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Inte Writing

The lecture challenges the idea that dinosaurs were endotherms by highlighting that the presence of Haversian canals is not exclusive to endotherms, as some ectothermic animals also possess them. Additionally, it argues that the leg positioning of dinosaurs could be attributed to other factors rather than being a definitive indicator of endothermy. Lastly, the lecture questions the interpretation of fossil locations, suggesting that polar fossils may not necessarily imply endothermic activity in dinosaurs.

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8 views1 page

Inte Writing

The lecture challenges the idea that dinosaurs were endotherms by highlighting that the presence of Haversian canals is not exclusive to endotherms, as some ectothermic animals also possess them. Additionally, it argues that the leg positioning of dinosaurs could be attributed to other factors rather than being a definitive indicator of endothermy. Lastly, the lecture questions the interpretation of fossil locations, suggesting that polar fossils may not necessarily imply endothermic activity in dinosaurs.

Uploaded by

202411226
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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Test 4

Reading Time – 3 minutes

Endotherms are animals such as modern birds and mammals that keep their body
temperatures constant. For instance, humans are endotherms and maintain an
internal temperature of 37°C, no matter whether the environment is warm or cold.
Because dinosaurs were reptiles, and modern reptiles are not endotherms, it was long
assumed that dinosaurs were not endotherms. However, dinosaurs differ in many
ways from modem reptiles, and there is now considerable evidence that dinosaurs
were, in fact, endotherms.

Polar dinosaurs
One reason for believing that dinosaurs were endotherms is that dinosaur fossils have
been discovered in polar regions. Only animals that can maintain a temperature well
above that of the surrounding environment could be active in such cold climates.

Leg position and movement


There is a connection between endothermy and the position and movement of the
legs. The physiology of endothermy allows sustained physical activity, such as
running. But running is efficient only if an animal's legs are positioned underneath its
body, not at the body's side, as they are for crocodiles and many lizards. The legs of
all modern endotherms are underneath the body, and so were the legs of dinosaurs.
This strongly suggests that dinosaurs were endotherms.

Haversian canals
There is also a connection between endothermy and bone structure. The bones of
endotherms usually include structures called Haversian canals. These canals house
nerves and blood vessels that allow the living animal to grow quickly, and rapid body
growth is in fact a characteristic of endothermy. The presence of Haversian canals in
bone is a strong indicator that the animal is an endotherm, and fossilized bones of
dinosaurs are usually dense with Haversian canals.

Now listen to part of a lecture on the topic you just read about.

Q Summarize the points made in the lecture, being sure to specifically explain how they cast
doubt on specific points made in the reading passage.

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