qVault bio question.

[NDPitch]

See attached question. I'm confused as to why the most recent common ancestor has those three features. It seems to me that the most recent ancestor to both crows and lizards would be the salamander, which only had jaws and lungs. Am I reading the cladogram incorrectly? It says the most common ancestor is at the fourth node from the bottom. Isn't that a lizard? How can a lizard be its own most recent ancestor?

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[dent4]

When you look at that cladogram, 'Hagfish' (class Agnatha) are considered the earliest species of this particular cladogram. So when looking at lizards and crows, what features did their ancestors have? (a better way to ask the question). They had jaws, claws, and lungs.

 

[NDPitch]

I understand that hagfish are the earliest species on the cladogram. But the question asks, what characteristics did the most recent ancestor to BOTH lizards and crows have? Isn't the most recent common ancestor to both of these species the salamander (According to the cladogram)? And if that's the case, doesn't the cladogram indicate that the salamander only had jaws and lungs, and that the lizards gained claws?

Further, the solution states that the most common ancestor is located at the 4th node from the bottom. The 4th node from the bottom is the lizard. How can a lizard be its own ancestor?

Again, I might just be reading this thing completely wrong.

 

[wb1]

you are right, the most common ancestor to crows and lizard are Salamander. the common feature will be lungs and claws, but it wasn't in the answer choice.
the next common ancestor for all of the above crow, lizard, and salamander are salmon. the ans is then Jaws, Lungs, and claws.

 

[wasetzer]

From the way I understand it, the points of divergence (nodes) indicate common ancestors to the resultant clades. In this example, this ancestors are unnamed. The unnamed clade at node 4 had claws, lungs, and jaws and diverged to the lizard and another unnamed clade (which ultimately led to the crow, rat, and ape).

 

[BRZ24]

The most recent common ancestor to crows and lizard is a circle I made below in red

SO all characteristics that are present before that branch point/MOST recent common ancestor will be present.

the most recent common ancestor is the BRANCH point NOT the salamander.

 

[joeeeey3]

The most recent common ancestor to crows and lizard is a circle I made below in red

SO all characteristics that are present before that branch point/MOST recent common ancestor will be present.

the most recent common ancestor is the BRANCH point NOT the salamander.

this makes a little more sense