Penguins Part II

Inkayacu, was approximately the same size as Palaeeudyptes

 

Fossil penguins were not always penguin "shaped", as we saw with Waimanu, but they became more distinctively penguin-like over time, as we saw with Kumimanu. Intermediate family members like Perudyptes and Anthropornis continue this "penguinification" trend of the overall body plan throughout the Eocene era and, by the times of Icadyptes, Palaeeudyptes, and Inkayacu, penguins look like the animals we think of when we hear the name penguin. There is one rather enormous exception to their recognizable penguin form: these are very tall penguins. Additionally, some of these penguins were likely still using their feet, in some capacity, in propulsion for swimming. Though we mentioned that it appeared as though Kumimanu may not be using its feet anymore to swim, it has been noted that the feet and ankles of some of these larger penguins indicate that they may have still played a role in swimming.The Eocene was an age of giant birds. Whereas the "Terror Birds" ruled portions of South America terrestrially, the giant penguins were taking to the ocean and at least terrorizing fish populations. Sharks were still apex predators in the ocean. Whales were in the process of fully transitioning from land to water. Enormous penguins could have been filling a niche that is now occupied by small whales and dolphins (and even smaller sharks like the reef sharks). Whatever their absolutely exact role, they were clearly highly successful birds that transitioned back from a terrestrial lifestyle to a nearly fully aquatic lifestyle. They did so as large animals that, over time, became increasingly efficient swimmers with streamlined bodies. Even if whales, dolphins, and smaller sharks (possibly seals and sea lions as well) pushed them into a finer definition of a niche, one which they currently occupy as pursuit predators. The nuances of penguin evolution, locomotion, diet, and the life histories of individual species are all complex topics that span the careers of scientists. Hopefully these two discussions are helpful in a very general sense to understanding penguins and their history.