7/27/2019 Elc Ielts - Reading_ Task1c

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spec es p ys o ogy s g y a ape o s env ronmen an esy e. amma s a so ave arge

systems, enabling more intelligence and resourcefulness than other animals, a key survival feature. Le

generation to another, so younger generations benefit from their ancestors' experience. This was

adaptation and problem solving skills are still an exceptional feature of our species.

C) The earliest true mammals, appearing over 200 million years ago, were small shrew -like tree dw

some extent until the demise of the dinosaurs, around 65 million years ago, after the cataclysmic co

what is now the Yucatan desert caused dramatic changes in climate and conditions worldwide. Fossil

exploit Earth's resources freely, mammals diversified enormously. There are now around 4600 speci

live on land and move about on four legs but some are aquatic (e.g the whale) and some fly (e.g a Thai

D) The separation and (in some places) the reformation of land masses resulted in groups of species

of years. Some eventually succumbed to environmental changes, geographic events or other a

flourished and adapted to become even more successful, perhaps also migrating to another areas.

E) Variations in size and specialisations are enormous. Lifespan ranges from less than a year (sh

range from the arctic, with temperatures of minus 68 C (polar bears, foxes), to deserts of up to 50 C (

6000m high altitude plateaux; sperm whales dive to 2000m underwater; grassland ruminants graze in

escape predators, forest mammals are usually solo, nocturnal and often camouflaged. Desert mam

retaining water; high altitude animals carry extra red blood cells to maximise oxygen capacity.

F) Recent advances in genetic science and improved technological tools have led to some contr

mammals. In the 1960s, evidence emerged to indicate that originally, earth had one single land ma

two about 225 million years ago, with each 'continent' carrying certain evolving species. Fossil finds i

northern land mass and later migrated south over land bridges that formed at various times. Howev

found evidence of advanced mammals from a much earlier period than in the north, turning the

Additionally, geneticists can now compare fossil DNA with the genes of living mammals. They are fi

groups of mammals is not accurate; that hippos and whales for example are not distant but very clos

of their genetic material with chimpanzees.

G) All mammals have four-chambered hearts, a muscular diaphragm separating their heart and lungs

jaw made of a single bone, and the same arrangement of tiny bones in the inner ears. Almost all

giraffes, have seven vertebrae in their necks. The arms of humans, the flippers of seals, and the wing

arrangement of bones.

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