A New Giant Penguin Weighs In

March of the Fossil Penguins is gearing up for more penguin paleontology posts. We will start with a big story from the close of 2017. A new species, Kumimanu biceae, was discovered in New Zealand. The fantastic slippered fossil tipped the scales at 101kg (over 220lbs) and lived in the Paleocene Epoch, the first time period after the extinction of the dinosaurs. The team that discovered and studied the new species named it Kumimanu biceae. The genus name refers to it being a monstrous bird: “Kumi” is a Maori name for a huge sea monster whereas, and “manu” is the Maori word for bird. The species name “biceae” is based on “Bice”, the nickname of paleontologist Alan Tennyson’s mother Beatrice.

Top row: The broken humerus (main flipper bone) of Kumimanu compared to that of Pachydyptes (another extinct giant penguin) and Aptenodytes (emperor penguin). Bottom row: The coracoids of the same three species. Both of the fossil coracoids are broken. Photo courtesy of Dr. Gerald Mayr.

What makes the fossil really cool is is the combination of ancient age and giant size. We already knew that penguins appeared very soon after the extinction of the dinosaurs, as the oldest penguin fossils are about 62 million years old. And, we already knew giant penguins existed based on tremendous fossils such as Pachdyptes ponderosus and Kairuku waitaki. Kumimanu biceae pushes the jump to giant size in penguins right back near their origin. The new fossil is between 55 and 60 million years old and also of the largest on record. That is very interesting, because it means penguins ramped up to huge sizes very quickly after losing flight. They may have been able to balloon up to grand scales quickly because of a lack of competitors in the post-extinction world, after marine reptiles like mosasaurs andplesiosaurs vanished but before marine mammals like seals and sea lions had appeared.

Artist reconstruction of Kumimanu biceae with a human scuba diver for scale. Image courtesy Dr. Gerald Mayr.

Where does Kumimanu biceae rank on the scale of penguin size? It is hard to say precisely because many individuals are known only form a single bone, but the new species is likely the second largest penguin discovered so far. The humerus (main flipper bone) is not complete, but the intact portion is almost as big as that of Pachydyptes ponderosus, a contender for the title. It is clear there was quite a bit more to the humerus before it was broken, so we can rest assured it was larger overall. More importantly, the femur (thigh bone) is huge. While the femur of Pachydyptes ponderosus remains unknown, this giant femur shows that the penguin was huge overall rather than just having a long flipper. The one penguin that may have the edge on Kumimanu biceae is Palaeeudyptes klekowskii. A massive tarsometatarsus assigned to that species is the biggest on record and suggests it belonged to an even larger penguin. However, we can’t really be sure from just one bone as different species of penguins have different proportions (e.g., some have stouter legs and longer bodies, others have long flippers and small skulls, etc.). Regardless, we can be sure giant penguin prowled the waterways of the Southern Hemisphere for a very long time.