Question

What evidence can you find that the axial skeletons of higher vertebrates have homologous parts? What inferences would this lead scientists to conclude?

Answer 1

Skeleton Is of two types a) exoskeleton-seen in invertebrates

b) endoskeleton-seen in vertebrates

In higher vertebrates skeletal system comprises of axial skeleton and appendicular skeleton.Axial skeleton includes skull,vertebrae,spinal cord, sternum and ribs. Appendicular skeleton includes limbs and their attachments with axial skeleton.

Common characteristics of vertebrates a) notochord

b)dorsal hollow nerve cord

c)pharyngeal slits

d)post anal tail

In higher vertebrates which includes reptiles,birds and mammals dorsal hollow nerve cord develops into brain whereas notochord develops into spinal cord and vertebrae.

These evidence suggest that axial skeleton of higher vertebrates have homologous parts.

Scientists had concluded this taking into account of common characteristics of vertebrates viz.notochord,dorsal hollow nerve cord,pharyngeal slits,post anal tail.Morphological homologous structures are produced through different developmental process .Another common feature of higher vertebrates show amniotic embryos.