What Is Megafauna: The Definition and Examples of Living and Extinct Species

Megafauna are the planet’s largest animals. Today the term generally refers to vertebrates: herbivores weighing over 1,000 kilograms (2,200 pounds) and to carnivores weighing over 100 kilograms (220 pounds).

The largest terrestrial herbivore on the planet today is the African elephant, an average adult weighing around 5,500 kg (12,000 pounds). The largest terrestrial carnivore is the polar bear, an average adult weighing around 500 kg (1,100 pounds).

The largest animal alive, and the loudest, is a marine mammal, the Antarctic blue whale. An adult can weigh up to 181,500 kilograms (over 400,000 pounds) and reach 30 meters (98 feet) in length. Its call, a low frequency whistle, is louder than a jet engine.

The definition and the meaning of megafauna

Less scientifically, the term megafauna can refer to any animal larger than a human.

Some common characteristics of megafauna:

• megafauna have a long period of parental care
• a long period until sexual maturity
• long gestation
• only a few offspring

In the wild, that is a world absent of humans, megafauna are able to maintain their population numbers because their size bars them from all but the most intrepid and desperate natural predators.

But when their populations are reduced, they quickly become endangered as they cannot reproduce quickly. And newborns require an extended period of nurturing before they are able to survive independently.

Different types of megafauna that have ever lived

Until recently, with the exception of a period following the sudden mass extinction of dinosaurs 66 million years ago, our earth and oceans have supported an abundance and rich variety of terrestrial mammals for hundreds of millions of years. Animals flourished even through periods of dramatic climate change, including multiple glacial and interglacial transitions [1].

Dinosaurs dominated the earth for 180 million years, increasing in size as time passed. At their peak 66 million years ago, the King of the Lizards, an adult Tyrannosaurus Rex measured 13 meters (42 feet) long and weighed 6,000 kilograms (13,000 pounds). Mammals shared the earth with dinosaurs, but as far as we know none were larger than modern day badgers.

After dinosaurs became extinct around 66 million years ago following a cataclysmic asteroid strike, smaller mammals filled in the ecological niche by growing in size [2]. Megaherbivores like hornless rhinoceros and proboscids (elephant family) reached 10,000 kilograms (22,000 pounds) before leveling off in size about forty million years ago.

The tallest creature we know of to walk the earth was a megaherbivore, the Paraceratherium who stood nearly 6 meters (20 feet) tall at the shoulder and lived in Asia lived around 25 million years ago. A carnivorous monitor lizard living in southern Australia, the Varanus priscus, grew to 7 meters (23 feet) long and weighed nearly 2 tons (4,400 pounds). It may have been venous and if so, it would be the largest known venomous vertebrate [3].

Terrestrial mammalian carnivores like the South American short-faced bear and super giant hyena-like animals reached 1,000 kilograms. This is a great example of how predator and prey co-evolved in size and ingenuity.

Birds, which are technically genetically surviving dinosaurs, also grew in size. Giant flightless birds roamed the planet as well. South American terror birds are estimated to have been just under three meters (10 feet) tall and weighed around 400 kilograms (880 pounds). Madagascar’s elephant bird was just three meters tall and weighed 730 kilograms (1,600 pounds).

While some sources note that terrestrial megafauna began disappearing around 125,000 years ago, a marked and relentless reduction began toward the end of the Pleistocene Era, about 50,000 years ago.

At that time, we had at least 50 species of terrestrial megaherbivores, including:

• 16 species in the Probsicidea (elephant) family,
• 7 in the Cetartiodactyla (hippopotamus, bovids, camels) family,
• 5 species of Cingulata (giant armadillo-like creatires),
• 8 species of Pilosa (giant sloths),
• 3 species of Notoingulata, (once an abundant species with diverse characteristics beyond the requisite hoofed feet, some looking like giant rabbits and some bearing a closer resemblance to pachyderms),
• 1 Liptoterna (large, fast-running mammals),
• 1 Diprotodontia (marsupials) [4].

While fifty species may not sound like a lot to start out with, in fact it included thousands and thousands of animals. Today, we can only guess at the numbers.

What caused the extinction of megafauna in the past?

The Pleistocene Era ended 11,500 years ago. During the final 2,000 years of the Pleistocene Era, the world suddenly became a very different place.

In short order, only nine species of the fifty megaherbivores remained worldwide:

• 3 species of elephants,
• 5 species of rhinoceros,
• 1 species of hippopotamus.

Some continents have been hit harder than others.

Some extant species come close to the weight threshold. A large American buffalo or bison can tip the scales at around 2,000 pounds (900 kg). And the largest moose recorded weighed a whopping 1,800 pounds (over 800 kg). But now America’s grassy plains are primarily industrial agricultural areas and bison can only be seen grazing in national parks.

Terrestrial mammal megacarnivores fared just as poorly. Before the twilight years of the Pleistocene, the Earth was home to 15 species of megacarnivores:

• 9 big cats,
• 5 bears,
• 1 Australia marsupial lion.

In the final 2,000 years, North America lost all nine of its species. Only six species of megacarnivores survive globally.

Did humans drive megafauna to extinction?

This is a hotly debated question, primarily because we must rely upon incomplete archaeological evidence to reconstruct the past, and new findings tend to rearrange previous theories. We do not know for sure whether there is a strong correlation between the migration of humans and the extinction of megafauna.

Interestingly Africa, considered the birthplace of humankind, has more diverse megafauna than any other continent on Earth. Although it does have far less in variety and numbers than it once did.

Africa has extensive protected savannas and these magnificent animals are largely found in these protected areas. But even there, they must be carefully guarded from poachers. Perhaps it is not a coincidence that Africa’s last marked mass extinction of megafauna correlated with the advent of stone tools used for butchery by homo erectus around 1.4 million years ago [6].

Species extinction is difficult to chronicle with precision because we cannot anticipate if or where fossil remains will show up. Animals have been found to migrate surprisingly long distances and to have adapted to a wide range of environments.

Even today species extinction of smaller animals occurs under the radar because it is often only when a species is no longer seen regularly that one realizes it has disappeared forever.

The most recent marked decline in megafauna populations, the late Quaternary Extinction Episode, known more colloquially as the American megafauna extinction event, began at the end of the Pleistocene Era.

The Pleistocene Era was a period of alternating glaciations and warming periods. It lasted from around two and a half million years ago to 11,500 years ago, when more temperate Holocene Era began. The final two thousand years of the Pleistocene Era, which coincided with the migration of humans to North America, saw a drastic extinction of large mammals.

In fact, all of the species within 32 genera vanished [8]. We lost:

• the giant ground sloth
• the American lion
• the dire wolf
• the short-faced bear
• the wooly mammoth
• the mastodon
• the glyptodon, a very, very large armadillo

All species larger than 1,000 kilograms vanished [9]. Likewise, fifty-two genera disappeared from South America [10].

This extinction event differs from previous megafaunal extinctions in that new species have not succeeded in replacing the lost ones.

The most popular theory for the extinctions is overkill by humans and other pressures from human expansion which limited the food supply and range of the megafauna.

Up to this day, animals are slaughtered for many reasons not just for food. They are hunted as trophies. Various animal parts are sought for adornment and status like ivory tusks for cameo necklaces and ivory chessboards or sword hilts. Some are also sought as perceived medical cures (panaceas) for everything ranging from lactation difficulties to arthritis or virility. Animal skins are cherished by some as rugs or for clothing.

Animals are also captured to sell as exotic pets or to zoos, tourist parks, circuses and sometimes, as in the case of elephants, as work animals. When removed from their natural habitat in the wild, megafauna have a dismal record of procreating successfully, even with intensive human intervention.

What are the other theories advanced for the loss of the megafauna?

The second most serious contender in the Extinction Debate is that climate change drove the animals to extinction.

Did climate perhaps diminish their food sources?

There is no evidence that the last two thousand years of glaciation and warming were more dramatic than other times during the preceding millennia. In fact, much of the flora that characterized the Pleistocene, many genera of conifers, mosses, flowers and plants as well as many insects, mollusks, mammals and birds survive to this day, but most of the large animals were not so lucky [11].

Earth’s climate has always been in flux and species have survived extraordinary fluctuations. The evidence that climate change caused the mass die-out in the Americas is scant.

Conversely, we do know that the migrants to North America’s southwest at that time, known as the Clovis culture, were skilled Eurasian hunters. We also know that the mammoths and subsequently bison were part of their diet and both quickly became extinct.

Many archeologists believe that the human migration proceeded south into South America, again coinciding with the mass megafaunal extinction at the end of the Pleistocene Era [12]. But other analyses of the climate effects of that period on vegetation and human impact on the megafauna there are inconclusive, suggesting that these factors combined to cause the extinctions [13].

Another theory advanced is that the migrants brought with them deadly viruses, zoonotic diseases that spread across terrestrial megafauna species. And yet another is that a comet impact or airburst over North America was responsible.

Neither of the latter two theories have garnered the number of followers the Overkill and Climate Change theories have.

Examples of recently extinct megafauna

The world is now a very different place. Near the end of the Pleistocene, some animals that became extinct were:

• mastodons
• long-horned bison
• woolly-rhinoceros and mammoths
• giant ground sloths
• giant beavers
• great teratorn birds with 25-foot wingspans

As megafauna became extinct, their predators also vanished. This includes:

• the saber-toothed and scimitar cats
• the leopard
• the cave lion

Recent years have seen a population explosion of homo sapiens with commensurate expansion and environmental degradation. Expansion has meant the fragmentation or destruction of habitats.

Megafauna typically need a very large area in order to forage or find prey. Human settlement or development in the midst of an animal corridor has often spelled death for creatures following ancient migratory paths across the newly claimed land.

Fragmentation also plays a large role in reducing the ability of animals to find mates. In recent years we have lost:

• the western black rhinos and white rhinos who lived in the wild in Africa
• the Caspian Tigers who once roamed throughout Asia and the Middle East
• the Barbary lion
• Steller’s sea cow
• Chinese river dolphin
• the Caribbean seal

Many more species large and small have been reduced to dangerous levels. Once a species reaches its minimum viable population, the odds are stacked against it. It becomes statistically improbable that it will survive much longer [14].

Examples of the living megafauna that still exists on Earth

Thankfully, the last thirty years or so has seen a growing awareness of man’s deleterious effects on animal populations.

Some of this has grown out of a rising sense of compassion, an aversion to cruel practices like cattle and elephant slaughter along with a realization that many animals have a higher intelligence than was previously believed. Some of it is more selfish: a new understanding that biodiversity, the web of life must be maintained intact in order for humans to survive.

The result has been a number of organizations and governments stepping in to save species from extinction. Some of the lucky ones like polar bears, tigers and baby seals have become iconic in the world consciousness. Governments have been pressured to impose trade bans on wild animals, enforced by international police.

Still, protecting our remaining megafauna is challenging.

How do we co-exist with megafauna today?

Many theorize that the reason why megafauna exists (primarily in Africa) is because humans co-evolved with them.

It is sometimes an uneasy task as in the case of the villagers who live just outside the borders of the Kaziranga National Park in northeast India. It is home to a population of Asian elephants. Every night the elephants push their boundaries, trampling crops and knocking down walls of villager’s barns to get at their stores of food. Their sheer size and numbers are terrifying families. And every night the park rangers respond to the villager’s phone calls, arriving to encourage the familiar elephants back into the park.

Interestingly, it is the two species of elephants who have survived, the African elephant and the Asian elephant are animals who have learned to live with humans, serving in warfare and as rescue and work animals [15]. Burma’s teak industry relies heavily on elephant labor and India’s forest rangers rely upon them for transportation.

During Asia’s monsoon season, elephants are often the only reliable transportation as their feet are webbed, designed to sink through mud until they hit the ground and are easily able to lift again.

Four out of the five remaining species of terrestrial megafauna live in Africa. Only large bovines (cattle, buffalo and bison) live elsewhere.

Examples of the most charismatic megafauna throughout history

Tyrannosaurus Rex, T-rex, king of the lizards takes the crown for most popular giant vertebrate.

There may not be a four-year old on the planet who has not heard of him. Who would have guessed that T-rex was once a fledgling in the world of dinosaurs? New evidence reveals that 175 million years ago he weighed a mere 100 kilograms, easily thrashed around by larger dinosaurs. Fossilized remains of an ancestor were found in a lakebed in China.

It is likely that violent volcanic eruptions set the earth ablaze and forced the dinosaurs to flee. They eventually ended up in North America among much, much larger dinosaurs like the Siats who weighed four tons. The race was on to evolve or perish. T-rex rose to the challenge, relatively quickly growing to become the largest dinosaur on the planet.

Along the way, T-rex developed a bigger brain and more intelligence, became capable of running faster, developed a keen sense of hearing as well as vision, together allowing it to stalk unwary prey at night. And at the height of its glory, just before the asteroid hit, it had a bite force of six tons!

Elephants, the gentle giants

Elephants have held a place in the heart and spirituality of humans over thousands of years.  Colorfully painted, delicate scrolls of ivy and flowers spreading from its hooves to the tip of its trunk, bejeweled and draped in silk blankets, a majestic elephant pads softly, bells tinkling, proudly balancing the rajah of the land, who rests on his velvet chair on the howdah, its frame carved ornately and gilded with copper.

Every bit as stately as the leader, the elephant leads the procession, an extension of the rajah’s wisdom and compassion. Perhaps one of the reasons that elephants have survived alongside humans in Asia is that the major religions of the region’s people, Buddhism and Hinduism embrace a belief in reincarnation and the transmigration of souls. It is not inconceivable that a spirit will pass a lifetime as an animal. Both religions also espouse nonviolence.  

Accordingly, respect for animals is imbued in the culture. Both religions hold well-attended annual elephant festivals where elephants are adorned and revered for their qualities of strength, patience, loyalty and wisdom.

Elephants are considered one of the most intelligent animals [16]. Their ingenuity in accomplishing engineering feats exceeding the imagination of their mahouts in river log jamming and rescue operations has been documented time and again [17].

Their ability to remember elephants met far back in time and across vast distances has been noted as well as their ability to remember the places of distant watering holes visited long ago [18].

Stories abound of their ability to feel deeply, shedding their equivalent of tears at the loss of loved ones [19].

Polar bears, the symbol of changing climate

God’s dog, grandfather, the ever-wandering one, the master of helping spirits, the old man in the fur cloak, these are all names of respect given the polar bear by northern peoples [21].

Today our computer screens and televisions flash heartrending images of polar bears stranded on ice floes that have broken from glaciers melting from global warming.

Melting sea ice will mean the extinction of their food source, seals who rely upon sea ice to molt, mate, reproduce and rest. These scenes are painfully emblematic of man losing his connection to nature, to his own essence.

We are only now learning that polar bears evolved from brown bears, their bodies adapting perfectly to a life of extreme cold and hunting seals. Insulating fur covers a thick layer of fat. Their paws are engineered for treading on thin ice, with a bumpy tread and fur between the toes as well as claws to help maintain a grip, and they are large enough that the bears can lower their bodies and spread their weight.

Polar bears have small ears and tails to minimize heat loss. Their skulls are developed to clamp down on the back of the neck of seals with large canine teeth. And they don’t suffer heart disease from their fatty diets.

They have a very keen sense of smell, used in part to find a mate sometimes across thousands of miles. And they have good hearing, but not much known about their visual acuity. They are strong swimmers.

Polar bears are solitary creatures, except for moms who teach their playful cubs life skills for two and a half years before they are ready to live independently. It is these pictures that have captured our imagination: these small families snuggling together, their fluffy snow-white fur blending perfectly in a pristine white world under stark blue skies.