The first mammals arose about 220 million years ago, about the time of the first
Remained small, shrew-sized insect-eaters through the Mesozoic.
Some larger ones towards the end of the Cretaceous - maybe cat- or badger-sized.
Bone structure and histology:
Endothermic animals have a complex bone structure made up of closely spaced
cavities caused by the growth and resorption of bone. This is called the Haversian
System (see Haversian Canals in Figures). The exact
The word Dinosaur comes from the Greek words: deinos meaning
"terrible" or "formidable, and saura meaning "lizard" or "reptile".
Dinosaur Qualities (Endothermic)
Some scientists believe that dinosaurs did not need to be warm-blooded (endothermic) to
develop into all the different sizes and shapes we have discovered and live in a variety of
environments. The main lines of evidence a
The Cretaceous-Tertiary extinction event was the large-scale mass extinction of
animal and plant species in a geologically short period of time, approximately 65
million years ago.
It is widely known as the K-T extinction event (K is t