By J. Dale James, PhD
Waterfowl have always held a special place in human culture. Their significance to mankind can be seen in cave paintings found in Europe, which depict ducks, geese, and swans (Anseriformes), and in ancient Egyptian literature that describes the hunting and trapping of waterfowl. Of course, Ducks Unlimited members and many other people remain fascinated with this wonderful group of birds, which consists of 167 species worldwide.
However, the history of waterfowl begins much earlier and greatly precedes that of humanity. Compared to other bird groups, waterfowl are well represented in the fossil record. While much of what we know is based on incomplete skeletons and even bone fragments, we can piece together the evolutionary trees of birds living today. The fossil history of waterfowl continues to improve as more discoveries are made, providing new insights into how these species evolved and the characteristics that enabled them to survive an extinction event that killed nearly 75 percent of all plant and animal species on earth.
One of the earliest waterfowl ancestors was Asteriornis, known as the “Wonderchicken.” This species lived nearly 67 million years ago, right before an asteroid impact led to the extinction of all non-avian dinosaurs. Fossils indicate that its hind limbs and skull had features similar to those of today’s ducks and chickens, which suggests that the species was related to a shared ancestor of both groups. This prehistoric bird was likely the size of a quail, and its long, slender legs suggest it was well adapted to shoreline habitats. These characteristics place the Wonderchicken near the evolutionary juncture where waterfowl and chicken-like land fowl split.
Asteriornis is the oldest known member of the contemporary branch of the avian family tree. Birds first showed up in the fossil record some 150 million years ago, when they likely resembled their more reptilian dinosaur-like ancestors. At some point they began to shed these characteristics and began to look more like the birds we have today. Evidence of these early avian species is rather scarce, but more study of the Wonder-chicken may help fill the gap.
Vegavis was an ancient relative of ducks and geese that was discovered in 66.5-million-year-old rocks on Vega Island, located off the coast of what is now the Antarctic Peninsula. Most skeletal features of Vegavis suggest that it was a diving species that propelled itself with its feet and was perhaps well adapted to life in both the water and the air. Another interesting feature present in one Vegavis specimen is a fossilized syrinx, the organ that birds use to produce sound. This fossilized syrinx has a distinctively goose-like asymmetrical shape, suggesting that it may have produced a honking sound.
Other fossils from waterfowl-like birds have been recovered from rock deposits in Europe and North America dating back about 55 million years. The most famous of these is Presbyornis pervetus. Initially, this discovery was thought to provide evidence of an evolutionary link between a number of modern avian orders. However, recent analyses of Presbyornis fossils have demonstrated that these birds clearly belong among the Anseriformes, which include today’s ducks, known as the Anatidae.
Presbyornis had a long neck, tall legs, webbed feet with large claws, and a duck-like head. Some individuals were roughly goose sized, while others were larger, about the size of modern swans. Based on fossil evidence, these extinct birds nested together in large colonies on the edges of lakes. Fossils have been found in Asia and even more widely across North America. They appear to have been filter feeders and may have foraged much like dabbling ducks. Given that fossils of these birds have been found in huge bone beds in several rock formations, they appear to have been gregarious, like today’s ducks and geese, living in flocks of many hundreds or even thousands of individuals.
Among the most interesting ancient waterfowl ancestors was Dromornis planei, also known as the “Demon Duck of Doom.” This impressive creature was an eight-foot-tall flightless bird that weighed over 500 pounds and belonged to a uniquely Australian family of extinct birds, the Dromornithids. Well-preserved fossils, including skulls, bills, vertebrae, and leg bones, suggest that Dromornithids are closely related to Anseriformes.
Dromornis planei was a heavily built bird with a long neck and enormous legs. It was as tall as an ostrich but far more colossal in stature. Its skull was similar in size to that of a horse, and it had a deep, curved bill. While fossil records of wing bones are scarce, Dromornithids are believed to have had short stubby wings and lacked a keel on the sternum, which are features associated with flightless birds. These birds lived alongside members of the genus Emuarius (relatives of today’s emus and cassowaries) in an area that is thought to have been a large meandering river and surrounding floodplain with seasonal fluctuations in water levels. Crocodile predation was likely a significant cause of mortality among these huge birds, as many fossilized bones have puncture marks that match the tooth size and structure of ancestral crocodiles.
The diet of Dromornithids has been debated, with the skull and massive bill of Dromornis planei being at the center of the discussion. Scientists first suggested that the bird’s bill was specialized for harvesting and breaking tough plant material. In addition, gastroliths (gizzard stones) have been discovered at some fossil sites. Birds swallow gastroliths to help grind seeds and other hard plant materials in the gizzard. In addition, the best fossil specimen of Dromornis planei has a deep yet thin bill with limited attachment areas for muscles. This suggests that the bird had a weak bite. But some researchers have argued that the bill was better suited for tearing meat and crushing bones, similar to the unrelated “terror birds” (Diatryma) of South America. Thus, the colorful nickname Demon Duck of Doom. More fossil discoveries may help solve the mystery of whether Dromornis planei was a vegetarian or carnivore.
Those are just a few examples of what we know today about prehistoric waterfowl. Understanding how these ancient birds lived and interacted with their environments can help us recognize changes occurring in our ecosystems today and how they might impact waterfowl and other wildlife. Unlike their ancient ancestors, however, today’s waterfowl have powerful advocates working to ensure their abundance and long-term survival. Ducks Unlimited and its conservation partners are dedicated to ensuring that the ecosystems that are important to waterfowl are sustained for future generations, not just for our avian friends but for all the species that inhabit these special places, including people.
Dr. Dale James is the director of conservation science and planning in Ducks Unlimited’s Southern Region.