Fossil shows how penguins' wings evolved

A tiny fossil penguin plays a huge role in the evolutionary history of the bird, an international study shows.

Published in the Journal of the Royal Society of New Zealand, the study describes a new species of fossil penguin which lived in Otago about 24 million years ago.

Named Pakudyptes hakataramea, the penguin was very small -- about the same size as the little blue penguin, the smallest in the world -- with anatomical adaptations that allowed it to dive.

Lead author Dr Tatsuro Ando, formerly a PhD candidate at the University of Otago -- Ōtākou Whakaihu Waka and now at the Ashoro Museum of Palentology in Japan, collaborated with researchers from Otago, Okayama University of Science and Osaka University.

Dr Ando's inspiration for the paper came from discussions with the late Professor Ewan Fordyce, his supervisor and mentor at Otago.

Researchers analysed three bones -- a humerus, femur and ulna -- found by Professor Fordyce in the Hakataramea Valley, South Canterbury.

Dr Ando says Pakudyptes fills a morphological gap between modern and fossil penguins.

"In particular, the shape of the wing bones differed greatly, and the process by which penguin wings came to have their present form and function remained unclear," he says.

The humerus and ulna highlight how penguins' wings have evolved.

"Surprisingly, while the shoulder joints of the wing of Pakudyptes were very close to the condition of the present-day penguin, the elbow joints were very similar to those of older types of fossil penguins.

"Pakudyptes is the first fossil penguin ever found with this combination, and it is the 'key' fossil to unlocking the evolution of penguin wings."

Co-author Dr Carolina Loch, from Otago's Faculty of Dentistry, says analysis of the internal bone structure conducted at the Faculty of Dentistry, with comparison with data on living penguins provided from the Okayama University of Science, shows these penguins had microanatomical features suggestive of diving.

Modern penguins have excellent swimming abilities, largely due to their dense, thick bones that contribute to buoyancy during diving.

In Pakudyptes, the bone cortex was reasonably thick although the medullary cavity, which contains bone marrow, was open, similar to what we see in the modern little blue penguin, which tends to swim in shallow waters.

The ability for Pakudyptes to dive and swim comes down to the distinctive combination of its bones.

Bones such as the humerus and ulna show areas for attachment of muscles and ligaments which reveal how the wings were being used to swim and manoeuvre under water.

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This Japanese 'dragon' terrorized ancient seas

Researchers have described a Japanese mosasaur the size of a great white shark that terrorized Pacific seas 72 million years ago.

Extra-long rear flippers might have aided propulsion in concert with its long finned tail.

And unlike other mosasaurs, or large extinct marine reptiles, it had a dorsal fin like a shark's that would have helped it turn quickly and with precision in the water.

University of Cincinnati Associate Professor Takuya Konishi and his international co-authors described the mosasaur and placed it in a taxonomic context in the Journal of Systematic Palaeontology.

The mosasaur was named for the place where it was found, Wakayama Prefecture.

Researchers call it the Wakayama Soryu, which means blue dragon.

Dragons are creatures of legend in Japanese folklore, Konishi said.

"In China, dragons make thunder and live in the sky. They became aquatic in Japanese mythology," he said.

The specimen was discovered along the Aridagawa River in Wakayama by co-author Akihiro Misaki in 2006.

The specimen is the most complete skeleton of a mosasaur ever found in Japan or the northwestern Pacific, Konishi said.

"In this case, it was nearly the entire specimen, which was astounding," Konishi said.

He has dedicated his career to studying these ancient marine reptiles.

But the Japanese specimen has unique features that defies simple classification, he said.

Its rear flippers are longer than its front ones. These enormous flippers are even longer than its crocodile-like head, which is unique among mosasaurs.

"I thought I knew them quite well by now," Konishi said. "Immediately it was something I had never seen before."

Mosasaurs were apex predators in prehistoric oceans from about 100 million years ago to 66 million years ago.

They were contemporaries of Tyrannosaurus rex and other late Cretaceous dinosaurs that ruled the Earth.

Mosasaurs were victims of the same mass extinction that killed off nearly all dinosaurs when an asteroid struck what is now the Gulf of Mexico.

Researchers placed the specimen in the subfamily Mosasaurinae and named it Megapterygius wakayamaensis to recognize where it was found.

Megapterygius means "large winged" in keeping with the mosasaur's enormous flippers.

Konishi said those big paddle-shaped flippers might have been used for locomotion.

But that type of swimming would be extraordinary not only among mosasaurs but among virtually all other animals.

"We lack any modern analog that has this kind of body morphology -- from fish to penguins to sea turtles," he said.

"None has four large flippers they use in conjunction with a tail fin."

Researchers speculated that the large front fins might have helped with rapid maneuvering while its large rear fins might have provided pitch to dive or surface.

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Loss of Antarctic sea ice causes catastrophic breeding failure for emperor penguins

Emperor penguin colonies experienced unprecedented breeding failure in a region of Antarctica where there was total sea ice loss in 2022. The discovery supports predictions that over 90% of emperor penguin colonies will be quasi-extinct by the end of the century, based on current global warming trends.

In a new study published today in Communications Earth & Environment, researchers from British Antarctic Survey discussed the high probability that no chicks had survived from four of the five known emperor penguin colonies in the central and eastern Bellingshausen Sea. The scientists examined satellite images that showed the loss of sea ice at breeding sites, well before chicks would have developed waterproof feathers.

Emperor penguins are dependent on stable sea ice that is firmly attached to the shore ('land-fast' ice) for the majority of the year, from April through to January. Once they arrive at their chosen breeding site, penguins lay eggs in Antarctic winter from May to June. Eggs hatch after 65 days, but chicks do not fledge until summer, between December and January.

At the beginning of December 2022, the Antarctic sea ice extent had matched the previous all-time low set in 2021. The most extreme loss was seen in the central and eastern Bellingshausen Sea region, west of the Antarctic Peninsula where there was a 100% loss of sea ice in November 2022.

Lead author of the study, Dr Peter Fretwell, said:

"We have never seen emperor penguins fail to breed, at this scale, in a single season. The loss of sea ice in this region during the Antarctic summer made it very unlikely that displaced chicks would survive.

We know that emperor penguins are highly vulnerable in a warming climate -- and current scientific evidence suggests that extreme sea ice loss events like this will become more frequent and widespread.

Since 2016, Antarctica has seen the four years with the lowest sea ice extents in the 45-year satellite record, with the two lowest years in 2021/22 and 2022/23. Between 2018 and 2022, 30% of the 62 known emperor penguin colonies in Antarctica were affected by partial or total sea ice loss. Although it is difficult to immediately link specific extreme seasons to climate change, a longer-term decline in sea ice extent is expected from the current generation of climate models.

Understanding emperor penguin colonies

Emperor penguins have previously responded to incidents of sea ice loss by moving to more stable sites the following year. However, scientists say that this strategy won't work if sea ice habitat across an entire region is affected.

Emperor penguin populations have never been subject to large scale hunting, habitat loss, overfishing or other local anthropogenic interactions in the modern era. Unusually for a vertebrate species, climate change is considered the only major factor influencing their long-term population change. Recent efforts to predict emperor penguin population trends from forecasts of sea ice loss have painted a bleak picture, showing that if present rates of warming persist, over 90% of colonies will be quasi-extinct by the end of this century.

The five colonies of penguins studied were all discovered in the last 14 years using satellite imagery -- Rothschild Island, Verdi Inlet, Smyley Island, Bryan Peninsula and Pfrogner Point. All five colonies had been shown to return to the same location each year to breed, with only one previous instance of breeding failure at Bryan Peninsula in 2010.

Scientists now routinely use satellite imagery to discover and monitor emperor penguin colonies, as the brown stains of the birds' guano stands out clearly against the stark white of ice and snow. The team used images from the European Commission's Copernicus Sentinel-2 satellite mission, which has continuously monitored the area in Antarctica since 2018.

The impact of Antarctic sea ice loss

Over the past seven years, sea ice around Antarctica has decreased significantly. By the end of December 2022, sea ice extent was the lowest experienced in the 45-year satellite record. In the Bellingshausen Sea, the home of the penguin colonies in this study, sea ice didn't start to re-form until late April 2023.

Since then, the deviation from the norm has intensified: as of 20 August 2023 the sea ice extent was 2.2 million km2 lower than the 1981-2022 median (17.9 million km2) significantly surpassing the record winter low on 20 August 2022 of 17.1 million km2. This missing area is larger than the size of Greenland, or around ten times the size of the United Kingdom.

Dr Caroline Holmes, a polar climate scientist at BAS, said:

"Right now, in August 2023, the sea ice extent in Antarctica is still far below all previous records for this time of year. In this period where oceans are freezing up, we're seeing areas that are still, remarkably, largely ice-free.

Year-to-year changes in sea ice extent are linked to natural atmospheric patterns such as El Niño-Southern Oscillation, the strength of the southern hemisphere jet stream, and regional low-pressure systems.

We'll need years of targeted observations and modelling to know precisely how much the current conditions are being influenced by these phenomena and by natural ocean variability. However, the recent years of tumbling sea ice records and warming of the subsurface Southern Ocean point strongly to human-induced global warming exacerbating these extremes."

Climate models show a decline in Antarctic sea ice both under present and forecast human carbon dioxide emissions.

Dr Jeremy Wilkinson, a sea ice physicist at BAS, commented:

"This paper dramatically reveals the connection between sea ice loss and ecosystem annihilation. Climate change is melting sea ice at an alarming rate. It is likely to be absent from the Arctic in the 2030s -- and in the Antarctic, the four lowest sea ice extents recorded have been since 2016.

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