Fossils of ancient creatures found in the ground show that species have changed over time, providing evidence of evolution. Comparisons of anatomy between species reveal similarities in bone and muscle structures, showing adaptations to environments. Examination of embryonic development indicates that different species share similarities in early stages, implying descent from common ancestors. Distribution of related species on islands and mainland areas also points to evolution of new forms from earlier ones. Genetic studies find all life uses the same basic DNA code, except viruses, supporting all organisms evolving from earlier common ancestors.