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Description

A selection of extinct species of anatids, to scale.

Thanks to the ubiquitous nature of waterfowl floating on ponds and farmed poultry, everybody knows what an anatid is, though they may not be familiar with the scientific term. Apart from two very small oddball families (screamers and magpie goose), anatids are the largest family within the Anseriformes and all are referred to as either ducks, geese or swans. Outside of the mostly flightless Palaeognaths (ratites), anatids and their sister group (Galliformes) are the most basal forms of modern birds. While the most definitive waterfowl fossil date only to the Oligocene, the group almost certainly extends way back to the Late Cretaceous. Several more distantly related families of waterfowl such as vegaviids and presbyornithids are known from the late Mesozoic.

While most fossil species, for example Australotadorna and Matanas, would be fairly recognisable to modern eyes, anatids differentiated into wildly different forms.

* Split off from the mainland on an archipelago of islands, a highly endemic fauna evolved at Miocene Gargano in Italy. Examples of island gigantism were widespread amongst a variety of groups including moonrats, dormice, pikas, owls and even waterfowl. Free of terrestrial predatation, Garganornis was 30% larger than the largest living swan, vaguely resembling a sheldgoose and was probably flightless. Apart from sheer size it was able to protect itself with the bony knobs on the wrist of the shortened wing. Anybody who has been hit by the wing of an aggressive geese or swan will understand how effective this weapon would be.

* Further north in Miocene Tuscany was a duck that did it's best to pass itself off as an ocean-going auk. Bambolinetta was a small flightless species which uniquely used it's wings to propell through the water (all other waterfowl are foot-propelled).

* Much later in the Pleistocene saw the various islands of the Mediterranean produce their own endemic faunas with both giant rodents and dwarfed elephants, hippopotamuses and deer. This unusual species assortment allowed the odd juxaposition on Siciliy and Malta of giant swans taller than the minature elephants that they lived alongside. This large species of Cygnus was far more robust than living swans and almost certainly flightless.

* The Hawaiian islands also produced a range of unusual flightless waterfowl. Resembling large geese, the moa-nalos filled the otherwise absent niche of herbivores on the islands, using their deep bills to crop vegetation. Surprisingly the moa-nalos don't originate from a line of geese (the modern nene is closely related to Canada geese) but from the very familiar dabbling ducks.

* However the most bizarre anatid is probably Talpanas or the Hawaiian Mole duck. Virtually blind with an extremely tactile beak, Talpanas is a remarkable case of convergent evolution with kiwis from New Zealand.

* In another case of convergent evolution, two Pleistocene species were similarly large flightless coastal dwellers. Interestingly they were not at all closely related (two different tribes) and present on either side of the Pacific - Shiriyanetta in Japan and Chendytes on the Channel Islands off the Californian coast.

Description

A selection of extinct species of anatids, to scale.

Thanks to the ubiquitous nature of waterfowl floating on ponds and farmed poultry, everybody knows what an anatid is, though they may not be familiar with the scientific term. Apart from two very small oddball families (screamers and magpie goose), anatids are the largest family within the Anseriformes and all are referred to as either ducks, geese or swans. Outside of the mostly flightless Palaeognaths (ratites), anatids and their sister group (Galliformes) are the most basal forms of modern birds. While the most definitive waterfowl fossil date only to the Oligocene, the group almost certainly extends way back to the Late Cretaceous. Several more distantly related families of waterfowl such as vegaviids and presbyornithids are known from the late Mesozoic.

While most fossil species, for example Australotadorna and Matanas, would be fairly recognisable to modern eyes, anatids differentiated into wildly different forms.

* Split off from the mainland on an archipelago of islands, a highly endemic fauna evolved at Miocene Gargano in Italy. Examples of island gigantism were widespread amongst a variety of groups including moonrats, dormice, pikas, owls and even waterfowl. Free of terrestrial predatation, Garganornis was 30% larger than the largest living swan, vaguely resembling a sheldgoose and was probably flightless. Apart from sheer size it was able to protect itself with the bony knobs on the wrist of the shortened wing. Anybody who has been hit by the wing of an aggressive geese or swan will understand how effective this weapon would be.

* Further north in Miocene Tuscany was a duck that did it's best to pass itself off as an ocean-going auk. Bambolinetta was a small flightless species which uniquely used it's wings to propell through the water (all other waterfowl are foot-propelled).

* Much later in the Pleistocene saw the various islands of the Mediterranean produce their own endemic faunas with both giant rodents and dwarfed elephants, hippopotamuses and deer. This unusual species assortment allowed the odd juxaposition on Siciliy and Malta of giant swans taller than the minature elephants that they lived alongside. This large species of Cygnus was far more robust than living swans and almost certainly flightless.

* The Hawaiian islands also produced a range of unusual flightless waterfowl. Resembling large geese, the moa-nalos filled the otherwise absent niche of herbivores on the islands, using their deep bills to crop vegetation. Surprisingly the moa-nalos don't originate from a line of geese (the modern nene is closely related to Canada geese) but from the very familiar dabbling ducks.

* However the most bizarre anatid is probably Talpanas or the Hawaiian Mole duck. Virtually blind with an extremely tactile beak, Talpanas is a remarkable case of convergent evolution with kiwis from New Zealand.

* In another case of convergent evolution, two Pleistocene species were similarly large flightless coastal dwellers. Interestingly they were not at all closely related (two different tribes) and present on either side of the Pacific - Shiriyanetta in Japan and Chendytes on the Channel Islands off the Californian coast.