Dinosaurs - Were they warm- or cold-blooded?


For a long time scientists have been trying to find out if dinosaurs were warm- or cold-blooded. For some time they thought that dinosaurs, which became extinct 65 million years ago, were reptiles and therefore cold-blooded like their successors.

In today's world, creatures are either warm-blooded, with a constant body temperature or cold-blooded, with a body temperature that changes in the world around them.

New facts suggest that they might have been neither, and both at the same time. Today, tuna fish, white sharks and leatherback turtles are animals that fall into this category.

In recent research, scientists have started comparing dinosaur bones to those of modern mammals. Similar to the rings of a tree, examining bones can show you how fast an animal grows or gains weight. According to the results, they had growth rates and metabolic rates that are somewhere in-between warm- and cold-blooded animals. Information shows that dinosaurs had high a metabolic rate, letting them to grow faster. This allowed dinosaurs to get bigger than they would normally have become. Warm-blooded animals, mammals and birds, usually eat a lot to keep up their body temperature.

Cold-blooded animals need less food and are rather slow in their movements. While this is the case with most dinosaurs, there were also some, like the Tyrannosaurus rex, that were rather fast.


Triceratops horridus - Nobu Tamura (http://spinops.blogspot.com)




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  • according to = look at …
  • category = group
  • compare = look at two things  closely, side by side
  • constant = always the same
  • creature = something living
  • examine = to look at closely
  • extinct = die out; not survive
  • gain weight = become heavier
  • growth rate = how fast an animal grows
  • keep up = maintain, hold
  • mammal = animal that drinks milk from its mother when it is young; humans, dogs and whales are mammals
  • metabolic rate = how fast food is changed into energy
  • movement = move from one place to another
  • neither = here: none of both
  • rather = somewhat, quite
  • recent = new, latest
  • reptile = animal, like a snake or a lizard, whose body temperature changes according to the world around it
  • research =study about a subject in order to find out more facts
  • scientist = person who works in a lab and is trained in science
  • similar = like
  • successor = here: animal that grew out an animal that lived before it
  • suggest = show
  • turtle = reptile that lives mostly in water and has a soft body covered with a hard shell
  • tyrannosaurus rex = very large, meat-eating dinosaur