Modern Animal - Common Eel
Future Animal - Scaled Camouflaging EelEnchelion Montium
The Enchelion Montium was a species of eel that lived in the Cretaceous period (65 – 144 million years ago). This period of time is usually noted for being the last period of time where dinosaurs existed. The Enchelion Montium is an ancestor to the modern day Conger eels, which can grow up to 3m in length. Even though this particular type of eel went extinct in the late Cretaceous period, the Congridae family still exists until this very day. The Enchelion Montium is one of the oldest eels on earth. The following report will outline the eel’s 5 adaptations and its pressure to extinction.

Scientific Classification

LEVEL
CLASSIFICATION
Kingdom
Animalia
Phylum
Chordata
Class
Actinopterygii
Order
Anguilliformes
Family
Congridae
Genus
Enchelion
Species
Enchelion Montium

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Figure 1: Labelled Diagram of Fossilized Enchelion Montium




Habitat
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Figure 2: Cretaceous Period Source: http://www.dinosaur-facts.com/wordpress/wp-content/ uploads/2009/01/cretaceous-period-dinosaurs-250x250.png

The Enchelion Montium existed in the Cretaceous period, a time when dinosaurs roamed the earth, plesiosaurs swam in the seas and pterosaurs flew in the air. This was the period that these animals last survived. From space, the Cretaceous continents would look remarkably different from the continents we know nowadays. The massive continent Pangaea has begun to split, dividing the land mass into Northern and Southern continents. Africa, South America, Antarctica and Australia were still joined together, and North America and Eurasia was one land mass.

One of the most significant factors on the Cretaceous period is the high level of sea level. The global sea level was at its highest during this period of time. Scientists have estimated the Cretaceous sea level to be a couple of hundred metres above the modern sea level. This may have been one of the factors that resulted in the ancestral eel favouring a deep underwater habitat, like most eels in the modern world.

During the Cretaceous period, the global climate was much hotter on average. This was due to the much higher carbon dioxide level in the air, some scientists believed it to have been four times higher than the modern temperature. The Cretaceous period was an intense “Greenhouse world”. From this point, we are able to draw conclusion that the Enchelion Montium could survive in much higher temperatures than the modern eels.
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Figure 3: Cretaceous Marine Life Source: http://www.search4dinosaurs.com/carr_cretaceous_marine.jpg

Even though scientists cannot be definitely sure of where the exact location of the Enchelion Montium lived they can briefly outline its habitat. Fossils of the ancestral eel have been found in Africa, Europe, North America, the East Indies, Australia and New Zealand. This provides enough information for scientists to have a basic knowledge of where the eel used to live. It is most likely that the Enchelion Montium had the same breeding habits as the eels nowadays, migrating from freshwater to salt water and vice versa.





Structural ONE - Powerful Jaws and Sharp Teeth

The Enchelion Montium has a set of extremely powerful jaw and very sharp teeth. This feature greatly assists the carnivorous eel to kill its prey. With a snap from its jaws, no Cretaceous fish will be able to escape from its bite. The ancestral eel’s eating habit had been fairly similar to the modern eel’s. They probably fed on worms, crustaceans and small fish.
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Figure 4: Strong Jaws Source: http://www.starthrower.org/products/DDDB/DDDB_200-249/DDDB%20228%20moray%20skull%20sm.jpg

The Cretaceous ocean was much different from the ocean we know now; dangerous creatures we’ve never imagined roamed the sea. Large marine reptiles such as mosasaurs and plesiosaurs were very abundant in that era. Both of these massive carnivorous giants definitely had been threats to the ancestral eel. The mosasaur had a similar appearance to a modern day crocodile, but had flippers instead of legs. The plesiosaur’s significant feature is its long snake like neck. Just from this environmental pressure, we can be sure that the Enchelion Montium needed its muscular jaws and sharp teeth not only for hunting, but also to defend itself from predators like the shark.



Structural TWO - Scale Body

Nearly all fish in the sea have scales on their bodies, including the Enchelion Montium from the Cretaceous period. Scales vary greatly in sizes and shapes depending of the species of the fish. There are mainly four types of scales, the placoid, cosmoid, ganoid and cycloid and ctenoid. The scales on fish help to prevent injuries and to prevent bacteria from entering the body. There is a thin layer of skin covering the scales. This skin produces mucous like substance that protects the fish from infection. It also assists them to glide through water much faster by creating a more streamlined shape. As the snake-like eels grow bigger, they do not get more scales, instead the scales will become larger to fit the rest of their bodies.



Behavioural ONE - Travelling in Group

The ancient Enchelion Montium travels in a large group, unlike the modern Common Eel, which usually travels alone. The main reason eels travel in a group is to protect themselves from carnivorous enemies. When in a group, they are able to attack in unity and there is also a much less chance of being attacked. The movements of the eel create a current which reduces the friction between the group and the water. This allows the group to move through the water much faster than being alone. Travelling in a group allows the eel to find food much easier. When one eel finds it, the rest can share the prey.



Behavioural TWO - Ability to Scavenge for Food

One of the main differences between the ancient Enchelion Montium and the modern Common Eel is that the ancestral eel has the ability to scavenge for food around the sea. They usually search on the seabed for any remnants of dead fish. The eel will practically eat anything they can find. The mating season is the most vulnerable time for baby fish. The ancient eel will hide near coral reefs waiting for its chance to strike its prey. When the mother fish leaves its roes, the eel will quickly attack and eat all of them. With this advantage, the Enchelion Montium is much easier to find food.



Physiological ONE - Keen Sense of Smell

Since the Enchelion Montium is a night hunter, it doesn’t need its eyes to see and has pretty poor eyesight. However, they rely on their keen sense of smell to locate their prey. Like modern eels, the ancestral eel hide in narrow gaps between rocks near the seabed, waiting patiently for its unfortunate prey to pass by. When a prey swims close enough to the Enchelion Montium, it will catch its smell and lunges from its hiding spot to catch it.

The Cretaceous marine life is considerably different from the modern marine life. The most prominent reason is because of the mass extinction of organisms throughout these millions of years. Many organisms went extinct after the Cretaceous period, including the dinosaurs and the Enchelion Montium itself.



Extinction Pressure
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Figure 5: Cretaceous Mass Extinction Source: http://www.plantapalm.com/vce/ evolution/images/Impact.jpg

The reason fot the Enchelion Montium's extinction is caused by the mass extinction that occurreed in the end of the Cretaceous period. During End-Cretaceous extinction, 85% of all living organisms died. The extinction became the escond largest extinction in the history of our Earth. This is remarkable that most mammals and amphibians have survived this extinction, however many families of sea spoonges and other planktons disappeared.

Even today, scientists do not know the exact cause of this mass extinction that occurred in the end of the Cretaceous period. The most likely cause of this extinction is an extraterrestrial impact, meaning an asteroid or a coment. This scenario would send ash particles into the sky and darken the Earth for a long period of time. Without the sun, the Earth is most vulnerable to fall into ice age, causing a mass extinction in the iosphere. This is an excellent exmple of natural selection as it is evident that the Enchelion Montium has already begun evolving into the modern eel and it has survived the extinction instead of its ancestor.





Bibliography
Enchelion Montium – A Cretaceous Eel. (2010). Last Retrieved 22nd July 2010.
http://www.infohub.com/forums/archive/index.php?t-6743.html
Large Cretaceous Eel Fossil from Lebanon. (2010). Last Retrieved 22nd July 2010. http://www.fossilmall.com/EDCOPE_Enterprises/fish/Fish9/Fossil-Fish-9.htm
The Cretaceous Period. University of California Museum of Paleontology. (2010). Last Retrieved 22nd July 2010. http://www.ucmp.berkeley.edu/mesozoic/cretaceous/cretaceous.html
The environment of Cretaceous. The geology of portsdown hill. (2003). Last Retrieved 22nd July 2010. http://www.bbm.me.uk/portsdown/PH_120_Envmnt.htm
The Life That Was In The Cretaceous. K/T Extinction. (2010). Last Retrieved 22nd July 2010. http://hoopermuseum.earthsci.carleton.ca/saleem/creatures.htm