Thursday, May 26, 2011

Online Lecture

Click here to watch the lecture from the U of NC: Fossil Penguins--A 60 Million Journey from Wings to Flippers

New Paper on Kaiika Maxwelli Published

Kaiika maxwelli, a new Early Eocene archaic penguin (Sphenisciformes, Aves) from Waihao Valley, South Canterbury, New Zealand 
New Zealand Journal of Geology and Geophysics
Volume 54, Issue 1, March 2011, Pages 43 - 51
Authors: RE Fordycea; DB Thomasa
DOI: 10.1080/00288306.2011.536521


Kaiika maxwelli is a new species of archaic fossil penguin from the Kauru Formation (Waipawan-Mangaorapan, Early Eocene) of the southern Canterbury Basin, Waihao River, South Canterbury, New Zealand. Kaiika maxwelli is represented by a well-preserved large and robust humerus, in which the broad m. scapulotricipitalis tendon sulcus, sigmoidal shaft and vestigial supracondylar process are similar to those of the basal penguin Waimanu, but differs from Waimanu and other penguins by having a deeply incised ventral tubercle and a smoothly curved profile of the deltoid crest and head. Humeral length suggests a body length of 1.3 m comparable to that of an emperor penguin, indicating that large penguins lived at a time of global warmth. This is the first significant fossil penguin named from pre-Bortonian (Middle Eocene) strata of the southern Canterbury Basin. Kaiika maxwelli is only the seventh species of fossil penguin reportedly older than Middle Eocene. 

Friday, May 20, 2011

China Fossil Shows Bird, Crocodile Family Trees Split Earlier Than Thought

This is a reconstruction of X. sapingensis, based on the fossil. (Credit: Sterling Nesbitt)

ScienceDaily (May 19, 2011) — A fossil unearthed in China in the 1970s of a creature that died about 247 million years ago, originally thought to be a distant relative of both birds and crocodiles, turns out to have come from the crocodile family tree after it had already split from the bird family tree, according to research led by a University of Washington paleontologist.

The only known specimen of Xilousuchus sapingensis has been reexamined and is now classified as an archosaur. Archosaurs, characterized by skulls with long, narrow snouts and teeth set in sockets, include dinosaurs as well as crocodiles and birds.

The new examination dates the X. sapingensis specimen to the early Triassic period, 247 million to 252 million years ago, said Sterling Nesbitt, a UW postdoctoral researcher in biology. That means the creature lived just a short geological time after the largest mass extinction in Earth's history, 252 million years ago at the end of the Permian period, when as much as 95 percent of marine life and 70 percent of land creatures perished. The evidence, he said, places X. sapingensis on the crocodile side of the archosaur family tree.

"We're marching closer and closer to the Permian-Triassic boundary with the origin of archosaurs," Nesbitt said. "And today the archosaurs are still the dominant land vertebrate, when you look at the diversity of birds."

The work could sharpen debate among paleontologists about whether archosaurs existed before the Permian period and survived the extinction event, or if only archosaur precursors were on the scene before the end of the Permian.

"Archosaurs might have survived the extinction or they might have been a product of the recovery from the extinction," Nesbitt said.

The research is published May 17 online in Earth and Environmental Science Transactions of the Royal Society of Edinburgh, a journal of Cambridge University in the United Kingdom.
Co-authors are Jun Liu of the American Museum of Natural History in New York and Chun Li of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China. Nesbitt did most of his work on the project while a postdoctoral researcher at the University of Texas at Austin.

The X. sapingensis specimen -- a skull and 10 vertebrae -- was found in the Heshanggou Formation in northern China, an area with deposits that date from the early and mid-Triassic period, from 252 million to 230 million years ago, and further back, before the mass extinction.

The fossil was originally classified as an archosauriform, a "cousin" of archosaurs, rather than a true archosaur, but that was before the discovery of more complete early archosaur specimens from other parts of the Triassic period. The researchers examined bones from the specimen in detail, comparing them to those from the closest relatives of archosaurs, and discovered that X. sapingensis differed from virtually every archosauriform.

Among their findings was that bones at the tip of the jaw that bear the teeth likely were not downturned as much as originally thought when the specimen was first described in the 1980s. They also found that neural spines of the neck formed the forward part of a sail similar to that found on another ancient archosaur called Arizonasaurus, a very close relative of Xilousuchus found in Arizona.

The family trees of birds and crocodiles meet somewhere in the early Triassic and archosauriforms are the closest cousin to those archosaurs, Nesbitt said. But the new research places X. sapingensis firmly within the archosaur family tree, providing evidence that the early members of the crocodile and bird family trees evolved earlier than previously thought.
"This animal is closer to a crocodile, but it's not a crocodile. If you saw it today you wouldn't think it was a crocodile, especially not with a sail on its back," he said.

The research was funded by the National Science Foundation, the Society of Vertebrate Paleontology, the American Museum of Natural History and the Chinese Academy of Sciences.

Story Source:
The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Washington. The original article was written by Vince Stricherz.

University of Washington (2011, May 19). China fossil shows bird, crocodile family trees split earlier than thought. ScienceDaily. Retrieved May 20, 2011, from­ /releases/2011/05/110518151822.htm

Friday, May 13, 2011

Penguins' Oxygen Trick: How They Survive Deep Dives

Date: 12 May 2011

Thursday, May 12, 2011

Why Global Warming Spells Disaster For Adélie Penguins (VIDEO)

by: Kristina Chew

The Western Antarctic Peninsula is one of the most rapidly warming areas on the earth: In just the past half-century, its temperatures have risen by 10.8 degrees Fahrenheit. Adélie penguins rely on the ice to live and global warming is taking its toll on their numbers, though not exactly in ways one might think.

Indeed, Adélie penguin colonies on the Antarctic Peninsula, on the northern edge of Antarctica, have declined by 90 percent, and the only colony of emperor penguins that once lived there is now extinct. But it turns out that elsewhere, specifically in the Ross Sea, a southern extension of the Pacific Ocean, Adélie colonies have been growing significantly, as winter sea ice cover grows there.

Indeed, climate change has benefited penguins in some ways, as the New York Times observes: the Ross Sea a reverse trend is occurring: Winter sea ice cover is growing, and Adélie populations are actually thriving. The Cape Royds colony grew more than 10 percent every year, until 2001, when an iceberg roughly the size of Jamaica calved off the Ross Sea ice shelf and forced residents to move 70 kilometers north to find open water. (The iceberg broke up in 2006, and the colony of 1,400 breeding pairs is now recovering robustly.) Across Ross Island, the Adélie colony at Cape Crozier -- one of the largest known, with an estimated 230,000 breeding pairs -- has increased by about 20 percent.
Climate change has created a paradise for some pack ice penguin colonies and a purgatory for others, but the long-term fate of all Adélie and emperor penguins seems sealed, as relentless warming eventually pulls their rug of sea ice out from under them. Some scientists attribute the recent sea ice growth in the Ross Sea to the persistent ozone hole, a legacy of the human use of chlorofluorocarbons that cools the upper atmosphere over the continent, increasing the temperature difference with the lower atmosphere and equator, and over the last 30 years has delivered significantly brisker westerly winds in the summer and autumn. The warming of Earth's middle latitudes is having a similar effect, increasing that temperature difference and sending stronger winds that push sea ice off the coast and expose pockets of open water, called polynyas, that give nesting Adélie penguins easier access to food.

Other factors including consumers' taste for Chilean sea bass have also helped the Ross Sea penguins' survival. Fishing fleets and a fishery in the Ross Sea have encroached on the last refuge of the fish, lessening the Adélie penguins' competition for food.

Despite this, the fate of the penguins seems sealed. As the boundary of the sea ice retreats south, the penguins' chances for survival diminishes. Global warming has also had a drastic effect on the food chain: A recent study in the Proceedings of the National Academy of Sciences has found that the warmer temperatures are killing off as much as 80 percent of the phytoplankton that grow under ice floes and the krill, a staple of the penguin diet.

Further, temperatures are rising in the Ross Sea: The average summer temperature at McMurdo Station, the American research base on Ross Island, has gone up 2.7 degrees Fahrenheit in the past 30 years, which is more than the global average. As the ice pack melts, the Ross Sea penguins will have no choice but to "shift their range farther south toward the pole."

David Ainley, an ecologist with the consulting firm H. T. Harvey and Associates who has been studying Ross Sea penguins for 40 years, notes that the penguins "appear to need light -- if only twilight -- to forage and navigate, and as comfort against predators." As the Adélie penguins have to go further south as the pack ice retreats, they may face extinction not only because their habitat is gone, but because of an "unshakable fear of darkness" -- because they find themselves living in a dark part of the world far from where they once made their colonies.

This video shows Adélie penguins on Ross Island, their home for the time being.