Layers of fossils in pillars, the rock covering them is dated and we get an exact time of each layer.
Answer:
go to school and learn somethinggg ,listen to your teacher and you will soon,
The following structural changes occur as conducting tubes
become smaller;
- support structures change. The trachea has more hyaline cartilage
than the bronchioles
- epithelium type changes with bronchioles having ciliated
columnar cells with the trachea having tall columnar pseudostratified
- amount of smooth muscle increases as you go lower the respiratory tract
