Difference Between Mammals and Reptiles


Main Difference

The main difference between Mammals and Reptiles is that Mammals have live births and produce milk for their young, whereas Reptiles lay eggs.

Mammals vs. Reptiles

Mammals are warm-blooded animals, while reptiles are cold-blooded animals. Mammals give birth to young ones live; on the other hand, reptiles are egg-laying animals. Mammals have hairs like fur on their body, whereas reptiles have a hard scaly type body.

Mammals heart contains four chambers: right atrium, left atrium, right ventricle, and left ventricle; on the contrary, reptiles heart contains three chambers; right auricle, left auricle, and ventricle. Mammals have a diaphragm for respiration, while reptiles have no diaphragm.


Mammals’ bodies have high metabolic rates; on the other side, reptiles have low metabolic rates. Mammals are viviparous animals, whereas reptiles are oviparous. Mammals have mammary glands for milk production; on the converse, reptiles have no mammary glands.

Mammals have limited growth after adulthood, while reptiles are found with continuous growth. Mammals cerebrum is larger than reptiles; on the other hand, They have small cerebrum. Mammals have three middle ear bones: the malleus, incus, and stapes, while Reptiles have a single middle ear bone columella.

In mammals, teeth occur two times during their lifetime: deciduous and permanent teeth; on the converse, in reptiles, teeth are continuously replaced by simple cheek teeth. Mammals have fused pelvic bones; on the other hand, In reptiles, pelvic bones are separated.


In mammals, growth limited after adulthood, whereas in reptiles, growth continues through life. Mammals’ pelvic bones are fused, while reptiles pelvic bones are separate.

Comparison Chart

Mammals give births to young onesReptiles do not give birth to their young ones instead of that they lay eggs
Change Colors
Stay the same colorChange colors depending on their mood and surroundings
Diaphragm for respirationMost with no diaphragm
Covered With
Epidermis covered with hairEpidermis covered with scales
Metabolic Rate
High metabolic rateLow metabolic rate
Limited after adulthoodContinues through life
Middle Ear Bone
Pelvic Bones
Bony Palate
Completely separates nasal passages from mouthUsually incomplete
Levels of Cognitive Ability
Heart Chambers
Mammary Glands
They haveThey don’t have

What are Mammals?

Mammals are the type of animals which is categorized by the existence of mammary glands that exist in females that make or produce milk for their young. Mammals belong to class Mammalia. Mammals word is originated from (Latin word mamma), which means “breast.” Dogs, whales, horses, and elephants are also examples of mammals. Humans are also mammals.

Major Characters of Mammals

  • Mammals have a special type of brain part, which is called Neocortex.
  • They have fur or hair on their whole body.
  • Mammals have three middle ears. (missing word bones)
  • They have a four-chambered heart.
  • The single bone jaw is present in mammals.
  • Mammary glands are present for milk production.

What are Reptiles?

Reptiles animals are also known as egg-laying animals. They crawl on their belly or on their short legs. They are also known as cold-blooded animals. Reptile’s name was originated from the French word (Reptilis), which means Creeping. It belongs to the class “Reptilia.” Examples of Reptiles are snakes, turtle, lizard, crocodile, tuatara, etc.

Major Characters of Reptiles

  • They are cold-blooded animals. Reptiles are ectothermic; that’s why they cannot control their own body temperature.
  • They are tetrapod animals.
  • They have a scaly hard body.
  • All reptiles produce eggs, most reptiles lay hard-shelled eggs, but a few give birth to live
  • They breathe by lungs.
  • Most reptiles reproduce sexually, but some reproduce asexually.

Key Differences

  1. Mammals are warm-blooded. This helps mammals live in a variety of different temperatures. Some mammals live in freezing temperatures while others live in very hot temperatures. Reptiles are cold-blooded. They can regulate the temperature of their own body.
  2. Mammals are endothermic and internally regulate their body temperature, but reptiles are ectothermic because they rely on the environment to do it for them.
  3. Mammals can produce body heat while reptiles need an external heat source such as the sun.
  4. Mammals have skins usually covered with hairs, whereas reptiles have scaly skin (the skin has a large number of plate-like structures).
  5. Mammals have oil and sweat glands on their body; on the other side, most reptiles do not have oil and sweat glands.
  6. Mammals give births to young ones and feed them with their own milk(only females do so), while reptiles do not give birth to their young ones instead of that they lay eggs. (except few like yellow anacondas but they are still reptiles because the egg hatches in their stomach ).
  7. Mammals stay the same color, while reptiles can change colors depending on their mood and surroundings.
  8. Mammals stay with their young after birth and nurture them. Reptiles leave their young once they give birth.
  9. A placenta is developed in mammals, whereas no placenta is developed in reptiles.
  10. Mammal skull is found with an expanded braincase, while reptiles They a small braincase.
  11. Mammals have high levels of cognitive ability; on the other hand, reptiles have low levels of cognitive ability.
  12. Mammal jaw is formed by single bone; on the converse, Jaw of reptile is formed by several bones.
  13. All mammals with four-chambered heart, whereas most reptiles with a three-chambered heart
  14. In mammals, the bony plate separates the mouth and nasal passage; on the other hand, the bony plate is incomplete in reptiles.
  15. Mammals partake ribs narrowed to vertebrae thoracic, while reptiles ribs are found on entirely vertebrae.
  16. In mammals, limbs are found directly beneath the body, whereas reptiles have the limbs emerging horizontally from the body.
  17. Mammals have a high metabolic rate; on the other hand, reptiles have a low metabolic rate.


Mammals give birth to live young, and they have mammary glands to feed their babies. Reptiles nurse or feed their offspring by hunting or stalking food. The body of mammals is covered by hairs, while the body of reptiles is covered with scales. The key dissimilarity among mammals and reptiles is the mode of reproduction.

Janet White

Janet White is a writer and blogger for Difference Wiki since 2015. She has a master's degree in science and medical journalism from Boston University. Apart from work, she enjoys exercising, reading, and spending time with her friends and family. Connect with her on Twitter @Janet__White