As one of the major divisions of animal life – and the one that includes our own species – the origins of Deuterostomia (Chordata, Echinodermata, and Hemichordata) have been the subject of significant investigation for decades. While there are strong embryological features uniting these animals, their adult forms bear little resemblance to each other; therefore, illuminating their common ancestry has been a considerable challenge. How can we link our own evolutionary history to gut-breathing worms and armor-plated urchins?
      
In this talk, I will present an overview of recent insights into deuterostome origins from my own research. I will begin with a deep dive into the enigmatic group of deuterostomes known as hemichordates. Despite being poorly understood in the past, these animals were a diverse, behaviorally complex, and ecologically significant component of early Paleozoic ecosystems. These new fossil discoveries give us the ability to reconstruct the form and function of the last common ancestor to Hemichordata for the first time. I will then present the first fossil tunicate ever discovered. This new species has major implications for how we understand the evolution of this group, and the emergence of invertebrate body plans in general. Further, as the closest relatives of the vertebrates, the evolutionary history of tunicates gives us the clearest view of how we diverged from invertebrates.
      
Finally, I will address major outstanding questions in our search to understand deuterostome origins, including the idea that deuterostomes are the best analogues for understanding the last common ancestor to all bilaterian animals. Taken together, this highlights the crucial role of fossil morphology and palaeoecology in demystifying the roots of animal evolution.