Focusing on fossils from a dog-sized cousin of the dinosaurs, paleontologists have learned more about the variable growth patterns between individuals of an ancient species.

The researchers focused their analysis on 27 femur bones from a reptilian species called Asilisaurus kongwe, which lived about 240 million years ago and predated dinosaurs by about 10 million years. What they learned sheds new light about the variable ways that these creatures grew into adults.

The scientists studied bone scars, which result from where muscle connected to bone, to learn more about how the species grew. The bones scars increase in number and size as an animal ages.