Answer to Question #141887 in Zoology for ramaune

Question

Discuss
the
skeletal
modifications
and
reasons
for
vertebrates
colonising
land.

Answer 1

The skeleton of vertebrates are modified in a way they facilitate movement. Appendicular skeleton consists of shoulders, bones of the limbs and limbs girdles that attach the limbs to the rest of the body with joints to facilitate movement on the land.

Axial skeleton consists of the skull, vertebral column, ribs and sternum. The skull protect the brain and support eyes. Vertebral column and rib cage is modified to protect the lungs and heart.

In amphibians for example, they have calcified bones to support their body weight under the force of gravity. Their skull is light and flattened for motility. Their pectoral girdle is modified to give support for the fore limbs, which absorb the body weight when landing after a jump.

In flying animals like birds they have light skeletons and very strong sternums for wing muscle attachment.

Leg bones of most vertebrates are held directly underneath the body. In this position they acts as props or struts and it is the bones rather than the muscles that take most of the strain of body's weight.