Vertebrates are one of the most diverse and successful groups of animals on the planet. Modern vertebrates come in an astounding array of sizes and shapes and can be found anywhere from the deepest oceans to the highest mountains. Yet vertebrates did not attain such success from the outset; their rise to dominance was gradual. The early evolution of vertebrates was a dynamic and, at times, a turbulent interval which, through studying the fossil record, we are able to understand in increasing detail. We talk to Dr Lauren Sallan, who is an Assistant Professor at the University of Michigan studying early vertebrate evolution, biodiversity and ecology.