What Is A Dinosaur? - IELTS Reading Answers & Explanations
From IELTS Recent Actual Test 1 Academic Reading Test 2 · Part 3 · Questions 27–40
Reading Passage
You should spend about 20 minutes on Questions 27-40 which are based on Reading Passage 3 on the next page.
What Is a Dinosaur?
A Although the name dinosaur is derived from the Greek for "terrible lizard", dinosaurs were not, in fact, lizards at all. Like lizards, dinosaurs are included in the class Reptilia or reptiles, one of the five main classes of Vertebrata, animals with backbones. However, at the next level of classification, within reptiles, significant differences in the skeletal anatomy of lizards and dinosaurs have led scientists to place these groups of animals into two different superorders: Lepidosauria or lepidosaurs, and Archosauria or archosaurs.
B Classified as lepidosaurs are lizards and snakes and their prehistoric ancestors. Included among the archosaurs or "ruling reptiles" are prehistoric and modern crocodiles, and the now extinct thecodonts, pterosaurs and dinosaurs. Palaeontologists believe that both dinosaurs and crocodiles evolved, in the later years of the Triassic Period (c248-208 million years ago), from creatures called pseudosuchian thecodonts. Lizards, snakes and different types of thecodont are believed to have evolved earlier in the Triassic Period from reptiles known as eosuchians.
C The most important skeletal differences between dinosaurs and other archosaurs are in the bones of the skull, pelvis and limbs. Dinosaur skulls are found in a great range of shapes and sizes, reflecting the different eating habits and lifestyles of a large and varied group of animals that dominated life on Earth for an extraordinary 165 million years. However, unlike the skulls of any other known animals, the skulls of dinosaurs had two long bones known as vomers. These bones extended on either side of the head, from the front of the snout to the level of the holes in the skull known as the antorbital fenestra, situated in front of the dinosaur's orbits, or eye sockets.
D All dinosaurs, whether large or small, quadrupedal or bipedal, fleet-footed or slow-moving, shared a common body plan. Identification of this plan makes it possible to differentiate dinosaurs from any other types of animal, even other archosaurs. Most significantly, in dinosaurs, the pelvis and femur had evolved so that the hind limbs were held vertically beneath the body, rather than sprawling out to the sides like the limbs of a lizard. The femur of a dinosaur had a sharply in-turned neck and a ball-shaped head, which slotted into a fully open acetabulum or hip socket. A supra-acetabular crest helped prevent dislocation of the femur. The position of the knee joint, aligned below the acetabulum, made it possible for the whole hind limb to swing backwards and forwards. This unique combination of features gave dinosaurs what is known as a "fully improved gait". Evolution of this highly efficient method of walking also developed in mammals, but among reptiles it occurred only in dinosaurs.
E For the purpose of further classification, dinosaurs are divided into two orders: Saurischia or saurischian dinosaurs, and Ornithischia or ornithischian dinosaurs. This division is made on the basis of their pelvic anatomy. All dinosaurs had a pelvic girdle with each side comprised of three bones: the pubis, ilium and ischium. However, the orientation of these bones follows one of two patterns. In saurischian dinosaurs, also known as lizard-hipped dinosaurs, the pubis points forwards, as is usual in most types of reptile. By contrast, in ornithischian or bird-hipped dinosaurs, the pubis points backwards towards the rear of the animal, which is also true of birds.
F Of the two orders of dinosaurs, the Saurischia was the larger and the first to evolve. It is divided into two suborders: Therapoda or therapods, and Sauropodomorpha or sauropodomorphs. The therapods or "beast feet" were bipedal, predatory carnivores. They ranged in size from the mighty Tyrannosaurus rex, 12m long, 5.6m tall and weighing an estimated 6.4 tonnes, to the smallest known dinosaur, Compsognathus, merely 1.4m long and estimated 3kg in weight when fully grown. The sauropodomorphs or "lizard feet forms" included both bipedal and quadrupedal dinosaurs. Some sauropodomorphs were carnivorous or omnivorous, but later species were typically herbivorous. They included some of the largest and best known of all dinosaurs, such as Diplodocus, a huge quadruped with an elephant-like body, a long, thin tail and neck that gave it a total length of 27m and a tiny head.
G Ornithischian dinosaurs were bipedal or quadrupedal herbivores. They are now usually divided into three suborders: Ornithopoda, Thyreophora and Marginocephalia. The ornithopods or "bird feet", both large and small, could walk or run on their long hind legs, balancing their body by holding their tails stiffly off the ground behind them. An example is Iguanodon, up to 9m long, 5m tall and weighing 4.5 tonnes. The thyreophorans or "shield bearers", also known as armoured dinosaurs, were quadrupeds with rows of protective bony spikes, studs, or plates along their backs and tails. They included Stegosaurus, 9m long and weighing 2 tonnes.
H The marginocephalians or "margined heads" were bipedal or quadrupedal ornithischians with a deep bony frill or narrow shelf at the back of the skull. An example is Triceratops, a rhinoceros-like dinosaur, 9m long, weighing 5.4 tonnes and bearing a prominent neck frill and three large horns.
Questions
Questions 27–33 Matching Headings
Choose the correct heading for each paragraph from the list of headings below.
i. 165 million years
ii. The body plan of archosaurs
iii. Dinosaurs - terrible lizards
iv. Classification according to pelvic anatomy
v. The suborders of Saurischia
vi. Lizards and dinosaurs - two distinct superorders
vii. Unique body plan helps identify dinosaurs from other animals
viii. Herbivore dinosaurs
ix. Lepidosaurs
x. Frills and shelves
xi. The origins of dinosaurs and lizards
xii. Bird-hipped dinosaurs
xiii. Skull bones distinguish dinosaurs from other archosaurs
Questions 34–36 Sentence Completion
Complete the sentences below with NO MORE THAN THREE WORDS from the passage for each answer.
- Lizards and dinosaurs are classified into two different superorders because of the difference in their 34.
- In the Triassic Period, 35 evolved into thecodonts, for example, lizards and snakes.
- Dinosaur skulls differed from those of any other known animals because of the presence of vomers: 36.
Questions 37–40 Matching Sentence Endings
Choose one phrase from the list of features to match with the dinosaurs listed below.
NB You may use each letter once only.
A. are both divided into two orders
B. the former had a "fully improved gait"
C. were not usually very heavy
D. could walk or run on their back legs
E. their hind limbs sprawled out to the sides
F. walked or ran on four legs rather than two
G. both had a pelvic girdle comprising six bones
H. did not always eat meat
Answers & Explanations Summary
| # | Answer | Evidence | Explanation |
|---|---|---|---|
| Q27 | vi | However, at the next level of classification, within reptiles, significant differences in the skeletal anatomy of lizards and dinosaurs have led scientists to place these groups of animals into two different superorders: Lepidosauria or lepidosaurs, and Archosauria or archosaurs | Excerpt/Passage Explanation: The passage says that scientists saw big differences in the bones of lizards and dinosaurs. Because of these differences, scientists put them in two separate big groups. One group is named Lepidosauria, which includes lizards. The other group is named Archosauria, which includes dinosaurs. Answer Explanation: The answer means that Paragraph A is about how lizards and dinosaurs are separate and belong to two different large groups. Reason For Correctness: The correct answer is chosen because Paragraph A explains that even though both dinosaurs and lizards are reptiles, scientists have placed them in two separate groups, called superorders. The paragraph names these two groups: Lepidosauria for lizards and Archosauria for dinosaurs. This shows they are 'distinct', or different. |
| Q28 | xi | Palaeontologists believe that both dinosaurs and crocodiles evolved, in the later years of the Triassic Period (c248-208 million years ago), from creatures called pseudosuchian thecodonts. Lizards, snakes and different types of thecodont are believed to have evolved earlier in the Triassic Period from reptiles known as eosuchians | Excerpt/Passage Explanation: The passage says that scientists think dinosaurs and crocodiles came from an animal called a 'pseudosuchian thecodont'. It also says that lizards and snakes came from an animal called an 'eosuchian'. The word 'evolved' means they developed from these older animals. This tells us about their beginnings, or 'origins'. Answer Explanation: The answer means the paragraph is about where dinosaurs and lizards came from in history. Reason For Correctness: The correct answer is 'xi' because Paragraph B talks about the history of dinosaurs and lizards. It says that scientists believe dinosaurs and lizards 'evolved', which means they developed from older animals. The paragraph names the specific reptile groups that dinosaurs and lizards came from. The word 'origins' in the heading means the beginning or start of something, which is what 'evolved' describes. |
| Q29 | xiii | However, unlike the skulls of any other known animals, the skulls of dinosaurs had two long bones known as vomers | Excerpt/Passage Explanation: The passage says that dinosaur heads (skulls) were different from the skulls of all other animals. This is because dinosaur skulls had two special long bones called 'vomers' that no other animal had. Answer Explanation: The answer means that Paragraph C is about the special bones in a dinosaur's head, or skull, that made them different from other reptile-like animals called archosaurs. Reason For Correctness: The correct answer is 'xiii' because Paragraph C focuses on what makes a dinosaur's skull unique. The paragraph starts by mentioning that one of the most important differences ('skeletal differences') between dinosaurs and other archosaurs is in their skull bones. It then describes a specific feature, the 'vomers', which were two long bones in the skull that only dinosaurs had. This information about unique skull bones directly matches the heading 'Skull bones distinguish dinosaurs from other archosaurs'. |
| Q30 | vii | All dinosaurs, whether large or small, quadrupedal or bipedal, fleet-footed or slow-moving, shared a common body plan. Identification of this plan makes it possible to differentiate dinosaurs from any other types of animal, even other archosaurs | Excerpt/Passage Explanation: The passage says that no matter if dinosaurs were big or small, or walked on two or four legs, they all had the same basic body structure. Knowing this special body structure helps us tell dinosaurs apart from all other animals. Answer Explanation: The answer means that the special way a dinosaur's body was built helps us to know that it is a dinosaur and not another kind of animal. Reason For Correctness: The correct answer is chosen because Paragraph D explains that all dinosaurs had a specific "body plan". The paragraph then says that understanding this plan is how we can "differentiate" or tell the difference between dinosaurs and other animals. It describes unique features, like how their legs were under their bodies, which was different from other reptiles. |
| Q31 | iv | For the purpose of further classification, dinosaurs are divided into two orders: Saurischia or saurischian dinosaurs, and Ornithischia or ornithischian dinosaurs. This division is made on the basis of their pelvic anatomy | Excerpt/Passage Explanation: The passage says that to organize or 'classify' dinosaurs more, they are separated into two main groups. This separation, or 'division', is decided by looking at the structure of their hip bones, which is called 'pelvic anatomy'. Answer Explanation: The answer means that dinosaurs are put into different groups based on the shape and structure of their hip bones. Reason For Correctness: The correct answer is 'Classification according to pelvic anatomy' because Paragraph E explains how scientists divide dinosaurs into two main groups or 'orders'. The paragraph clearly states that this 'division is made on the basis of their pelvic anatomy', which means the structure of their hip bones. It then describes the two types of hip structures found in dinosaurs, showing how this classification works. |
| Q32 | v | It is divided into two suborders: Therapoda or therapods, and Sauropodomorpha or sauropodomorphs | Excerpt/Passage Explanation: The passage says that the Saurischia group of dinosaurs is split into two smaller groups. These smaller groups are called suborders. The names of the two suborders are Therapoda (therapods) and Sauropodomorpha (sauropodomorphs). Answer Explanation: The answer means that the paragraph is mainly about the different groups within the Saurischia type of dinosaur. These smaller groups are called 'suborders'. Reason For Correctness: The correct answer is 'v' because paragraph F introduces one of the main dinosaur orders, Saurischia. It then clearly states that this order is 'divided into two suborders'. The rest of the paragraph is dedicated to describing these two suborders, named Therapoda and Sauropodomorpha, and providing examples for each. The heading 'The suborders of Saurischia' perfectly summarises the main topic of this paragraph. |
| Q33 | viii | Ornithischian dinosaurs were bipedal or quadrupedal herbivores | Excerpt/Passage Explanation: The passage says that this group of dinosaurs, called Ornithischians, were 'herbivores'. This is a scientific word for animals that only eat plants. Answer Explanation: The answer means the paragraph is about dinosaurs that only ate plants. Reason For Correctness: The correct answer is 'Herbivore dinosaurs' because the first sentence of the paragraph clearly states that Ornithischian dinosaurs were 'herbivores'. The word 'herbivores' means animals that eat plants. The paragraph then gives examples of these plant-eating dinosaurs. |
| Q34 | skeletal anatomy | However, at the next level of classification, within reptiles, significant differences in the skeletal anatomy of lizards and dinosaurs have led scientists to place these groups of animals into two different superorders: Lepidosauria or lepidosaurs, and Archosauria or archosaurs | Excerpt/Passage Explanation: The passage says that there are important ('significant') differences in the bone structure ('skeletal anatomy') of lizards and dinosaurs. Because of these differences, scientists decided to put them into two separate big groups ('superorders'). Answer Explanation: The answer means the way their skeletons, or bones, are built. Reason For Correctness: The correct answer is 'skeletal anatomy' because the passage says this is the reason scientists put lizards and dinosaurs into different groups called 'superorders'. The passage states there are 'significant differences in the skeletal anatomy' between the two. |
| Q35 | eosuchians | Lizards, snakes and different types of thecodont are believed to have evolved earlier in the Triassic Period from reptiles known as eosuchians | Excerpt/Passage Explanation: The passage says that scientists believe that lizards, snakes, and certain kinds of thecodonts developed from an older group of reptiles named 'eosuchians'. 'Evolved from' means they came from this older group. Answer Explanation: The answer 'eosuchians' is the name for a group of very old reptiles that lived a long time ago. Reason For Correctness: The correct answer is 'eosuchians' because the passage talks about how different animals developed during the Triassic Period. It says that lizards, snakes, and some types of thecodonts are thought to have 'evolved from' a group of reptiles called 'eosuchians'. This means that eosuchians were the animals that later turned into lizards, snakes, and thecodonts. |
| Q36 | two long bones | However, unlike the skulls of any other known animals, the skulls of dinosaurs had two long bones known as vomers | Excerpt/Passage Explanation: The passage says that dinosaur skulls were different from the skulls of all other animals. This difference was because the dinosaur skulls had 'two long bones known as vomers.' This means that 'vomers' are a pair of long bones. Answer Explanation: The answer means that vomers are two bones that are long. Reason For Correctness: The correct answer is 'two long bones' because the question asks for a description of 'vomers,' which made dinosaur skulls different from other animals. The passage states that what made dinosaur skulls unique ('unlike the skulls of any other known animals') was that they 'had two long bones known as vomers.' This phrase directly defines vomers as 'two long bones'. |
| Q37 | B | Most significantly, in dinosaurs, the pelvis and femur had evolved so that the hind limbs were held vertically beneath the body, rather than sprawling out to the sides like the limbs of a lizard. The femur of a dinosaur had a sharply in-turned neck and a ball-shaped head, which slotted into a fully open acetabulum or hip socket. A supra-acetabular crest helped prevent dislocation of the femur. The position of the knee joint, aligned below the acetabulum, made it possible for the whole hind limb to swing backwards and forwards. This unique combination of features gave dinosaurs what is known as a "fully improved gait" | Excerpt/Passage Explanation: The passage says that a very important difference is that dinosaurs' back legs were straight under their bodies. Lizards' legs, on the other hand, stick out to the sides. This special leg and hip structure allowed dinosaurs to swing their legs forwards and backwards easily. The passage calls this special way of walking a 'fully improved gait'. Answer Explanation: The answer means that dinosaurs were different from lizards because dinosaurs had a very good and effective way of walking. Reason For Correctness: The correct answer is 'B' because the passage explains that dinosaurs' legs were positioned directly under their bodies, which was different from lizards whose legs spread out to the sides. The passage calls this special and efficient way of walking a 'fully improved gait' and says it was unique to dinosaurs among reptiles. |
| Q38 | G | All dinosaurs had a pelvic girdle with each side comprised of three bones: the pubis, ilium and ischium | Excerpt/Passage Explanation: The passage says that every dinosaur had hip bones called a 'pelvic girdle'. This part of the body had two sides, and each side was made of three bones. This means both Saurischian and ornithischian dinosaurs had this feature. Answer Explanation: The answer means that both types of dinosaurs, Saurischian and ornithischian, had a hip structure (pelvic girdle) made of a total of six bones. Reason For Correctness: The correct answer is G because the passage states that all dinosaurs, which are divided into the Saurischian and Ornithischian orders, had a pelvic girdle. It explains that this girdle had two sides, and each side was made of three bones. Two sides with three bones each means a total of six bones. |
| Q39 | H | The therapods or 'beast feet' were bipedal, predatory carnivores Some sauropodomorphs were carnivorous or omnivorous, but later species were typically herbivorous |
Excerpt/Passage Explanation: The passage first states that therapods were 'carnivores', which means they were animals that eat meat. Then, the passage says that sauropodomorphs could be 'carnivorous' (ate meat), 'omnivorous' (ate both plants and meat), or 'herbivorous' (ate plants). This means that sauropodomorphs had a mixed diet and did not only eat meat like the therapods did. Answer Explanation: The answer means that the food sauropodomorphs ate was not always meat. They could eat plants, meat, or both. Reason For Correctness: The correct answer is H because the passage describes the different diets of therapods and sauropodomorphs. It says that therapods were 'predatory carnivores', meaning they only ate meat. In contrast, it says sauropodomorphs could be 'carnivorous' (meat-eaters), 'omnivorous' (plant- and meat-eaters), or 'herbivorous' (plant-eaters). This shows that unlike therapods, sauropodomorphs had a varied diet and did not always eat meat. |
| Q40 | F | The ornithopods or 'bird feet', both large and small, could walk or run on their long hind legs, balancing their body by holding their tails stiffly off the ground behind them The thyreophorans or 'shield bearers', also known as armoured dinosaurs, were quadrupeds with rows of protective bony spikes, studs, or plates along their backs and tails |
Excerpt/Passage Explanation: The passage explains that one type of dinosaur, the ornithopod, walked on its two back legs and used its tail to keep its balance. Another type of dinosaur, the thyreophoran, was a 'quadruped', which means it walked on all four of its feet. Answer Explanation: The answer means that while some dinosaurs walked on two legs, other dinosaurs walked on four legs. Reason For Correctness: The correct answer is 'F' because the passage describes different ways dinosaurs moved. It explains that some dinosaurs, called ornithopods, walked on two back legs and used their tails to stay balanced. It also describes other dinosaurs, like thyreophorans, as 'quadrupeds'. The word 'quadruped' means an animal that walks on four feet. Therefore, the passage contrasts dinosaurs that walked on two legs with others that 'walked or ran on four legs rather than two.' |