fossils

Giant "ducks" of the North Pole

3986b46bb4f35aa1ff4d42167a12e0fc

Vasika
Udurawane

Writer
New fossils tell us that previously known giant “ducks” lived farther north than ever before. More than 53 million years ago, the Arctic was warm, and covered with extensive jungles and swamps. It was a far cry from the icy carpet that covers the region today.

Neither Gastornis nor Presbyornis are new animals in the fossil record. They were both huge “ducks” that dominated their ecosystem, and were among the largest birds of their time. We have found their fossils all over the Northern Hemisphere from Germany to Wyoming since the early days of paleontology in the 19th and 20th centuries. One was a graceful, long-legged wader while the other was a bulky and flightless nutcracker with a huge beak. Now though, a series of new and surprising fossil fragments has been receiving extra attention.


These new fossil fragments were discovered in the 1970s by a team under the leadership of Professor Thomas Stidham and the Chinese Academy of Sciences in Beijing and scientists at CU-Boulder. The location of the new find was the Eureka Sound Group of Ellesmere Island, one of the larger islands in the Arctic Ocean and Canada’s third largest island. It is one of the coldest and driest places in the world today, lying somewhat above the Arctic Circle. Much of it is locked within glaciers and ice caps these days, supporting only the traditional Arctic fare of polar bears, seals, marine birds and whales.


A number of marine ducks like eiders and scoters exist in this region today and have varying habits. Some species are migratory, traveling vast distances across the Northern Hemisphere while other seabirds spend their time braving the harsh Arctic winter. Both Gastornis and Presbyornis were somewhat similar in that one was a breeding resident and the other was a migrant.


Yet the world these birds lived in was very different from what it is today. Stidham and team had uncovered the remains of a lost forest, one that stretched from Germany and France, all the way up to England and to Ellesmere itself. It existed during the Early Eocene, around 53 million years ago. The plants found here include dawn redwoods, fast-growing deciduous trees up to sixty meters in height, as well as swamp cypresses. At the time it was more like a wetland in Louisiana or Florida but somewhat milder, with summer temperatures as much as 20 degrees Celsius. Yet the lights still went out during winter, even if it probably never got too far below freezing.


The Eocene world was humid during periods of extended warmth and the earliest mammals were just beginning to enlarge into somewhat recognizable forms. In fact, for a long time after the extinction of the dinosaurs, there were no ice caps at the poles, instead having thick and lush jungles and animals that might be found farther south today. The ancestors of horses, rhinos, cats and dogs were all part of this fauna and today, and might seem like just your generic little mammals. Only a few were as big as or bigger than a tapir or a pygmy hippo.


The Ellesmere fossils also show us that crocodiles, turtles and freshwater fish existed here too. Their fossils were also found in the 1970s, by a team consisting of paleontologists Malcolm McKenna, Mary Dawson, Robert (Mac) West and J. Howard Hutchison. Yet despite the existence of rather sizable herbivorous mammals the most charismatic animals in these forests were the huge birds. It had been just 13 million years since the death of the dinosaurs and their closest relatives now still ruled over the early mammals. And just what were these monster ducks like in life?


When the earliest fossils of Gastornis were described in 1855 on the basis of remains found close to Paris, they were thought to be relatives of the modern ostriches and emus. At one time they were even linked to the crane family. Other fossils from around the Northern Hemisphere though, revealed that it was a relative of ducks and geese, but unlike any other that ever lived. For one, it stood as tall as a man and was unable to fly. Its body and legs were very stocky and its head was topped with a massive beak. Earlier thought to be a fierce predator that preyed on early horses, it is now known to be a herbivore. That massive beak was heavy and lacked the hooked tip of a predatory bird and the bird even lacked sharp talons. It was certainly happier cracking the nuts of palm trees and other tough vegetation.


This made it like a giant, flightless parrot and not just a typical duck. Being taller than the contemporary mammals, it could probably browse from small trees and thus had a great impact on its environment. Thus instead of killing the mammals it lived with, it would be feeding alongside them. This left only the crocodiles and alligators of the time as the apex predators of the Eocene forests.


It was not, however the only big bird found here. Beside Gastornis was another well-known duck named Presbyornis, a somewhat smaller and less impressive creature. Presbyornis was roughly as big as a swan and was able to fly well. Its long legs and neck meant that it was thought to be a flamingo when it was first described in 1926. This bird was a wader, striding through swamps and rivers as it searched for fish or other aquatic meals. Being a flying aquatic bird, it was also probably a migrant that spent the winter at Eureka Sound.


This makes sense as aquatic birds migrate between the Arctic, Eurasia and North America. Plenty of ducks do this today and it makes sense that Presbyornis did the same thing 53 million years ago. Certainly Presbyornis has been discovered all over the Northern Hemisphere while the Ellesmere fossils show the northernmost extent of these creatures. The new remains consist of upper arm bones, with Stidham himself saying how similar they were to the bones found in Wyoming.


These fossils also give us an idea of the fate of the Eocene forests themselves. According to Eberle, a member of the research team, the Arctic ice caps are melting at a great rate, even though we may not get to see reptiles and birds dominate them during our lifetime. Ironically enough the Ellesmere fossils themselves also show us a very fragile ecosystem that would die out in just a few million years. The world would cool down and the glaciers would overtake the north at last, destroying the beautiful Arctic forests for good.


Read more here: http://www.nature.com/articles/srep20912

Image Credit: Joschua Knuppe

3986b46bb4f35aa1ff4d42167a12e0fc

Vasika
Udurawane

Writer


http://sulc.us/3vkez
http://www.eartharchives.org/articles/giant-ducks-of-the-north-pole/