Question

select the word or phrase that is redundant and can be removed without changing the meaning of the text.

if you can imagine a mental picture of a reptile encased in bone, then youll have an idea of what the pamelakoposuchus longus, an aquatic reptile of the triassic period, looked like.

Explanation:

The phrase "an aquatic reptile of the Triassic period" provides additional descriptive information about Parmakoselachos longus but is non - essential for the main idea of the sentence (which is to help the reader visualize what Parmakoselachos longus looked like). Removing it would not change the core meaning of the sentence as the main subject and the action (having an idea of what it looked like) remain intact.

Answer:

an aquatic reptile of the Triassic period