Are Pangolins Reptiles? The Scaly Mammal Explained

Why pangolins are mammals

Scientists group animals by their shared features and ancestry, not by how they look. Pangolins tick every box that defines a mammal:

• Hair: pangolins have hair on the face, throat, belly and inner legs, where there are no scales. Asian species, such as the Sunda pangolin, also have bristly hairs growing between their scales.
• Milk: females have mammary glands, with a pair of teats on the chest, and nurse their young with milk for several months.
• Live birth: pangolins are placental mammals. The young develops inside the mother and is born alive, not hatched from an egg.
• Warm blood: like other mammals, pangolins keep their body temperature steady from the inside rather than relying on the sun, as reptiles do.

They also have the typical mammal skeleton, including a lower jaw made of a single bone on each side and three small bones in the middle ear. Reptiles have several bones in the lower jaw and only one in the middle ear.

What are pangolin scales made of?

A pangolin’s scales are hard plates of keratin that overlap like the tiles on a roof or the parts of a pine cone. They cover the head, back, sides, legs and tail. The scales grow from the skin throughout the animal’s life, and their edges are worn sharp and smooth by digging and climbing.

Keratin is a tough protein found in many animals. In mammals it forms hair, nails, claws, hooves and horn sheaths. The pangolin’s scales are best thought of as giant, flattened, nail-like structures. Newborn pangolins have soft, pale scales that harden within a few days of birth.

How are pangolin scales different from reptile scales?

Reptile scales and pangolin scales only look alike. A snake’s or lizard’s scales are folds of the outer skin, all connected in one continuous layer that is shed regularly, sometimes in one piece. A pangolin’s scales are separate plates, each anchored in the skin and growing individually, and they are not shed as a whole.

Scientists who have studied their structure and chemistry find they are built quite differently from reptile scales. In other words, pangolins did not inherit their armor from reptile ancestors; it evolved within mammals on its own.

Where pangolins fit in the animal family tree

Pangolins belong to their own order, Pholidota, a name based on the Greek for “covered in scales”. All living species are in a single family, Manidae. For a long time they were placed near anteaters, sloths and armadillos because they share a toothless mouth, long tongue and diet of insects.

Genetic studies changed that picture. They show that the closest living relatives of pangolins are the carnivorans, the group that includes cats, dogs, bears, weasels and seals. Pangolins and carnivorans form a larger group called Ferae. The two lineages separated tens of millions of years ago, so the relationship is a distant one.

Are pangolins anteaters or armadillos?

No. The resemblance comes from convergent evolution, when unrelated animals evolve similar features because they live in similar ways.

The giant anteater shares the pangolin’s long sticky tongue and lack of teeth but has no armor. Armadillos have armor, but theirs is made of bone in the skin, and only a few species can roll into a complete ball, as explained in can armadillos roll into a ball.

How many kinds of pangolin are there?

Eight species are recognized today. Four live in Asia: the Sunda, Chinese, Indian and Philippine pangolins. Four live in sub-Saharan Africa: the white-bellied and black-bellied tree pangolins, the giant pangolin and Temminck’s ground pangolin. In 2023 researchers described a possible ninth species from seized scales, but it has not been confirmed alive in the wild.

They range from small tree-climbers of a few kilograms to the giant pangolin, which can weigh more than 30 kg (66 lb). All eight are threatened with extinction, largely because of hunting and illegal trade, described in why are pangolins trafficked.

Why the confusion?

The mix-up is easy to understand. Pangolins are covered in scales, have small heads and long tails, and move slowly with a slightly lizard-like gait. Old names such as “scaly anteater” did not help. But under the armor a pangolin is a furry, milk-producing mammal, closer in ancestry to a cat or a dog than to any lizard.