Which of the Following Could Be Considered the Most Recent

question 37

Multiple Choice

Which of the following could be considered the most recent common ancestor of living tetrapods?

• A) a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates
• B) an armored, jawed placoderm with two pairs of appendages
• C) an early ray-finned fish that developed bony skeletal supports in its paired fins
• D) a salamander that had legs supported by a bony skeleton but moved with the side-to-side bending typical of fishes
• E) an early terrestrial caecilian whose legless condition had evolved secondarily

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Definitions:

Mean

The arithmetic average of a data set, obtained by adding all the numbers and dividing by the count of numbers.

Normal Random Variable

A variable whose occurrences are distributed according to the normal distribution.

Percentile

A value on a scale of 100 that indicates the percentage of a distribution that is equal to or below it.

Standard Deviation

A quantification of how spread out or dispersed the values in a collection are, measuring the deviation of data points from their average.