The ‘ultimate bird’ once prowled the seas of a young Japan

It’s common in the present day to seek out swans on rivers and lakes, splitting their time between pulling up water crops and punishing the unwise with highly effective blows of their bony-elbowed wings.

Eleven million years in the past, nevertheless, swans in what’s in the present day referred to as Japan did one thing sudden: They took to the oceans. In a paper revealed this week in The Bulletin of Gunma Museum of Pure Historical past, Japanese paleontologists formally described this household or genus of swans, Annakacygna, which had lengthy, filter-feeding heads, small wings and critically unusual hips — all of which have led the researchers to name it the “final hen.”

The primary set of stays of Annakacygna — an almost articulated skeleton in a stone slab from a riverbed in Gunma Prefecture — had been excavated by a Japanese fossil hunter in 2000. After the fossil hunter donated the stays to the Gunma Museum of Pure Historical past, museum director Hasegawa Yoshikazu referred to as in Hiroshige Matsuoka, a paleontologist, to look at them.

Initially, Matsuoka thought he was taking a look at a wierd duck, maybe an animal that dove within the oceans simply offshore of the then-newly risen Japanese Archipelago. However as bones had been cleared from the slab, he concluded that the short-winged skeleton belonged to a flightless swan.

The species, which he and co-author Yoshikazu named Annakacygna hajimei, was about 1.2 meters lengthy, as giant as the fashionable black swan. One other set of stays from a associated species, which they named A. yoshiiensis, advised a hen so long as the most important dwelling swan species, the 1.7-meter trumpeter swan.

Each birds had been “fatter and heavier than these trendy swans,” Matsuoka stated. Evaluating their stays with the dissected physique of a typical extant swan, he discovered that the birds differed in different methods as properly. Their tails had been extremely cell. Their hips had been unusually broad and robust, and their bones had been thicker than common for a water hen, serving to them journey low within the water.

Oddest of all had been the wings. Flightless birds normally lose a few of the utility of their wings, Matsuoka stated, a course of referred to as degeneration. However in Annakacygna, the shoulder joints and muscle attachments that pull the arms backward had been unexpectedly properly developed, with uniquely formed wrists that stored the digits — and with them, the wings — completely bent.

At first, these wings puzzled the crew. However whereas watching a video of a mute swan holding a chick on her again, Matsuoka had a brainwave. Many trendy swans habitually carry their younger piggyback, he stated, with their wings held again and as much as defend the chicks. That posture in Annakacygna’s trendy family advised a brand new risk: that the flightless swans may need enshrined this conduct into their anatomy, changing their bent wings and broad hips into specifically tailored cradles to hold chicks safely throughout the briny deep.

The swans had been properly tailored to a coastal way of life in one other approach as properly: lengthy, filter-feeding beaks that resembled these of shoveler geese, permitting them to dabble for plankton within the cool, wealthy seas off the Japanese coast. Trendy swans, in contrast, have straight, vegetation-nibbling beaks.

Flightlessness isn’t uncommon in water birds; trendy steamer geese, just a few species of teal and several other extinct kinds of geese ditched the skies for the water. A few of these waterfowl hit exceptional sizes: The Pleistocene big swan of Malta, which some researchers have advised was land-bound, was 30% bigger than a dwelling mute swan.

However though it’s smaller, Matsuoka stated, Annakacygna is in a league of its personal. “I feel all wild animals stay for 2 functions,” he stated, particularly sustaining the self (by consuming) and the species (by breeding). Judged by that rubric, the bargelike, baby-cradling, filter-feeding sea swan is one thing particular.

“It’s the most effective survival type as an animal,” he stated. “That’s why we name it the ‘final hen.’”

This text initially appeared in The New York Occasions. © 2022 The New York Occasions Firm