Level 1 — Absolute Beginner
Scientists found a very old piece of fossilized dinosaur poop. It is 66 million years old. Inside the poop, there is a feather.
A big meat-eating dinosaur ate a bird a long, long time ago. The dinosaur might be a T-rex. The bird's feather stayed inside the dinosaur's poop, and now scientists can study it.
The feather comes from a small bird. This bird could swim very well, but it could not fly. Its group is called Hesperornithiformes.
A huge rock from space hit the Earth 66 million years ago. This bird's group did not survive. But some other kinds of birds did survive. Scientists study the feather to learn why.
- fossilized
- Turned into rock over a very long time.
- poop
- Waste that comes out of an animal's body.
- feather
- A soft, light part that covers a bird's body.
- scientist
- A person who studies how the world works.
- ancient
- Very, very old.
- swim
- To move through water using your body.
- fly
- To move through the air using wings.
- survive
- To stay alive.
Level 2 — Elementary
Scientists have studied a fossilized piece of dinosaur dropping that is 66 million years old, and inside it they found a remarkably well-preserved feather.
The dropping was discovered in Montana back in 2016, but researchers only published their full study about it in September 2026, in a journal called Current Biology.
Scientists believe a large meat-eating dinosaur, perhaps a Tyrannosaurus rex or a smaller relative called Nanotyrannus, swallowed a bird. The feather survived, preserved inside the dinosaur's fossilized dropping.
The feather likely belonged to a small bird that could not fly but was an excellent diver, somewhat like a modern loon. This bird belonged to an ancient group called Hesperornithiformes, and scientists think this group probably did not survive the disaster that wiped out the dinosaurs.
- dropping
- Waste material left behind by an animal.
- preserved
- Kept in good condition over a long time.
- researcher
- A person who studies a topic carefully to learn new facts.
- journal
- A publication where scientists share their studies.
- relative
- A living thing that is related to another by ancestry.
- diver
- An animal or person skilled at going underwater.
- disaster
- A sudden event that causes great harm.
- wipe out
- To destroy something completely.
Level 3 — Intermediate
A remarkably well-preserved feather has been discovered inside a 66-million-year-old coprolite, the scientific term for fossilized animal droppings, in a specimen that researchers describe as the finest example yet recovered from the age of dinosaurs.
The coprolite was unearthed in Montana in 2016, but a new analysis, published in the journal Current Biology in September 2026, has only now revealed what it contains. Researchers suspect that a large carnivorous dinosaur, possibly a Tyrannosaurus rex or its smaller relative Nanotyrannus, swallowed a bird whole, leaving a trace of the meal preserved inside its fossilized droppings.
The feather is believed to have belonged to a small, flightless diving bird from an extinct group called Hesperornithiformes, distant relatives of the well-known fossil bird Hesperornis and, in some respects, comparable to a modern loon. Some of these ancient diving birds combined sleek, waterproof outer feathers with fuzzier, more primitive body feathers, a combination also seen in non-avian dinosaurs and in another extinct bird group called enantiornithines.
Researchers suspect this less effective insulation may explain why groups such as the Hesperornithiformes and the enantiornithines perished in the impact winter that followed the asteroid strike 66 million years ago, while the ancestors of today's birds endured. The discovery offers a rare clue to a long-standing puzzle: why some birds survived the mass extinction that killed the dinosaurs while other, similarly built birds did not.
- coprolite
- The scientific term for a fossilized piece of animal dropping.
- carnivorous
- Feeding mainly on the flesh of other animals.
- specimen
- A single example used for scientific study.
- extinct
- No longer existing; died out completely.
- insulation
- A layer that helps keep something warm.
- ancestor
- An earlier relative from which a living thing descended.
- endure
- To continue existing through a difficult period.
- mass extinction
- An event in which very many species die out at once.
Level 4 — Advanced
Paleontologists have identified an exceptionally well-preserved feather entombed within a 66-million-year-old coprolite, a specimen its discoverers regard as the finest feather yet recovered from the age of dinosaurs. The fossilized dropping was unearthed in Montana in 2016, though its contents were only fully characterized in an analysis published in the journal Current Biology this September.
The prevailing interpretation holds that a large carnivorous dinosaur, either a Tyrannosaurus rex or its smaller relative Nanotyrannus, consumed a bird whole, and that remnants of the meal were preserved intact within the predator's droppings. What emerged is thought to be a feather from a small, flightless diving bird belonging to Hesperornithiformes, an extinct lineage related to the well-documented fossil bird Hesperornis and broadly comparable, in habit, to the modern loon.
The specimen is notable for what it reveals about plumage in this vanished lineage: alongside sleek, waterproof outer feathers suited to diving, these birds retained smaller, downier body feathers structurally reminiscent of those found on non-avian dinosaurs and on enantiornithines, another extinct group of birds from the age of dinosaurs. That combination stands in contrast to the plumage of Neornithes, the lineage from which all living birds descend.
Researchers now suspect that this comparatively primitive insulation may have proven fatal in the aftermath of the asteroid impact that ended the age of dinosaurs, when a prolonged impact winter would have placed a premium on the ability to retain body heat. If Hesperornithiformes and enantiornithines carried feathers less capable of conserving warmth than those of the Neornithes, that deficiency could help explain why these visually similar birds vanished alongside the dinosaurs while the ancestors of modern birds persisted, a rare thread connecting plumage, climate and survival.
- paleontologist
- A scientist who studies fossils and ancient life.
- entomb
- To enclose and preserve something, as if inside a tomb.
- lineage
- A line of descent from a shared ancestor.
- plumage
- The layer of feathers covering a bird.
- downy
- Covered in soft, fine, fluffy feathers.
- reminiscent
- Tending to remind one of something similar.
- deficiency
- A lack or shortage of something needed.
- persist
- To continue to exist over a long time.
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