| The relationships between hagfishes, lampreys, and jawed vertebrates are one of the still-unresolved problems in craniate phylogeny. |
| At a quick glance, jawless fish such as the lamprey above don't appear to have much in common with jawed fish or any other back-boned creature. |
| In contrast, people and other jawed vertebrates brandish adaptive immune systems. |
| Unlike all other jawed vertebrates, placoderms never had teeth, and did not descend from toothed ancestors. |
| No one had unambiguously located such genes in animals more primitive than the jawed vertebrates. |
| The first jawed fish in the fossil record are the acanthodians, which first occur in the Late Silurian. |
