Final answer:
Bilateral symmetry is a reasonable assumption in reconstructing vertebrate fossils, and convergent evolution is the independent evolution of similar traits in unrelated species.
Step-by-step explanation:
Bilateral symmetry is a reasonable assumption in reconstructing vertebrate fossils because most vertebrates exhibit bilateral symmetry. This means that their left and right sides are mirror images of each other. By assuming bilateral symmetry, paleontologists can often infer the presence and structure of missing body parts in fossil specimens. For example, if one half of a fossilized jawbone is found, the other half can be reconstructed by symmetrical comparison. Convergent evolution refers to the independent evolution of similar traits in unrelated species due to similar selective pressures. It occurs when different species adapt to similar environments or perform similar functions, resulting in the development of analogous structures. For example, both birds and bats have wings that help them fly, but their wing structures are different because birds evolved from dinosaurs, while bats evolved from mammals. Convergent evolution can occur when different species face similar ecological challenges.