Is a lion a bony fish?

Question

If you ask Wikidata "Does the species lion (Q140) have a parent taxon line up to the Osteichthyes (Q27207, bony fishes)?", it answers yes:

SELECT ?item1
 WHERE {
  wd:Q140 wdt:P171* ?item1.
  ?item1 wdt:P171 wd:Q27207.
 }

Here's a direct link.

Now, I assume that this must be wrong at some level (I'm no biologist, so please correct me if I'm wrong), so I tried to find the error.

This query displays that path more explicitly, starting with mammals:

1. Mammals (Q7377) have Tetrapoda (Q19159) as a parent taxon.
2. Tetrapoda (Q19159) have Tetrapodomorph (Q1209254) as a parent taxon.
3. Tetrapodomorph (Q1209254) have Rhipidistia (Q150598) as a parent taxon.
4. Rhipidistia (Q150598) have Sarcopterygii (Q160830) as a parent taxon.
5. Sarcopterygii (Q160830) have Osteichthyes (Q27207) as a parent taxon.

The third point seems strange, because Rhipidistia are described as a taxon of fish, which would mean that all mammals are fish.

Maybe this comes from the fact that tetrapods (and therefore mammals) evolved from Sarcopterygii 390 million years ago, as described here.

Is "having evolved from" considered a parent taxon in biology? If not, which of the five statements above is wrong?

Answer 1

The path is correct. The safest reading is to say that the lion shares a set of characteristics with the lungfish. You can also say that lion and carps are bony vertebrates (Euteleostomes).

In evolutionary taxonomy, each taxon does not need to consist of a single ancestral node and all its descendants: it allows for groups to be excluded from their parent taxa (in other words, not "being part of" but, as you said, "having evolved from"). Thus, lungfishes are closer to the lions than they are from, e.g., sharks or trout. In other words (even if this is too simplistic to say so), their "common ancestor" is more "recent".

In the Linnaean taxonomic system, all fishes were in the same class. This corresponds to our "everyday life" classification of fishes but not to the most recents findings about the "common ancestors".

To make things clearer, you need to understand the concept of paraphyly. The bony fishes group is paraphyletic with respect to the tetrapoda. In other words, it consists of the group's last common ancestor and all descendants of that ancestor excluding the tetrapoda. "Bony fish" is therefore not a clade, but "Osteichthyes/Euteleostomes" is a clade (= a monophyletic group of the bony vertebrate with a common ancestor that looked like our "modern" fishes).