An important evolutionary innovation and a major difference...

An important evolutionary innovation and a major difference between the limbs of extant lobe-finned fish and extant tetrapods is: Select one: 1. The presence of lobes on the fish fins. 2. Retention of fin rays in tetrapod limbs. 3. Limbs of tetrapods have associated muscles. 4. Limbs are supported by a single basal bone in tetrapods 5. Attachment of the pelvic limbs to the vertebral column via the pelvis in tetrapods.

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Transcript

00:01 We're looking at fish and tetrapods.

00:03 Which of these is an important evolutionary innovation and a major difference between the two.

00:09 One, the presence of lobes on the fish fins.

00:12 Two, retention of thin rays in the tetrapod limbs.

00:16 Three, limbs of tetrapods have associated muscles.

00:19 Four limbs are supported by a single basal bone in tetrapods.

00:23 Or five.

00:24 Attachment of the limbs to the column by the pelvis in tetrapods.

00:29 So we're looking for a development in tetrapod evolution, and it's probably going to be something that adapted them to land because that's big difference between fish and tetrapods, or rather the evolutionary pressure they weren't under.

00:45 So let's go through these.

00:46 Is it going to be the presence of lobes on fish fins? no.

00:49 This isn't a development in tetrapod evolution.

00:51 This is a feature of fish.

00:53 It's not the important evolutionary innovation we're looking for.

00:57 Similarly, if we look at two, not going to be the case.

00:59 If this retention of thin rays, that's going to be a vestigial feature, not an innovation that sets tetrapods apart.

01:09 Three, limbs of tetrapods have associated muscles.

01:12 Yes, they do.

01:14 So do fish.

01:15 Fish fins...