What do scientists think were the first eukaryotic organisms on Earth? paramecium
euglena
plasmodium
amoeba

The oldest evidence of eukaryotes is from 2.7 billion years ago. Scientists believe that a nucleus and other organelles inside a eukaryotic cell formed when one prokaryotic organism engulfed another, which then lived inside and contributed to the functioning of its host. Eukaryotes differ from bacteria and other prokaryotes in many ways.

Explanation:

phylogenetic tree is the tree of life or evolution tree. it shows the different branches of evolution. the sequence goes like tissues - coelom - backbone - endoskeleton - segmentation

stress fractures occur largely in the feet and legs and are common in sports that require repetitive impact, primarily running/jumping sports such as gymnastics or track and field.