雅思阅读 76: Feathered Dinosaurs and the Rise of Birds（带羽毛恐龙与鸟类的崛起）

改编自 Palaeontology reviews / IVPP（2025）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://bynumpedia.com/paleontology/dinosaur-to-bird-transition

Reading Passage

A. Few transformations in the history of life are as well documented as the one that turned a ground-dwelling predatory dinosaur into a flying bird. Biologists now accept that birds are not merely related to dinosaurs — they are dinosaurs, the living descendants of a group of small, feathered, two-legged predators known as maniraptorans. The transition unfolded over roughly a hundred million years, during which a lineage of bipedal theropods gradually altered its size, skeleton, skin covering and way of moving until it produced the group that today includes every sparrow, hawk and penguin. What makes the story remarkable is the sheer volume of evidence supporting it. Hundreds of fossils, many preserved with exquisite detail in fine lake sediments, reveal feathered non-avian dinosaurs, four-winged gliders and toothed birds arranged along an almost continuous gradient from earthbound hunter to powered flier. Familiar features once thought unique to birds — feathers, hollow bones, a wishbone, a deep breastbone — turn out to have appeared piecemeal, at different points on the family tree, long before the origin of flight itself.

B. The story's most famous fossil is Archaeopteryx, unearthed in a limestone quarry at Solnhofen in Bavaria in 1861 and dating to roughly 150 million years ago. It is a near-perfect mosaic: a toothed jaw, clawed fingers and a long bony tail, inherited from dinosaurs, alongside fully formed, asymmetrical flight feathers and a wishbone characteristic of birds. The English biologist Thomas Henry Huxley used just such similarities in the 1860s to argue that birds had descended from dinosaurs. That idea fell out of favour for most of the twentieth century, only to be revived in 1969 when the American palaeontologist John Ostrom described Deinonychus, a swift predator whose wrist, hand and shoulder echoed a bird's. In 1986 a comprehensive family-tree analysis finally placed birds firmly inside the dinosaur group, as a subgroup of the maniraptorans — the same branch that includes the sickle-clawed dromaeosaurids. The dividing line between "non-avian dinosaur" and "bird", it turned out, is not a sharp edge but an arbitrary mark drawn across a smooth, graded series of forms, each differing from the last by only a few anatomical details. This is why the fossil has so often featured in textbook debates about evolution: it sits squarely on the boundary between two groups, possessing the raw tools of flight while still carrying the teeth, claws and long tail of its predatory ancestors. Newer specimens continue to blur the line further, and some researchers now argue that Archaeopteryx itself may not be a true bird at all, but one branch of a broad family of feathered dinosaurs that includes the direct ancestors of today's birds.

C. The decisive confirmation came from China. In 1996, scientists working in Liaoning Province in the north-east described Sinosauropteryx, a small predatory dinosaur whose back, neck and tail were fringed with simple, unbranched filaments — the earliest known stage in the evolution of a feather. Crucially, Sinosauropteryx sat far from birds on the family tree, which meant that feather-like structures must have arisen long before birds themselves, among dinosaurs that never flew. Over the following decades, dozens of feathered species poured out of the same ancient lake beds. They ranged from a tiny gliding predator to a giant relative of Tyrannosaurus, proving that feathers were not a bird's private invention but a dinosaurian inheritance shared across a vast and varied family. The earliest feathers were simple insulating or decorative filaments; the intricate, branching structures of modern wings developed only later, as the avian lineage took to the air.

D. Some of the new fossils overturned old assumptions about how flight began. In 2003, researchers described Microraptor gui, a crow-sized predator that bore long, asymmetrical flight feathers on all four limbs — wings on its arms and matching plumes on its legs, producing a "four-winged" body plan with no exact living counterpart. It is now interpreted as a glider that probably spread its feathered limbs like a parachute and coasted between trees. Other finds pushed the origin of feathers further back in time: Anchiornis, a small dinosaur from the Late Jurassic, sported plumage on its head, arms, legs and tail, and predated even Archaeopteryx. At the opposite extreme, Yutyrannus, a relative of Tyrannosaurus weighing roughly 1,400 kilograms, was covered in filaments up to 20 centimetres long, showing that even gigantic theropods could be feathered. Flight, it seems, was not the reason feathers first evolved; feathers were recruited for flight only after they had existed for millions of years serving other purposes.

E. Taken together, these discoveries rewrite the narrative of bird origins. There was never a single moment at which a dinosaur became a bird, no first pair of wings unfurled in one evolutionary leap. Instead, familiar avian features were assembled one by one across tens of millions of years, while a sustained trend toward smaller body size — a miniaturisation that lasted at least fifty million years — lightened the body and accelerated skeletal change until powered flight became physically possible. The boundary experts draw between dinosaurs and birds is, in this light, a convenience rather than a fact of nature. It also carries a sobering lesson about extinction: the giant feathered predators, four-winged gliders and toothed early birds are all gone, and only one branch of that once-diverse dynasty survives — the 10,000 or so bird species that fill the skies today, each one a living theropod dinosaur in feathers. That single surviving branch outlasted a meteor strike and the disappearance of almost all its relatives, adapting to habitats from the Arctic to the open ocean. In a very real sense, then, dinosaurs did not vanish entirely when the asteroid fell. They simply shrank, took to the air, and kept on evolving — a reminder that the boundary between triumph and survival is thinner than the drama of extinction suggests.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. Archaeopteryx and the century-long scientific debate ii. How Chinese fossils confirmed the dinosaur link iii. Four-winged gliders and early experiments in flight iv. Piecemeal change and the surviving feathered legacy v. Why the dinosaurs all died out 66 million years ago vi. Powered flight evolving in a single sudden leap vii. How warm-bloodedness replaced scales

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. What is the modern scientific view of birds' origins? A. Birds evolved from early flying mammals. B. Birds are themselves living theropod dinosaurs. C. Birds appeared suddenly, unrelated to dinosaurs. D. Birds are a kind of lizard, not a dinosaur.

6. Why was the 1996 discovery of Sinosauropteryx important? A. It was the very first bird ever discovered. B. It was a non-avian dinosaur bearing simple filamentous feathers. C. It proved that no dinosaur had feathers. D. It could fly farther than most modern birds.

7. What was unusual about Microraptor gui? A. It had flight feathers on all four limbs, forming a "four-winged" body plan. B. It was the largest predator of its time. C. It had no feathers on its limbs. D. It lived long after modern birds had appeared.

8. What does the passage conclude about the origin of feathers? A. Feathers evolved specifically for powered flight from the start. B. Feathers arose long before flight, probably for insulation or display. C. Feathers evolved only in animals that could already fly. D. Feathers were first invented by Archaeopteryx.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. Archaeopteryx was discovered in a limestone quarry in Bavaria.
10. Sinosauropteryx possessed fully formed asymmetrical flight feathers.
11. Yutyrannus weighed approximately 1,400 kilograms.
12. Archaeopteryx is known to have made long, powered, flapping flights.
13. Archaeopteryx lived around 150 million years ago.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

The earliest feathers were simple (14) __________ filaments used for insulation or display, and were only later co-opted for (15) __________.

答案与解析

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