Odontochelys Semitestacea: The Green Sea Turtle Ancestor


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Odontochelys

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Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Order: Testudines
Family: Odontochelyidae
Genus: Odontochelys
Species: O. Semitestacea




Habitat


The ancestor of the ancient green sea turtle (Odontochelys) shared some similarities in it's preferred habitat. The Odontochelys spent most of its life in shallow waters along the coastline, in bays and coves, and around coral reefs. However in modern times only adult green sea turtles spend their lives near the shallows of the waters, young green sea turtles ventured into the deeper parts of the open ocean. Scientists have suggested that the Odontochelys did not spend lots of time or anytime in the open ocean and only spent time in the shallows. Mainly because that was where the Odontochelys could find food, the animals would have easy access to land and being closer to shore kept them away from many of their ancient predators.

Many scientists also believed that Odontochelys frequently visited the shore, and some scientists believe that Odontochelys only inhabited the water fifty percent of the time or possibly less then fifty percent of the time. Unlike the modern animal Odnotochelys only had one habitat the shoreline instead of three (open ocean, shoreline, bays and coves) during their lifetime. This differs greatly from the Green Sea Turtle (Chelonia Mydas).

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Ancient Landform Gondwana-Odontochelys Habitat


However many scientists are still unsure of the exact habitat of this ancient sea turtle. It i suggested that both ancient and modern turtles share a similar habitat. However only adult green sea turtles (modern) share the closet resemblances to Odontochelys habitat which was water near the coastline.

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Coastline Habitat of Odontochelys

The ancient habitat may have looked something like the tropical beaches we find around areas like Hawaii, South Asia, South America, and Australia.


Structural Adaptation 1: Sharp teeth

Unlike the modern green sea turtle, its ancient relative had a row of sharp teeth that lined both its upper jaw and its lower jaw. This adaptation may have occurred for the sea turtles protection in both the water and on the land. As well as adapting to eat the types of food available to the animal. Many of the fish available or other types of food would be extremely different so the Odontochelys would need sharper teeth in order to catch it's prey, and the animals may have needed far more force to catch they prey. The animals sharp teeth may have resembled that of the KOMODO DRAGON.

Structural Adaptation 2: Full stomach shell

This ancient sea turtle unlike the modern green sea turtle only carried a full shell on its stomach rather than a full outer shell covering both the stomach and the back. Scientists suggest that the turtle adapted this way for both protection and its different lifestyle. The turtle needed more protection on its stomach as it lived closer to the coast and predators were more likely to attack from underneath, and the animal may have also needed from protection from rocks along the shallow waters they inhabited. The turtles lifestyle prevented it from having a heavy full armour as it spent more time on land and it would be far too heavy, if they needed to escape from a predator or just to walk around on land, or catch potential prey if they had a heavy shell like the modern green sea turtle.


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Most Distinct Physical Features


Behavioural Adaptation 1: More time out of the water

Unlike modern sea turtles who generally are out of the water only to lay eggs, the Odontochelys seemed to spend more time on land, possibly even fifty percent of their life was spent out of water. Scientists gathered this information based on the build and size of the Odontochelys as well as some key characteristics mentioned below. This may have been due to the lack of food in the shallows of the water or it could be due to the fact that most of the food sources were on land such as in the mud or along the beach.

Behavioural Adaptation 2:More of their life spent near the waters edge

Scientists have gathered information about the Odontochelys which may suggest that unlike the modern turtle, Odontochelys spent more time out of the water. The longer legs of the Ondontochelys and the only partial shell would have allowed the Odontochelys greater ability for movement on land to protect it from land predators as well it would have allowed the animal more movement in finding food along the beaches near the ocean. An ancient Gopher Tortoise may have lived near the waters edge.

Physiological Adaptation: Partial shell on the back

An adaption of the Odontochelys was a partial hard shell on the top of the ancient turtles back. It gave the animal more flexibility and they were likely faster on land and possibly in water than the modern green sea turtle. The partial shell on the back was more like a set of ribs than a full body armour.

Extinction Pressure:


This ancient ancestor of the sea turtle did not simply die out, it evolved into the many different sea turtles such as the green sea turtle we see today. This species however evolved and adapted to look differently, and survive in a new environment. One of the reasons why this species may have had to evolve was because they did not have a full shell surrounding the top of the animals back. Without the full back shell the animals was more vulnerable to predators. The animal may have found itself running out of sea creatures to eat so it had to adapt to suit a different eating style. The animal may have also evolved to spend almost all their time in the water to escape from deadly predators or they could no longer find food along the shores of the coastline. No matter which way these animals evolved, it was pressure from nature to help them adapt to a changing world.

All about Reptiles, Initials. (2010, July 16). The Oldest water turtle: odontochelys. Retrieved from http://www.all-about-reptiles.com/water-turtle.html Retrieved July 24 2010

Meyers, PZ. (2008, November 28). Odontochelys transitional turtle. Retrieved from http://scienceblogs.com/pharyngula/2008/11/odontochelys_a_transitional_tu.php Retrieved July 26 2010

Odontochelys. (2010, May 4). In Wikipedia, The Free Encyclopedia. Retrieved 12:49, July 22, 2010, from http://en.wikipedia.org/w/index.php?title=Odontochelys&oldid=359984322