QUEST Community Science Blog Author: Nick Pyenson

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Carving the Holiday Dinosaur: A Phylogeny of Wishbones

November 25th, 2007 by Nick Pyenson

A wishbone from a theropod and a turkey.This week, many of us celebrated one of the most American of holidays: Thanksgiving. Following tradition, most of us probably had a bite or two of turkey — if you were one of the fortunate to get your hands dirty, you may have used this New York Times video as a guide.

What you may not know is that we can find homologies of many birds parts — thigh bones, arm hones, and even wishbones — in our own skeleton, and it’s not happenstance. The ultimate reason for this similarity is ancestry: birds, mammals and all other tetrapods (four-legged, air-breathing vertebrates) share a common ancestor, over 300 million years old. And, as the descendents, we all exhibit the same basic body plan, with additional anatomical refinements specific to each evolutionary history. Whether a tetrapod’s arm is a fin, a wing or a limb throwing a baseball, a common structure is shared among them because of their evolutionary past.

Back to turkeys: in your holiday meal, you may have come across a very particular y-shaped bone: the wishbone. (The one from my turkey is drying on the counter above the kitchen sink). Humans actually have homologues of wishbones, but we don’t call them that — they’re our collarbones, or clavicles. These bones are long and slender, and they form a key part of complex of bones and muscles that allow us to move our arms. Living birds are unique among tetrapods in having clavicles that are fused together into the y-shaped structure called a furcula, and it plays a key roles in allowing birds to fly. Furculae stiffen the thoracic skeleton, and, in conjunction with a keeled breastbone (or sternum), they provide key muscle anchors for the unique flight stroke of the bird arm.

So, how did two bones get fused into one? Birds are descended from one particular line of dinosaurs called theropods, which includes dinosaurs like T. rex or Velociraptor. Over the last 20 years, paleontologists have assembled a detailed picture of the family tree, or phylogeny, of these animals, showing the exact anatomical changes that occurred along the lineage of theropods to living birds. The changes in the furcula plays a key role in this evolutionary sequence: it turns out that relatives of T. rex and many other theropods had fused furculae, but clearly these animals did not use the fused furcula to fly. Some paleontologists have suggested that fused furculae in theropods increased the mobility of the forelimbs. Then, as birds evolved flight, a fused furcula turned out to be wonderfully useful as a brace for a flapping limb.

Evolution often works in this manner: recruiting old structures to use in a new context, and many examples of such improvisation have been shown in the fossil record. Together, phylogeny and the fossil record reveal more about evolution that might not have been apparent when you were first biting into that savory chunk of turkey meat. To check find out more about your holiday dinosaur, check out this link too.

Nick Pyenson is a PhD candidate at the University of California, Berkeley, in the department of integrative biology and the museum of paleontology.



latitude: 37.7819, longitude: -122.286




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Science v. Pseudoscience on Trial

November 16th, 2007 by Nick Pyenson

NOVA commemorates the historical evolution trial of 2005.


Credit: NOVAIf you tune in or point your web browser to PBS this week, you’ll see a whole bunch about evolution. It’s not Charles Darwin’s birthday, but it’s a celebration that may one day carry much more significance: it’s the two year anniversary of the Kitzmiller vs. Dover trial. In 2005, parents of high school students in the Dover, Pennsylvania school district took the education board to court over attempts to teach intelligent design as a bona fide alternative to evolution in public high schools. The juryless trial assembled a first-rate list of witnesses for the plaintiffs (pro-science, pro-evolution), all of whom eloquently spoke about the foundations of science and evolution, and how we know what we do about the history and diversity of life. Intelligent design advocates, in their defense, had to present evidence supporting intelligent design as a genuine scientific argument. In the end, the judge (who was named one of Time’s 100 most influential people last year) ruled that intelligent design is not science and that, furthermore, teaching intelligent design is unconstitutional. His verdict is well worth reading in its entirety (for legal fans out there), or you can check out summarized versions online.

NOVA online has great clips from the show, including additional interviews elaborating on the science behind evolution. Interestingly, there are many Bay Area connections in the show. NOVA prominently features Oakland-based National Center for Science Education (including Eugenie Scott and current Cal graduate student Nick Matze), clearly reflecting the center’s long-standing support for science standards in education, especially in biology. Kevin Padian, a Cal professor in integrative biology, provided articulate explanations of evolution as part of his expert testimony, and many of the clips on the website include examples that are now textbook cases of evolutionary processes, some of which are explained the on the Understanding Evolution website, hosted by the UC Museum of Paleontology and the Berkeley Natural History Museums.

Overall, the case is now seen as a landmark event in the on-going battle of teaching evolution and championing science literacy in the public. Intelligent design, which is really creationism in a different guise, fails in clear and dramatic ways to explain the natural world in the way that evolution, by natural selection, has successfully done for over 150 years. For more, be sure to check out the NOVA online features or the Understanding Evolution websites. After all, who doesn’t want to live in a scientifically literate society?

Nick Pyenson is a PhD candidate at the University of California, Berkeley, in the department of integrative biology and the museum of paleontology.



latitude: 37.7819, longitude: -122.286




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A Whale in Your Backyard

October 29th, 2007 by Nick Pyenson

Carcass of a Blue Whale, Balaenoptera musculus
Credit: analog chainsawWhen zoologists speak about superlatives among animals, blue whales (Balaenoptera musculus) often play a key role at the high end of the scale of organisms. With good reason, too: they are not only the largest baleen whales, but also the largest mammals ever to have lived — no mammoth, rhino or hippo, extinct or living comes close. Blue whales are also in the contest for largest backboned animal ever, measuring up against some of the largest dinosaurs. When blue whales and their close relatives open their mouths to feed, some scientists calculate they can even engulf a volume of water the size of a school bus. And, here in California, we are lucky enough to have blue whales right off our coast.

Blue whales often frequent the coast of southern California, especially to feed in the nutrient-rich waters of the Southern California Bight. Unfortunately, this feeding preference puts this population of blue whales (numbering perhaps in the few thousands) directly in the same area where many shipping lanes converge, near Long Beach and San Diego. This situation is all the more crucial for blue whales, whose population size is a mere shadow of its former self. For most of the twentieth century, blue whales teetered on the brink of extinction, as industrial whaling in the 1940s-1960s reduced blue whale populations in both the North and South Pacific Ocean. Cetologists (scientists who study cetaceans) still are trying to understand the exact magnitude of this decimation, and its effects on the genetic viability of the species, as well as potential ecological outcomes.

Inevitably, as the population recovers, we’ll be seeing more of what happened a few weeks ago, near Ventura: a blue carcass, 78 feet long, washed up on the beach, within throwing distance of a county park. Early clues seem to indicate that the whale died from ship strike, although it will probably be some time before the final word is in. Disposing of such a carcass, however, is no trivial issue — check out this video of what the Oregon State Highway patrol did to resolve one sperm whale standing (and its disastrous aftermath). Let’s hope Ventura County officials forgo the dynamite solution, in this case.

Nick Pyenson is a PhD candidate at the University of California, Berkeley, in the department of integrative biology and the museum of paleontology.




latitude 34.0837, longitude -119.061




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Roll Over You Bears! (Part 2)

October 29th, 2007 by Nick Pyenson

Joseph Grinell (center) and team, in 1908Last time, I wrote briefly about the history of grizzly bears in California and how there are no grizzlies in California anymore (an irony, given the animal’s image on many of our state’s symbols). The story of the grizzly’s demise in California is the same narrative for many other large mammals throughout the world over the last few centuries: habitat loss, plus human hunting, does a number on mammal populations, especially mammals that have very large individual geographic ranges (bears, lions, elephants). Grizzly bears can still be seen in their native habitat, but the contraction of their range of the past 200 years limits these places to remote, unsettled tracts in Canada and the northwestern US states.

How has habitat change affected the distribution of mammals over this time? What kind of role has climate change played? Researchers at the UC Museum of Vertebrate Zoology (MVZ) are actively working to understand these questions, and others, through the Grinnell Resurvey Project. In the early part of last century, Joseph Grinnell, the founding director the MVZ, was one of the first naturalists to create systematic collections of living vertebrates with precise natural history data (taking weight measurements, identifying the sex of the individual animal, or recording the day and place of collection). Grinnell and his students recorded this information for large parts of California (and other western states), creating an archive of natural history data (in the form of field notes) that is unrivaled in its breadth, content, and precision. Since Grinnell’s time, the landscape and climate of California has changed in many ways, and many people (politicians, economists, and scientists alike) are eager to know how animal communities have changed as well.

Using Grinnell’s data as a baseline, MVZ researchers now are in the process of retracing his footsteps through California, and undertaking new surveys of the exact same places that Grinnell sampled. In doing so, researchers are recording new data about the presence, abundance and kind of species that now live in these habitats. By comparing what’s found now with what was there 100 years ago, researchers will be able to see how the composition of mammal communities has changed over this period. Detailed records of climate change in the same places over the last 100 years can also be added to the analyses, to show how concomitant changes in rain or temperature might also have affected mammal communities.

All of the science in the project hinges on the foresight of Joseph Grinnell, who, at a time when ecology not even a real discipline, understood how the value of natural history collections can well outlast its creators. Read more about some early results from the Grinnell Resurvey Projects here:

http://alumni.berkeley.edu/calmag/200605/yosemite.asp

Nick Pyenson is a PhD candidate at the University of California, Berkeley, in the department of integrative biology and the museum of paleontology.



latitude: 37.8642, longitude: -122.286




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Roll Over You Bears! (Part 1)

October 16th, 2007 by Nick Pyenson

Grizzly bears are iconic Californian mammals — they’re on our state flag; many creeks, hills and passes are named after them; and they’re the mascot of many UC schools — but you won’t ever see one out in your backyard or anywhere else in California. Unlike black bears, which are relatively common in the state, grizzlies went extinct in California sometime in the 1920s. The last verified account was an individual shot in 1922 in Tulare County. The species is now restricted to populations that survive well north of California, in Idaho, Montana and through Canada and Alaska.

The story of what happened to the California grizzly also, by way, tells the history of conservation in this state, as documented in Tracy Irwin Storer’s classic book “California Grizzly.” Grizzlies evolved in North America along with a suite of other so-called megafauna (basically, mammals over 44 kg) that dispersed across the emergent Bering Strait during low global sea-levels in the past 1 million years or so. The ancestors of grizzlies lived along side saber-toothed cats, mammoths and mastodons, camels and even other bears, like the enormous short-faced faced bear. The short-faced bear probably was a distant relative of grizzlies, but the fossil record of bears from the last million years in North America is unrevealing about the true ancestry of grizzlies. We do know that grizzlies were in California into historical times, with plenty of accounts from Spanish missionaries, American explorers and settlers too. Even into the end of the 19th century, many towns that we now recognize as cities (e.g. Pasadena) had grizzly bear problems. Unfortunately, it seems that humans and grizzlies have long had an antagonistic relationship, with grizzlies losing numbers and habitat to a growing population.

In some ways, then, it’s not surprising that the largest species of predatory mammal went extinct , but it is interesting to note that relatively smaller mammals — raccoons, coyotes and mountain lions — have survived quite well along the fringes of California urban life. How else have mammal communities changed over the past 100-200 years? How has climate changed played a role? Which mammals are the winners and losers, and can we know? Researchers at UC’s Museum of Vertebrate Zoology are actively looking into the details of these questions, and I’ll save that for next week. But until then, you can get a preview and poke around:

http://mvz.berkeley.edu/Grinnell/index.html

Nick Pyenson is a PhD candidate at the University of California, Berkeley, in the department of integrative biology and the museum of paleontology.




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Champion Divers of the Deep-Sea

September 28th, 2007 by Nick Pyenson

Photo Credit: John CalambokidisChances are, if you’ve ever been swimming, you understand that it’s hard to dive deep. But marine mammals do it all the time — and they dive to depths beyond our imagination. Sperm whales, beaked whales, elephant seals all have an amazing ability for deep-diving, and along with that, fascinating specializations to their anatomy and physiology. Decades of research have demonstrated that diving mammals undergo a reduction in heartrate (bradycardia), a shunting of blood from the periphery to the core of their body, and have innovative features for preventing lung collapse and maximizing heat storage and blood oxygen. These features seem to have evolved multiple times in marine mammals and, interestingly, marine mammals of all sizes, from seals to blue whales, use the same energy-saving behaviors.

One of the reasons why we know so many details about the diving of oceanic mammals has to do with a wonderful device called the Crittercam. If you’ve seen “March of the Penguins” or if you’ve seen natural history films in the past decade, you’ve probably seen footage shot by the Crittercam: it’s a small, lightweight camera that can be attached (via a harness or a suction cup) to wild animals. It’s no trivial task to accomplish, but the results have produced stunning insights into the behavior of not just marine mammals, but many other land animals too. Check out an upcoming conference in Washington, D.C., all about Crittercam (and other so-called animal-borne imaging systems).

Nick Pyenson is a PhD candidate at the University of California, Berkeley, in the department of integrative biology and the museum of paleontology.




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Whales in the Desert, and Vandalizing World Heritage Sites

September 2nd, 2007 by Nick Pyenson

Credit: P.D. Gingerich, Univ. Michigan.This past week, fossil whales made it into the newswires again. This time, the news wasn’t strictly about a new discovery or new insight — instead, it has to with accusations of vandalism.

About 150 km south of Cairo lies a huge expanse of desert, called Wadi Al-Hitan. Unlike the classic desert of dunes upon dunes, Wadi Hitan preserves large exposures of rocks from the late Eocene through the early Oligocene (~40-30 million years ago). The first fossil whales– from beasts like the large, eel-like Basilosaurus, which reached over 50 feet long — were found in 1905. For the subsequent 100 years, paleontologists have recovered a trove of other marine mammals including severalspecies of fossil whales (archaeocetes) and sea cows. Rocks from higher up in the Wadi Al-Hitan sequence, near the Qasr El Saga temple, have also produced some of the oldest primates in the world. Over 390 whale skeletons have been found in the area, earning it the nickname “Valley of the Whales.” Detailed studies of the rocks in which the fossil whales are embedded indicate a lagoon-like environment when the whales lived, and, possibly, a calving ground for these early whales.

Aside from the supreme paleontological importance of the site, the Wadi Hitan is also full of important archeological remains as well. Together, this led UNESCO to recognize the area as a Natural World Heritage Site, a rare accolade for a fossil site. One of the problems with designating such places (especially in a remote area) is ensuring resource protection, not only from the elements but also human activity. Enter Egyptian officials, who last week formally accused Belgian diplomats of driving 4WD vehicles over key fossil sites this summer. Egyptian officials estimate that the alleged vandalism caused USD 325,000 worth of damage, while Belgian officials
deny the charges.

Even with UNSECO’s name, true protection is a matter of money (park rangers and guards), and also vigilance — and getting both is as hard in Egypt as it is in the US. As a whale paleontologist, the disregard for their fossil remains infuriates me, but as a citizen, I find wanton damage to any heritage site shameful. How would you feel if someone dynamited the top of Half Dome in Yosemite, or spray-painted George Washington’s nose at Mt. Rushmore? Like one of the Egyptian officials said, “The financial value doesn’t really matter. What matters is the historical value.”

Nick Pyenson is a PhD candidate at the University of California, Berkeley, in the department of integrative biology and the museum of paleontology.




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…and Penguin-Look-a-Likes From the Northern Hemisphere (Part 2)

August 16th, 2007 by Nick Pyenson

Credit: NHM, London.
With a string of Hollywood smash hits about penguins and polar bears, more people than ever now know that polar bears live near the North Pole, and penguins live at the South Pole. Penguins not only just live at the South Pole–they thrive all throughout the Southern Oceans, from the South Pole to the Galapagos Islands . Last time, I had mentioned giant fossil penguins from Peru. These new fossils, in addition to those that are almost twice as old from New Zealand, tell us about the ancient history of penguins in the Southern Hemisphere. But why have penguins never made it to the Northern Hemisphere? If penguins were so wildly successful, in the their own peculiar lifestyle, why didn’t they go global?

Looking around the Northern Hemisphere, we see plenty of skimming, plunging, and diving birds, but nothing penguin-like at all. Not so fast, though–one problem is our sense of time scale. Up until recent historical times, a very penguin-like, forelimb–swimming bird did live in the Northern Hemisphere: the Great Auk ( Pinguinus impennis). This bird, which was hunted to extinction in the mid 19th century, lived on rocky coasts of the North Atlantic Ocean, and looked very much like a penguin (its genus name even reflects the historical confusion too), and swam with its forelimbs too. Further back in time, from 3-11 million years ago, extinct relatives of the North Atlantic auks called mancallines lived in the North Pacific Ocean, and many fossils species have been recognized from California and Mexico. Going back even further in time, from 40 to 20 million years ago, another completely unrelated group of penguin-like seabirds lived in the North Pacific: the plotopterids. Their evolutionary relationships continue to be debated, but the anatomy of their forelimbs leave no doubt that plotopterids were penguin convergents, just like the convergence between placental and marsupial mammals.

The fossil record shows that plotopterids and the archaic giant penguins (like those in Peru) both went extinct about the same time that marine mammals emerged to become dominant marine predators, about 15-20 million years ago. The implication is that early relatives of sea lions and dolphins out competed plotopterids, but this idea doesn’t explain the whole story because their southern convergents, penguins, continue to co-exist with marine mammals all throughout the Southern Oceans. Other factors, like ocean conditions and changes in sea level, might also have precipitated the demise of plotopterids; likewise, the onset of the Ice Ages might have also driven mancallines to extinction.

Living penguins, therefore, are the only reminder of this unique kind of seabird, and the penguin-like strategy is something that has been repeated several times by unrelated groups of seabirds, in both hemispheres. Pretty cool!

Nick Pyenson is a PhD candidate at the University of California, Berkeley, in the department of integrative biology and the museum of paleontology.




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Giant Penguins From the Southern Hemisphere… (Part 1)

August 2nd, 2007 by Nick Pyenson

Photo courtesy of the American Museum of Natural History
Earlier this summer, you may have heard about a surprising paleontological discovery from southern Peru. In a paper published in the journal PNAS, a team of paleontologists announced the discovery of two new species of fossil penguins, Icadyptes and Perudyptes, from an area a few hundred kiometers south of Lima. This desert region is one of the most arid places on the world, but 36 million years ago, it was the shoreline of a balmy, humid world. During this time (the late Eocene), global climate was much warmer than it is today, and neither polar region was especially cold.

So what does this have to do with penguins? The skeletons of these new species have hallmark penguin characteristics shared with living penguins, but they also differ in significant ways: their snouts, for example, are much longer and narrow than any living one. Most interestingly, one of these penguins was enormous– Icadyptes was nearly 5 feet tall, making it larger than the largest living penguin (the emperor penguin, Aptenodytes forsteri), which is about 4 feet tall.

Size is important because evolutionary biologists have proposed a general trend, called Bergmann’s rule, to describe the phenomenon of large animal body size at high latitudes. Birds have mammal-like metabolisms too, and scientists were generally content that penguins demonstrated Bergmann’s rule because the largest living penguins were also those that lived in the highest latitudes. The pattern seemed true until the Peruvian discoveries, because the largest fossil penguins were found at high latitudes (with localities in Peru, Argentina, New Zealand). Icadyptes and Perudyptes tell us that the picture is much more complex, and that Bergmann’s rule may not apply to penguin evolution– giant penguins did fine at the equator (that area of Peru was even closer to the equator than it is today, based on paleogeographic reconstructions). Icadyptes and Perudyptes are also all the more important because the skeletons are relatively complete– in the past, penguins had been described with far fewer comparable parts, a problem which is all to familiar to dinosaur and hominid paleontologists.

If penguins were so successful in warm climates, why don’t we have Happy Feet off the coast of California? I’ll save that for next post…

Nick Pyenson is a PhD candidate at the University of California, Berkeley, in the department of integrative biology and the museum of paleontology.




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The Real Davy Jones Locker

June 12th, 2007 by Nick Pyenson

Laboratory photo of one of the newly discovered
bone-eating worms, Osedax frankpressi, which has been
removed from a whale bone On the heels of two humpbacks leaving the Sacramento River for the ocean, you may have seen this other news report on a rotting gray whale carcass on waterfront property at Point Richmond. (There’s a historical irony here too, because Point Richmond was also the site of the last whaling station in the US). As Bay Area residents know all too well, whales are frequent visitors to the SF Bay, and often times they do strand themselves, die or simply get carried into the Bay by prevailing ocean currents.

Dead whale carcasses can be an awful mess (literally, logistically, and administratively), but 30 years ago, a group of scientists in a deep-sea submersible discovered something amazing in the Santa Catalina Basin: dead whale carcasses that sink to the bottom of the ocean floor can support a unique deep-sea community of invertebrates and scavenging vertebrates in an environment completely divorced from the light of the sun. What’s amazing is that some of these whale-fall invertebrates have evolved a means of harnessing the lipid-rich resources of the whale carcass via chemosythentic bacteria that live symbiotically — that is, right within their own bodies. Some species of molluscs that do this are the same ones that have been found at deep-sea hot vents; others, like Osedax, seem to be restricted to whale-falls.

Because whale-falls are oases of nutrients in an otherwise low-nutrient environment (the ocean floor), scientists have proposed that whale-falls have provided “stepping-stones” for deep-sea invertebrates to disperse across ocean basins, and to over nutrient-rich environments like hot vents and cold seeps. If whale carcasses are crucial to the deep-sea organisms, we might expect that a century’s worth of whaling — and the removal of whale carcasses from the oceans — had serious effects on these deep-sea communities. Unfortunately, as with many enigmas of marine ecosystems, we still don’t enough about the oceans right in our backyard to know the answers to these riddles.

Nick Pyenson is a PhD candidate at the University of California, Berkeley, in the department of integrative biology and the museum of paleontology.




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