* Actinopterygian fish are a diverse group of ray-finned fish. They are the most successful group of vertebrates on Earth, representing over half of all vertebrate species. They are the ancestors of all tetrapods (four-limbed vertebrates).
* Terrestrial tetrapods evolved from lobe-finned fish, which are related to actinopterygians but not their direct ancestors.
* Whale sharks, hagfish, and coelacanths are all fish, but they belong to different lineages and are not directly ancestral to tetrapods.
Here's a simplified evolutionary tree to help visualize this:
```
----------------------
| |
-------- | | --------
| | | |
------- | | -------
| | | |
| Actinopterygians | |
| (Ray-finned fish) | |
| | |
| | |
|--------------------------------| |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| -----------------------------------
| | |
| | |
| | |
| | Lobe-finned fish |
| | |
| | |
| | |
| | |
| |----------------------------------|
| | |
| | |
| | |
| | Tetrapods (Amphibians, Reptiles, |
| | Birds, Mammals) |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| |----------------------------------|
| | |
| | |
| | Coelacanth |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| |----------------------------------|
| | |
| | |
| | Whale Sharks |
| | |
| | |
| | |
| | |
| | |
| | |
| |----------------------------------|
| | |
| | Hagfish |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| |----------------------------------|
```