雅思阅读 26: A Feather in the Dung（粪便里的羽毛）

改编自 Field Museum / ScienceDaily（2026年9月）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://www.sciencedaily.com/releases/2026/09/260911003849.htm

Reading Passage

A. Sixty-six million years ago, a large predatory dinosaur — possibly a young Tyrannosaurus rex, possibly a smaller relative called Nanotyrannus — swallowed a bird. Sometime later, it defecated. The dropping fossilised in the mud of a river floodplain, and was not seen again until 2016, when a research scientist crawled over a rocky outcrop in northeastern Montana collecting fish fossils and picked up a dark, reddish-brown nodule about half the size of a golf ball. Viewed through a hand lens, its surface bore a tiny fossil feather. Published in Current Biology in September 2026, the specimen is not merely the best-preserved feather ever recovered from the age of dinosaurs. It is, according to its lead author Jingmai O'Connor of the Field Museum in Chicago, a clue to one of palaeontology's most enduring puzzles: why, when an asteroid wiped out the dinosaurs, did one branch of feathered dinosaurs — the ancestors of every living bird — survive while all the others vanished?

B. The bird that was eaten was a hesperornithiform: a flightless, loon-like diver that used lobed feet to pursue fish in Cretaceous lakes and shallow seas. Along with the feathers, the coprolite contained tiny scales from a gar fish and the leg bones of the bird itself, all preserved in three dimensions inside the mineralised dropping. Gar scales are tough, enamel-coated structures that fossilise readily, and their presence alongside the bird bones confirms that the predator had been feeding in or near fresh water, not on land. Because the feathers and the bones occurred together, the team concluded they belonged to the same animal — the dinosaur had swallowed a bird, and whatever it did not digest had been preserved for them. Hesperornithiforms were close cousins of the birds that survived the extinction, but they were not on the surviving branch. Their lineage vanished along with the enantiornithines — the most numerous birds of the Cretaceous, which had sparrow-like bodies and clawed wings — and with every other group of non-avian dinosaurs. The only lineage that made it through is Neornithes, the group from which all roughly eleven thousand living bird species descend, from hummingbirds to ostriches. The survival of that one lineage, against so many close competitors, is the puzzle the coprolite was preserved to help solve.

C. Why Neornithes alone endured has long been contested. One influential hypothesis pointed to habitat: many early neornithines lived in or near fresh water, and it was suggested that aquatic environments might have buffered them against the devastation that followed the impact — the sun-blocking dust, the collapse of plant life, the decades-long cold known as the impact winter. Birds that fed on fish or aquatic plants, the reasoning went, might have had access to food that did not depend on forests that were dying. The new feather complicates that story. Hesperornithiforms were also aquatic, perhaps more aquatic than the early neornithines: they could not even walk well on land. They lived in the same lakes and shallow seas, dove after the same fish, and were still extinct. Aquatic habitat, it seems, was necessary but not sufficient. The feathers themselves, O'Connor argues, may hold the answer that habitat alone could not provide.

D. The feather's structure is transitional. Some of it looks modern: tightly interlocked, waterproof barbs adapted for an underwater life, of a kind that living loons and grebes use. But mixed in are smaller, fuzzy, primitive body feathers of a kind previously known from non-avian dinosaurs and enantiornithines, not from living birds. Body feathers matter because they insulate. In the months after the asteroid struck, sunlight was reduced to a fraction of its normal level; temperatures dropped; plants died; food chains collapsed. A bird with inefficient plumage — one that lost heat too quickly, or that could not replace its feathers quickly enough when the impact winter set in — would have been at a severe disadvantage. The hesperornithiform's mixed plumage may have been adequate in the warm, stable Cretaceous but inadequate in the sudden cold. The neornithines that survived, the reasoning goes, were those whose body feathers trapped heat most effectively, or whose moulting schedule let them replace damaged plumage fast enough to stay alive through the years of darkness. A bird that moulted gradually, as modern ducks and pigeons do, could keep flying and feeding while it replaced feathers; a bird that moulted all at once, as some primitive birds may have done, would have been grounded and vulnerable for weeks at a time.

E. The specimen is also a detective story of a different kind. The team did not start with a complete skeleton. They started with a lump of rock, and used CT scanning — thousands of X-rays combined into a three-dimensional digital view — to reveal, layer by layer, what the dung had trapped: feathers, scales, bone. Nobody had previously thought to look for feathers in coprolites, and O'Connor suspects the same technique applied to museum drawers full of unstudied fossil droppings may yield similar prizes. The specimen captures, in the end, two moments at once: the instant a predator made a meal of a diver, and the longer catastrophe that decided which birds, sixty-six million years later, would be the ones still waking us at dawn. It also reminds us that the most unlikely objects — a lump of fossilised dung — can carry the most unexpected evidence. The team cautions, however, that a single feather from a single coprolite is a thin thread on which to hang a grand theory of extinction; many more such specimens, and many more CT scans of unpromising lumps, will be needed before the story is secure. Palaeontology, after all, has a long history of elegant explanations that turned out, on the next specimen, to be wrong.

Questions 1-4

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

List of Headings i. What was inside the droppings, and who was eaten ii. The CT-scan detective work and its limits iii. A survival hypothesis that the new feather complicates iv. How Tyrannosaurus rex is identified v. Why feather insulation may have decided the extinction vi. The day the asteroid struck vii. Why Montana is good for fish fossils

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 was the nodule that David DeMar picked up in 2016? A. A complete T. rex skeleton. B. A fossilised dropping containing a feather. C. A piece of amber. D. A modern bird egg.

6. Why is the hesperornithiform important to the survival debate? A. It was the ancestor of all modern birds. B. It was aquatic yet still went extinct, weakening the aquatic-habitat hypothesis. C. It could fly better than any modern bird. D. It survived the asteroid impact.

7. What does the feather's structure suggest? A. It was entirely modern. B. It was a mixture of modern waterproof parts and primitive fuzzy insulation. C. It was made of metal. D. It came from a mammal.

8. How did the team see inside the coprolite? A. By dissolving the rock in acid. B. By CT scanning it without destroying it. C. By cutting it in half. D. By waiting for a palaeontologist to guess.

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. The coprolite was found in Montana.
10. Hesperornithiforms were close relatives of the birds that survived the extinction.
11. Aquatic living alone explains why Neornithes survived.
12. The team found the coprolite by using CT scanning on museum drawers.
13. Enantiornithines are the ancestors of all modern birds.

Questions 14-15

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

The bird inside the coprolite was a (14) __________, a flightless diver; its mixed plumage may have been inadequate for the cold that followed the (15) __________.

答案与解析

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