One of the significant characteristics of old growth forests is that we can better appreciate things that are older some organisms only survive in the complex ecosystems of old growth forests taller trees have more leaves for photosynthesis they are home to animals that are older

Some organisms can only survive in the complex ecosystems of old growth forests

Explanation:

young forests will have smaller animals like robins, rabbits, and mice while old growth forests can have wolves, deer, elk, and bears too.

explanation:

the fossil record extends back to a dog-like ancestor some 55 million years ago, which gave rise to the first horse-like species 55 to 42 million years ago in the genus eohippus.

i think it is dna, i'm not totally sure but i think it might be.