Evidence of Solution

Fossils

preserved remains of past life

transitional fossils

share traits w/ present dayl similarities can be used to determine relatedness

tiktaalik

four-legged semi-aquatic fish

archaeopteryx

reptilian and avian ( birds )

homologous structures

look differetn externally, however, actually link two species to a common ancestor. The same but differ in shape, size, etc. These can be attributed to how the structure has adpated to suit unique environmental selction pressures to aid survival

pentadactyl limb, insect mouthparts, mollusc foot, vertebrate hearts

examples of homologous structures

similar in appearance are not a result of recent common ancestry, similarities can be attributed to the organisms experiencing similar environmental pressure

analogous structures

wings of mammals, birds, insects / dorsal vins of fish, marine mammals

examples of analogous structures

vestigial structures

anatomical structures are present but no longer functional in modern-day organisms; functionality in ther ancestors ( shared ancestry )

ratite ( flightless birds ) wings, pelvis, wisdom tooth

examples of vestigial structures

biogeography

studies where organisms live around the world, it shows that:

species in nearby regions are often closely related

island species resemble mainland species, but w/ unique adaptations