Skeleton

The term skeleton refers to rigid structures within living bodies, that provide support. Mammals, birds, reptiles, and most fish, have skeletons. Insects and arthropods employ external exoskeletons, a very different kind of structure.

Most living beings, that rely on skeletons, rely on bones, with a Calcium matrix. Sharks are an exception. There skeletons are made of cartilidge.

Bones are so durable that animal bones exist endure so long that minerals dissolved in water precipitate in the bones, and this can form fossils that can endure for hundreds of millions of years.

• 
• 
• 
• 
• 
• 
• 
• 
• 
•