Report

Implementors
Tanner Maddox
Tanner Maddox

Step Files:

File Type File Name Thumbnail Submitted By Date Created Description Action
jpg Elephant Evolution
Elephant Evolution
Ken Pitts 06/15/2011
jpg elephant evolution 2
elephant evolution 2
Ken Pitts 06/15/2011


Step: Tanner Maddox Spring Research Report_Report

Directions for Step: For the project, you will use the rtf editor as your word processor. You will create copies of your sources by going to 'Share -> Collaboration -> New.' You will create one per source, naming it effectively. For the category of your collaboration, make one titles 'Sources.' For your bibliography hyperlink to your original sources, and reference the copy you made in your appendix. In the appendix, attach your sources.
Directions for Form: Please complete the form. For your bibliograpy remember to also hyper link to your sources and to reference the appendix. For appendix section, store your sources as collaboration objections and attach.

Step 1: Report

What is the title of your report?
The Evolution of Elephants
Report:
The past of an elephant is very interesting. Their evolution ladder is one almost as interesting as the human evolution ladder. Elephants even resemble humans with their big brains and their extensive lives (Goodman et al 2011,1). They have the bigger brains than any other land animal. Asian elephants have average brains masses of 5.5 kg and African ones average 6.5 kg (Goodman et al 2011,2). They had to take many steps to get where they are today, though. Elephants have gradually evolved over time.

Research shows that elephants have an aquatic past. Their ancestors used to live in a water environment. The ancient animal is called a Moeritherium. Its teeth has evidence that shows that it used to live in river systems and swamps. Scientists infer this because their teeth shows that they ate freshwater plants (Handwerk 2008,1). Alexander Liu, from Oxford University's department of earth sciences says that the Moeritherium lived about 37 million years ago. This is a long time after the genetic lineages split between elephants and sirenians. Elephants today and their ancestry also share common ancestors with manatees and dugongs along with the water mammals called sirenians (Handwerk 2008,2).

Although it is an elephant ancestor, the Moeritherium did not resemble the elephant we think of today. It was about the size of a tapir, at shoulder height it was between 29 and 42 inches tall. Also, instead of a trunk, it had a prehensile upper lip. This means that it used its upper lip to grasp things by wrapping around it. The Moeritherium's teeth were dug up in northern Egypt's Faiyum region. In the time that this animal lived, this area was a shallow estuary, or coastal system. This means that it was the wide mouth of a river (Handwerk 2008,3). The fossils were found in rock that suggested is was from a swamp or river environment. The scientists are not too sure though, because the possibilty of the Moeritherium fossils washing up there after they died somewhere else (Handwerk 2008,4). The teeth of the fossil of the Moeritherium helped out significantly in trying to find out its history (Handwerk 2008,5).
 
The elephant trunk is a very special feature. It is strong, mobile, sensitive, and elephants can use it to grasp things with it. It also seems to be a different animal on the elephants body because how it moves independently. The trunk has certainly helped out elephants and their ancestors a lot. All animals with trunks are called proboscideans, or trunk bearers. The trunk has helped the mammals adapt to strange environments that they encountered and use it for special things. Fossils of proboscideans have been found on all the continents on our planet, but not including Australia and Antarctica. This shows that the trunk bearers have lived in diverse places. These include lake shores, marshes, swamps, savannas, deserts, and mountains.

At the present time, there are only two proboscidean species alive. One of them is the African elephant (Loxodonta africana) and it is found in Sub-Saharan forests and grasslands. The other one is the Asian elephant (Elephas maximus) and it is found in mixed habitat zones in Sri Lanka, India, and parts of Southeast Asia (Hans 2007,1).

The name 'elephant' was derived from the Greek word 'elephas' which means ivory. The name is referring to the long, ivory tusks that elephants have. Elephants are from the Elephantidae family. These amazing large mammals are studied in three different species now a days. These include the African Wild or Bush, African Forest, and the Asian elephant. Studies show that there were also more related species in the past, but they all became extinct during the last ice age. Mammoths lived up to 2,000 BC, from what fossil findings show. Before, the gigantic mammals known as mammoths were under the Pachydermata order because of their thick skin, but now they are classified as a part of Proboscidea order because of their trunks (Borade 2011,1).

The study of the ancient Eocene starts off the study of the evolution of elephants. According to gene comparisons, Sirenians and Hyraxes have a linked ancestry with elephants. Research showed that hyrax family were made up of amphibious hyracoids that grew to very big sizes. There is also a theory that early on, mammals spent most of their life underwater, and they used their trunks as snorkels for oxygen. This would make sense because the trunk size would grow to allow a greater depth in water that mammals could go. Modern elephants could swim in water for up to 6 hours, so the arguement suffices (Borade 2011,2).

The fossils of Moeritheriums that were dug up in Egypt in 1904, show the stage of evolution of elephants with large incisors, or tusks, and a lifestyle like a modern hippo. Due to the elongated nose and enlarged incisors of elephants, they are believed to be from the paleomastodon and gomphothere families (Borade 2011,3). It is a popular idea that mammoths and mastodons are related, but it is not true. Mastodons have heavier frames and flatter skulls than the mammoths. It is also confusing because both species inhabited the same areas as each other.

The highest species on the ladder of the evolution of elephants is the Primelphas. It is the oldest ancestor of the Elephantidae family, which was on this planet about 7 million years ago. The species ladder seemed to split at the Primelphas, while the Loxodonta became today's African elephants, the Elephas evolved into modern Asian elephants (Borade 2011,4). Although the elephants are known for their wisdom and memory and they are big parts of cultures across the world, the elephants take a big toll on their environment (Borade 2011,5).

Due to Hollywood movies over the last century, it is a popular belief that mammoths, mastodons, and other ancient elephants lived with the dinosaurs. This is false. The mammoths, mastodons, and other ancient elephants evolved from a mouse-sized mammal that survived the K/T Extinction that happened 65 million years ago. It was not until 5 million years after the dinosaurs went extinct that the first mammal that resembled an elephant appeared (Strauss 2011,1). That mammal was a  Phosphatherium, a small pig-like animal that, 60 million years ago, appeared in Africa. The Phosphatherium is the first known proboscid. This means that it was the first mammal to be classified for their long, flexible noses. They lived like a hippo. Because we know that elephants' tusks evolved from incisors, not canines, the Phosphatherium's teeth fit right in (Strauss 2011,2).

The two more famous proboscids after the Phosphatherium were the Phiomia and the Moeritherium. They lived in African swamps and woodlands about 30 to 37 million years ago. The more known is the Moeritherium, and it had a prehensile upper lip, a snout, and extended canines, which are considered rudimentary tusks. The Moeritherium spent most of its time floating around in swamps, like a small hippo. The Phiomia was more like an elephant, because it ate land plants instead of marine plants, and it weighed a half ton (Strauss 2011,3).

About 25 million years after dinosaurs ceased to exist, the first proboscids appeared that was actually like an ancient elephant. The most important of the proboscids was the gomphotheres ("bolted mammals"). The most impressive, though, was the deinotheres, or deinotherium ("terrible mammal"). The gomphotheres were important in the evolution of elephants, but the deinotherium were one of the biggest mammals to ever exist on earth. They weighed 10 tons, and had downward curving tusks, they may have influenced tales of "giants" because it survived into the ice age (Strauss 2011,4).

Although the deinotheres were scary, the gomphotheres were the real action in the branch of the evolution of elephants. Their name was coined from their "shovel" like tusks that they used to dig in soft swampy ground, trying to find vegetation. The genus Gomphotherium was very widespread between 15 and 5 million years ago. They were in North America, Africa, and Eurasia. There was also two distinct species of gomphotheres in that era, Amebelodon ("shovel tusk") and Platybelodon ("flat tusk"). They had very specialized tusks, and when the rivers and lakebeds dried up where they dug up for food, they also ceased to exist (Strauss 2011,5).

There is a very confusing problem in natural history that is mind-boggling. This problem is the difference between mastodons and mammoths. They even have similar names. The mastodon's genus name is mammut, while the mammoth's is mamthus. These names are alike because they are both from the greek root meaning "earth burrower". The mastodons are more ancient than the mammoths, though, they evolved from gomphotheres 20 million years ago. The mastodons were also slightly smaller and bulkier, and had flatter skulls than mammoths. The most important difference, though, is that the mastodons had teeth that were specialized for grinding leaves of plants, while mammoths had ones to graze on grass (Strauss 2011,6). Mammoths showed up in the fossil record about 2 million years ago, so they are much younger than mastodons. They also lived well into the last ice age, like the mastodons. The North American Mastodon had a thick fur coat, which adds to the confusion since mammoths are known for that. Mammoths had fat humps on their necks and were larger and more widespread than mastodons. The best known mammoth of all time is the Wooly Mammoth. Entire bodies of Wooly Mammoths have been found in arctic permafrost in blocks of ice. It might even be possible in the future for scientists to make clone of a Wooly Mammoth in the womb of an elephant (Strauss 2011,7).

Although there are many important differences between mammoths and mastodons, there is also an important similarity. This similarity is that they both lived into historic times, about as late as 10,000 to 4,000 BC. They were also hunted to extinction by early humans (Strauss 2011,8).

 Obviously, elephants' pasts are very interesting. They had many ancestors that took one step at a time to get where the modern elephant is today. The ancient elephants used to even be aquatic animals, so that shows you the power of evolution because now elephants are a prime example of a terrestrial mammal. They also used to be mouse-sized mammals during the era of the dinosaurs. Although it took many million of years, the end of the chain is now here, or is it?
Bibliography:
Allen, W. R. "Ovulation, Pregnancy, Placentation and Husbandry in the African Elephant
(Loxodonta Africana)." Philosophical Transactions of the Royal Society B: Biological Sciences.
Web. 01 May 2011. <http://rstb.royalsocietypublishing.org/content/361/1469/821.full?maxtoshow=>.

Borade, Gaynor. "Evolution of Elephants." Buzzle Web Portal: Intelligent Life on the Web. Web.
Apr. 2011. <http://www.buzzle.com/articles/evolution-of-elephants.html>.

Brenner Et Al, Sydney. HiWire. Web. <http://www.pnas.org/content/106/38/16327.full?
maxtoshow=&HITS=10&hits=50&RESULTFORMAT=1&fulltext=evolution+of+elephants
&andorexactfulltext=and&searchid=1&FIRSTINDEX=0&sortspec=match&resourcetype=HWCIT>.

Goodman, Morris, Kirsten Sterner, and Munirul Islam Et Al. "Phylogenomic Analyses Reveal
Convergent Patterns of Adaptive Evolution in Elephant and Human Ancestries." Proceedings
of the National Academy of Sciences
. Web. 01 May 2011. <http://www.pnas.org/content/106/49
/20824.full?maxtoshow=>.

Handwerk, Brian. "Ancient Elephant Ancestor Lived in Water, Study Finds." Daily Nature and Science
News and Headlines | National Geographic News
. 14 Apr. 2008. Web. Apr. 2011.
<http://news.nationalgeographic.com/news/2008/04/080414-elephant-evolution.html>.

Hans. "Evolution and Use of Elephant Trunks." ATE. 19 July 2007. Web. Apr. 2011.
<http://www.elephanttrust.org/node/140>.

Strauss, Bob. "Elephant Evolution - The Story of Prehistoric Elephants and Elephant Evolution."
Dinosaurs - Types, Behavior and Evolution of Dinosaurs. Web. Apr. 2011.
 <http://dinosaurs.about.com/od/mesozoicmammals/a/elephants.htm>.

Vidya Et Al, TN C. "Range-wide MtDNA Phylogeography Yields Insights into the Origins of
Asian Elephants." Proceedings of the Royal Society B: Biological Sciences. Web. 01 May
2011. <http://rspb.royalsocietypublishing.org/content/276/1658/893.full?maxtoshow=>.
Appendix:
File Type File Name Attachment Description
Elephant Evolution
elephant evolution 2