If you go back far enough, everything lived in the sea. At various points in evolutionary history, enterprising individuals within many different animal groups moved out onto the land, sometimes even to the most parched deserts, taking their own private seawater with them in blood and cellular fluids. In addition to the reptiles, birds, mammals and insects which we see all around us, other groups that have succeeded out of water include scorpions, snails, crustaceans such as woodlice and land crabs, millipedes and centipedes, spiders and various worms. And we mustn’t forget the plants, without whose prior invasion of the land, none of the other migrations could have happened.
Moving from water to land involved a major redesign of every aspect of life, including breathing and reproduction. Nevertheless, a good number of thoroughgoing land animals later turned around, abandoned their hard-earned terrestrial re-tooling, and returned to the water again. Seals have only gone part way back. They show us what the intermediates might have been like, on the way to extreme cases such as whales and dugongs. Whales (including the small whales we call dolphins) and dugongs, with their close cousins, the manatees, ceased to be land creatures altogether and reverted to the full marine habits of their remote ancestors. They don’t even come ashore to breed. They do, however, still breathe air, having never developed anything equivalent to the gills of their earlier marine incarnation. Turtles went back to the sea a very long time ago and, like all vertebrate returnees to the water, they breathe air. However, they are, in one respect, less fully given back to the water than whales or dugongs, for turtles still lay their eggs on beaches.
There is evidence that all modem turtles are descended from a terrestrial ancestor which lived before most of the dinosaurs. There are two key fossils called Proganochelys quenstedti and Palaeochersis talampayensis dating from early dinosaur times, which appear to be close to the ancestry of all modem turtles and tortoise. You might wonder how we can tell whether fossil animals lived in land or in water, especially if only fragments are found. Sometimes it’s obvious. Ichthyosaurs were reptilian contemporaries of the dinosaurs, with fins and streamlined bodies. The fossils look like dolphins and they surely lived like dolphins, in the water. With turtles it is a little less obvious. One way to tell is by measuring the bones of their forelimbs.
Question 44: Which of the following best serves as the main idea for the passage?
A. The relationship between terrestrial species and marine creatures.
B. The reasons why species had to change their living place.
C. The evidences of the time marine animals moved to land.
D. The evolution of marine species in changing places to live.
Question 45: As mentioned in paragraph 2, which of the following species returned to the water least completely?
A. Manatees B. Whales C. Dugongs D. Turtles
Question 46: The word “ceased” in paragraph 2 mostly means _______.
A. got familiar B. soon became
C. stopped happening or existing D. began to happen or exist
Question 47: The word “incarnation” in paragraph 2 could be best replaced by _______.
A. evolution B. ancestor C. natural selection D. embodiment
Question 48: According to the passage, which of the following is NOT true?
A. Apart from breathing and breeding, marine species were expected to change nothing to live on land.
B. Seals are able to live on land and in the water.
C. Some terrestrial habits were remained when the species reverted to water life.
D. Proganochelys quenstedti and Palaeochersis talampayensis appear to be close to the ancestry of all modern turtles and tortoise.
Question 49: What does the word “they” in the last paragraph refer to?
A. dolphins B. fragments C. ichthyosaurs D. turtles
Question 50: It can be inferred from the passage that _______.
A. it’s clear to determine the living places of all species through the fragments found
B. the body features of the fossil animals help scientists to distinguish the terrestrial and marine species
C. turtles’ ancestor and dinosaurs became extinct contemporarily
D. the fossils of turtles and tortoises might have the similar appearances with dolphins
