The inception of the earth took place some 4.5 billion years ago. Life is estimated to have first appeared on earth some 3.6 billion years ago and ever since, there has been a continuous evolution and extinction of countless microbes, animals and plants. The animal life on earth is particularly fascinating. Their evolution from a minute cells to such complex lifeforms that ambulate, hunt, reproduce and fight for survival is truly amazing. The animals that we see today such as lions and tigers, rhinos, elephants, dolphins and whales, are particularly attractive due to their large size. Interestingly, the ancestors were even larger and more dominant than their descendants today. These extinct and extant large animals are collectively referred to as megafauna.
The term megafauna translates to “large animals”. Although the term includes the extant species of large terrestrial and aquatic animals in a geographic area, the term is also used to refer to the large animals that predominated earth during the Pleistocene period (2.5 million to 11, 700 years ago).
Charismatic megafauna” are large animals with some attractive features and are very popular among the public.
These animals are often used by conservationists to create awareness about the threatened status and endangerment of other animals as well as the environment as a whole.
A well-known example of charismatic megafauna is the giant panda. This endangered animal is the face of The World Wildlife Fund (WWF).
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Other examples include the elephant, the royal Bengal tiger, the African lion, the rhino, and aquatic animals such as dolphins, orcas, humpback whales, penguins and the great white shark.
The megafauna dominated the earth during the Pleistocene period, and ambulated on earth, had flourished on its resources for hundreds of millions of years. Some of the most significant megafaunas which are now extinct have been described below −
Diprotodon optatum − A resident of Pleistocene Australia, the Diprotodon was the largest marsupial and was a herbivore. It was quadruped with a heavy build. Its large belly allowed it to eat as much as 150kg of vegetation, daily!
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Glyptodon − The Glyptodon was a giant armored mammal that lived around 10,000 years ago. The tail of the Glyptodon has a club-shaped end, which was used as a defence.
Paraceratherium − characterised by its long neck and described as a gigantic hornless rhino, this herbivore is supposed to have lived about 25 million years ago, in parts of what is now Asia. The Paraceratherium is considered to be one of the largest beasts to have existed on land.
Ground sloth - Prominent land creatures that faced extinction around 10,000 years ago, the herbivorous ground sloths weighed around 9000 pounds and were as much as 20 feet tall!
Megalodon − Otodus megalodon, alternatively referred to as Carcharocles megalodon or simply Megalodon was a humongous shark, about 50 feet in length.
It had huge teeth, which is the origin of its name. This apex predator was lost to extinction some 2.6 to 3 million years ago.
Argentavis − Argentavis magnificens was a huge avian supposed to be the largest bird that ever flew. The huge carnivorous bird had a wingspan of 24 feet, tip to tip.
In the present-day, megafauna is referred to carnivorous animals that weigh more than 100 kg, or herbivores that weigh 1000 kg. Examples of extant megafauna include the following animals:
The elephant − referred as the largest living terrestrial animal and there are currently three living species of this animal- the Asian elephant (Elephas maximus), the African bush elephant (Loxodonta africana) and the African forest elephant (Loxodonta cyclotis).
The rhinoceros − Weighing about a tonne and currently represented by 5 extant species. It is a herbivore megafauna with one/two nose horns and hence the name rhinoceros.
The hippopotamus − The heaviest terrestrial megafauna after the elephant, the hippo is native to sub-Saharan Africa.
Giraffes − famously characterized by their long necks and legs, the giraffe is the tallest terrestrial megafauna and also the largest ruminant.
The Chinese giant salamander − the largest living mega-amphibian and is considered a living fossil.
The Pleistocene epoch was the last point in time when the earth was teeming with giant mammals and abundant zoological diversity.
The megafauna saw a decline in their population and eventual extinction during the late Pleistocene.
By the end of the last Ice Age, the extinction of megafauna was almost complete.
The reason for their extinction is largely considered to be environmental and ecological.
Some reasons put forward by scientists and palaeontologists include changes in vegetation cover, changes in climatic conditions, the ecosystem structure, the trophic levels and their interactions, etc.
Probably a huge reason for their decreasing number was the evolution of man. Humans evolved during the Pleistocene and by the late Pleistocene epoch, humans had successfully spread to different geographical locations.
Humans learned to attack, kill, and use the megafauna to their advantage, eventually leading to their extinction.
The transition from colder conditions to warmer climates is supposedly the main reason for the extinction of megafauna such as the woolly mammoth.
The megafauna are the largest extant or extinct animals that live or have lived on the earth. These animals are characterised by their huge size including both herbivores and carnivores. Charismatic megafauna is especially popular among the public and are used to create awareness.
The extinct megafauna includes giant sharks such as the Megalodon, humongous birds like the Argentavis, and terrestrial animals such as the Paraceratherium and the Diprotodon. The reasons for the extinction of megafauna are both ecological and environmental. Extant megafauna includes the elephant, the giant whale, the hippopotamus, etc.
Q1. What is the difference between the megafauna of today and the extinct species?
Ans. The megafauna that exist in the world today are quite different from the extinct species. The main difference lies in their sizes, their numbers and their diversities.
Q2. How did the Megalodon go extinct, if it was an apex predator at one time and lived in deep waters?
Ans. The main reason for its extinction is thought to be global cooling that occurred after the Pliocene era.
Q3. Why are most of the fossils of sharks usually teeth?
Ans. This is because sharks are known to shed and grow new teeth every week or so. This implies that the ocean floor probably consists of hundreds of thousands of shark teeth that eventually fossilize.
Q4. Which modern-day animal does the Glyptodon resemble?
Ans. Glyptodon’s armour consisted of bony plates, making the animal very much similar to its modern-day relative, the armadillo.
Q5. Which charismatic megafauna are found in India?
Ans. India is home to 7 major charismatic megafauna- the royal Bengal tiger, the Asiatic lion, the Indian elephant, the gharial, the great Indian one-horned rhinoceros, the Ganges river dolphin, and the Himalayan snow leopard.
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