At nearly three feet tall and weighing ten pounds, the Great Auk was the bulkiest member of its family of seabirds. But, despite its name, it wasn’t the largest of all time. Between 8.7 and 4.9 million years ago, there was an even bigger auk.

The bird, named Miomancalla howardae by paleontologist N. Adam Smith in 2011, was found in the Pliocene rock of southern California. It didn’t belong to the same group as modern auks and murres – called alcids – but was on just the next branch over, fitting into a wider group called pan-alcids. A sort of proto-auk, in other words. And in a new analysis of how the body sizes of pan-alcids changed over time, Smith found