bird
The number of bones depends on the species.
Bones are light because they are hollow in the middle.
parrots have 13 to 25 bones, depending on their species.
The largest crocodile species in the world, sometimes called the 'super croc' has 250 bones, not including the skull. Smaller species have fewer bones.
No. Many animal species have an exoskeleton or no skeleton at all. The huge amount of animals that fall into these two categories makes it impossible for 95% of known species to have bones. Insects make up over half of the known species. Insects have an exoskeleton and do not have bones like humans and other vertebrates do. Since more than 50% of species are insects and therefore have an exoskeleton, it is impossible for more than 50% of species to have bones.
Homo sapiens, modern man, has 206 bones in the adult skeleton.
they have hollow bones because they need to be light
Bones are light because they are hollow inside and filled primarily with marrow, a spongy substance which produces new red blood cells in large bones.
The type of muscles that wrap around bones are typically skeletal muscles, but muscles do not make the bones light. What makes bones light are the fact that they are porous. There are a lot of holes within the bones that make it lighter, but those holes make sort of arcs and what not, similar to those in the Eiffel tower, for example. They are light weight, but very strong.
About 210.
You can learn how these species have been evolving.