The+Chambered+Nautilus+(extinct)

Ammonites are an extinct group of marine invertebrate animals in the subclass Ammonoidea of the Cephalopoda class. Ammonites are the ancestors of the nautilus today. Ammonites are excellent index fossils. They rock layer that they are found are often possible to use it to link it to a specific geological time periods. Ammonites originated from the bactritoidnautiloids. They first appeared in the Devonian period (400 million years ago) and extinct close to the Cretaceous period (65.5 million years ago) along with the dinosaurs.One theory suggested that months or years of overcast skies causes by the meteor impact disable the ability of planktons to photosynthesis which causes the Ammonites to starve to death. Another theory suggested that the shell of Ammonites could not withstand the acid rain that probably following the vaporization of limestone in the atmosphere caus Artist's reconstruction of [|//Asteroceras//] || [|Zittel] , 1884 || ====Ammonites are an extinct group of marine invertebrate animals in the subclass Ammonoidea of the Cephalopoda class. Ammonites are the ancestors of the nautilus today. Ammonites are excellent index fossils. They rock layer that they are found are often possible to use it to link it to a specific geological time periods. Ammonites originated from the bactritoidnautiloids. They first appeared in the Devonian period (400 million years ago) and extinct close to the Cretaceous period (65.5 million years ago) along with the dinosaurs.====
 * **Ammonites ****Temporal range: 400–65.5 Ma **[|**Devonian**]** - **[|**Cretaceous**] ||
 * [[image:220px-Asteroceras_BW.jpg align="center"]]
 * [[image:220px-Asteroceras_BW.jpg align="center"]]
 * [|**Scientific classification**] ||
 * Kingdom: || [|Animalia] ||
 * Phylum: || [|Mollusca] ||
 * Class: || [|Cephalopoda] ||
 * Subclass: || †**Ammonoidea**

Since the ammonites and their close relatives are extinct, scientists only know little about their lives. The knowledge we know today are obtained by examining ammonoid shells and models.
=Modern Animal= =Future Animal=

= **//Adaptations//** =

**//Structural: Shell-Chambers//**
When attacked the animal would squeeze into all the other chambers || ====The ammonite’s shells are coiled and contain chambers that are linked to each other. The last chamber, which is also the largest chamber, is the only chamber that contains the body. If a predator approaches, the ammonite could withdraw itself into the shell and squeeze into different chambers so that the chambers are concealed. The shell can provide protection for the ammonite in dangerous situations such as being hunted by predators. The chambers also contain gases, which help them regulate their buoyancy, and support the shell from water pressure preventing it from breaking.==== ====**Environmental Pressure:** I think that they had been adapted this way mainly because in their past generations, their ancestors lack the ability to withdraw itself into the shell which makes it unable to protect itself against predators.====
 * [[image:shelll_diagram.jpeg width="344" height="283"]]

**//Structural: Jet propulsion//**
Water leaves the funnel and causes the animal to Jet backwards || ====Although ammonitesare able to float and swim due to their unique construction of the shell, they also use jet propulsion to move through water. Jet propulsion is a common way for Cephalopod to swim fast. Ammonites use a funnel-like opening to propel itself in the opposite direction. Rather than waiting for their food to float around, this gave them control moving around for food and swim away from predators faster. This also improved their living style and at the same time it increases its survivability from predators.==== ====**Environmental Pressure:** Throughout their pass generations, they were not able to get away from predators quick enough or not being able to move through water as freely as it is. Therefore, I believe they were adapted this way to increase their survivability when encountered a predator and maximizing its movement in water.====
 * [[image:jetPropulsion.jpg]]

**//Behavior: Squirting Ink//**
When being attacked, the Ammonites was able to blur the vision of the diver by squirting ink. However it’s likely to have no effect on larger predators as seen in the image above beacause large predators can easily get a strong grip of the animal making it impossible to escape even with the squirting ink ability. || ====Ammonites have the ability to squirt ink. Ammonites use this ability to scare of predators or hide from them while being attacked. This ability allows the ammonite to blur the predator’s vision giving itself time to hide or get away from the predator. However this only works on small predators. Large predators such as megalodons will be unlikely affected by it. This ability allows ammonites to have larger survivability and a less chance for it to be captured by a predator.==== ====**Environmental Pressure:** In my opinion, it’s ancestors lack the ability to escape from predators once captured giving it no chance to survive, therefore they develop the ability to squirt ink to get away from dangerous situations. Their close relatives such as the octopus and the squid do the same thing.====
 * < [[image:ink.jpg]]

During day time, Ammonites descend to darker and deeper waters to avoid predators. Ammonites shells were not as well developed as the Chambered Nautilus today.
Deep waters like the image shown above usually have less predators and makes it hard for the Ammonites to be spotted. When seen from above the shell of the Ammonite will blend into the shadows of the dark waters making it really hard to be spotted by the predators. || ====They were not able to descend to waters more than 100m due to the lack of water pressure resistant their shell provides. Their shell would appear darker when seen from above which makes it hard for other marine creatures to spot them at the bottom of the sea where waters are usually darker.==== ====**Environmental Pressure:** I believe that in their past generations, they are easily spotted by their predators and often being hunted. They realize that they are less likely to be hunted by predators in deep waters, therefore they always descend to dark waters during times where predators were usually around.====
 * [[image:Deepest-Lakes-Earth-1.jpg]]

Ammonites had a higher metabolism than the Chambered Nautilus today. This was mainly due to their feeding habit. Their body was able to consume more food and allows the food to be digested faster.
====**Environmental Pressure:** I believe that their past ancestors often get over fed and results in death due to eating too much. Therefore, their metabolism increases to prevent it from dying and allows it to digest food fast due to their feeding habits.====

**//Habitat//**
====Ammonites lived in the oceans of the Jurrasic and Cretaceous periods. When Ammonites still exists, the world was a very different place than the world we live in today. During the Jurrasic Period, the supercontinent [|Pangaea] was broken up into two supercontinent Laurasia(Northern supercontinent) and Gondwana(Southern supercontinent).==== ====The climate was likely to be warmer as there was no evidence of icecaps. Ammonites live in oceans which genrally has a higher temperature than the environment that the Chambered Nautilus lives in today. They would be found in larger groups as they have a larger population than the Chambered Nautilus today. They lived on the edges of rocks and coral reefs which lead down into deeper waters.====

**Diet **
====X-rays reveals that [|Planktons] were the main source of food for Ammonites. If these are actual food that it feeds on, then it will probably explain why Ammonites extinct after the meteor impact.====

The Ammonite species disappeared along with the dinosaurs 65 million years ago. However the real reason responsible for the extinction of Ammonites are still unknown.
====There was a huge decline in the Ammonite species at that time and previous ammonoid cephalopods barely survived several earlier major extinctions. But the sudden disappearance of the all Ammonites along with dinosaurs cannot be due to natural extinction.====

Another theory suggested that the shell of Ammonites could not withstand the acid rain that probably following the vaporization of limestone in the atmosphere caused by the impact.
=<span style="color: #00ffff; font-family: 'Comic Sans MS',cursive;">Bibliography = //Pangaea Supercontinent//. (n.d.). Retrieved June 26, 2011, from Geology.com: http://geology.com/articles/supercontinent.shtml

//Ammonite//. (n.d.). Retrieved June 26, 2011, from Wikipedia: http://en.wikipedia.org/wiki/Ammonite

//Ammonites: A general overview//. (n.d.). Retrieved June 26, 2011, from Tonmo: http://www.tonmo.com/science/public/ammonites.php