Penguins Part I

Waimanu manneringi ©Nobu Tamura

We know a lot about fossil penguins. Partly, this is because we have a fairly large number of fossils from penguins, which is a rarity for birds as a group in general. It's also a bit of a blessing. There are a number that are a little more well-known for various reasons (mostly to do with publication and news cycles) like Waimanu, Inkayacu, and Perudyptes; all penguins described since 2006. However, we have been recovering and describing penguin fossils since much earlier times: Pachydyptes (Oliver, 1930), Paraptenodytes (Ameghino, 1891), and Palaeosphenicus (Morino and Mercerat, 1891) are notable examples. Not all penguins are the same, so lumping them together is not really fair. However, their overall body plans are fairly conservative. Most members of the penguin family are recognizably penguin-like though ancestral members of the family are not exceptionally penguin-like. This includes Waimanu, an early member of the penguin family that has some penguin-like traits, but looks less like a penguin than we would imagine even an early penguin might appear. Waimanu has a longer tail and more wing-like upper limbs than we would expect a penguin to possess. However, its bill does look very much like the bill that we associate with fish catching birds and is reminiscent of that we see in penguins. The legs of Waimanu are more like those of a loon or a grebe and do not appear to be very useful for walking on land (just like those of loons and grebes). The position of the legs are better for swimming than for walking, to be honest, and from what we know about penguins, this makes a lot of sense.

Kumimanu biceae ©Nobu Tamura

Penguins do not swim with their legs though, they swim with their fins, their wings, providing propulsion underwater. So how does a penguin transition from leg power to wing power? The next oldest penguin we know (currently) from fossils, Kumimanu is decidedly more penguin-like. The feet look more like penguin feet. The tail is shorter than Waimanu's tail. The bill is still rather large and fish catching; not entirely penguin-like yet. We do have more flipper-like wings with Kumimanu, likely indicating that the legs are no longer propulsive and the flippers have taken over this function. The wings are not entirely like flippers that we see in modern day penguins though. Also, as we can see in Nobu Tamura's illustration, Kumimanu was a rather large early penguin. There are larger penguins that we know of, but rather than attempting to discuss all of the very important penguin fossils in one post, we will continue tomorrow with other notable penguins, some of which may be the largest penguins that ever lived.