Waimanu on the Rocks
Waipara Greensand, Middle Palaeocene, Chatham Islands, New Zealand.
Today, penguins are confined to the southern hemisphere, except for the Galapagos penguin, just north of the equator. From their inception penguins appear to have been limited to the southern hemisphere of our planet, the majority of fossil remains coming from New Zealand, Argentina and South Africa.
The earliest recognised fossils that can be accurately attributed to the sphenisciformes, the taxonomic order of which Waimanu is a basal representative, come from the Greensand sediments from the south Island of New Zealand.
Exposed by the cutting of the Waipara River, these dark sediments are marine in origin and represent the shallow seafloor as laid down some 62 million years ago. Here the first remains of Waimanu were recovered, a Neoave clearly already adapted to an aquatic lifestyle.
Waimanu is the earliest known fossil penguin species, but its ancestry is certainly much older, originating in the late cretaceous period. Its unknown cretaceous forebears may have retained the power of flight, having not yet become the fully aquatic birds we know today. If fossil remains are found, they may be hard to recognise as penguin ancestors.
At the time Waimanu evolved, the earth was generally much warmer than it is to today and, unlike most extant penguins, Waimanu did not live or breed on ice.
I have depicted it here on seaweed-covered rocks. Its short legs and webbed feet are very like modern penguins, so its upright stance and walk would also have been similar. Its wings too would have been penguin-like, but less well adapted to ‘flight’ under water, the bones not yet as flattened in profile as in modern birds. Here, the similarities end, for Waimanu’s head differs considerably from modern penguins, with a longer beak, and a head profile similar to that of a Loon.
Etching on paper.
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