Navels, or belly buttons, are a scar that remains from our time before birth when we received nutrients from our mothers through the placenta and umbilical cord. Most placental mammals have navels, although they can be hard to find. You might be surprised to learn that birds and reptiles have a similar type of scar called an umbilicus from their attachment to a yolk sac inside their egg, although in many species that scar completely disappears over time. What's really amazing is that in 2022, scientists identified an umbilicus in a 130 million-year-old non-avian dinosaur fossil! What's more, it was an adult specimen, which means dinosaurs may have had belly buttons that lasted their whole lives. Sci Show explains how they found this surprising scar and why it might be particularly fascinating for kids to learn about.