The answer is mutation
of genes. The mutations were beneficial and gave the individuals of the population
advantage and hence increased their survival. The classic features of birds
evolved one by one and gave birds advantage over their dinosaurs counterparts, especially the feature of small size.
<h2><u>its is (A) skeletal and muscular</u> </h2><h2>because without skeletal ur body want be able to move also the muscular system do the sam but it give u strength to move it.</h2>
