Andrew Farke

10 posts · 3,914 views

Andrew A. Farke is a paleontologist, whose interests include horned dinosaurs, cranial functional morphology, and the paleontology of Madagascar.

Sort by Latest Post, Most Popular

View by Condensed, Full

  • March 4, 2009
  • 12:50 AM
  • 595 views

Crouching Theropod, Hidden Dragon

by Andrew Farke in The Open Source Paleontologist

Fossil footprints (falling in the general category of "ichnofossils") reveal a wealth of information about dinosaur biology, such as speed, posture, and behavior. These traces are particularly useful when offering information independent from, but consistent with, hypotheses derived from purely anatomical studies.Today, a new paper in the open access journal PLoS ONE presents an unusual set of theropod (meat-eating dinosaur) ichnofossils from the Early Jurassic-aged Moenave Formation of southwestern Utah. The tracks are preserved within the St. George Dinosaur Discovery Site at Johnson Farm, a massive facility housing thousands of footprints (for additional scientific publications and background on the site, refer to this page). But, if there are thousands of footprints known at the site (in addition to the thousands known from other sites throughout the world), what makes the fossils featured in the paper so special?Theropods were bipedal animals, and known ichnofossils typically only preserve evidence of the hindlimb. But, one specimen in particular at the St. George locality preserves impressions of the hind feet, forefeet, and the rear end of a lazy carnivore. A resting trace!Artist's conception of the St. George trackmaker at rest. Note in particular the resting posture and the orientation of the hands. From Milner et al. 2009; painting by Heather Kyoht Luterman.Yet, even resting traces aren't completely unheard of for theropod dinosaurs. The really interesting thing here is that the specimen preserves relatively unambiguous impressions of the hand posture. The animal was resting with its hands turned inward, and the outer surfaces of the fingers and wrist (rather than the palms) touching the substrate.Why does this matter? Well, it all has to do with reconstructions of forelimb mobility and posture. Old reconstructions of theropod dinosaurs showed them walking around with palms down (think of an alligator dragged upright); later work has strongly suggested that the palms faced inward, more like birds.Traditional restoration of two theropods, by Charles R. Knight. Note the palm-down, rather than palm-in, posture of the hands.So, the new St. George tracks are the first good ichno-evidence of forelimb posture in theropod dinosaurs. Furthermore, and perhaps most importantly, it suggests that this posture evolved pretty early on, in some of the first theropod dinosaurs.As the authors note, anatomical reconstructions of forearm movement have primarily focused on more "derived" theropods (animals from the Late Jurassic and beyond). It would be really, really nice to get additional studies on the anatomical structures of the forelimb in animals like Dilophosaurus and Coelophysis (Ken Carpenter did get a good start on this a few years back; see his 2002 paper, "Forelimb biomechanics of nonavian theropod dinosaurs in predation." Senckenbergiana Lethaea 82: 59-76). Also, paleontologists will want to be on the lookout for similar traces. Is the specimen described here typical, or an individual anomaly? The authors reviewed other alleged resting traces from theropods, but considered that most of them were either misidentified or too poorly preserved to offer usable information. Finally, does resting posture of the forelimbs necessarily reflect what the animals were doing the other 99 percent of the time?Congratulations to the authors on a stimulating paper. If you have an opinion on this research, don't just post it in the blog's comment section (although please do that, too). Head over the the PLoS ONE website, and register your own comments, notes, and ratings on the article!The ReferenceAndrew R. C. Milner, Jerald D. Harris, Martin G. Lockley, James I. Kirkland, Neffra A. Matthews (2009). Bird-Like Anatomy, Posture, and Behavior Revealed by an Early Jurassic Theropod Dinosaur Resting Trace. PLoS ONE, 4 (3) DOI: 10.1371/journal.pone.0004591... Read more »

Andrew R. C. Milner, Jerald D. Harris, Martin G. Lockley, James I. Kirkland, & Neffra A. Matthews. (2009) Bird-Like Anatomy, Posture, and Behavior Revealed by an Early Jurassic Theropod Dinosaur Resting Trace. PLoS ONE, 4(3). DOI: 10.1371/journal.pone.0004591  

  • January 27, 2009
  • 08:00 PM
  • 589 views

Triceratops Combat?

by Andrew Farke in The Open Source Paleontologist

Exactly how did Triceratops and other horned dinosaurs use their cranial weaponry? Today, my co-authors Ewan Wolff, Darren Tanke, and I published new research in the online, open access journal PLoS ONE, giving our take on the issue. In a study spanning four years and over a dozen museums, we have marshalled what we think is the best evidence to date that Triceratops may have locked horns with their own kind.Restoration of Triceratops in horn-to-horn combat. Image copyright Lukas Panzarin, courtesy Raymond M. Alf Museum of Paleontology.The BackgroundThe ceratopsids, or horned dinosaurs, present a bewildering array of cranial headgear. Triceratops was one of the earliest discovered and best known, with its distinctive dual brow horns, single nose horn, and a solid frill of bone over the neck. Subsequent discoveries revealed a clade chock full of anatomical diversity - single horns, triple horns, and frills sporting all sorts of odd accessories. Consequently, a whole host of functional explanations have been dreamed up for these bones.Defense against predators was an early, popular explanation. With threats such as Tyrannosaurus stalking the Cretaceous landscape, Triceratops and relatives surely would have used their horns for defense if they had to. Yet, this is not the primary function of the horns in modern animals. More commonly, horns, antlers, and other appendages are used for intraspecific combat and display--not against predators. A good example is the massive horns of the bighorn sheep. Careful behavioral studies have shown them to be employed in impressive visual display to other sheep, or for combat over territory, mating rights, dominance, etc. These modern analogs were quickly compared with ceratopsids.In addition to the determination of function by analogy, some paleontologists noted odd markings on the skulls of some horned dinosaurs. Perhaps a chunk of the frill was missing, with evidence of healing. Maybe there was an abnormal, oddly positioned hole on the skull. Inevitably, these oddities were attributed to "horn gouge wounds." These alleged pathologies were interesting--but anecdotal. Without a broader context, any attempts to infer a cause for the "injuries" usually amounted to constructing a "Just So Story."Recently, the tide has turned against the idea of horns-as-weapons in Triceratops and its relatives. Research by Kevin Padian, Jack Horner, Mark Goodwin, and others have suggested that the odd cranial ornamentation of many dinosaurs was for more peaceful purposes--specifically, species recognition (picking out members of their own kind amongst a sea of similar species). Although this idea certainly has its merits, I was never quite convinced that the horns of Triceratops were completely benign (and to be fair, I don't know that the species recognition proponents were suggesting this as the only function, either). At the same time, I wasn't exactly convinced that every single ding on a fossil skull should be considered evidence for combat.What We DidI've been really interested in the issue of horned combat in Triceratops for some time. Several years ago, I published a brief study, using plastic models, that demonstrated such combat was at least physically possible. I made some predictions about where we should expect injuries on the skull, noted similarities with published anecdotes of alleged injuries, and left the issue open for a follow-up study. The models were fun to play with, but I wanted to know if this combat actually happened in real life! And, I knew that paleopathology--the study of disease and injury in fossils animals--was probably the best approach. Unfortunately, I didn't know that much about the topic.So, I teamed up with two experts. Darren Tanke works at the Royal Tyrrell Museum of Paleontology, and is an expert in both paleopathology and ceratopsian dinosaurs. Ewan Wolff recently finished his dissertation on oral pathology in archosaurs at Montana State University, and now is a student at the University of Wisconsin-Madison School of Veterinary Medicine. Ewan and Darren provided expertise in identifying and interpreting the markings we observed on the ceratopsid skulls.Our logic was simple--if ceratopsid dinosaurs used their horns against each other in combat, evidence of this should be found in bony lesions on the skull. And, assuming that animals with different horn configurations fight differently (a fair assumption from observations of modern horned critters), we should find differing rates and patterns of lesions between different species of horned dinosaurs. If the horns were not used in combat (or specifically, patterns of horn locking that could result in injury to the skull), we should see no difference between various species.So, we surveyed many, many specimens at over a dozen museums across North America. We looked for any evidence of pathology, and recorded its location on the skull. Two genera were the focus of our research--Triceratops (pictured at the top of the post) and Centrosaurus (pictured below this paragraph). Centrosaurus has only a single nasal horn (and no massive brow horns), so we assumed that it would be most likely to show differences from Triceratops if there were any to be found. After years of data collection, we subjected all of the numbers to statistical analysis. Lots of folks (Darren and I included) had described anecodotal reports of pathology before--but nobody had subjected them to the rigors of statistics.One artist's concept (courtesy Wikimedia Commons) of Centrosaurus in combat.What We FoundBriefly, we found that most bones of the skull that we examined did not show statistically significant differences (i.e., P0.05) in rate of pathology between the two genera. Except, that is, for the squamosal bone of the frill (shown on the figure below). But what does this mean?Schematic showing rates of pathology (number of pathological elements/total elements examined) for Triceratops (top) and Centrosaurus (bottom). The squamosal rates, highlighted here, were different from each other at P... Read more »

Farke AA, Wolff EDS, & Tanke DH. (2009) Evidence of Combat in Triceratops. PLoS ONE, 4(1). DOI: 10.1371/journal.pone.0004252  

  • March 24, 2009
  • 10:52 PM
  • 552 views

Bone-ing Up on Allometry

by Andrew Farke in The Open Source Paleontologist

Allometric scaling - roughly defined, when different parts of an organism grow at different rates - is an important factor in biology. In part, allometry describes how babies have relatively larger heads than adults (we exhibit negative allometry in this trait, because our skulls don't grow as quickly as the rest of the body) or how some crabs have gigantic claws (an example of positive allometry, in which the claw grows much faster than the rest of the body). Allometry (and its counterpart isometry, in which proportions don't change at all) can be examined on an intraspecific level, such as the example in humans, or on an interspecific level.It's not cute - it's allometric! Toronja Azul, Chihuahua Puppy, 5 August 2007 via Wikimedia Commons, Creative Commons Attribution 2.0For paleontologists and biologists, allometry and isometry are particularly interesting when it comes to understanding groups with large ranges in body size. When you grow a Tyrannosaurus from an Eoraptor-like ancestor, what has to change in order to support the body mass? Sometimes it's postural - big animals tend to have more "columnar" posture (with the supporting legs straight beneath the body) and small animals tend to have more "flexed" posture. In other cases, it's allometric - big animals might tend to have relatively thicker bones than small animals. Sometimes, it might even be both. And sometimes, none of these comfortable patterns seem to fit perfectly.Looking at CatsRegardless of the patterns (and often because of them), scaling studies of limb bones have attracted a lot of ink over the years. A recent contribution, authored by Michael Doube and colleagues, appeared the other week in the open access journal PLoS ONE. Their paper, entitled "Three-dimensional geometric analysis of felid limb bone allometry," takes a novel peek at how different limb bones scale within cats. Cats are a particularly interesting study subject, because they span a range of adult body masses - from as little as 3 kg in the domesticated cat to 306 kg in the largest tiger.Domesticated cat (left) and lion skeletons, scaled to roughly the same height at the shoulders.Limb bone allometry in its own right is an interesting, but rather conventional, topic. Most studies are content to take some linear measurements, or perhaps a cross-section or two, for a range of species. Doube and colleagues did something unique - they examined the three-dimensional properties of entire limb bones, as well as two-dimensional properties in series along the entire bone, using CT scans coupled with custom-written software macros.The macros (which are one of the really cool things about this paper, and a big reason for why I'm highlighting it here) calculate a variety of cross-sectional properties automatically from CT scan data. Previous macros (such as the very useful MomentMacroJ) required a human operator to do things one slice at a time. Believe me, this can take forever for a limb bone data set of 200 CT slices. The authors of the paper in question were able to quickly and efficiently assemble data sets for a variety of measurements from a variety of limb bones for a variety of felid species - over 16,000 CT slices in total! So, this allowed compilation of a database for measurements throughout the bone - not just at the boring old mid-shaft. Furthermore, they calculated joint geometries (through a sphere-fitting routine, to approximate surface area of certain joints) as well as moments of inertia for entire bones.This data set allowed the authors to get one of the the most complete pictures of limb bone properties ever assembled. In general, cross-sectional properties at mid-shaft (a standard location for measurement) did not differ significantly from isometry (i.e., big cat bones look the same as little cat bones). Of course, a larger sample might achieve statistical significance at P less than 0.05 (results are suggestive, but don't differ significantly from isometry). Interestingly, joint surfaces and moments of inertia tend to scale with positive allometry. In other words, big cats have relatively bigger joints and beefier bones (a more thorough and accurate explanation of moments of inertia is beyond the scope of this post) than do small cats.So why are these results interesting? Well, it appears that cats "get big" differently from other animals. Whereas comparably sized mammals tend to change from flexed limb postures to more columnar limb postures as body size increases, cats apparently maintain a relatively flexed posture across their size range. Instead, cats compensate for the change in body mass by beefing up their bones. Skeletal and postural responses to increased body size are pretty darned diverse, and there is no "one size-fits-all" solution. It will be very interesting to see broader applications of this methodology.Open Source SolutionsThe authors used ImageJ, an open source image processing system (detailed in a previous post here) for much of their data collection. The macro they wrote and used is also freely available with their paper--so feel free to try it out with your own data. Their massive datafiles were collated with MySQL, and the statistical analysis was conducted within R, using the SMATR package for regression analysis. So, it was an open source project from start to finish! As the cherry on top of the cake, publication in PLoS ONE means that the paper is easily and freely accessible to all. I've already made a few notes on the paper, with quick and gracious responses from one of the authors. If you have anything to add to the discussion, don't be shy!Further ReadingIf you're interested in more open source solutions to these sorts of problems, check out lead author Michael Doube's web page. He's got lots of macros, pretty pictures, and other goodies for enjoyment and download.The CitationDoube, M., Conroy, A., Christiansen, P., Hutchinson, J., & Shefelbine, S. (2009). Three-dimensional geometric analysis of felid limb bone allometry. PLoS ONE, 4 (3) DOI: 10.1371/journal.pone.0004742... Read more »

Doube, M., Conroy, A., Christiansen, P., Hutchinson, J., & Shefelbine, S. (2009) Three-Dimensional Geometric Analysis of Felid Limb Bone Allometry. PLoS ONE, 4(3). DOI: 10.1371/journal.pone.0004742  

  • April 29, 2009
  • 11:28 PM
  • 483 views

Albatross vs. Pterosaur

by Andrew Farke in The Open Source Paleontologist

Today, there was a paper tangentially related to pterosaurs in the open access journal PLoS ONE. A team of investigators wired up albatrosses and petrels with accelerometers, in order to measure the percentage of time these animals spent flapping their wings and soaring. They found two main styles of wing flapping (as inferred from the accelerometer measurements): 1) high frequency flapping during take-off; and 2) low-frequency flapping during soaring. Interestingly, the frequencies scale with body mass in such a way that a maximum possible body size for the albatross-like body plan that still allows flight is extrapolated to a body mass of 41 kg and wingspan of 5.1 m (with the requisite error bars, of course).The authors then go on to discuss the implications for pterosaur paleobiology, essentially suggesting that albatross-style soaring was physically impossible for pterosaurs such as Quetzlcoatlus (assuming that it also had albatross-style wings). Frustratingly, there is little discussion of the alternative possibilities of wing shape in pterosaurs, among other things. Furthermore, the underlying data for the analysis only focus on four species of birds with limited morphological diversity. As suggested by the authors of the current paper, data on thermal-soaring birds such as condors (which have a decidedly un-albatross-like form) are sorely needed.So, kudos to Sato et al. for collecting some interesting morphological data. This sort of information is invaluable for verifying and refining existing models of vertebrate flight. However, the relevance of the data to pterosaurs should probably be reviewed by someone who knows the group better than I do - so if you're one of those people, hop (or soar) on over to PLoS ONE and comment on the article!ReferenceSato, K., Sakamoto, K., Watanuki, Y., Takahashi, A., Katsumata, N., Bost, C., & Weimerskirch, H. (2009). Scaling of soaring seabirds and implications for flight abilities of giant pterosaurs. PLoS ONE, 4 (4) DOI: 10.1371/journal.pone.0005400... Read more »

Sato, K., Sakamoto, K., Watanuki, Y., Takahashi, A., Katsumata, N., Bost, C., & Weimerskirch, H. (2009) Scaling of soaring seabirds and implications for flight abilities of giant pterosaurs. PLoS ONE, 4(4). DOI: 10.1371/journal.pone.0005400  

  • May 19, 2009
  • 09:33 PM
  • 466 views

About That Adapid. . .Or, Hype In the Digital Age

by Andrew Farke in The Open Source Paleontologist

Today's PLoS ONE includes an article on a new primate from the Eocene of Germany, Darwinius masillae. Poor Darwinius has suffered heaps of abuse over her existence (we know the specimen is probably a she, based on the lack of a baculum). She died young, possibly suffocating during a belch of noxious gas from a volcanic lake. She got squashed ("lightly crushed," as her describers euphemistically say) under tons of rock, and then was rudely given a split personality upon her discovery. Each half of Darwinius was sold privately to a different collector, and eventually one half made it as far as a museum in Wyoming. This half received a little bit of creative restoration somewhere in between. The other, more intact half eventually made it to a museum in Norway. But, the fun was only beginning!Our friend was described by a multi-national team of scientists, who teamed up with the History Channel, BBC, and other outlets to create a media blitz the likes of which the world has never seen before. Not only a peer-reviewed article, but press conferences, book deals, television programs, interviews, and much more.Why is there such a fuss over such a little specimen (weighing in at approximately a kilogram while alive)?First off, this is a spectacular fossil. The Messel Beds of Germany have produced truckloads of spectacular specimens with exquisite soft tissue preservation (everything from bats to birds to rodents), but primates are exceedingly, exceedingly rare. Nobody would debate the tremendous scientific value of the find. People are debating the authors' interpretation of the find.The authors claim that Darwinius is a haplorhine primate. That is, Darwinius (and other members of its clade, the adapoid primates) is more closely related to anthropoid primates (including monkeys of all sorts, apes, humans, etc.) than to strepsirrhine primates (the group including lemurs). It's hard to believe for those of us who study dinosaurs, but this is a ridiculously contentious claim. To put it into context for you dinosaur nerds, this would be similar to someone claiming that Compsognathus is more closely related to birds than Velociraptor. Oh, the humanity!The claim of Darwinius and other adapoids as a haplorhine is contentious for two reasons: 1) most recent, widely accepted cladistic analyses place adapoids as closer to lemurs (strepsirrhines) than to monkeys (haplorhines); and 2) there is no real cladistic analysis to support the claim made by the present paper. Instead, the authors give a list of characters that they believe to support the assignment to the haplorhine clade. Unfortunately, there is little or no discussion as to what these characters (including absence of a "toilet-claw" and "tooth comb," features found within, but not universally across, lemurs and kin) mean, including the possibility of convergence or mosaic evolution.So, it appears that some extraordinary claims are made about Darwinius, but the supporting analyses are non-existent. Given the wonderful preservation of the skeleton, it should be relatively straight-forward to code this specimen and present a cladistic hypothesis. Darwinius is an important fossil. The problem is that the interpretation of this specimen is highly debateable. The authors may very well be right. . .but the burden of proof is still upon them.As always with articles in PLoS ONE, the paper is free for everyone. Judging by the blogosphere today, there are some very strong opinions about this specimen - if you have thoughts on the little critter, please post a comment or note over at PLoS ONE!Further Reading in the BlogosphereBrian Switek presents an excellent, in-depth analysis of Darwinius over at Laelaps.ReferenceFranzen, J., Gingerich, P., Habersetzer, J., Hurum, J., von Koenigswald, W., & Smith, B. (2009). Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology PLoS ONE, 4 (5) DOI: 10.1371/journal.pone.0005723Image at top from the original article at PLoS ONE.... Read more »

Franzen, J., Gingerich, P., Habersetzer, J., Hurum, J., von Koenigswald, W., & Smith, B. (2009) Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology. PLoS ONE, 4(5). DOI: 10.1371/journal.pone.0005723  

  • July 3, 2009
  • 02:34 AM
  • 449 views

An Australian Dinosaur Extravaganza

by Andrew Farke in The Open Source Paleontologist

The Cretaceous of Gondwana - the formerly connected southern landmasses of Antarctica, Australia, South America, Africa, India, Madagascar, and Arabia - is a sticky problem. The terrestrial fossil record is spotty at best in most locations, and tremendous geographic and temporal gaps remain. As a consequence, there is considerable debate about the sequence of the tectonic breakup of Gondwana and even the very identity and relationships of some of its dinosaurs and other Mesozoic beasts. Once in a great while, some intrepid field paleontologists take a chance and make discoveries that move our knowledge ahead by leaps and bounds. Areas of Gondwana such as Madagascar and Argentina have had fossils rolling out of the Cretaceous hills, doing wonders for paleontological knowledge. Today, a new paper in PLoS ONE has done such a thing for Australia.Historically, paleontologists working in the Cretaceous of Oz have had to make do with pretty fragmentary material. With the exception of Muttaburrasaurus (a plant eating ornithopod known from reasonably complete skulls and skeletal material) and Minmi (an armored ankylosaur known from a relatively complete skeleton), most of the other named taxa from this time are known only from scrappy elements (e.g., Kakura, a theropod known from an isolated, opalized tibia). This poor fossil record has resulted in some odd, and highly unlikely, claims. For instance, it has been suggested that ceratopsians (otherwise known only from the northern hemisphere) lived in Australia (based on isolated ulnae that admittedly do look rather ceratopsian - although other assignments haven't necessarily been ruled out effectively), and that Allosaurus (a late Jurassic theropod from North America) survived into the early Cretaceous here. When it comes to the meat-eating theropods and the long-necked sauropods, the material is pretty frustrating. Without better specimens, it's virtually impossible to know how Australia's animals compared to those elsewhere!For this reason, the new paper is so very important. A team of paleontologists from the Queensland Museum and the Australian Age of Dinosaurs Museum of Natural History here describe three completely new dinosaur species. Two are sauropods, the third is a theropod, and all come from the Winton Formation of Queensland. The portion of the Winton Formation hosting the dinosaurs is estimated as late Albian in age (based on fossil pollen, an important criterion in the absence of radiometric dates), or roughly 100 million years old.The two sauropods belong to a group called titanosaurs. Titanosaurs were the dominant sauropods of the Cretaceous, with a virtually global distribution. Diamantinasaurus matildae (the sauropod at the top in the illustration, charmingly named after "Waltzing Matilda") and Wintonotitan wattsi (bottom) are both known from partial skeletons, whose owners might have measured 50 feet in total length (~14.8 m) when alive. Unfortunately, the phylogenetic position of the two animals is somewhat uncertain. The authors chose to put the animals into two very different datasets for their cladistic analysis (in terms of characters and taxon selection), so it's tough to know where the things actually fall out. It would be informative to merge the two datasets as much as possible and see how that affects tree topology. The incongruent trees also complicate any biogeographic conclusions that might be drawn. Regardless, it looks like Wintonotitan is a relatively basal titanosauriform (what some folks might call "primitive"), and Diamantinasaurus falls out within a group called Lithostratia, close to or within the saltasaurids (many of these animals are well-known for the armor studding their backs).There is a slim possibility that one or both new species of sauropod are synonymous with Austrosaurus mckillopi, a taxon based on poorly preserved, incomplete vertebrae from a roughly contemporaneous formation. There is some overlap with Wintonotitan, but the vertebrae from the two animals are apparently pretty different. Diamantinasaurus doesn't preserve any vertebrae, so we can't directly compare it with Austrosaurus. But because the type of Austrosaurus is so incomplete, it might be safely ignored as a nomen dubium. I'll leave it to the sauropod experts to decide that!Our third beast is a theropod (meat-eating dinosaur) named Australovenator wintonensis. It was perhaps a third of the body length of the two sauropods and is represented by a partial skeleton including a complete hindlimb, partial forelimbs, and a portion of the lower jaw. For Australian theropods, this is simply dumbfounding material (remember Kakura, only known from a fragmentary leg bone?). Heck, for theropods anywhere this is pretty darned good. Australovenator falls out as an allosauroid (a pretty common group of predators from the Jurassic and Cretaceous) just outside of carcharodontosaurids. With Australovenator thrown into the mix, allosauroids had a nearly global distribution.Open Access NerdinessThis paper is a fantastic example of the real benefits of an on-line, open access journal like PLoS ONE. Without page limitations, the authors were allowed to truly monograph the heck out of the bones. Virtually every element is illustrated from multiple angles (with high resolution photos downloadable from the website!) and accompanied by thorough text descriptions and measurements. The editors of most journals would freak out over such a "waste" of precious space - but I have a feeling that future researchers are going to thank the authors for their thoroughness. As a PDF, the paper weighs in at 51 pages - and this doesn't include the supplementary information!The authors (perhaps at the editors' behest) also make very explicit statements about the nomenclatural availability of the names, a direct result of the Darwinius fallout. Hopefully this will satisfy the requirements ICZN.On the rather nitpicky side, I would note that the minimal post-processing of the manuscripts employed by PLoS ONE shows up here and there. For instance, the term "phalange" is used as the singular instead of the correct "phalanx" (one of my few pet peeves), among a few other oddities. These are rather minor bones to pick in an otherwise weighty manuscript.As always, if you have something to say, post a comment here and then go provide your comments, notes, and ratings of the article at the PLoS ONE website.The Bottom LineSo what's so important about this paper? Well, we finally have good sauropod material from the Cretaceous of Australia, and an excellent theropod specimen to go along with it. No doubt--these specimens are going to be critical for future studies on the evolution and biogeography of both groups, as well as greatly filling in our understanding of Australia's geo... Read more »

Hocknull, S., White, M., Tischler, T., Cook, A., Calleja, N., Sloan, T., & Elliott, D. (2009) New mid-Cretaceous (Latest Albian) dinosaurs from Winton, Queensland, Australia. PLoS ONE, 4(7). DOI: 10.1371/journal.pone.0006190  

  • June 5, 2009
  • 02:13 AM
  • 437 views

How Big (Dead) Mammals Respond(ed) to Global Warming: Paleontology and Our Climate Crisis

by Andrew Farke in The Open Source Paleontologist

After all of the commotion over "Ida," I'm happy to point out a new, thought-provoking paper in PLoS ONE that perhaps has more relevance to modern humans than any old primate of debated affinity. This new contribution ties two rather cool issues together: charismatic megafauna and global warming. And what might they have to do with each other?Within the scientific community, our current cycle of climate change ("global warming") is pretty well-supported by numerous lines of evidence. In light of this change, many biologists, conservationists, and policy-makers want to know exactly how this change will affect living things (humans and wildlife alike). Will animals adapt to the new conditions? Will they die out? Will different animals cope in different ways? Models, simulations, and short-term studies are all useful, but only provide one small piece of the puzzle. Short-term studies (by short-term, I mean on the scale of months, years or decades) provide useful ground-truthing for the models, but in matters of conservation and policy, they may come too late for imperiled ecosystems. It's like having your house burn down around you before you can see the smoke.An oft-overlooked source of data comes from the fossil record. Earth's climate has changed numerous times over the millenia, and by studying previous warming or cooling episodes we may be able to understand our own times. This is where a new study, led by Larisa R. G. DeSantis in collaboration with Robert Feranec and Bruce MacFadden, comes in.Ice Age AnticsBeginning around 2.58 million years ago, in the late Pliocene, our planet has been in an Ice Age. This ice age is characterized by cooling periods (glacial periods, in which the ice sheets advance) and warming periods (interglacial periods, in which the ice sheets retreat). For the last 10,000 years or so, we've been in an interglacial period (and our present climate change is above and beyond this). As a neat natural experiment, DeSantis and colleagues decided to look at how large animals reacted (in terms of diet, etc.) to the switch from a cool period to a warm period.Grind Up Fossils in the Name of ScienceThe team focused on two sites from Florida: one from a glacial period, between 2.0 and 1.6 million years old, and another from an interglacial period, between 1.6 and 1.3 million years old. Using a little drill, the researchers sampled tooth enamel from a variety of Ice Age organisms, including horses, deer, tapirs, elephants, and other herbivorous critters that roamed Florida during that interval. And why grind up fossil specimens? It turns out that you can run the enamel powder through a spectrometer that measures the proportions of various isotopes of carbon and oxygen.And what do these isotopes tell us? Simply put, you are what you eat. Different plants use different pathways of carbon fixation (C3 and C4 were investigated here). Animals eating lots of C4 plants (primarily "warm season grasses") have one isotopic signature for carbon, and animals eating C3 plants ("cool season grasses," trees, and shrubs) have another. Furthermore, oxygen isotopes are different for arid environments and relatively wet environments. So, by looking at oxygen and carbon isotopes in concert, you can get an idea of the relative aridity of the area as well as the diet of a given animal.And now the modern tie-in: According to DeSantis and colleagues, many studies and models have concluded that under environmental change, animals tend to try to be pretty consistent in what they eat. In other words, if you start out at a grass-eater, you will try and stay a grass eater. So, mammals don't really do much in response to warming (or cooling). Of course, this has pretty important implications for conservation: once the grass disappears in the face of a changing climate (whatever the cause), our grass-eaters are toast.The ResultsInterestingly, it turns out that different mammals had different stories over the course of the glacial cycle. Based on the isotopic data, the types of plants changed over time, with C3 plants dominating the cooler cycle (as would be expected) and C4 plants predominating in the warm interval. And, many of the same animals are found in both the "warm" and the "cool" study sites. Although some apparently maintained similar diets (e.g., tapirs), most other animals (e.g., deer and horses) showed very different isotopic signatures over time. They were eating different foods. . .thus, these animals were quite adaptable!What It All MeansA striking implication of the study is that some animals may not be as vulnerable to climate change as previously thought. These Ice Age species changed their ecological niches in the face of climate change. So, if large modern animals can adapt their diets relatively easily, they may be able to escape extinction too. The bottom line still is that previous assumptions of do-or-die dietary stability for large mammals are not valid in all cases. Here we have yet another cool example of how paleontology can provide important information for "real-world" problems!Parting ThoughtsThe paper, posted at PLoS ONE, covers much more than the little bit I've highlighted here. There are some interesting tidbits on changes in rainfall and ecological partitioning, among other things. It's a quick and very accessible read (weighing in at 7 PDF pages, including figures and references), and even this non-geochemist followed the text pretty easily. So, go check it out! As always, you can rate the paper or make comments at the PLoS ONE website.The CitationDeSantis, L., Feranec, R., & MacFadden, B. (2009). Effects of global warming on ancient mammalian communities and their environments PLoS ONE, 4 (6) DOI: 10.1371/journal.pone.0005750... Read more »

DeSantis, L., Feranec, R., & MacFadden, B. (2009) Effects of global warming on ancient mammalian communities and their environments. PLoS ONE, 4(6). DOI: 10.1371/journal.pone.0005750  

  • October 28, 2009
  • 10:18 AM
  • 171 views

A Happy Family of Pachycephalosaurus

by Andrew Farke in The Open Source Paleontologist

Distinguishing the skulls of juveniles and adults of the same species, and sometimes different species, can be a prickly thing in the fossil record. The result is that paleontology is littered with juvenile fossils that have been considered adults at some time or another. The crested duck-billed dinosaur Corythosaurus has also been known under names like Procheneosaurus, the famous Monoclonius is actually a juvenile of adult Centrosaurus, Styracosaurus, and kin, and the debate still continues on whether Nanotyrannus is a juvenile Tyrannosaurus.Yesterday in the open access journal PLoS ONE, paleontologists Jack Horner and Mark Goodwin published a long-awaited paper positing synonymy for a trio of iconic (and melodiously-named) dinosaurs. The bone-headed dinosaurs Pachycephalosaurus, Stygimoloch, and Dracorex are all one and the same animal, according to their work. The latter two are juvenile stages, whereas Pachycephalosaurus represents a full adult.Skulls of Pachycephalosaurus (top), Stygimoloch (middle; the front of the skull is missing), and Dracorex (bottom; the skull is crushed from top to bottom). In particular, note the changes in skull size and similarities in spike placement. Modified after the original in Horner and Goodwin 2009.How is this possible? The animals look so different, right? Pachycephalosaurus has this big bowling ball on top of its head, which the other two lack. Stygimoloch has a uniquely-shaped, narrow dome, and Dracorex has a completely flat head. Furthermore, Pachycephalosaurus lacks the elongated spikes that make the other two look so fearsome.Well, it turns out that this can all be attributed to ontogenetic changes (i.e., change as the animals get older). Horner and Goodwin assemble multiple lines of evidence for this hypothesis.First, the skulls of Dracorex, Stygimoloch, and Pachycephalosaurus form a size gradation from smallest to largest--exactly what one would expect for a growth series. By itself, this is not irrefutable proof, of course--it could just be that Dracorex had a small adult size compared to Pachycephalosaurus.Second, many of the knobs and bumps on the skulls can be matched up one for one between individuals of the various specimens. Alternatively, one would also expect that closely related (but different) species might have similar patterns of bumps. As Horner and Goodwin admit, there is some variation between individuals of the different "species"--but, the authors also note that this sort of variation is entirely expected and occurs even within undisputed adult Pachycephalosaurus.Third, specimens of Stygimoloch, both in CT scans and physically cut specimens, show an open suture between the two frontal bones of the dome. Pachycephalosaurus domes are completely fused up. Open sutures are often strong indications that an animal is still growing--and, it's particularly intriguing that a small "species" has them but a large "species" doesn't!Finally, microscopic examination of the bones in two of the three "species" (Stygimoloch and Pachycephalosaurus; there weren't any Dracorex available for cutting up) shows that Stygimoloch was still growing (and thus not a full adult)--but Pachycephalosaurus specimens weren't growing much at all (and therefore were probably full adults).Any one of these lines of evidence might be interesting, but not completely convincing. Taken together, however, they make a pretty compelling case that Dracorex and Stygimoloch are juvenile Pachycephalosaurus. Because Pachycephalosaurus was named first, the first two become junior synonyms. It's a shame, because they're such cool names!As for duckbilled dinosaurs, horned dinosaurs, and even modern crested birds like the cassowary, the story in the pachycephalosaurs suggests that weird ornaments on the skull were something that happened only as the animals approached full size. The domes practically appeared overnight! The teenage years must have been a real headache for these dinosaurs.Thanks to the wonders of open access, the article is freely available for all to read. Additionally, it is worth taking advantage of the rating and comment features at PLoS ONE [disclaimer: I am a section editor for that journal]. . .few other scientific publications allow the readers to annotate the papers directly!CitationHorner, J., & Goodwin, M. (2009). Extreme cranial ontogeny in the Upper Cretaceous dinosaur Pachycephalosaurus. PLoS ONE, 4 (10) DOI: 10.1371/journal.pone.0007626... Read more »

Horner, J., & Goodwin, M. (2009) Extreme cranial ontogeny in the Upper Cretaceous dinosaur Pachycephalosaurus. PLoS ONE, 4(10). DOI: 10.1371/journal.pone.0007626  

  • February 13, 2010
  • 04:21 PM
  • 91 views

Four-Winged, Psychedelic Dinosaurs

by Andrew Farke in The Open Source Paleontologist

When many of us think of viewing things under a "black light," we either think of those psychedelic posters from the 1960s or else the displays of fluorescent minerals that nearly every science museum has. It's also virtually mandatory to have a scene involving the use of "black light" in the popular CSI television programs - many bodily fluids show up nice and pretty under these conditions. "Black light," more properly known as "ultraviolet (UV) spectrum light", is just outside the visible light spectrum for us humans (past violet, hence the name). And, through some neat tricks of physics, many objects will brightly fluoresce under intense UV light when they wouldn't look like anything special under your standard sunlight or incandescent light bulb.Oddly enough, many fossils fluoresce under UV light (certain minerals in fossils, including phosphates, are behind this phenomenon). Thus, this technique has been used to look for otherwise hidden features of some exceptionally well-preserved fossils. Historically, it's been the domain of invertebrate paleontologists (looking at crustaceans from the Jurassic of Germany, for instance), but vertebrate paleontologists have used the technique to identify forged fossils (like Archaeoraptor), study Archaeopteryx, and much more. What might be a very subtle or invisible structure under regular light (such as a feather shaft, or antenna, or soft tissue outlines) sometimes shines nicely under UV light.Thus, Beijing paleontologist Dave Hone and colleagues applied the UV light technique to some of the spectacular fossils coming out of the Cretaceous-aged beds of China. In particular, they were interested in a little critter called Microraptor. A dromaeosaur (part of the same group including Velociraptor), Microraptor is relatively well-known as the "four-winged dinosaur." Spectacular fossils with feather impressions show the standard pair of bird-like wings on the arms and a second set of wings on the hind limbs. This suggests to some researchers that birds went through a four-winged flight phase early in their evolution, and the two-winged flight with which we are familiar only happened later.Type specimen of Microraptor gui, from the Wikimedia Commons, reproduced under a Creative Commons Attribution-Share Alike 2.5 Generic license.Although the fossil looks spectacular, many paleontologists speculated that appearances might be deceiving. Were the feathers on the legs actually in place, near their life position? Or had they gotten moved around from somewhere else on the body? A pale halo of sediment (probably from the decomposition process) obscured the contact of the feathers with the bones, so the issue remained unresolved. Either way, it had major implications for avian evolution.Hone and colleagues wondered if the full anatomy was obscured under visible light. So, they turned a UV light source against the specimen. It turns out that the feather structures fluoresce quite nicely - and can be traced right through the "halo" and up to the very edge of the leg bones. So, the feathers really are in place. Problem solved! [image, showing full skeleton, modified from Figure 2 in Hone et al. 2010]Now that we're more confident that Microraptor really was four-winged (and not just an accident of fossilization), the conversation can move forward. And, this is a great rallying cry for other researchers - who knows what structures we might discover with UV light!Close-up of hind legs of Microraptor under UV light, with arrows indicating feathers. The yellow stripes leading up to the leg bones are portions of the feathers visible only under UV. Modified from Figure 3 in Hone et al. 2010Read the full paper in the freely-available, open access journal PLoS ONE (full disclosure: I was the editor who handled this manuscript). You can post comments or ratings for the article there, too! In the blogosphere, check out Dave Hone's posting on his article, as well as ReBecca Hunt's interview with Dave.CitationD. W. E. Hone, H. Tischlinger, X. Xu, & F. Zhang (2010) The extent of the preserved feathers on the four-winged dinosaur Microraptor gui under ultraviolet light PLoS ONE 5 (2) : 10.1371/journal.pone.0009223... Read more »

David W. E. Hone1, Helmut Tischlinger, Xing Xu, & Fucheng Zhang. (2010) The extent of the preserved feathers on the four-winged dinosaur Microraptor gui under ultraviolet light. PLoS ONE, 5(2). info:/10.1371/journal.pone.0009223

  • January 28, 2010
  • 10:41 AM
  • 81 views

Where is paleontology?

by Andrew Farke in The Open Source Paleontologist

Last week, many of the leading journals in evolutionary biology - including The American Naturalist, Molecular Ecology, Journal of Evolutionary Biology, Evolution, and a number of others - announced a data archiving policy. In short, this policy states that the data behind the results of a paper should be publicly archived in well-known respositories such as Data Dryad, GenBank, or TreeBASE. Do you notice anything missing in this illustrious list of publications?Not a single one of those journals explicitly focuses on paleontology. Last time I checked, we paleontologists like to think of ourselves as evolutionary biologists. Time and time again, we lament how we're not allowed a place at "The High Table" of evolutionary thought, and how paleontology is viewed as largely irrelevant by the "people who matter." So why weren't any paleontology publications on this list? Will we see any on the list in the near future?The article in The American Naturalist gives a good run-down of the arguments for sharing data, so I'll only briefly summarize them here:It allows reproducibility of analyses.It allows others to build upon your work more easily.Papers that release their data may get cited more frequently.The data will be lost to science otherwise.It's the right thing to do.And to counter some potential objections:This would only request the release of data directly relevant to the study. Not your pages and pages of raw notes. Just that Excel spreadsheet that you already generated on your way to the analysis. Seriously. It's not a lot of extra work, if any.This is not requesting the digitization and distribution of video, CT scan, or similarly large and unwieldy data (although that would be nice in the future).No, it does not mandate the release of locality data, or similarly privileged information.The policy does not require immediate release of the data, if there's a good reason (i.e., another pending publication) to do so. I'm not sure I entirely support this (if you're publishing the analysis, you should publish the data), but I understand it as a necessary compromise to get more individuals on board. I won't let the perfect be the enemy of the good.Some of the most ground-breaking and high-profile work in paleontology is happening on account of large meta-analyses of data pulled together from the literature - largely thanks to efforts like the Paleobiology Database. This work has real implications for big questions facing our science and our world: Climate change. The pace of evolutionary radiations. The origins of modern biological diversity. These sorts of databases focus primarily on geographic, stratigraphic, and taxonomic data - but think how much more powerful they could be if all of the morphological data ever published were available! Or if the PBDB volunteers didn't always have to transcribe the information from a PDF file.Look. Amateur hour is over. If we want to play in the big leagues, we have to start acting like a real science. Real science is reproducible. Real science is data-driven. Real science involves sharing data. Yes, I know it's hard. It's new. We haven't done things this way before. There are potential problems. Not everyone is adopting it quickly. But if we always wait five years to "see what happens," we paleontologists quite frankly don't deserve a place at the High Table. Let's be leaders, not followers.ReferencesPiwowar, H. A., R. S. Day, and D. B. Fridsma. (2007). Sharing detailed research data is associated with increased citation rate. PLoS ONE 2(3):e308, DOI: 10.1371/journal.pone.0000308.Whitlock, M., McPeek, M., Rausher, M., Rieseberg, L., & Moore, A. (2010). Data archiving. The American Naturalist, 175 (2), 145-146 DOI: 10.1086/650340For previous posts on data sharing in paleontology, see here and here. Want to get involved? Spread the word. Talk to your local journal editor. Let the people who count know what you think.... Read more »

Whitlock, M., McPeek, M., Rausher, M., Rieseberg, L., & Moore, A. (2010) Data Archiving. The American Naturalist, 175(2), 145-146. DOI: 10.1086/650340  

join us!

Do you write about peer-reviewed research in your blog? Use ResearchBlogging.org to make it easy for your readers — and others from around the world — to find your serious posts about academic research.

If you don't have a blog, you can still use our site to learn about fascinating developments in cutting-edge research from around the world.

Register Now

News

Editor's selections: corporate water abuse, vanishing audiophiles, artificial coffee smelling and 60k-year-old canteens

Editor's Selections: An asteroid killed the dinosaurs, innate immunity and obesity, and vaccinia virus in Brazil

Exploitation Nation: Cheating Microbes, Parasites, and Your Colon

Research Blogging is powered by SMG Technology.

To learn more, visit seedmediagroup.com.