I think it is common knowledge that amphibians are descended from fish. At some point there was a transition from sea to land.

But when I try to confirm this through the Animalia taxonomy, the scientific classification of fish goes

enter image description here https://en.wikipedia.org/wiki/Fish

while the scientific classification of amphibians go

enter image description here https://en.wikipedia.org/wiki/Amphibian

If we draw this as a tree of sorts, we end up with

enter image description here

it seems to be quite obvious that fish and amphibians belong to the same phylum but different clades, but I'm not sure how that proves that amphibians are directly descended from fish?

I'm interested in a tree that shows amphibians branching off of the fish lineage.

  • 2
    $\begingroup$ Look in to the difference between cladistics and phenetics/phylogenetic trees. $\endgroup$
    – Bryan Krause
    Dec 24, 2020 at 14:38
  • $\begingroup$ the phylogenetic trees i found only went as far as animalia, if were looking for fish or amphibians. so i was hoping cladistics would be like another focused phylogenetic approximation of the animalia kingdom, are they not related? $\endgroup$
    – notacorn
    Dec 24, 2020 at 19:42
  • $\begingroup$ They are related but not the same. If you read about them it's easy to find comparisons of how they differ. $\endgroup$
    – Bryan Krause
    Dec 25, 2020 at 0:21
  • $\begingroup$ Your "tree" is drawn incorrectly. What you have labeled as ancestors and descendants are nested groups. Vertebrates and amphibians are both chordates, and amphibians are also vertebrates. The wikipedia taxonomy box uses outdated, non-phylogenetic terminology. $\endgroup$
    – kmm
    Jan 23, 2021 at 14:21

2 Answers 2


Fish are a paraphyletic group: that is, any clade containing all fish also contains the tetrapods, which are not fish. For this reason, groups such as the class Pisces seen in older reference works are no longer used in formal classifications.

You got something completely wrong. In evolution one can not say that one taxonomical group evolved from the other. We say that two taxonomical groups have common distant relative. With that said all vertebrates have common distant relatives. Important is to know when did the branching in speciation happened.

Proto-amphibians evolved in Devonian by further speciation from relative that was sarcopterygiian (fish). It was a fish with some properties of amphibians (lungs and bones in appendages).

You can see the relation of fish and fish-like animals to other vertebrates in this taxonomical tree



  • 2
    $\begingroup$ Can you please put a source for your quote and the phylogenetic tree? $\endgroup$
    – MattDMo
    Dec 24, 2020 at 17:53
  • 1
    $\begingroup$ are you trying to say that all amphibians are fish but not all fish are amphibians? If that is true I don't understand how you cannot logically conclude that amphibians have to have evolved from fish, without making any inferences about intermediate transitory forms? $\endgroup$
    – notacorn
    Dec 24, 2020 at 19:44
  • $\begingroup$ "The first major groups of amphibians developed in the Devonian period, around 370 million years ago, from lobe-finned fish which were similar to the modern coelacanth and lungfish." <- this is the language from wikipedia that led me to believe amphibians evolved from fish $\endgroup$
    – notacorn
    Dec 24, 2020 at 19:46
  • 3
    $\begingroup$ @notacorn Yes, what you said is exactly how it works. Amphibians, as well as reptiles, mammals, and birds, are technically a type of highly modified fish. They don't stop being fish just because they are highly modified from the ancestral form. Some fishes, such as lungfish and coelocanths, are more closely related to amphibians and reptiles than they are to sharks, bass, or other fishes. $\endgroup$ Jan 24, 2021 at 4:08
  • 3
    $\begingroup$ @notacorn I think that Domagoj's point is that "fish" is not a very useful grouping in the first place. "lobe-finned fish" is a slightly more useful classification, as it's much more specific. $\endgroup$ May 23, 2021 at 17:01

Check through the classification of lungfush:

under a cladistic view, tetrapods are themselves considered a group within Sarcopterygii





Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.