One species of the recently discovered Piotopterids was over 2 m (6.5 ft) long. These huge, flightless Pelecaniformes of the northern hemisphere occurred in the late Oligocene and early Miocene periods of Japan, Washington and California some 20—25 million years ago. Like the giant penguins, these were wing-propelled divers but differed in having teeth.
The largest penguins were somewhat smaller, but nonetheless some stood as tall as many men, Pachydyptes and Anthropornis being 1.64 m (5.33 ft) and 1.54 m (5 ft) respectively.
The Largest Swimming Bird in Britain
This very large, ratite-like bird from the late Paleocene/early Eocene period (50—55 million years ago) reached up to 2.15 m (7 ft) and is the largest bird known to have lived in Britain. It was originally compared with geese but is now said to have had rail-like affinities. It is also suggested that it was closely related to Diatryma.
Known from a number of European sites, Gastornis was first described by E. T. Newton in 1886 from remains found in the lower Eocene beds near Croydon by Mr. H. M. Klaassen. They were exposed during the excavation of the Park-Hill railway-cutting in 1883.
Newton suggested that Gastornis was ‘at least as large as, and far heavier in build than, any recent ostrich’, but a subsequent study found that the proportions were very hard to determine and the height of 2.15 m (7 ft) is the best recent estimate.
As the six specimens of bone from the Park-Hill cutting represented at least four individuals and were from a comparatively small area, Newton concluded that these birds were locally very numerous.