What (if anything) can be inferred about whether the common ancestor of each of the three major bilaterian clades had a true coelom? what (if anything) can be inferred about whether the common ancestor of each of the three major bilaterian clades had a true coelom? we cannot infer anything about the status of the ancestor of the lophotrochozoa, ecdysozoa, or deuterostomia. the common ancestor of each of the three clades -- lophotrochozoa, deuterostomia, and ecdysozoa -- had a true coelom. the common ancestor of the lophotrochozoa and the deuterostomia had a true coelom, but we cannot infer anything about the ancestor of the ecdysozoa. the common ancestor of the deuterostomia had a true coelom, but we cannot infer anything about the ancestor of the lophotrochozoa or the ecdysozoa.