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The tale of
The duck clade has greatly diverged since its first appearance in Antarctica. They are so diversified and specialized that they are unrecognizable from their quacking ancestors. A new story has begun...a duck tale. A ducktail, even.
The new clade of ducks was named Pygostylidae, now comprising 7 species.
Like their ancestors (angucks), pygostylids possess a three-chambered gizzard, where they can slow down and better digest cellulose, analogous to mammalian ruminants. In the face of their size, these ducks have developed an unusual adaptation for supporting their weight: their tail. Pygostylids have drastically increased the size of their pygostyle (the fused caudal vertebrae of birds), becoming functional again for balancing, after more than 100 million years of bird evolution. Due to this, pygostylids are often vernacularly called ducktails. (other names are bullducks and drums)
Depending on their size, ducktails have variable anatomical structures: large species possess longer tails, with a more horizontal posture of the back, like non-avian theropods; oppositely, small species have progressively reduced their tail, with a more semi erected posture off the back, like any other bird.
The honking ducktail (Longanas fermentum) is a clear example of a relatively small ducktail. Not larger than an emu, this bird possesses a mediocre-size tail and short tarsus; they are not very good runners, since they live in woodlands rich in the undergrowth.
The honking ducktail is social, living in groups of 10-30. During winter, neighbor groups fused, forming herds of hundreds of individuals, a good strategy to protect juveniles from frosty temperatures and land predators. They use their legs as a weapon, capable of crushing the head or breaking a leg of an herdstalker.
During the reproductive period, males produce very loud calls to attract females and deter other males; on average, their "quacking" (that is more similar to a truck horn) can reach 103 decibels, like a pneumatic drill.
Other 2 species of Longanas sp. are present in Polarica, all specialized in living in different types of habitats. Two species are also present on Marie Byrd island, thanks to periodical land bridges that connected the mainland to it. An extinct population was also known on Ellsworth island.
Talking about large herbivorous birds, bullducks (Sociarampho sp.) are the main ones. Two species are present at the moment, all distributed only in Polarica. Due to their size, these ducks could potentially crush their eggs during incubation; to solve this problem, sub-adults are in charge to incubate the eggs (that are disposed not under but around their body, similarly to ostriches), while adults protect the nesting sites from predators. You are always useful in a bullduck society.
The pelican bullduck (Sociarampho pelecanis) is a large ducktail (150 kg/ 330 lbs) with a gular pouch, used for display and carrying food. They are very generalistic and they can be found in both woodland and tundra, preferentially eating grassy plants. They have a complex list of vocalizations, typical of highly social species.
In the planitial tundra, pelican bullducks coexist with the woolly bullduck (Sociarampho bos), which can attain a weight of 500 kg in large males (1100 lbs), a size that few birds were able to reach. They are specialized grazers, with moderately short and round beaks to strip grass and a multitude of false teeth to crumble it. They have a more graviportal structure than their smaller cousins, reducing their running ability. But that's not important, since no antarctic predator has the guts to attack this bird. Wholly bullduck carrions are crucial for the tundra ecosystems of Polarica, feeding a huge amount of carnivores and omnivores.
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