New research shows how technology and experimental methods in science can always help and be of help when trying to find out the fine details and see how a theory should be updated and what is needed to be corrected in a certain hypothesis or theory. 
Dinosaurs they are termed as a diverse group of reptiles. They first appeared in the time of triassic.
After triassic and jurassic extinction event, dinosaurs became terrestrial vertebrates. 
 
        
                    
             
        
        
        
Answer:
Stabilizing selection results in a decrease of a population 's genetic variance when natural selection favors an average phenotype and selects against extreme variations. In directional selection, a population's genetic variance shifts toward a new phenotype when exposed to environmental changes.
Explanation:
I don't bite, don't worry
 
        
             
        
        
        
<span>Unidirectional flow in the heart is ensured because the heart contains valves that prevent backflow.
These valves keep the flow of the heart going in one direction (hence the name "unidirectional").</span>