Dolphin-Extinct

Mesonychids (Latin name: Mesonychia) are an extinct family of large-sized carnivorous animals that are related to artiodactlys and cetaceans (such as the Killer Whale). They first appeared in the Early Paleocene, and became extinct in the Early Oligocene. They lived from Paleocene to the Eocene periods. Mesonychids dominated the large predator group in the Paleocene Asia. Mesonychids were very similar to wolves, but with bigger heads and hooves, instead of paws.
 * Modern Animal: Dolphin> ** **__ Extinct Animal: Mesonychid __**
 * Introduction: **

Mesonychids were found in the Early Paleocene, which was the epoch followed by the mass extinction event at the end of Cretaceous, which was when dinosaurs and other fauna and flora died out. During the Early Paleocene, the climate was cool and dry. Areas that were close to the equator had tropical climates, on the north and south of these areas; the climate was quite hot and dry. In Europe, Australia, North and South of America, it was warm and temperate. During the Paleocene, smaller mammals, such as reptiles and birds existed. (refer to Figure 1) It was not until the Eocene, that true modern mammals were developed. Because of the warm climate in the Paleocene, there was also the development of modern plant species, such as Cacti and palm trees. There were thick tropical forests around the globe, without any dinosaurs to destroy them.
 * Habitat: **



Mesonychids were found in North America, Canada West, North China and Mongolia. (refer to Figure 2)The climate they lived in was mostly tropical and warm. They were also surrounded by tropical vegetation in areas, such as Greenland (part of North America) and Patagonia (close to Asia).

In the Early Paleocene, there was a low diversity and abundance of marine life, but later in the epoch, the oceans transformed, and there were huge abundance of marine life, such as coral reefs. The warm seas and abundance of food attracted a lot of different species.

Through fossils of Mesonychids’ sharp teeth, they were suspected to be used for tearing meat and crushing bones. They were speculated to be fish-eaters. Others that were physically larger were considered to be scavengers.

Mesonychids had thin and long sharp teeth. They used their pointed **canines** (refer to Figure 3) for killing and tearing meat. It is speculated that some of them were scavengers (such as modern hyenas), and some of them were fish-eaters.(such as modern seals and toothed whales) Mesonychids had bone crushing teeth, just like hyenas. Both these animals’ **sagital crest** (refer to Figure 3 and 4)show that they have strong jaw muscles, so that they will have stronger grips on sea animals and they are also used to crush bones. The larger the **sagital crest** is, the larger the muscle is attached. Their sharp teeth help them to survive the wild, and not starve to death. The environmental factor that caused this could have been the speed of the sea animals that they feed on. For example, a fish can swim away so quickly, their strong teeth and jaw muscles will not only help them have a strong grip on their food, but also to crush their bones.
 * Adaptations 1: Teeth **

Mesonychids had four digits on their feet. They walked with their hoofed feet. (Refer to Figure 5) The structure of their feet suggests that they were more adapted to endurance rather than speed when running. This helps it to survive by running away from bigger animals otherwise they’ll get eaten and they also won’t get tired. The environmental factor that caused this could have been the distance they had to travel from place to place so their high endurance will be adapted to that.
 * Adaptations 2: Feet **




 * Adaptations 3: Eyes **

Mesonychids had forward-facing eyes, that are positioned in the lower part of their heads. This allowed them to find preys in a downward and upward direction, This helps them hunt easier, therefore, they won’t starve to death. The environmental factor that caused this could have been the speed of its pretty. For example, its eyes would allow it to locate the prey easily in a short period of time, and then it will be able to hunt the prey down.


 * Adaptations 4: Hind Limbs **

Mesonychids had strong hind limbs, which allowed them to run faster. This helps them to survive by catching preys and running away from larger animals, so it won’t get eaten or starve to death. The environmental factor that caused this could have been the speed of the prey. Mesonychids’ strong legs could help it move faster.


 * Adaptations 5: Long and Strong Neck **

Their long and strong necks allow them to locate preys more easily. And since their food was mainly fishes, they needed a strong neck to be able to hold on to the struggling animal. This helps them catch preys and not starve to death. The environmental factor that caused this could have been the speed of the prey. Having stronger necks allowed them to have better grip on the animals.

One possible reason to why Mesonychids have evolved into a marine animal is because their teeth were more suitable for eating fish, than meat. They were blunt, rounded cusps, and were not developed to eat meat, therefore they were less efficient at eating meat than other carnivores. They also lived close to the water, and became more and more dependent on the sea. That’s why they slowly evolved into a water environment.


 * Bibliography: **

1) Bluelion.org (2006) What are Mesonychids. Retrieved 22nd June, 2011, from []  2) The Cryptid Zoo: A Menagerie of Cryptozoology (2005) Mesonychids. Retrieved 20th June, 2011, from [] 3) WiseGeek (2003) What is a Mesonychid. Retrieved 26th June, 2011, from []


 * Picture Sources: **

Figure 1: [] Figure 2: [] Figure 3: [] Figure 4: []