1. Embryonic similarities: Comparative embryology reveals striking similarities in the early developmental stages of different species, despite their diverse adult forms. Animals as diverse as humans, fish, and birds share similar embryonic features, such as the presence of a tail, pharyngeal arches, and a notochord. These similarities suggest a common ancestry and developmental plan.

2. Evolutionary history: Embryonic development often reflects an organism's evolutionary history. For instance, some reptiles, such as turtles, go through a distinct "amniotic" stage in their development, similar to birds and mammals. This suggests a shared ancestry and a divergence from a common ancestor that possessed these characteristics.

3. Atavistic structures: Occasionally, embryonic development can lead to the reappearance of ancestral structures or traits that are no longer present in adult organisms. For example, human embryos briefly possess a tail during their early development, which serves as evidence of our shared ancestry with other mammals.

4. Molecular similarities: The molecular mechanisms and genetic regulation of embryonic development show remarkable conservation across different species. The same set of genes and developmental pathways are utilized by diverse organisms, further supporting the notion of common ancestry.

5. Fossil evidence: Embryonic development can be linked to fossil evidence, particularly in the case of extinct species. Fossils of early embryos can provide insights into the evolutionary relationships between species and the progression of developmental changes over time.

6. Developmental plasticity: The capacity for embryonic development to adapt and exhibit variations is crucial for evolutionary processes. Evolutionary adaptations can arise from modifications in developmental processes, such as changes in gene expression or the timing of developmental events.

7. Evo-devo studies: The field of evolutionary developmental biology (evo-devo) focuses on understanding the genetic and developmental mechanisms underlying evolutionary change. By studying the processes that shape embryonic development, scientists can gain insights into how new structures evolve and how organisms adapt to their environments over time.

In summary, embryonic development provides multiple lines of evidence for evolution by demonstrating shared ancestry, tracing evolutionary history, revealing molecular similarities, and highlighting the role of developmental processes in driving evolutionary change.