Are Birds More Closely Related to Mammals or Reptiles?
Scientists believe birds are actually more related to mammals than reptiles. Both birds and mammals evolved from common ancestors that were theropod dinosaurs over 170 million years ago. This is why birds and mammals share so many of the same physical characteristics.
Reasons Why Birds are Tied to Mammals
- Physiology – birds have many of the same internal and external organs that other mammals have
- Feathers – feathers are actually made from a type of keratin which is the same protein that makes up mammalian hair
- Beaks – the beak of a bird is more like human fingernails than a reptile’s scaly skin
- Reproduction – birds lay eggs and mammals give birth, but most birds share many of the same traits when it comes to reproducing
Distinctive Differences
Despite all of the similarities between birds and mammals, there are still some distinct differences between the two. For example, birds have hollow bones and a four-chambered heart while mammals have cellular bones and a three-chambered heart. Reptiles also have several characteristics that are not shared by birds and mammals, such as laying eggs and having scaly skin.
Overall, it is apparent that birds are more closely related to mammals than they are to reptiles. While both groups share some common physical characteristics, the differences between them make it evident that birds are more closely related to mammals than to reptiles.
