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Pterosaurs had two stomachs for sorting food, bones and scales

The Sun, March 31, 2022 7:00PM Kids News

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Two pterosaur fossils from China dating to the Late Jurassic, with green arrows indicating the pellets; the yellow arrows indicate fish scales. Picture: Jiang et al/ Philosophical Transactions of the Royal Society B, 2022 media_cameraTwo pterosaur fossils from China dating to the Late Jurassic, with green arrows indicating the pellets; the yellow arrows indicate fish scales. Picture: Jiang et al/ Philosophical Transactions of the Royal Society B, 2022


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Pterosaurs swallowed their prey* whole and spat out the bones, scientists have found.

Newly discovered fossils suggest giant flying pterosaurs had two ­stomachs – one for digesting* food and another for collecting inedible* bones and scales.

It means their bigger land-based dinosaur cousins, such as the mighty T-Rex, probably did the same.

“The two-part stomach could have evolved early on, adding credence* to the hypothesis* that it was common to all dinosaurs,” said Beijing’s Chinese Academy of Sciences Dr Shunxing Jiang.

Modern birds all have two stomachs and some, such as the owl, still swallow food whole and regurgitate* the bones. The parts they spit out are known as pellets.

A young pterosaur and the pellet (dark brown circle, left) of fish scales it regurgitated shortly before its death have been preserved in stone for more than 100 million years. Credit: Jiang Shunxing et al. / Philosophical Transactions of the Royal Society B, 2022 media_cameraFossils of the juvenile pterosaur and a pellet – the dark brown circle pictured left – made of fish scales that the pterosaur regurgitated shortly before its death. Picture: Jiang Shunxing et al/Philosophical Transactions of the Royal Society B, 2022

A team of Chinese palaeontologists* last month announced in the journal Philosophical* Transactions* of the Royal Society B the discovery of two finely preserved pterosaurs – one adult and one juvenile – and the pellets left over from parts of their meals.

The fossilised pellets, found outside the pterosaurs’ bodies, contained scales from an unknown species of fish.

The pellets were wider than the pterosaurs’ pelvises, suggesting they could not have been passed through the animals’ bowels.

All modern-day birds have two-part stomachs. In owls, this second chamber is called the gizzard and collects bone, teeth and fur, which is later expelled*.

Like owls, pterosaurs did not chew their food.

Birds of Prey media_cameraLike Late Jurassic pterosaurs, owls have two-part stomachs for managing prey that is swallowed whole. Pictured is Lucy, a beautiful barn owl. Picture: David Caird

“Most pterosaurs cannot chew their food because their teeth did not have the structure for chewing,” Dr Jiang told Live Science. “Also, some nearly complete fish were found in the stomachs of pterosaurs and it is apparent that the fish were not chewed.”

The pterosaur and nearby pellet fossils were found in northeast China.

The flying predators* would have lived in the forests surrounding the region’s lakes in the Late Jurassic period about 160 million years ago.

The two specimens are thought to have died and sunk into deep water, where their bodies were covered by soft sediment*.

Pterosaurs first emerged 250 million years ago before becoming extinct* with the rest of the dinosaurs 65 million years ago.

Pterosaur Quetzalcoatlus media_cameraPterosaurs first emerged around 250 million years ago. This computer-generated 3D illustration depicts the pterosaur species Quetzalcoatlus, a North American species unrelated to the fossils discovered in China.

This story was originally published by The Sun and is reproduced here with permission.


  • prey: animal that is hunted, killed and eaten by another animal
  • digesting: breaking down food so it can be absorbed by the body
  • inedible: not suitable or fit for eating
  • credence: acceptance, support, or belief that something is true
  • hypothesis: idea or explanation for something based on known facts but still unproven
  • regurgitate: act of bringing swallowed food back up to the mouth
  • philosophical: relating to philosophy, the study of the nature of reality and existence
  • transactions: instances of something being exchanged, in this case ideas
  • palaeontologists: specialist in studying fossils to learn about the history of life on Earth
  • expelled: let out, discharged, ejected, excreted
  • predators: an animal that hunts, kills, and eats other animals
  • sediment: matter that settles at the bottom of a liquid
  • extinct: died out, no longer exists


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  1. What were the two stomachs used for?
  2. Which modern bird swallows food whole and regurgitates the bones?
  3. All modern-day birds have what?
  4. Where were the pterosaur and pellet fossils found and how old are they thought to be?
  5. Pterosaurs first emerged in what era how many years ago?


1. Think about it
Why do you think humans have only one stomach? Write down as many reasons that you can think of.

Time: allow 30 minutes to complete this activity
Curriculum Links: English, Science, Critical and Creative Thinking

2. Extension
The scales from an unknown species of fish were found near the pterosaur. What do you think a fish that lived 160 million years ago would have looked like? Use your imagination and information in the story to create a picture and write a description of a Late Jurassic fish. Don’t forget to give it a name.

Time: allow 30 minutes to complete this activity
Curriculum Links: English, Science

Chew your food!
Wow! How many times has an adult told you to chew your food? Clearly, the pterosaurs’ parents did not bother.

Can you show your knowledge of the article by completing these sentence fragments? You will need to fix the punctuation as well.

– pterosaurs swallowed
– first emerged 250 million
– land-based dinosaur cousins

You can check the article to see how you went.

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