The Mighty Elephant Is Both Beautiful and Functional in Design

Elephant Evolution

The mighty elephant is both beautiful and functional in design.

Assuming that this level of development was as a result of evolution (versus creation), it is thought that the first elephant ancestors began their trek through the evolutionary cycle 60 million years ago.

It was at this time that Condylartha (herbivorous mammals) evolved into Ungulata (the Latin word for "provided with hooves").

From here, according to Eisenberg, the ungulate split into 5 groups:
1.Eparctocyon (animals with cloven hooves or even toes)
2.Cete (whales and dolphins)
3.Phenacodonta (horses, tapirs and rhinos)
4.Meridungulata (an extinct species)
5.Paenungulata (super order elephant ancestors)

It is thought that the modern-day elephant evolved from an aquatic animal that used its trunk as a sort of snorkel while it spent extended periods of time beneath the surface of the water. Even today, elephants are able to swim in this way, staying underwater for hours at a time, with only the tip of their trunk exposed. According to these theories, elephants (Proboscidea) are closely related to manatees and dugong (Sirenia). It is deduced, then, that Proboscidea and Sirenia must share a common ancestor, from which each developed into different species. The Paenungulata group has been identified as the elephant ancestor by intensive DNA research, which revealed that the hyraxes branch off earlier, while the Proboscidea and Sirenia are still closely related in Tethytheria.

"Proboscidea" is a Greek word that means "having a nose". Over 350 Proboscidea have been identified as having existed over the last 50 million years. The only areas that were not found to have been home at least some of these species are Antarctica and Australia. All but 3 of these species are now extinct, leaving only the Asian Elephant, African Savanna Elephant (the world's largest land mammal) and African Forest Elephant. Many of the more delicate and specialized species are likely to have died due to environmental changes that, when coupled with slow reproductive rates, spelt extinction.

The herd will take great care in the burial of the dead. Cows walk to and fro in search of leaves and twigs. The African species can be found in nearly 40 African countries. They are larger than their Asian counterparts. They are further distinguished by different ear- and head shapes. Originally, the two different African elephants were considered to be subspecies. However, DNA research has revealed that they are actually two separate species. This classification has important ramifications in terms of conservation and the population statistics.

Research continues in an effort to bridge the gaps that exist in the evolutionary development of these extraordinary animals. There remain mysteries regarding associated species and the exact path these ancestors followed before evolving into the elephant as we know it today.

From Mammoth to Modern Elephant

The Asian elephant appears to be the closest living relative of the woolly mammoth, now extinct.

BYEMILY SOHN

Thousands of years ago, an elephant-like creature called the woolly mammoth roamed Earth. Except for fossilized bones and remains found trapped in ice, it's now gone. Scientists have long wondered whether the extinct mammoth is more closely related to today's African elephant or Asian elephant.

Modern elephants and woolly mammoths share a common ancestor that lived about 6 million years ago. Exactly how and when the species split over time, though, hasn't been clear. Now, researchers are using modern techniques to piece together ancient elephant history.

From looking at fossilized bones and other features, scientists had proposed that woolly mammoths are more closely related to Asian elephants than to African elephants. Tiny pieces of evidence from the genetic material DNA, on the other hand, hinted at the opposite conclusion.

Because DNA is often the most reliable way to trace evolutionary links, a team led by scientists at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, set out to document part of the mammoth genome, which is a map of the creature's DNA. Only recently has technology become available to recreate a genome based on old, damaged DNA.

The scientists first took just 200 milligrams of bone from a mammoth that had lived 12,000 years ago in northeastern Siberia. Then, they used a chemical reaction to make many copies of whatever pieces remained of the mammoth's DNA. Many of the pieces overlapped, so the scientists were able to put them together, like a jigsaw puzzle, into a complete whole.

In this study, the researchers focused on a type of DNA called mitochondrial DNA. It's a ring-shaped structure found inside a cell part called the mitochondrion. Analyses showed that the modern Asian elephant shares 95.8 percent of its mitochondrial DNA with the woolly mammoth. The modern African elephant has a slightly smaller overlap, sharing about 95.5 percent of its mitochondrial DNA with the woolly mammoth.

The difference suggests that African elephants were the first modern species to split from the main branch of the elephant family tree. Asian elephants and woolly mammoths branched off about 440,000 years later, the scientists say. In other words, Asian elephants are more closely related to mammoths than are African elephants.

The findings should be weighed cautiously, some scientists warn, because looking only at mitochondrial DNA can be misleading. Instead, a group of researchers in Canada is using new high-speed machines to analyze every piece of DNA in the nucleus of a mammoth's cell.

Strands of DNA in the cell nucleus are millions of times longer than those in the mitochondrion, so the project may take a couple of years. When it's done, though, we may finally have a clear picture of the elephant family tree.—E. Sohn

50 Million Years of Elephant Evolution

The Evolution of Elephants, from Phosphatherium to the Woolly Mammoth

Thanks to a hundred years of Hollywood movies, many people are convinced that mammoths, mastodons and other prehistoric elephants lived alongside dinosaurs. In fact, these huge, lumbering beasts evolved from the tiny,mouse-sized mammalsthat survived theK/T Extinction65 million years ago, and the first mammal even remotely recognizable as a primitive elephant didn't appear until five million years after the dinosaurs went kaput. (See a gallery ofprehistoric elephant picturesand a slideshow of10 prehistoric elephants everyone should know.)

That creature wasPhosphatherium, a small, squat, pig-sized herbivore that popped up in Africa about 60 million years ago. Classified by paleontologists as the earliest known proboscid (an order of mammals distinguished by their long, flexible noses), Phosphatherium looked and behaved more like a pygmy hippopotamus than an early elephant. The giveaway was this creature's tooth structure: we know that the tusks of elephants evolved from incisors rather than canines, and Phosphatherium's choppers fit the evolutionary bill.

The two most notable proboscids after Phosphatherium werePhiomiaandMoeritherium, which also lived in northern African swamps and woodlands circa 37-30 million years ago. The better known of the two, Moeritherium, sported a flexible upper lip and snout, as well as extended canines that (in light of future elephant developments) could be considered rudimentary tusks. Like a small hippo, Moeritherium spent most of its time half-submerged in swamps; its contemporary Phiomia was more elephant-like, weighing about half a ton and dining on terrestrial (rather than marine) vegetation.

Yet another northern African proboscid of this time was the confusingly namedPalaeomastodon, which should not be confused with the Mastodon (genus nameMammut) that ruled the North American plains 20 million years later.

What's important about Palaeomastodon is that it was recognizably a prehistoric elephant, demonstrating that by 35 million years ago nature had pretty much settled on the basic pachyderm body plan (thick legs, long trunk, large size and tusks).

Toward True Elephants: Deinotheres and Gomphotheres

Twenty-five million years or so after the dinosaurs went extinct, the first proboscids appeared that could easily be discerned as prehistoric elephants.

The most important of these, from an evolutionary perspective, were the gomphotheres ("bolted mammals"), but the most impressive were the deinotheres, typified byDeinotherium("terrible mammal"). This 10-ton proboscid sported downward-curving lower tusks and was one of thelargest mammalsever to roam the earth; in fact, Deinotherium may have inspired tales of "giants" in historical times, since it survived well into the Ice Age.

As terrifying as Deinotherium was, though, it represented a side branch in elephant evolution. The real action was among the gomphotheres, the odd name of which derives from their "welded," shovel-like lower tusks, which were used to dig for plants in soft, swampy ground.

The signature genus,Gomphotherium, was especially widespread, stomping across the lowlands of North America, Africa and Eurasia from about 15 million to 5 million years ago. Two other gomphotheres of this era--Amebelodon("shovel tusk") andPlatybelodon("flat tusk")--had even more distinctive tusks, so much so that these elephants went extinct when the lakebeds and riverbeds where they dredged up food went dry.

Mammoths and Mastodons - What's the Difference?

Few things in natural history are as confusing as the difference between mammoths and mastodons. Even these elephants' scientific names seem designed to befuddle kids: what we know informally as theNorth American Mastodongoes by the genus nameMammut, while the genus name for theWoolly Mammothis the confusingly similarMammuthus(both names partake of the same Greek root, meaning "earth burrower"). Mastodons are the more ancient of the two, evolving from gomphotheres about 20 million years ago and persisting well into historical times. As a rule, mastodons had flatter heads than mammoths, and they were also slightly smaller and bulkier. More important, the teeth of mastodons were well-adapted to grinding the leaves of plants, whereas mammoths grazed on grass, like modern cattle.

Mammoths emerged on the historical scene much later than mastodons, popping up in the fossil record about two million years ago and, like mastodons, surviving well into the last Ice Age (which, along with the hairy coat of the North American Mastodon, accounts for much of the confusion between these two elephants). Mammoths were slightly bigger and more widespread than mastodons, and had fatty humps on their necks, a much-needed source of nutrition in the harsh northern climates in which some species lived. TheWoolly Mammoth,Mammuthusprimigenius, is one of the best-known of all prehistoric animals, since entire specimens have been found encased in Arctic permafrost. It's not beyond the realm of possibility that scientists will one day sequence thecomplete genomeof the Woolly Mammoth and gestate a cloned fetus in the womb of a modern elephant!

There is one important thing mammoths and mastodons shared in common: both of these prehistoric elephants managed to survive well into historical times (as late as 10,000 to 4,000 B.C.), and both were hunted to extinction by early humans.

Here's a list of the most notable prehistoric elephants; just click on the links for more information.

AmebelodonThis "shovel-toothed" elephant thrived in flooded lowlands.

AnancusThis early elephant's tusks were as long as its entire body.

BarytheriumThis ancient elephant sported eight short, stubby tusks.

CuvieroniusOne of the few prehistoric elephants to have lived in South America.

DeinotheriumOne of the largest mammals ever to roam the earth.

Dwarf ElephantThis pint-sized proboscid went extinct 10,000 years ago.

GomphotheriumOne of the earliest shovel-toothed elephants.

MammutBetter known as the North American mastodon.

MammuthusThe one, and only, woolly mammoth.

MoeritheriumThis ancient elephant was about the size of a pig.

PalaeomastodonOne of the earliest elephant-like proboscids.

PhiomiaAn early ancestor of modern elephants.

PhosphatheriumThe earliest known ancestor of modern elephants.

PlatybelodonThis prehistoric elephant came equipped with its own spork.

PrimelephasThe immediate predecessor of the modern elephant.

StegomastodonNot quite a cross between a Stegosaurus and a mastodon.

StegotetrabelodonThis elephant's footprints have been found in the Arabian peninsula.

Straight-Tusked Elephant (ElephasAntiquus)This elephant species went extinct 50,000 years ago.

TetralophodonA widespread elephant of the Miocene epoch.

Name______Period ______Date ______

1. List any vocabulary word that you do not know.

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1. List three things that you found interesting.

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1. Use evidence to show the evolution of extant elephants from extinct members at least 4 steps back on the evolutionary tree.(use fossil evidence, homologous structures)

1. Examine the evolution of modern elephants and determine how they have been able to be successfulspecies. Use evidence to explain that evolution along the elephant evolutionary tree was driven by either genetic variation, mutation, sexual reproduction, competition for limited resources, and/or various adaptation. Your findings will be used to help support your claim in determining the mass extinction taking place.