Earlier this week, paleontologists described another of our distant, ancient cousins. This was no hominin, early primate, or even archaic mammal, but a much, much older variety of creature that would superficially seem to have more in common with terrible primeval reptiles than with us. Named Pampaphoneus biccai, this knobby-headed, 260-million-year-old predator is a clue to one of life’s major events in the time before the dinosaurs.

There is no common name for the peculiar group of animals Pampaphoneus belonged to. Researchers and science writers alike used to call such creatures “mammal-like reptiles”, but that title has been tossed. The old phrase no longer makes any sense.

At a broad level, Pampaphoneus was a synapsid – a member