The endocones would also have sealed off the more apical chambers from the siphuncle limiting changes in ballast to the more forward, centrally located, chambers. The result is that changes in buoyancy would have had little effect on horizontal stability.

### Physical appearance and biology

The *Orthocone is* a large mollusk that belonged to the nautiloids, such as the modern *Nautilus*. It had several tentacles, which, unlike the tentacles of modern cephalopods like the cuttlefish and the squid, didn't range in size, but were of a generally similar length. Also, these tentacles didn't have suction cups, but rather the tentacles were ridged on their inner side.

In the center of its face was a large, sharp, parrot-like beak that was used to crush through carapaces of such arthropods like *Megalograptus*.

It had large, primitive eyes which were sensitive to contact with bright lights.

At the bottom of the animal was a tube-shaped device called a hyponome. This was used to propel the animal through the water.

The *Orthocone* has a long, cone-shaped shell which was covered in stripes. The shell was largely hollow, the mollusk occupied only its front end, and the rest of it consisted of gas-filled chambers that could be flooded with water, which could be expelled lately. In this manner *Cameroceras* adjusted its buoyancy and weight as it rose to the surface or sank - this creature wasn't very manuverable.

### Behavior and traits

The Orthocone was an alpha predator of the Ordovician, as it was the largest animal. Most of its size consisted of its long, narrow shell. The size ratio between the shell and the animal itself was very large - the shell could amount up to 90% of the animal's entire length.

The *Orthocone* lived in dimly-lit parts of the sea as its eyes were very primitive and were sensitive to light. In any instance where bright light came in contact with its eyes, the mollusk would try to escape it.

The primary weapon of the *Orthocone* was its beak. Once it caught its prey, it would drag the animal towards its beak with its tentacles. The beak would then crack apart the carapace and would then proceed in feeding on the softer innards.