Article: A new giant penguin from the Eocene of Australia
Pachydyptes simpsoni sp. nov., a 'giant' fossil penguin, is described from fragmentary remains found at two levels in the Upper Eocene, Blanche Point Marls, South Australia. The remains from the lowest level immediately predate the first appearance of the index coccolith Isthmolithus recurvus Deflandre and are amongst the oldest well-dated penguin bones known.Comparison with the largest modern penguin Aptenodytes forsteri Grey suggests that the fossil species probably stood about 140 cm tall. Its coracoid was relatively short compared to this modern species, one cervical vertebra relatively longer, and the wing length similar proportionally. Penguins are considered to have evolved from flying birds (Simpson 1946, 1971a) and the short coracoid is interpreted as supporting this. The inferred relatively long neck may have been inherited from the volant ancestor of the penguins or represent an early specialization. The length of the wing reflects its function as a propulsive organ in water and reinforces the suggestion by Simpson that 'all the basic locomotory adaptations of the Spheniscidae were virtually complete in the late Eocene'.The need for precise stratigraphic data in analysing the palaeoecology of fossil penguins is emphasized, and so far as is possible, P. simpsoni and other Eocene fossil penguins are placed in a context of biostratigraphic, bio-geographic, and palaeoclimatic data. This suggests that the Eocene penguins from Australasia lived in seas with surface water temperatures of about 12-16 C. They are interpreted as recording northward penetration of Antarctic populations, perhaps to a palaeolatitude of 45 S.