BIOLOGY Case study (4 Marks)

→ About 15 mya primates such as Dryopithecus and Ramapithecus existed.
→ They appeared to be similar to Gorillas and Chimpanzees in their appearance and walking.
→ Ramapithecus was more similar to man whereas Dryopithecus was more similar to apes.
→ Few fossils of bones that resemble human bones have been discovered in Ethiopia and Tanzania.
→ The skull of a child Chimpanzee is more similar to that of an adult human than that of an adult chimpanzee.
→ These human-like features further support the belief that 3-4 million years ago human-like primates roamed East Africa.
→ They were probably 4 feet tall or less, but could walk upright.
→ Australopithecines:
→ Two mya Australopithecines existed. They most likely lived in East African grasslands.
→ They used stone weapons for hunting.
→ Essentially had a fruit-based diet. They also survived on plant-based diet and did not eat meat.
→ The first human-like organism was the hominid and was called Homo habilis.
Brain capacity was 650 - 800 сс.
→ Homo erectus:
→ Fossils discovered in Java in 1891 seemed to be of the next stage i.e. Homo erectus.
→ They evolved about 1.5 mya.
→ Had large brain with capacity around 900 cc.
→ Probably ate meat.
→ Neanderthal man:
→ Brain size was around 1400 сс.
→ Lived in east and central Asia between 1,00,000 - 40,000 years back.
→ They developed use of animal hides to protect their body.
→ Buried their dead.
→ Homo sapiens:
→ Arose in Africa.
→ Migrated across continents and developed distinct races.
→ During ice age 75,000 - 10,000 years ago
modern Homo sapiens arose.
→ Prehistoric cave art developed about 18,000 years ago.
→ Prehistoric man-made paintings are found in one such cave on the Bhimbetka rock in Raisen district of Madhya Pradesh.
→ Agriculture came around 10,000 years back and human settlement started.

→ About 2000 million years ago the first cellular life was found on earth.
→ About 350 million years ago, jawless fishes emerged.
→ Fish caught in South Africa in 1938, believed to be coelacanth, were thought to be extinct. → These animals evolved into known as lobefins, the first amphibians that could live on both land and water.
→ Although none of these specimens have survived to us, they were the ancestors of today's frogs and salamanders.
→ Reptiles descended from amphibians.They laid thick shelled eggs which did not dry out like amphibian eggs.
→ At the present time once again we can only see their descendants, tortoise, kashyapa and crocodile.
→ 200 million years or during which reptiles of different shapes and sizes dominated the earth.
→ Probably 200 million years ago evolved into reptiles like mastya and returned from land to water.
→ The land-dwelling reptiles were definitely dinosaurs.
→ The largest reptile Tyrannosaurus rex (T-rex) was 20 feet tall and had huge fearsome spear- like teeth.
→ About 65 million years ago, dinosaurs suddenly disappeared from the earth, which some believe to have been wiped out due to climatic changes.
→ Some even say that most of them may have evolved into birds.
→ But the truth is somewhere between these two. Because the small size reptiles of that time still exist.
→ Earlier mammals were like shrews.
Mammals were very intelligent in terms of sensitivity and overcoming fear.
→ When the reptiles decreased, the mammals took over the earth.
→ Mammals like horses, hippopotamus, bears, rabbits etc. were seen in South America.
→ Due to the continental drift, when North America joined South America, the animals of North America were scattered.
→ Due to similar continental drift, marsupials
survived in Australia because they did not have to compete with other mammals.
→ Some mammals live entirely in water. Whales, dolphins, seals and sea cows are some examples.