Saturday, November 1, 2014

Guest Post | Fossil Evidence for the Rise of Penguins: Australia and Africa

Daniel Ksepka, PhD, is the Curator of Science at the Bruce Museum. Ksepka earned his PhD in Earth and Environmental Sciences from Columbia University in 2007 and spent five years in residence at the American Museum of Natural History in New York, where he performed his dissertation research on the fossil record of penguins and gained broad experience in the curation and study of natural history objects including fossils, skeletal materials, skins and geological specimens.

In this last post of the series, Daniel will share information about prehistoric penguins. 

Like South America, Australia was just a short distance from Antarctica during the Eocene Epoch but would later drift northwards. Despite being much larger than New Zealand, Australia has far fewer penguins. Today, the only penguin that breeds on the Australian mainland is the little blue penguin, a tiny bird that stands, or perhaps one should say hunches, about one foot tall. This delightful species can be seen at the New England Aquarium, and in fact many of the individuals in the enclosure are birds who were hatched in Australian zoos from rehabbed parents but could not be released in the wild and needed a safe new home.

Little blue penguin

Our knowledge of Australia's ancient penguins is very fuzzy, coming from just a handful of fossil specimens that have been collected over the years. Palaeontologists have discovered evidence that penguins made it to the southern coast of Australia by the Eocene Epoch, and some reached sizes that would have made a little blue penguin look like a bug. However, with only bits of flipper bones and similar scraps left behind, these ancient penguins have revealed little about their overall appearance.

The large species vanished before modern little blue penguins started arriving from New Zealand, but we do not know why. Bones of penguins have been found in pre-colonial middens, indicating humans hunted some species during the pre-colonial era. However, most of the large extinct penguin species such as Anthropodyptes gilli were long gone by the time humans appeared on the scene, so overhunting cannot completely explain why Australia is so depleted of penguin diversity today.

Fossil humerus (flipper bone) of the mysterious Australian penguin Pseudaptenodytes macraei,
compared to the same bone from a modern emperor penguin.
Image courtesy of Travis Park

Finally, we reach Africa. Africa appears to be the last major landmass that penguins reached in their sweeping journey across the southern ocean. The oldest penguin fossils discovered in African sediments come from the Saldanha Steel site and are between 10 and 12 million years in age. These bones were fortuitously exposed while an industrial steel plant was being constructed, which is an isolated incident. Indeed, one extinct species of African penguin is named Nucleornis insolitus because it was discovered during construction at a reactor site. There seem to have been at least four different species of penguins living side by side in Africa in the past, swimming along the coast of an area inhabited by such oddities as the extinct African Bear (Agriotherium africanum) and the short-necked giraffe (Sivatherium hendeyi).

This reproduction of a painting shows a Sivatherium of an undetermined species | Via

The New England Aquarium's own African penguins (also known as black-footed penguins or jackass penguins) are members of the sole species that breeds in Africa today. These fine fellows appear to be newcomers to Africa. They only start showing up about half a million years ago, at a point when all the ancient species seem to have already vanished.

Skeletal reconstruction of the extinct African penguin Inguza predemersus with a modern
black-footed penguin for scale. Fossil art by Kristin Lamm, living penguin art by Barbara Harmon.

So the march of penguins was completed. Beyond the three continents we covered, penguins also live on many small islands today, though we have little knowledge of their ancient history in these locales because fossils tend not to be available. Far from being restricted to icy Antarctica, penguins have truly conquered the myriad environments of the southern hemisphere.

By request of my image providers, the standard conditions are: one time single use, with no transfer of copyright. 


Wednesday, October 29, 2014

Guest Post | Fossil Evidence for the Rise of Penguins: South America

Daniel Ksepka, PhD, is the Curator of Science at the Bruce Museum. Ksepka earned his PhD in Earth and Environmental Sciences from Columbia University in 2007 and spent five years in residence at the American Museum of Natural History in New York, where he performed his dissertation research on the fossil record of penguins and gained broad experience in the curation and study of natural history objects including fossils, skeletal materials, skins and geological specimens.

Over the next couple posts, Daniel will share information about prehistoric penguins. Learn more about penguins, their ancestors, their physiology and their biology. Visit the Aquarium! Keep reading for more about the first penguins in South America's fossil record.

South America welcomed its first penguin visitors about 40 million years ago, roughly 15 million years after as our flippered friends established themselves in Antarctica. The oldest fossils from this continent were discovered in Tierra del Fuego, at the southern tip of the landmass. Looking back at the geological record, this is not surprising. During the Eocene Epoch, South America was much further South then it is today. The swim from the Antarctic Peninsula to Tierra del Fuego would have been an easy journey for penguins.

Penguins quickly progressed north on both coasts, and fossils have been discovered in Peru, Chile, and Argentina recording their past diversity. In fact, they soon reached latitudes of 14°S in Peru, well within the tropics. Early subequatorial penguins soaked up rays on the beaches of a “Greenhouse Earth” during the Eocene, at a time when global sea surface temperatures averaged more than 5°C (~10° F) higher than today. Several unusual types of penguins thrived in this region. Roughly 34 million years ago, a spear-billed penguin called Icadyptes salasi prowled the coast.  This species was able to impale its prey with a long, straight, reinforced beak unlike any modern penguin.

Fossil skull of the spear-billed penguin Icadyptes salasi with a modern Humboldt penguin for scale

Later, around 10 million years ago, “bobble-headed” penguins like Spheniscus megaramphus and Spheniscus urbinai appeared.  These species are extinct relatives of the modern banded penguin group that includes Humboldt and Magellanic penguins. Each had a powerfully hooked beak with a sharp, downturned tip. This beak shape likely helped these menacing birds get a grip on prey like fish. These intimidating penguins were likely ensconced at the upper levels of the food chain for a long time. 

Today, mainland South America hosts more unimposing penguins, included the banded Humboldt penguin and Magellanic penguin, and the crested macaroni penguin and Southern rockhopper penguin. (The last of these can be seen at the New England Aquarium today!) These species are important predators of small fish and other marine life, but penguins as a whole seem to have relinquished part of their former role in the ecosystem to marine mammals like seals and sea lions in the modern day.

Silhouettes of a modern Humboldt Penguin and the extinct
"bobble-headed" 
Spheniscus urbinai to the same scale.

By request of my image providers, the standard conditions are: one time single use, with no transfer of copyright. 

Tuesday, October 28, 2014

Guest Post | Fossil Evidence for the Rise of Penguins: Antarctica

Daniel Ksepka, PhD, is the Curator of Science at the Bruce Museum. Ksepka earned his PhD in Earth and Environmental Sciences from Columbia University in 2007 and spent five years in residence at the American Museum of Natural History in New York, where he performed his dissertation research on the fossil record of penguins and gained broad experience in the curation and study of natural history objects including fossils, skeletal materials, skins and geological specimens.

Over the next couple posts, Daniel will share information about prehistoric penguins. Learn more about penguins, their ancestors, their physiology and their biology. Visit the Aquarium! Keep reading for more about the first penguins in the fossil record in Antarctica.

Antarctica was the first point of expansion for penguins. However, this was not the Antarctica we know today. There were no permanent ice sheets covering the continent, and forests spread over the land. Mountains rose over lakes and rivers, and vast plains spread over areas that today lie silently under tremendously thick layers of ice. Sometime around 55 million years ago, shortly after penguins appeared in New Zealand, they expanded their range and reached this forested Antarctica. Soon, an incredible diversity of penguins was gathering along the coast at Seymour Island on the Antarctic Peninsula, which was once the site of an estuary.

A gathering of penguins along the shoreline in Eocene Antarctica, with contemporary plants and animals.
Artwork © Martin Chavez.

It is sometimes difficult to tell whether two different sized bones belong to separate species or represent the male and female of the same species. In the case of Antarctica, even the most conservative counts would indicate 8 species lived side by side, and the true total may have reached 12 or more at the height of their diversity during the Late Eocene (roughly 35 million years ago). These ranged from “normal” penguins close in size to the modern Antarctic Adélie Penguin all the way up to giant species like Anthropornis nordenskjoeldi (a name meaning Nordenskjöld's man-bird, referring to both an Antarctic explorer and the enormous size of the bird).

A fossil beak fragment from a giant Antarctic penguin compared to the skull of a 
King Penguin (Aptenodytes patagonicus). Photo © Dr. Piotr Jadwiszczak.

Over time, Antarctica began to cool as it was placed in a freezer by changing ocean circulation patterns.
Australia and South America, once connected to Antarctica, drifted further north opening a deep seaway. Surrounded on all sides by a powerful clockwise circulating current, Antarctica was cut off from warmer ocean waters and entered an icebound phase. Penguins today call the ice shelves of Antarctica home, and even lay their eggs and raise their chicks on frozen sea ice. Yet, today's polar penguins are not direct descendants of the many penguin species that lived in Antarctica during the Eocene. Those species are all extinct now, yet we know precious little about what happened between the Eocene today. All we have to fill in the more than thirty million year gap are two bones deposited 10 million years ago on the east side of the continent and found during field work in the region.

Gentoo penguins | Photo © Brian Skerry

We know that penguins like the adorable Adélie and the regal Emperor eventually mastered the ice, but it will take further discoveries before we know when they arrived and whether any survivors of the warmer era where still hanging on to survival at that point.


By request of my image providers, the standard conditions are: one time single use, with no transfer of copyright. 

Monday, October 27, 2014

Guest Post | Fossil Evidence for the Rise of Penguins: Prehistoric Penguins

Daniel Ksepka, PhD, is the Curator of Science at the Bruce Museum. Ksepka earned his PhD in Earth and Environmental Sciences from Columbia University in 2007 and spent five years in residence at the American Museum of Natural History in New York, where he performed his dissertation research on the fossil record of penguins and gained broad experience in the curation and study of natural history objects including fossils, skeletal materials, skins and geological specimens.

Over the next couple posts, Daniel will share information about prehistoric penguins. Learn more about penguins, their ancestors, their physiology and their biology. Visit the Aquarium! Keep reading for more about the first penguins in the fossil record.

Penguins have a remarkable family tree. Today, there are 18 officially recognized species of penguin spread throughout the Southern Hemisphere. Each of these species is unique, and together they span a wide range of sizes, ecologies, and preferred environments. Yet, these spectacular birds are only the most recent branches of the extended penguin evolutionary tree. More than 50 extinct species of penguins have been discovered in the fossil record. Paleontologists have learned many secrets of ancient penguin evolution from this rich fossil record. In this series of posts, we will take a look at the march of penguins across the southern seas.

It all started when dinosaurs still roamed the Earth. Ornithologists have used DNA evidence to estimate that a group of ocean-going birds split off into two lineages sometime more than 66 million years ago. One of these branches gave rise to the tube-nosed albatrosses and petrels, and the other gave rise to penguins. These estimates would place the start of the penguin lineage during the Cretaceous Period, but at this first stage they were probably still capable of both wing-propelled diving and aerial flight, much like modern puffins. So far, paleontologists have not found any fossils to illuminate this first stage of penguin evolution.

Evolutionary tree showing the relationships of penguins to other waterbirds.

Fossil penguins appear on the stage in the Paleocene Epoch, the first phase of Earth history following the mass extinction that killed off the non-avian dinosaurs. These fossils turn up not in Antarctica as some might expect, but in New Zealand. This is appropriate enough, as New Zealand is one of the hotspots of modern penguin diversity. The oldest penguin fossils that have been reported so far date to about 61 million years in age. They belong to a species called Waimanu manneringi, (a name derived from the Maori word for “water bird” and the name of Al Mannering, discoverer of the fossil). A smaller species named Waimanu tuatahi lived around the same time. Within a few million years, more species started turning up and New Zealand became a penguin paradise. Almost completely devoid of mammals, the region was a perfect breeding ground for birds that seek to evade land predators.

Life reconstruction of the early penguin Waimanu tuatahi.
Artwork by Chris Gaskin, © Geology Museum, University of Otago.

Among the species that once swam the waters surrounding New Zealand were Kairuku waitaki and Kairuku grebneffi. Kairuku translates roughly to “diver who returns with food”, whereas waitaki references the region where the fossils were found and grebneffi honors Andrew Grebneff, who contributed to the collection and preparation of the fossils. These penguins would indeed have returned with great stores of food, as they were giants. Reaching heights more than a foot taller than living Emperor Penguins, Kairuku penguins would have cut regal figures on the ancient beaches. They were not alone, but lived alongside several smaller species, such as the roughly two foot tall Duntroonornis parvus. New Zealand has continued to host many penguins species through to the present, and today it is possible to find breeding Little Blue Penguins (Eudyptula minor), Yellow-eyed Penguins (Megadyptes antipodes), and Fiordland Crested Penguins (Eudyptes pachyrhynchus) on the mainland, as well as several other species of crested penguin on the outlying islands.

From their New Zealand stronghold, penguins were about to break loose. We'll watch the start of this expansion unfold in the next post.

Composite skeleton of a giant Kairuku penguin being examined by
blog author Dr. Daniel Ksepka. Photo © Dr. R. Ewan Fordyce

By request of my image providers, the standard conditions are: one time single use, with no transfer of copyright. 

Saturday, September 27, 2014

Breeding: Candling

Here is a video of a little blue penguin egg being candled several times throughout its 38 day incubation period.



By shining a concentrated beam of light though the egg we can get a glimpse inside to determine if the egg is fertile.

A penguin egg

We first candle the egg when it is about 10 days old.  If it is fertile, we will see a small bean sized embryo with a network of veins. As incubation continues, the developing chick gets bigger and bigger and we begin to see it moving inside the egg. Just before it is due to hatch the chick becomes so big that it takes up the entire available space inside the egg, and the light beam no longer passed through the egg. This means hatching is not far away.

This is the device we use for candling

The Aquarium takes part in a Species Survival Plans for African and little blue penguins. It's always exciting to track the growth of these chicks while they're in the eggs. Candling is an important part of this process.

Stay tuned for more about the breeding season that happened behind the scenes at the Aquarium. Want to learn more about penguins right now? Head down to the Aquarium and dive into our Penguinology program! You'll learn about the secret world of penguins and some amazing facts about these birds living at the Aquarium. Plan a visit!