In celebration of World Penguin Day (April 25), let’s review a recent research paper on three exciting topics: penguins, poop, and volcanoes! A new paper by Dr. Stephen Roberts and colleagues reported a history of penguin colony collapses and revivals. Technically, there are no fossil penguins here: the populations studied only date back to 6,700 years ago. While ancient by human standards, this represents only 1/10,000th of the history of penguins as a group. And, the populations were studied not by looking at skeletons, but by looking at droppings!
The team studied guano (bird droppings) on Ardley Island. This small island sits near the tip of the Antarctic Peninsula and is a nesting site for many seabirds, including a thousands of Gentoo Penguins. As the penguins occupied the site, their droppings accumulated into guano layers. While guano may seem like merely an unfortunate byproduct of penguin digestion, it is serious business. Guano has long bee used as fertilizer, and been the subject of treaties, territorial disputes, and even wars. The Guano Islands Act of 1856 basically claimed all unoccupied guano-bearing islands in the oceans for the United States. Peru and Chile even fought a “Guano War” (also known as the Chincha Islands War) over disputed guano-rich islands.
Guano is also a useful substance for scientists, as the ratios of different isotopes can reveal how long ago a guano layer formed and what the animals that made it might have been eating. The amount of guano that forms per year also gives an estimate of how many penguins were “contributing”. In this study, scientists found evidence that penguin populations on Ardley Island had crashed precipitously several times in the past. The culprit? A volcano. Roughly 60 miles to the southwest lies Deception Island. The volcano that created this island has erupted periodically over the past few thousand years.
By looking at carbon isotope levels in plants, bone, and sediments from guano layers, the team was able to estimate the age of each layer and tie the penguin poop peaks and crashes into the timeline of local events. At least three times, the belching eruptions of the Deception Island volcano wiped out the penguin colony. Because no skeletons from the time of the volcanic eruptions remain intact, the fate of the penguins living in the area in the days of the eruptions is uncertain. Falling ash may have wiped out nesting adults and chicks, buried eggs, or spoiled food sources. It is also possible the effects did not wipe out the full grown penguins, but instead forced them to flee their breeding colony leaving an abandoned landscape of rocky shores.
Nevertheless, the penguins ultimately prevailed. After each eruption, the penguins slowly returned, typically taking 400-800 years to regain their original population levels. Today, thousands of penguins are happily inhabiting the island (and building up that guano layer bit by bit).
Roberts, S. and Monien, P. and Foster, L. and Loftfield, J. and Hocking, E. and Schnetger, B. and Pearson, E. and Juggins, S. and Fretwell, P. and Ireland, L. and Ochyra, R. and Howarth, A. and Allen, C. and Moreton, S. and Davies, S. and Brumsack, H. and Bentley, M.J. and Hodgson, D. (2017) ‘Past penguin colony responses to explosive volcanism on the Antarctic Peninsula.’, Nature communications. .
As we mentioned last post, March of the Fossil Penguins will be covering some exciting new research over the next three years. I’m very fortunate to be involved in a new project working with Dr. Tracy Heath and Dr. Rob Meredith. One of the main goals of the grant is to develop more sophisticated computer models to reconstruct evolutionary trees that include both living and fossil species. We chose penguins as one of our “test cases”, because they have a rich fossil record with lots of specimens and well-constrained geological dates.
We are excited about sharing our results with the public, and helping build computer literacy is one of our major outreach goals. As part of the project, the Bruce Museum’s amazing Paul Griswold Howes Fellow, Kate Dzikiewicz, has been hitting the road to bring an Hour of Code to hundreds of students. Computer coding is one of the most widely useful skills students can learn, as basic coding abilities can be used in careers ranging from the biological sciences to graphic design. Hour of Code is a global initiative that aims to bring an hour of computer coding lessons to as many students as possible, and we are putting our own spin on it, with a little help from a new virtual friend named Kari the Kairuku penguin.
Kate created Kari to make coding more fun. She is based on an ancient penguin who lived in New Zealand 27 million years ago, and reached a height about a foot and a half taller than an Emperor Penguin. Kids learn techniques for guiding Kari’s movements, looping actions, adding animations and more. Then, they can turn their imaginations loose and code up their own adventure for Kari.
Check out the story of Kari here: https://scratch.mit.edu/projects/130254722/
This week, a new study of the penguin evolutionary tree officially appeared in Systematic Biology (though the proof has been available online ahead of formal publication). This represents the first paper from an exciting new project aiming to develop Bayesian methods for combining data from fossils and living species. I’ll be teaming with the exceptional duo of Dr. Tracy Heath of Iowa State University and Dr. Rob Meredith of Montclair State University on this project, and penguins will be one of the “test pilot” groups to try out the new methods.
Our first foray into this realm was to re-analyses a dataset that was originally developed for a parsimony analysis of the giant fossil penguin Kairuku in 2012. This dataset includes 245 morphological characters and >6000 molecular characters. Our re-appraisal was led by PhD student Sasha Gavryushkina of Auckland University. We applied the Fossilized Birth-Death Process, a model pioneered by Dr. Heath that explicitly acknowledges that extant species and fossils are representatives of the same macroevolutionary process, in a tip-dating framework which allows fossil ages to be incorporated into the tree directly. Our analyses thus allow the ages of the fossils to directly impact the shape of the tree, and in a new wrinkle also allow for the possibility that some fossils species may be ancestors to one or more other species.
The results are shown below. One pattern that emerges immediately is that penguins are a very old group, extending back past 60 million years, but that crown penguins only started radiating between 13 and 14 million years ago. Thus, we have evidence for a recent wholesale replacement of “primitive” penguins by “modern” forms. Our work also benefits from some recent geological work, which for example has shown that Spheniscus muizoni, a fossil penguin thought to be 11-13 million years old, is actually close to 9 million years in age. In one reversal of previous findings, the fossil penguin Madrynornis mirandus is pulled outside the Eudyptes–Megadyptes clade in our study.
To me, the most intriguing message comes from the dates: modern penguins are young. Our dates are much younger that those recovered by past studies that looked only at DNA from living penguins. Adding the fossil data has a major effect, and it is very important: because about 3/4 of all known penguin species are now extinct, ignoring the fossils is like looking at just one small piece of a large puzzle. Our new dates place the origin of modern penguins at a really interesting time in Earth history: the Middle Miocene Transition. This transition marks the start of a global shift from warmer to cooler climates that ultimately leads to the glacial-interglacial cycles of our modern world. The accompanying expansion of Antarctic ice sheets may have opened up new habitats for penguins. In deed, we find that the peaking of glacial advance-retreat cycles in the Pleistocene may have been a driver of penguin evolution: 12 of the 18 living species likely arose in the last 2 million years according to our results.
Over the next three years, our team will be working on improving these methods and expanding their capacity to incorporate other types of data, such as the geographic locations of fossils and how frequently fossils occur within their overall stratigraphic ranges.
Gavryushkina, A., T.A. Heath, D.T. Ksepka, T. Stadler, D. Welch, and A.J. Drummond. 2017. Bayesian total evidence dating reveals the recent crown radiation of penguins. Systematic Biology 66 (1): 57-73.
How old are penguins? A new article reports some of the most ancient fossils yet, and discuss their implications of penguin evolution. The bones in question are elements of the hind limb: the good old tarsometatarsus (the bone that forms the main body of the foot) and several phalanges (toe bones). They were discovered in New Zealand in the Waipara Greensand. which is the rock unit that yielded Waimanu manneringi. Both fossils are about 61 million years old, making them the oldest penguins known.
Despite being the same age as Waimanu manneringi, the new fossils are more “penguiny”, at least when it comes to the foot morphology. Whereas Waimanu manneringi has a slender tarsometatarsus with a raised articulation for the second toe like many non-penguin birds, the new fossil has a much stouter tarsometatarsus that resembles penguins that are several million years younger. The heftiness suggests it might belong to a much heavier bird than Waimanu manneringi. Overall, a number of fine features suggest the new Waipara penguin occupies a branch on the evolutionary tree that is one step closer to modern penguins than any other species swimming around 61 million years ago (though to clear it was still a very distant relative of any living species).
The authors of the new paper suggest that there must have been more than just 5 million years for such a variety of penguins to evolve, pushing the origin of penguins into the Cretaceous Period. Does this mean we are going to eventually find penguins in rocks from the Cretaceous Period? Personally, I am skeptical we will find a flightless penguin that old. We have found tons of penguin fossils from the Paleogene Period, but not a single such bone from the Cretaceous Period. So, it seems likely penguin evolved into flightless wing-propelled divers after the K-Pg mass extinction, which wiped out the dinosaurs and marine reptiles like plesiosaurs and mosasaurs. It is of course possible that the flying ancestors of penguins were roaming around during the Cretaceous, though this would be harder to prove because the delicate fossil bones of flying birds have much less of a chance of being preserved than the dense bones of diving birds. That would be quite a find.
Mayr, G., De Pietri, V.L. & Paul Scofield. 2017. A new fossil from the mid-Paleocene of New Zealand reveals an unexpected diversity of world’s oldest penguins. The Science of Nature 104:9.
Today is Penguin Awareness Day! What better day to get back to blogging about fossil penguins. In this morning’s post, I’d like to summarize a recent project on New Zealand’s fossil penguins.
A short while back, Dr. Daniel Thomas and I had the chance to team up for our fourth penguin paper together. We re-examined the fossil known as the “Glen Murray Penguin”, a set of leg bones collected from rocks that are roughly 30-35 million years in age. This fossil is important because it is one of the few records of fossil penguins from the North Island of New Zealand (specimens from the South Island are plentiful).
The fossil bones were first reported over 30 years ago, by Jack Grant-Mackie and George Gaylord Simpson (subject of our previous post). At the time, the taxonomy of fossil penguins from the region was still rather poorly known. Few reasonably complete skeletons had been collected, so it was rather difficult to tell which species that new isolated discoveries belonged to. Thus, the significance of the Glen Murray specimen for penguin diversity remained largely unresolved since initial description. One thing is certain though – it was a huge penguin! The bones make those of your average zoo penguin look like miniature carvings.
Dr. Thomas invited me to work on the specimen with him, and provided a wonderfully modern aid to collaboration. Although I had seen the Glen Murray Penguin in person in 2012, it was hard to make comparisons from just my photos. So, Dr. Thomas sent scanned the fossil with a laser scanner, printed out a 3D copy, and sent it right over. It was spectacular to be able to hold a precise replica of a fossil while the real thing was sitting on the other side of the world, and of course this helped facilitate our discussions.
After some anatomical work, we determined that the Glen Murray penguin shares two key traits that are only seen in the extinct genus Kairuku: the femur is very stout and the end of the tibiotarsus has a distinctly convex inner face. This led us to conclude that the Glen Murray penguin is most likely a new species of Kairuku which is distinct from its southern brethren, though we decided to wait until more of the skeleton is found to test this hypothesis before we go about applying names. Hopefully we will learn more about this penguin as more fossils are collected on the North Island – something I am sure Dr. Thomas has big plans to make happen!
Grant-Mackie M.J.A., and G.G. Simpson. 1973. Tertiary penguins from the North Island of New Zealand. J Roy Soc New Zeal. 3:441–451.
Today would have been the 114th birthday of George Gaylord Simpson had he lived to that implausible age. Simpson is well known for his paleontological research and his role in formulating the “new synthesis” of evolution. Although much of his work focused on fossil mammals, Simpson also collected and studied fossil penguins. His initial foray into the world penguins was by his own account accidental. Simpson traveled to Argentina several times in the 1930s to collect fossils and brought back a large number of penguin specimens. No bird experts at the American Museum of Natural History wanted to undertake a study of the material, so Simpson himself took up the reigns and wrote a monograph succinctly titled “Fossil Penguins” in 1946. This sparked a long term interest in fossil penguins that brought him to investigate collections throughout the Southern Hemisphere, identifying many new species and revising the taxonomic arrangement of the group. My own work on fossil penguins was kindled by Simpson’s legacy. As a graduate student at the American Museum of Natural History, I had the chance to examine the specimens he collected in Argentina, prodding the ancient bones with new methods that had existed in the mid-century such as CT-scanning and advanced microscopy. One of the amazing experiences about working in museums is you quite literally get to walk in the footsteps of legends, reading hand-written field notes (which in the case of Simpson often mix meticulous outcrop maps with witty remarks).
Aside from his many scholarly publications, Simpson wrote the popular book “Penguins: Past and Present, Here and There” in which he chronicled discoveries of living penguins and fossil penguins, including both historical events and penguin encounters from his own adventures. There is a quote near the end of the book that is simply delightful:
“What good are penguins?” It may be crass to ask what good a wild animal is, but I do think the question may be legitimate. That depends on what you mean by good. If you mean “good to eat,” you are perhaps being stupid. If you mean “good to hunt,” you are surely being vicious. If you mean “good as it is good in itself to be a living creature enjoying life,” you are not being crass, stupid, or vicious. I agree with you and I am your brother as well as the penguin’s.”