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For centuries, humans have been fascinated by amphibians, and the question of which group is most closely related to them has long been a topic of debate. While scientists previously believed that reptiles were amphibians’ closest relatives, recent research suggests otherwise.

In this article, we’ll explore the scientific evidence behind the answer to this age-old question. Amphibians are an ancient group of animals that have been around for hundreds of millions of years. They make up a unique branch of the vertebrate family tree and have some unique characteristics that set them apart from other animals.

reptile and amphibian
reptile and amphibian in front of white background

Overview Of Animal Phylogeny

Animals have been classified into various groups based on their evolutionary relationships.

Amphibians are a group of animals that are closely related to other vertebrates, such as reptiles, birds, and mammals. They have adapted to live both in water and on land and possess many unique characteristics, including the ability to respire through their skin.

Amphibians are part of a larger group of animals known as tetrapods. Tetrapods are animals with four limbs that evolved from ancient fishes about 380 million years ago. This group also includes reptiles, birds, and mammals; all of which share some common features with amphibians, such as lungs for respiration, paired appendages for locomotion, and a backbone or spinal cord containing nerve tissue.

The closest living relatives to amphibians are the living lobe-finned fishes. These fishes share some characteristics with amphibians, such as fleshy fins with bones in them and an adaptation to aquatic life by means of gills. However, they differ significantly in terms of anatomy and physiology from amphibians; for example, lobe-finned fishes lack legs or feet, while amphibians possess them.

Overall, the group most closely related to amphibians is the living lobe-finned fishes. While they share some common traits with amphibians due to their shared ancestry, they differ significantly in terms of anatomy and physiology.

Reptiles Vs Amphibians

Reptiles and amphibians are two distinct groups of animals that have been around since prehistoric times. Despite having a long, shared evolutionary history, they each have their own unique characteristics that differentiate them from one another.

Reptiles have dry, scaly skin and the majority of them lay eggs on land. They also tend to be more active during the day than other animals, making them diurnal creatures.

Amphibians, on the other hand, are usually characterized by moist skin that is often slimy or slimy-looking. Unlike reptiles, amphibians lay their eggs in water and tend to be more active at night. In addition, many species of amphibians undergo metamorphosis from larva to adult form during their life cycle.

It’s clear that although these two groups share some similarities, they are still two very distinct forms of life with their own unique characteristics and behaviors.

Primitive Amphibian Traits

Amphibians have been around for millions of years and are an important part of the evolutionary story. They have some amazing characteristics that make them unique and set them apart from other organisms. It’s no wonder why they’re so closely related to a variety of other animals, including reptiles!

Let’s explore some of the primitive traits that amphibians possess and how they help define their group. The most defining characteristic of amphibians is their skin, which has two layers with both a dry outer layer and a moist inner layer. This type of skin enables amphibians to absorb oxygen directly through their skin, allowing them to survive in places where other animals cannot exist.

In addition, amphibians also possess glands on their skin that produce chemicals like poison or antibiotics, which can help protect them from predators or infections. Amphibians also have special adaptations for breeding and reproducing. Most species lay eggs in water or very moist environments, which helps ensure that their young will be safe until they are ready to leave the water and venture into terrestrial habitats.

Amphibian larvae often have specialized gills for breathing underwater before transitioning into adults with lungs for breathing air. These primitive traits have helped amphibians survive on Earth for millions of years and continue to be key components in the classification process used by scientists today. As more is learned about these fascinating creatures, we will gain further insight into how they are related to other groups within the animal kingdom.

Evidence For A Closer Relationship

The similarities between amphibians and their closest relatives are abundant, and they often go beyond physical traits. Many amphibians share a number of physiological, reproductive, and behavioral characteristics with other tetrapod vertebrates such as reptiles, birds, and mammals.

Although there are some differences between these groups, the commonalities suggest that amphibians are most closely related to other land-based vertebrates.

One notable similarity is the presence of complicated courtship behavior in many species of amphibians and their close relatives. This courtship ritual involves vocalizations or movements that are used to attract mates or ward off rivals.

Additionally, all tetrapods have a four-chambered heart that helps oxygenate their blood and keep it circulating throughout the body.

Another similarity between amphibians and their closest relatives is the presence of specialized glands on their skin which secrete oils and mucus to help protect against disease-causing organisms. This type of gland is unique among land-based animals, as other vertebrate groups lack this protective adaptation.

Furthermore, amphibians also share certain developmental traits with other vertebrates; for example, all tetrapods undergo metamorphosis from an aquatic larval stage into a terrestrial adult form during their lifetime.

Overall, there is ample evidence to suggest that amphibians are most closely related to other tetrapod vertebrates like reptiles, birds and mammals. The similarities in morphology, physiology and behavior make it clear that they have evolved from a common ancestor and likely still share many genetic traits with each other today.

Collection of different reptiles isolated on white background

Re-Evaluating The Ancestry Of Amphibians

Recent research has revealed that amphibians are closely related to certain reptiles. Specifically, a group of extinct aquatic reptiles known as mesosaurs have been found to share many characteristics with amphibians, such as having a four-chambered heart and possessing gills in their larval stage.

The close genetic relationship between mesosaurs and amphibians is evidenced by the fact that both groups possess several proteins which are not found in any other organism. This indicates that the two groups had a common ancestor at some point in the distant past.

In addition, fossil evidence suggests that the last common ancestor of these two groups lived during the Permian period, nearly 300 million years ago.

This new information about the ancestry of amphibians has caused scientists to reevaluate how they classify animals into different taxonomic groups. Rather than simply focusing on physical characteristics, researchers now must consider other factors such as genetic similarity when determining how species are related to each other.

It is clear that further study into the evolution of various organisms is necessary in order to gain a deeper understanding of how life on Earth has changed over time.


In conclusion, the close relationship between amphibians and reptiles is clear. Both share primitive characteristics, indicating a shared ancestry.

Further research has re-evaluated this relationship and suggests that amphibians may be more closely related to a group of extinct tetrapods known as Temnospondyli.

It’s important to remember that these relationships are constantly evolving, so it’s my hope that further studies will continue to shed light on the evolutionary origins of amphibians and other animals.