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This is the mammoth image I remember, from a 1971 book, with no artist credited. It's actually not as good as I remember, by modern standards at least.

This is the mammoth image I remember, from a 1971 book, with no artist credited. It’s actually not as good as I remember, by modern standards at least.

Mammoths and I go way back, not quite to the Ice Age but at least to the late 1970s with my family’s visits to the University of Wisconsin Geology Museum, and Milwaukee Public Museum, to name two prominent places that inspired me. And one of my favourite science books had a colourful mammoth painting on the cover (above), an image that has stayed with me as awesomely evocative.

Stomach-Churning Rating: 3/10. But there’s a butt below, but that’s too late for you now. And there’s poo and other scatological (attempts at) humour. Otherwise, bones and a baby mammothsicle.

Fast forward to the 2000’s and I’m studying mammoths, along with their other kin amongst the Proboscidea (elephants and relatives). I even bumped into a frozen mammoth in Sapporo, Japan, nine years ago–

Yep. That's what it looks like. Nope, not the front end. That orifice is not the mouth. This is the XXXXX mammoth.

Yep. That’s what it looks like. Nope, not the front end. That dark orifice is not the mouth. This is a mammoth that was found on Bolshoi Lyakhovsky island, in the east Siberian arctic (New Siberian Islands archipelago), in 2003. Just think of finding this and being all excited then realizing, “Jackpot! Wait… Oh man, I just found the ass. I’ve discovered a mammoth bunghole, dammit.” Still, it’s pretty damn amazing, as frozen Ice Age buttocks go. I’d love to find one. I would not be bummed.

found on Bolshoi Lyakhovskiy island in 2003

What I know now that I didn’t realize as a kid, is that a mammoth is an elephant in all but name. Mammoths are more closely related to Asian elephants than either is to African elephants, and all of these elephants are members of the group Elephantidae. If we saw a smallish Columbian mammoth, we’d probably mostly look upon it as similar to a slightly hairy Asian elephant (but a scientist would be able to spot the distinctive traits that each has). Only woolly mammoths adopted the uber-hirsute state that we tend to think of as a “mammoth” trait. Think about it: a big animal would benefit most from a thick hairy insulation in an extremely cold habitat, and Columbian mammoths ranged further south than Woolly ones. No mammoths were radically different from living elephants, unless you count the dwarf ones. But as a kid, like most people do, I saw them as something else: an exotic monster of the past, eerily unlike anything today, and bigger too. And mammoths have the added mystique of the extinct.

Now I see mammoths as neither exotic nor that far in the past. Giant ground sloths, now those are still alien and exotic to me. I don’t get them. I know elephants pretty well, and I can understand mammoths in their light and in light of mammoth fossils. Various mammoth species persisted as late as maybe 10,000 (for the Woolly and Columbian species; the latter seeming to vanish earlier) to <4000 (for isolated Siberian forms) years ago, into quasi-historic times. And only some mammoths got larger than African elephants (Loxodonta) do, such as Columbian mammoths (~10,000 kg or more maximal body mass; Loxodonta is closer to 7-10 tonnes at best).

Lately, coincidence has brought me new knowledge of – and even greater interest in – mammoths.

First, a fortunate last-minute visit to Waco, Texas’s “Mammoth Site” (see my Flickr photo tour here) two weeks ago during a short visit to give a talk in that fine central Texan city.

Second, the subject of today’s post: the Natural History Museum’s new special exhibit “Mammoths: Ice Age Giants“, which is open until 7 September. The exhibit was created by the Field Museum in Chicago, but the NHM has given it a special upgrade under the expert guidance of mammoth guru Prof. Adrian Lister of the NHM, who was very kind to give me a tour of the exhibit.

What follows is primarily a photo-blog post and review of the exhibit, but with some thoughts and facts and anecdotes woven through it. Dark setting, glass cases, caffeination, crowds, and mobile phone camera rather than nice SLR in hand means that the quality isn’t great in my images– but all the more reason to go see the exhibit yourself! All images can be clicked to em-mammoth them.

On entry, one views a mammoth skeleton with a timelapse video backdrop that shows how the landscape (somewhere in USA) has changed since ~10,000 BCE.

On entry, one views a mammoth skeleton with a timelapse video backdrop that shows how the landscape (somewhere in USA) has changed since ~10,000 BCE.

The first part of the exhibit does a nice job of introducing key species of Proboscidea (elephants and their closest extinct relatives), with a phylogeny and timescale to put them into context, starting with the earliest forms:

The first part of the exhibit does a nice job of introducing key species of Proboscidea: from early species like Moeritherium...

from species like the tapir-sized Moeritherium

Skull of Moeritherium, reconstructed. Not that different from an early sirenian (seacow) in some ways, and general shape.

Skull of Moeritherium, reconstructed. Not that different from an early sirenian (seacow) in some ways, and general shape, whereas still quite a long way from a modern elephant in form– but the hints of tusks and trunk are already there.

...To the early elephantiform Phiomia, here shown as a small animal but I'm told it actually got quite large. And continuing with giant terrestrial taxa...

…To the early elephantiform Phiomia, here shown as a smallish animal but I’m told it actually got quite large. And continuing with giant terrestrial taxa…

I was awed by this reconstruction of the giant early elephantiform relative Deinotherium, with the short, swollen trunk and downturned tusks-- so bizarre!

I was awed by this reconstruction of the huge early elephantiform-relative Deinotherium, with the short, swollen trunk and downturned tusks– so bizarre!

Looking down onto the roof of the mouth of a NHM specimen of Deinotherium.

Looking down onto the roof of the mouth of an NHM specimen of Deinotherium. Big, sharper-edged, almost rhino-like teeth; far from the single mega-molars of modern elephants.

The lower jaw (top) and fairly straight tusk (bottom) of the widespread, early elephantiform Gomphotherium.

The lower jaw (top) and fairly straight tusk (bottom) of the widespread, early elephantiform Gomphotherium.

The big "shovel-tusker" elephantiform Amebelodon. This was one of the earliest stem elephants I learned of as a kid; the odd tusks still give me a sense of wonder.

The big “shovel-tusked” elephantiform Amebelodon. This was one of the earliest stem elephants I learned of as a kid; the odd tusks still stir wonder in me.

Amebelodon lower jaw, sans shovel tusks.

Amebelodon lower jaw, sans shovel tusks. Extended chin looks like some sort of childrens’ fun-slide. To me, anyway.

Next, there are some fun interactive displays of elephant biomechanics!

How would a mammoth hold up its head? This lever demonstration shows how a nuchal ligament helps.

How would a mammoth hold up its head? This lever demonstration shows how a nuchal ligament helps. Tension on the nuchal ligament is a force that acts with a large lever (represented by the big neural spines on the vertebrae around the shoulders, forming the mammoths’ “hump” there), creating a large moment (i.e. torque; rotational force) that holds the head aloft.

I love this robotic elephant trunk demonstration. It captures some of the weirdness of having a muscular hydrostat attached to your lip.

I love this robotic elephant trunk demonstration. It captures some of the weirdness of having a muscular hydrostat attached to your lip and nostrils. Not so easy for a human to control!

But forget the myths about elephants having 40,000 to 150,000 muscles in their trunk. They have three muscle layers: a circumferential one, an oblique one and a longitudinal one. Like any muscles, especially ones this large, the layers each consist of many muscle fibres. That’s where the 40-150k myth comes from, but muscle fibres (cells) are at a more microscopic level than whole muscles (organs). Elephants do have excellent control of their trunks, but it’s not magical. It’s just different.

Then we come to the centrepiece of the exhibit, the ~42,000 year old Woolly mammoth (Mammuthus primigenius) baby “Lyuba“, which the NHM added to the original exhibit in this new version, as a star attraction — and a big win. Adrian Lister related to me how he’d never seen Lyuba in person before (access to it was tightly guarded for years). So when the NHM received the crate and held a press event to open it and reveal Lyuba, a journalist asked Adrian to act excited, to which he responded something like, “I don’t need to act! I’m very excited!” I would be, too! Full story on Lyuba’s arrival, by NHM site here. A key paper on Lyuba by Fisher et al. is here.

Studies of tooth growth in Lyuba reveal her gestation period (like living elephants, around 22 months), season of birth (early spring), and age at death (1 month), among other information.

Studies of tooth growth in Lyuba reveal her gestation period (like living elephants, ~22 months), season of birth (early spring), and age at death (~1 month), among other information.

Here we can see the right ear, which was gnawed off along with the tail by dogs of the reindeer herders that found and retrieved Lyuba. Regardless, there's loads of anatomy preserved! A hump of juvenile "brown fat" atop the head, very strange flanges on the trunk (also visible in 1 other frozen mammoth specimen, but here preserved very clearly!), and more visible postcranially...

Here we can see the right ear, which was gnawed off along with the tail by dogs of the reindeer herders that found and retrieved Lyuba in 2006. Regardless, there’s loads of anatomy preserved!

A hump of juvenile “brown fat” sits atop the head and neck of Lyuba. This probably was  metabolized during growth to warm the baby; brown fat is packed with mitochondria and thereby conducts what is called “non-shivering thermogenesis”. Furthermore, Lyuba has very strange flanges on the trunk (also visible in 1 other frozen mammoth specimen, but here preserved very clearly! What were they used for?). More details are visible postcranially…

The body was naturally “freeze-dried”, with the addition of later rounds of soaking in formalin and ethanol, leaving the body dessicated and stiff, permanently stuck in a lifelike pose as seen below:

Whole view from an exhibit panel (you cannot photograph the specimen but these are fair game!). Here we see hair on the right forearm and remnant of the ear, and the labia and nipples showing it is a female mammoth are also preserved. The head-hump is lost during growth, and the shoulder changes to change the Asian elephant-like convex curvature of the back into the characteristic humped-shoulder form of a mammoth. But ontogeny still reveals the evolutionary connection of Elephas and Mammuthus.

Whole view from an exhibit panel (you cannot photograph the specimen but these are fair game!). Here we see hair on the right forearm and remnant of the ear, and the labia and nipples showing it is a female mammoth are also preserved. The head-hump is lost during growth, and the shoulder changes to change the Asian elephant-like convex curvature of the back into the characteristic humped-shoulder form of a mammoth. But ontogeny still reveals the evolutionary connection of Elephas and Mammuthus.

Lyuba and scientists studying her, which also shows how rigid the carcass is.

Lyuba and scientists studying her, which also shows how rigid the carcass is; one can almost stand it up. Inside the digestive tract, researchers found chewed up plant material that was probably dung eaten by the baby to gain vital bacterial digestive flora, and Lyuba had plenty of body fat and ingested milk, indicating that she did not starve to death. Rather, vivianite in the respiratory tract indicates drowning as the cause of her demise. Perfusion of the body by these vivianites may have helped to preserve the body.

Answering an question the public may be wondering about: is the hype about cloning a mammoth very soon true? Nope. Well addressed, including what to me is the urgent question: would cloning a mammoth be ethical?

Answering a question the public may be wondering about: is the hype about cloning a mammoth very soon true? Nope. Well addressed, including what to me is the urgent question: would cloning a mammoth be ethical?

The fourth part of the exhibit takes on a largely North American focus to first illustrate what mammoths were like biologically, and second to wow the visitor with some huge beasts in full body, full scale glory, as we shall see!

Mammoth hair! These samples and recent molecular studies show that mammoths were not ginger-coloured as we long thought, but rather the ginger color comes as the dark grey-brown-black colour fades postmortem, as a preservational artefact. I didn't know that; cool.

Mammoth hair! These samples and recent molecular studies show that mammoths were not ginger-coloured as we long thought, but rather the ginger color comes as the dark grey-brown-black colour fades postmortem, as a preservational artefact (story here). I didn’t know that; cool.

Mammoth chow!

Mammoth chow! I liked this addition to the exhibit. This brought mammoth ecology closer to home for me.

Mammoth poop!

Mammoth poop!

After the biology explanations, let there be megafauna!

Mammoth skull! A nice one, too.

Mammoth skull! A nice one, too.

Top predators of Ice Age North America: Arctodus (short-faced bear) and Homotherium (sabre-toothed cat).

Top predators of Ice Age North America: Arctodus (short-faced bear– does the short face mean they were happy, unlike a long face? Sorry but they never are shown as very happy, unless it is the joy of whupass) and Homotherium (the other sabre-toothed cat; not the longer-toothed Smilodon).

Skulls of North American megafauna: left to right, top to bottom: horse, short-faced bear, giant sloth, then camel, sabretooth,  rabbit, direwolf (viva Ned Stark!), and pronghorn antelope.

Skulls of North American (mega)fauna: left to right, top to bottom: horse, short-faced bear, giant ground sloth, then camel, sabretooth cat, rabbit, direwolf (viva Ned Stark!), and pronghorn antelope.

Mastodon skeleton!

Mastodon (Mammut americanum) skeleton!

Mammoths seem to have been wiped out by a combination of climate change and habitat fragmentation, combined with what this item symbolizes: human hunting. This beautiful piece is the main part of an atlatl, or javelin-hurling lever. It would give Ice Age hunters the extra power they'd need to penetrate mammoth hide and cause mortal injuries.

Mammoths (and perhaps mastodons, etc.) seem to have been wiped out by a combination of climate change and habitat fragmentation, combined with what this item symbolizes: human hunting. This beautiful piece is the main part of an atlatl, or javelin-hurling lever. It would have given Ice Age hunters the extra power they’d need to penetrate mammoth hide and cause mortal injuries. It is also a great tie-in to my recent post on the British Museum’s odd-animals-in-art.

Finally, the exhibit surveys the kinds of mammoths that existed- there is a huge reconstruction of a Columbian mammoth near the mastodon (above), then smaller kinds and discussions of dwarfism, which is another strength of NHM mammoth research:

Woolly mammoth lower jaw (right) and its likely descendant, the pygmy mammoth of the Californian coastline, Mammuthus exilis.

Woolly mammoth lower jaw (right) and its likely descendant, the pygmy mammoth of the Californian coastline, Mammuthus exilis.

The world's smallest mammoth (left), molar tooth compared with that of its much larger ancestor Palaeoloxodon. The status of Mammuthus creticus as a dwarf mammoth from Crete was cemented by Victoria Herridge and colleagues, including Adrian Lister at the NHM.

The world’s smallest mammoth (left), molar tooth compared with that of its much larger ancestor Palaeoloxodon. The status of Mammuthus creticus as a dwarf mammoth from Crete was cemented by Victoria Herridge and colleagues, including Adrian Lister at the NHM.

Pygmy mammoth reconstruction. Shorter than me. I want one!

Pygmy mammoth reconstruction. Shorter than me. I want one!

In the end, from all that proboscidean diversity we were left with just 2 or 3 species (depending on your species concepts; it's probably worth calling the African forest elephant its own species, Loxodonta cyclotis). The exhibit closes with a consideration of their conservation and fate. Ironically, this elephant skull could not be mounted with its tusks on display, because that would be commercializing ivory usage-- even though the whole point of the exhibit's denouement is to explain why elephants need protection!

In the end, from all that glorious proboscidean diversity we were left with just 2 or 3 species of elephantids today (depending on your species concepts; it’s probably worth calling the African forest elephant its own species, Loxodonta cyclotis). The exhibit closes with a consideration of their conservation and fate. Ironically, this elephant skull could not be mounted with its tusks on display, because that would be commercializing ivory usage– even though the whole point of the exhibit’s denouement is to explain why elephants need protection!

Reactions to the exhibit: the photos tell the tale. It’s undeniably great, in terms of showing off the coolness of mammoths, other proboscideans and Ice Age beasties, to the general public. I felt like the factual content and learning potential was good. It didn’t feel at all like pandering to the lowest common denominator like some other exhibits I’ve seen (cough, Dino Jaws, cough). I loved the reconstructions, which were top quality in my opinion. I could have done with some more real skeletons, yet more realistically the exhibit hall was already large and full of cool stuff. But give me a break: Lyuba. This trumps everything. Going to see a real friggin’ frozen mammoth baby buries the needle of the awesomeness meter on the far right. That’s pretty much all I need to say. The spectacle was a spectacle.

This exhibit shows a lot of work, a lot of thought, and a personalized NHM touch that reflects the actual research (even very recent work!) that NHM staff like Prof. Lister are doing with collaborators around the globe. What more could we want, a herd of cloned mammoth babies frolicking around and tickling guests with their flanged trunks? Don’t hold your breath.

You’ve got just over 2 months to see the exhibit. Don’t come complaining on September 8 “BBBBBbbbut I didn’t know, I didn’t think it would be that cool! I just thought there’d be a guy in a Snuffleupagus suit signing autographs!” You have a duty as a Freezerino to go bask in the frozen glory of these Ice Age critters. There may be an exam at the end. :)

Is the exhibit kid-friendly? More or less. The text is more targeted at teenager-level or so, but the visual impact is powerful without it. I’d warn a sensitive child about the withered baby mammoth body before showing it to them, so they aren’t caught off guard and scarred by the experience. I saw plenty of kids in the exhibit and they all seemed happy. Parents may want to linger longer and absorb all the interesting information, whereas kids may blitz through or goof around, so plan accordingly if you’re inbound with sprogs.

You know what I was eyeing up in the gift shop...

You know what I was eyeing up in the gift shop…

Aside: The frozen mammoths get me wondering- what else does the Siberian (or extreme northern Canadian/Scandinavian) permafrost conceal? There are a lot of awesome Ice Age megafauna I’d cut my left XXXXX off to study quasi-intact… think about how amazing it would be to find a giant ground sloth (not bloody likely), sabretooth cat, or other species. There’s a lot of north up north. A lot of space and ice. A lot could happen. And climate change will make discoveries like this more likely, while the melting (and humanity) lasts…

Wool we ever find the Lyuba of woolly rhinos? It could happen.

Wool we ever find the Lyuba of woolly rhinos (Coelodonta)? Cast of a mummified woolly rhino from the NHM’s entry hall. More of these finds are likely, I’d say.

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Less words, more pictures in this post, and I’ll get the one lame cake joke out of the way early. I’ve nearly finished my research blitz through the postcranial material of the NHM-Tring’s osteological collection and have made some pit-stops for cake skulls now and then when I see one that pleases me. Now I shall present a survey of some of the species I’ve examined. I’ll proceed up from the base of the crown clade of living birds (Neornithes/Aves; the most recent common ancestor of living birds and all its descendants) and first take a tour of Palaeognathae; the ratites and kin; then move another step up into the Neognathae, first featuring the lineage featuring the ground fowl (Galliformes) and then the waterfowl (Anseriformes). If all this taxonomy and phylogeny is a bit much, check out this page for a brush-up on the bushy branches of bird biodiversity.

First, lots of bones of our cast of currasows, chachalacas, cassowaries and other kooky characters. And then, perhaps, a stop to the excessive alliteration. Finally, I will finish with some examples of species oddity (hat tip to Chris Hadfield).

Stomach-Churning Rating: 2/10- some bony pathologies but still just dry bones. Minimal cake jokes, and no filthy swearing this time.


BRING ON THE BONES:

My photographs are shown with kind permission from the Natural History Museum, London.

Exploded skull of an ostrich/ This takes skill.

Exploded skull of an ostrich, Struthio camelus. This kind of careful preparation takes crazy skill, and creates a thing of rare beauty.

Neat skull of a cassowary, Casuarius casuarius.

Imposing skull of a cassowary, Casuarius casuarius, with a rather worn head casque.

Mummified Owen's Little Spotted kiwi, Apteryx owenii.

Mummified Owen’s Little Spotted Kiwi, Apteryx owenii. The feathers were still soft and fluffy, but I would not call this specimen cuddly.

Dorsal view of the back/hips of the Great Spotted kiwi, Apteryx haasti.

Dorsal view of the back/hips of the Great Spotted Kiwi, Apteryx haasti. I like this photo and am not sure why. The symmetry and shading pleases me, I guess.

Front view of the back/hips of the Great Spotted kiwi, Apteryx haasti.

Front view of the back/hips of the Great Spotted Kiwi, Apteryx haasti, watching over my laptop and watching me while I write this blog on my laptop… so meta(ornithine)!

Wing of a kiwi, showing the fragile bones and feather attachments.

Wing of a kiwi, showing the fragile bones and feather attachments. “Apteryx” = “no wings”… well not quite. Click to emkiwi(?) so you can identify the individual bones, from the humerus right down to the fingers! I love this specimen.

The left leg (in front view) of the elephant-bird, Aepyornis maximus, from Madagascar, with a small moa nearby in left side view.

The titanic left leg (in front view) of the Elephant Bird, Aepyornis maximus, from Madagascar, with a small moa nearby in left side view. There’s so much awesomeness about elephant birds I don’t know where to start, but this is one good place to do so.

Mummified Unulated tinamou, Crypturellus undulatus.

The smaller end of the palaeognath scale: a mummified Undulated Tinamou, Crypturellus undulatus. Somehow the head got stuck into the abdominal cavity underneath the sternum, so this tinamou almost had its head up its arse. A tinamou with head in its proper position looks and sounds like this (video).

And now we take a left turn into the Galloanseres, most basal branch of the neognath birds, to see some of the neglected, strange early branches off from the “main line” that led to the modern diversity of ducks, geeses and swans (Anatinae, Anserinae).

Screamers (Anhimidae) are to Anseriformes as megapodes (see below; brush turkeys) are to Galliformes. By that I mean that both screamers and megapodes are very early branches off the main line of their respective lineages’ evolution, and both are quite strange when seen in that context… an unfair one, frankly; over-focused on the most familiar, “modern” or most speciose group. More about this issue further below.

This was my first hands-on experience with screamer anatomy; I was familiar from reading Tetrapod Zoology and other material about them. Check out the sound that gives them their name here! I’m now a big fan- they have so many strange features: oddly chunky but often very light bones, big feet with long toes, and then these switchblade-wrists, which would make Batman jealous:

Crested screamer, Chauna torquata, showing the wicked spur on the carpometacarpus.

Crested Screamer, Chauna torquata, showing the wicked spur (and smaller one) on the carpometacarpus.

Horned screamer, Anhima cornuta; similar carpometacarpal spur as in Chauna.

Horned Screamer, Anhima cornuta; similar carpometacarpal spurs as in Chauna.

Torso of a screamer seen in top view. Nice narrow body.

Torso of a screamer seen in top view. Nice narrow body, and no uncinate processes (spur-like bony struts that cross the ribs and act as levers for the muscles that move the ribcage during breathing)

The long, gracile, clawed toes of a screamer.

The long, gracile, clawed toes of a screamer. Those toes, especially as they belong to an animal called a screamer, are spooky for me. Note also: very little toe-webbing for a “waterfowl.”

Not to be outdone, on the Galliformes side of Galloanserae, we have some funky headgear in the Maleo (a megapode bird/Megapodiidae; a very basal branch of “brush turkeys” and kin) and curassows (part of the Cracidae; odd South American birds whose males make booming sounds, presumably using their head-casques as resonating chambers?):

Skull of a male maleo, Macrocephalon maleo.

Skull of a male Maleo, Macrocephalon maleo. AR Wallace famously pursued it, and here is its funky call.

Australian brush-turkeys, Alectura lathami i, at the Alma Park Zoo near Brisbane, Australia; they run wild there. Here they are doing what they are best known for: making a mound-like nest.

Australian brush-turkeys, Alectura lathami, at the Alma Park Zoo near Brisbane, Australia; they run wild there. Here they are doing what they are best known for: making a mound-like nest. We were doing kangaroo biomechanics experiments and they were everywhere. I was in awe to see such exotic (to me) birds; locals seemed not so enthused (the birds are loud and make a lot of mess).

Skull of Helmeted curassow, Crax/Pauxi pauxi.

Skull of Helmeted Curassow, Crax/Pauxi pauxi,  showing that resonating chamber. Along with this boom-boom-room, the male uses a piece of food that he holds to draw in the female; if she takes it, then it’s sexy time.

Foot of a Russian Black Grouse, Tetrao tetrix (nothing to do with a certain videogame), with and without flesh.

Foot of a Siberian Black Grouse, Tetrao tetrix (nothing to do with a certain videogame), with and without flesh. Regard the broad, feathered feet, well insulated and with plenty of surface area for prancing around in the snow or moorlands. Tetrao engage in a cool display pattern called lekking, in which the males group together and show off to watching females.

A theme in the section above that is not to be missed is that there is some amazing disparity of anatomical forms in these basal lineages of poultry-relatives. Don’t dismiss the Galloanserae as just boring food-birds! Heaps of not-so-well-studied species exist here, surely with a treasure trove of cool neontological and evolutionary questions waiting for the right person to ask! Darwin’s chickens may get their share of neglect, but that pales in comparison to how little we understand about many basal Galloanserae.

What a lot of people think of as a “ground fowl” or galliform way of life is more of a way of life somewhat typical of the Phasanidae- chickens, pheasants and their familiar kin. Megapodes, curassows, guans, grouse and other Galliformes do not necessarily do things in the “typical” ground fowl way, much as the earlier branches of the Anseriformes don’t always look/act like “proper water fowl” (i.e. Anatidae). The phenomenon at play here is one of the great bugaboos in biology: essentialism– the often implicit misconception that variation away from some abstract ideal is negligible, uninteresting or just not conceivable due to mental blinders. When we say something like “the chicken is a fascinating species” we are sliding down the essentialistic slope. There is no “the chicken.” Not really. Oh dear, speaking of slippery slopes, I’d best stop here before I start talking about species concepts. And no one wants that to happen! Anyway, essentialism still pervades a lot of modern scientific thinking, and has its place as a conceptual crutch sometimes. But in biology, essentialism can be very insidious and misleading. It burrows in deep into the scientific mind and can be hard to root out. Unfortunately, it is entrenched in a lot of science education, as it makes things easier to teach if you sweep aside the exceptions to the essentialist “rules” in biology. I catch myself thinking in static, essentialist ways sometimes. The punishment is no cake for a week; so awful. :)

And speaking of “normal” or “typical,” morphology is of course often not that way even within a species, age class or gender. Pathology is a great example; by definition it is abnormal. It is a shattering of the “essence” of animals, brought on by some malady.

Next I’ve highlighted some of the amazing pathologies I’ve seen in the Tring skeletons. There have been so many I’ve been unable to keep track of them– some of these birds had the stuffing beaten out of them, and I’m not talking about Thanksgiving turkeys. Some were captive animals, in which the pathology might be blamed on living an inappropriate environment, but some were wild-caught — given the extreme pathologies, it’s a wonder those even survived to be found, but perhaps less a surprise that they were caught.


BONES GONE BONKERS:

View of left knee of a specimen of the Highland guan, Penelopina nigra, showing some nasty osteoarthritis around the whole joint.

View of left knee of a specimen of the Highland Guan, Penelopina nigra, showing some nasty osteoarthritis around the whole joint. Eew.  A happier Guan sounds like this.

Femora and tibiae of the Blue-throated Piping Guan, Aburria cumanensis. Amazing pathology involving the left femur (broken, rehealed) and tibiotarsus (secondary infection?).

Femora and tibiotarsi of the Blue-throated Piping Guan, Aburria cumanensis. Amazing pathology involving the left femur (broken, rehealed) and tibiotarsus (secondary infection?). Interestingly, the non-fractured limb also showed some pathology, perhaps indicating general infection and/or arthritis in reaction to the severe damage to the other leg, or just increased load-bearing on that leg.

Little Chachalaca, Ortalis motmot, showing a broken and rehealed right femur and the tibiotarsus.

Little Chachalaca, Ortalis motmot, showing a broken and rehealed right femur and the tibiotarsus. As in the guan above, this animal was not walking for many weeks; its femur had snapped in two, but somehow melted back together. The tibiotarsus didn’t look too great, either; lumpy and bendy. In better times, the Chachalaca does the cha-cha like this.

These two specimens blew my mind. On the right is a normal Tetrao tetrix (Black grouse); on the left is one hybridized with another (unknown) species.

These two specimens blew my mind. On the left is a normal Tetrao tetrix (Black Grouse); on the right is one hybridized with another (unknown) species.

In the picture above, what amazed me first was the very unusual flattened pelvis/synsacrum of Tetrao, which characteristically is light and wide. But in the hybrid this morphology was completely gone; the pelvis had a more standard “galliform” (read: Phasianid)-like shape, deeper and narrower and more solid in build. I am guessing that the hybrid was a cross with a pheasant like Phasianus itself, whose anatomy would be more like this. Somewhere in here there is a fantastic evo-devo/morphometrics project waiting to happen.

That’s my quick specimen-based tour of “basal birds”. Beyond these two clades of Palaeognathae and Galloanseres, there lies the forebidding territory of Neoaves: much of living avian diversity, and extremely contentious in its phylogenetic relationships. I’m tackling them next for my research on the evolution of the patella/kneecap. But first, I’ll be at the NHM-Tring today for a whirlwind tour through the respectably speciose “normal” Galloanseres clades of Phasianidae and Anserinae+Anatidae, so off I go! (It’s my wife’s birthday celebration, so cake may have to wait for later this time)

So what do you think? What’s your favourite neglected “primitive” bird group (more apropos: early branching avian lineage that may still be very specialized, rare and poorly understood), or cool factoid about palaeognaths and basal neognaths?

No quaggas were harmed during the writing of this post.

No quaggas were harmed during the writing of this post. Polly wanna quagga?

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Models of a basal dinosaur and bird, showing methods and key differences in body shape.

Our 3D computer models of a basal dinosaur and bird, showing methods and key differences in body shape. The numbers at the bottom are museum specimen numbers.

At about the moment I’m posting this, our Nature paper (our more formal page here, and the actual article here) embargo is ending, drawing a 14+ year gestation to a close. The paper is about how dinosaur 3D body shape changed during their evolution, and how that relates to changes in hindlimb posture from early dinosaurs/archosaurs to birds; “morpho-functional evolution” sums up the topic. We used the 3D whole-body computational modelling that I, Allen and Bates (among others) have developed to estimate evolutionary changes in body dimensions, rather than focusing on single specimens or (as in our last study) tyrannosaur ontogeny. We’ve strongly supported the notion (dating back to Gatesy’s seminal 1990 Paleobiology paper) that the centre of mass of dinosaurs shifted forwards during their evolution, and that this shift gradually led to the more crouched (flexed) hind leg posture that characterizes living birds. Here is a movie from our paper showing how we did the modelling:

And here is a summary of our 17 computer models of archosaur bodies, shown as one walks along the tips of the phylogeny shown in the video (the models are not considered to be ancestral to one another; we used a common computer algorithm called squared-change parsimony to estimate ancestral state changes of body dimensions between the 16 numbered nodes of the tree):

But we’ve done much more than just put numbers on conventional wisdom.

We’ve shown, to our own surprise, that the shift of the centre of mass was largely driven by evolutionary enlargements of the forelimbs (and the head and neck, and hindlimbs, to a less strong degree), not the tail as everyone including ourselves has assumed for almost 25 years. And the timing of this shift occurred inside the theropod dinosaur group that is called Maniraptora (or Maniraptoriformes, a slightly larger group), so the change began in animals that were not flying, but not long before flight evolved (depending on whom you ask, what taxonomy they favour and what evidence one accepts, either the smaller clade Eumaniraptora/Paraves or the bird clade Aves/Avialae).

Now, if you don’t like the cliche “rewriting the textbooks”, do have a look through texts on dinosaur/early avian palaeobiology and you probably will find a discussion of how the tail shortened, the centre of mass moved forwards as a consequence, the caudofemoral musculature diminished, and theropod dinosaurs (including birds) became more crouched as a result. We did that to confirm for ourselves that it’s a pretty well-accepted idea. Our study supports a large proportion of that idea’s reasoning, but modifies the emphasis to be on the forelimbs more than the tail for centre of mass effects, so the story gets more complex. The inference about caudofemoral muscles still seems quite sound, however, as is the general trend of increased limb crouching, but out paper approximates the timing of those changes.

Figure 3 from our paper, showing how the centre of mass moved forwards (up the y-axis) as one moves toward living birds (node 16); the funny dip at the end is an anomaly we discuss in the paper.

Figure 3 from our paper, showing how the centre of mass moved forwards (up the y-axis) as one moves toward living birds (node 16); the funny dip at the end is an anomaly we discuss in the paper.

A final implication of our study is that, because the forelimbs’ size influenced the centre of mass position, and thus influenced the ways the hindlimbs functioned, the forelimbs and hindlimbs are more coupled (via their effects on the centre of mass) than anyone has typically considered. Thus bipedalism and flight in theropods still have some functional coupling– although this is a matter of degree and not black/white, so by no means should we do away with helpful concepts like locomotor modules.

And in addition to doing science that we feel is good, we’ve gone the extra mile and presented all our data (yes, 17 dinosaurs’ worth of 3D whole body graphics!) and the critical software tools needed to replicate our analysis, in the Dryad database (link now working!), which should have now gone live with the paper! It was my first time using that database and it was incredibly easy (about 1 hour of work once we had all the final analysis’s files properly organized)– I strongly recommend others to try it out.

That’s my usual general summary of the paper, but that’s not what this blog article is about. I’ll provide my usual set of links to media coverage of the paper below, too. But the focus here is on the story behind the paper, to put a more personal spin on what it means to me (and my coauthors too). I’ll take a historical approach to explain how the paper evolved.


This paper’s story, with bits from the story of my life:

Embarassing picture of me before I became a scientist. Hardee's fast food restaurant cashier, my first "real job."

Embarassing picture of me before I became a scientist. Hardee’s fast food restaurant cashier, my first “real job”, from ~1999- no, wait, more like 1986. The 1980s-style feathered (and non-receding) hair gives it away!

Rewind to 1995. I started my PhD at Berkeley. I planned to use biomechanical methods and evidence to reconstruct how Tyrannosaurus rex moved, and started by synthesizing evidence on the anatomy and evolution of the hindlimb musculature in the whole archosaur group, with a focus on the lineage leading to Tyrannosaurus and to living birds. As my PhD project evolved, I became more interested and experienced in using 3D computational tools in biomechanics, which was my ultimate aim for T. rex.

In 1999, Don Henderson published his mathematical slicing approach to compute 3D body dimensions in extinct animals, which was a huge leap for the field forward beyond statistical estimates or physical toy models, because it represented dinosaurs-as-dinosaurs (not extrapolated reptiles/mammals/whatever) and gave you much more information than just body mass, with a lot of potential to do sensitivity analysis.

I struggled to upgrade my computer skills over the intervening years. I was developing the idea to reconstruct not only the biomechanics of T. rex, but also the evolutionary changes of biomechanics along the whole archosaur lineage to birds– because with a series of models of different species and a working phylogeny, you could do that. To me this was far more interesting than the morphology or function of any one taxon, BUT required you to be able to assess the latter. So Tyrannosaurus became a “case study” for me in how to reconstruct form and function in extinct animals, because it was interesting in its own right (mainly because of its giant size and bipedalism). (Much later, in 2007, I finally finished a collaboration to develop our own software package to do this 3D modelling, with Victor Ng-Thow-Hing and F. Clay Anderson at Honda and Stanford)

Me and a Mystery Scientist (then an undergrad; now a successful palaeontologist), measuring up a successful Cretaceous hypercarnivore at the UCMP; from my PhD days at Berkeley, ~2000 or so.

Me and a Mystery Scientist (then an undergrad; now a very successful palaeontologist!), measuring up a successful Cretaceous hypercarnivore at the UCMP; from my PhD days at Berkeley, ~2000 or so.

In all this research, I was inspired by not only my thesis committee and others at Berkeley, but also to a HUGE degree by Steve Gatesy, a very influential mentor and role model at Brown University. I owe a lot to him, and in a sense this paper is an homage to his trailblazing research; particularly his 1990 Paleobiology paper.

In 2001, I got the NSF bioinformatics postdoc I badly wanted, to go to the Neuromuscular Biomechanics lab at Stanford and learn the very latest 3D computational methods in biomechanics from Prof. Scott Delp’s team. This was a pivotal moment in my career; I became partly-an-engineer from that experience, and published some papers that I still look back fondly upon. Those papers, and many since (focused on validating and testing the accuracy/reliability of computer models of dinosaurs), set the stage for the present paper, which is one of the ones I’ve dreamed to do since the 1990s. So you may understand my excitement here…

Stanford's Neuromuscular Biomechanics Lab, just before I left in 2003.

Stanford’s Neuromuscular Biomechanics Lab, just before I left in 2003.

But the new paper is a team effort, and was driven by a very talented and fun then-PhD-student, now postdoc, Dr Vivian Allen. Viv’s PhD (2005-2009ish) was essentially intended to do all the things in biomechanics/evolution that I had run out of time/expertise to do in my PhD and postdoc, in regards to the evolution of dinosaur (especially theropod) locomotor biomechanics. And as I’d hoped, Viv put his own unique spin on the project, proving himself far better than me at writing software code and working with 3D graphics and biomechanical models. He’s now everything that I had hoped I’d become by the end of my postdoc, but didn’t really achieve, and more than that, too. So huge credit goes to Viv for this paper; it would never have happened without him.

We also got Karl Bates, another proven biomechanics/modelling expert, to contribute diverse ideas and data. Furthermore, Zhiheng Li (now at UT-Austin doing a PhD with Dr Julia Clarke) brought some awesome fossil birds (Pengornis and Yixianornis) from the IVPP in Beijing in order to microCT scan them in Londo. Zhiheng thus earned coauthorship on the paper — and I give big thanks to the Royal Society for funding this as an International Joint Project, with Dr Zhonghe Zhou at the IVPP.

That’s the team and the background, and I’ve already given you the punchlines for the paper; these are the primitive and the derived states of the paper. The rest of this post is about what happened behind the scenes. No huge drama or anything, but hard, cautious work and perseverance.

Me shortly after I moved to the RVC; video still frame from a dinosaur exhibit I was featured in. Embarassingly goofy pic, but I like the blurb at the bottom. It's all about the evolutionary polarity, baby!

Me shortly after I moved to the RVC; video still frame from a dinosaur exhibit (c. 2004) I was featured in. Embarassingly goofy pic, but I like the blurb at the bottom. It’s all about the evolutionary polarity, baby!

The paper of course got started during Viv’s PhD thesis; it was one of his chapters. However, back then it was just a focus on how the centre of mass changed, and the results for those simple patterns weren’t very different from those we present in the paper. We did spot, as our Nature supplementary information notes,  a strange trend in early theropods (like Dilophosaurus; to a lesser degree Coelophysis too) related to some unusual traits (e.g. a long torso) and suggested that there was a forward shift of centre of mass in these animals, but that wasn’t strongly upheld as we began to write the Nature paper.

On the urging of the PhD exam committee (and later the paper reviewers, too), Viv looked at the contributions of segment (i.e. head, neck, trunk, limbs, tail) mass and centre of mass to the overall whole body centre of mass. And I’m glad he did, since that uncovered the trend we did not expect to find: that the forelimb masses were far more important for moving the centre of mass forwards than the mass (or centre of mass) of the tail was– in other words, the statistical correlation of forelimb mass and centre of mass was strong, whereas changes of tail size didn’t correlate with the centre of mass nearly as much. We scrutinized those results quite carefully, even finding a very annoying bug in the 3D graphics files that required a major re-analysis during peer review (delaying the paper by ~6 months).

The paper was submitted to Nature first, passing a presubmission inquiry to check if the editor felt it fit the journal well enough. We had 3 anonymous peer reviewers; 1 gave extensive, detailed comments in the 3 rounds of review and was very fair and constructive, 1 gave helpful comments on writing style and other aspects of presentation as well as elements of the science, and 1 wasn’t that impressed by the paper’s novelty but wanted lots more species added, to investigate changes within different lineages of maniraptorans (e.g. therizinosaurs, oviraptorosaurs). That third reviewer only reviewed the paper for the first round (AFAIK), so I guess we won them over or else the editor overruled their concerns. We argued that 17 taxa were probably good enough to get the general evolutionary trends that we were after, and that number was ~16 more species than any prior studies had really done.

Above: CT scan reconstruction of the early extinct bird Yixianornis in slab conformation, and then Below: 3D skeletal reconstruction by Julia Molnar, missing just the final head (I find this very funny; Daffy Duck-esque) which we scaled to the fossil’s dimensions from the better data in our Archaeopteryx images. Yixianornis reconstruction There is also the concern, which the reviewers didn’t focus on but I could see other colleagues worrying about, that some of the specimens we used were either composites, sculpted, or otherwise not based on 100% complete, perfectly intact specimens. The latter are hard to come by for a diversity of extinct animals, especially in the maniraptoran/early bird group. We discussed some of these problems in our 3D Tyrannosaurus paper. The early dinosauromorph Marasuchus that we used was a cast/sculpted NHMUK specimen based on original material, as was our Coelophysis, Microraptor and Archaeopteryx; and our Carnegie ??Caenagnathus?? specimen was based more on measurements from 1 specimen than from direct scans, and there were a few other issues with our other specimens, all detailed in our paper’s Supplementary Information.

But our intuition, based on a lot of time spent with these models and the analysis of their data, is that these anatomical imperfections matter far, far less than the statistical methods that we employed– because we add a lot of flesh (like real animals have!) outside of the skeleton in our method, the precise morphology of the skeleton doesn’t matter much. It’s not like you need the kind of quality of anatomical detail that you need to do systematic analyses or osteological descriptive papers. The broad dimensions can matter, but those tend to be covered by the (overly, we suspect) broad error bars that our study had (see graph above). Hence while anyone could quibble ad infinitum about the accuracy of our skeletal data, I doubt it’s that bad– and it’s still a huge leap beyond previous studies, which did not present quantitative data, did not do comparative studies of multiple species, or did not construct models based on actual 3D skeletons as opposed to artists’ 2D shrinkwrapped reconstructions (the “Greg Paul method”). We also did directly measure the bodies of two extant archosaurs in our paper: a freshwater crocodile and a junglefowl (CT scan of the latter is reconstructed below in 3D).

One thing we still need to do, in future studies, is to look more carefully inside of the bird clade (Aves/Avialae) to see what’s going on there, especially as one moves closer to the crown group (modern birds). We represented modern birds with simply 1 bird: the “wild-type chicken” Red junglefowl, which isn’t drastically different in body shape from other basal modern birds such as a tinamou. Our paper was not about how diversity of body shape and centre of mass evolved within modern birds. But inspecting trends within Palaeognathae would be super interesting, because a lot of locomotor, size and body shape changes evolved therein; ostriches are probably a very, very poor proxy for the size and shape of the most recent common ancestor of all extant birds, for example, even though they seem to be fairly basal within that whole lineage. And, naturally, our study opens up opportunities for anyone to add feathers to our models and investigate aerodynamics, or to apply our methods to other dinosaur/vertebrate/metazoan groups. If the funding gods are kind to us, later this year we will be looking more closely, in particular, at the base of Archosauria and what was happening to locomotor mechanics in Triassic archosaurs…

Clickum to embiggum:

Australian freshwater crocodile, Crocodylus johnstoni; we CT scanned it in 3 pieces.

Australian freshwater crocodile, Crocodylus johnstoni; we CT scanned it in 3 pieces while visiting the Witmer lab in Ohio.

A Red junglefowl cockerel, spotted in Lampang, Thailand during one of my elephant gait research excursions there. Svelte, muscular and fast as hell.

A Red junglefowl cockerel, spotted in Lampang, Thailand during one of my elephant gait research excursions there. Svelte, muscular and fast as hell. This photo is here to remind me to TAKE BLOODY PICTURES OF MY ACTUAL RESEARCH SPECIMENS SO I CAN SHOW THEM!

I’d bore you with the statistical intricacies of the paper, but that’s not very fun and it’s not the style of this blog, which is not called “What’s in John’s Software Code?”. Viv really worked his butt off to get the stats right, and we did many rounds of revisions and checking together, in addition to consultations with statistics experts. So I feel we did a good job. See the paper if that kind of thing floats your boat. Someone could find a flaw or alternative method, and if that changed our major conclusions that would be a bummer– but that’s science. We took the plunge and put all of our data online, as noted above, so anyone can do that, and that optimizes the reproducibility of science.

What I hope people do, in particular, is to use the 3D graphics of our paper’s 17 specimen-based archosaur bodies for other things– new and original research, video games, animations, whatever. It has been very satisfying to finally, from fairly early in the paper-writing process onwards, present all of the complex data in an analysis like this so someone else can use it. My past modelling papers have not done this, but I aim to backtrack and bring them up to snuff like this. We couldn’t publish open access in Nature, but we achieved reasonably open data at least, and to me that’s as important. I am really excited at a personal level, and intrigued from a professional standpoint, to see how our data and tools get used. We’ll be posting refinements of our (Matlab software-based) tools, which we’re still finding ways to enhance, as we proceed with future research.

Velociraptor-model-min Dilophosaurus-model-min00

Above: Two of the 17 archosaur 3D models (the skinny “mininal” models; shrinkwrapped for your protection) that you can download and examine and do stuff with! Dilophosaurus on the left; Velociraptor on the right. Maybe you can use these to make a Jurassic Park 4 film that is better, or at least more scientifically accurate, than Hollywood’s version! ;-) Just download free software like Meshlab, drop the OBJ files in and go!

Now, to bring the story full circle, the paper is out at last! A 4 year journey from Viv’s PhD thesis to the journal, and for me a ~14 year journey from my mind’s eye to realization. Phew! The real fun begins now, as we see how the paper is received! I hope you like it, and if you work in this area I hope you like the big dataset that comes with it, too. Perhaps more than any other paper I’ve written, because of the long voyage this paper has taken, it has a special place in my heart. I’m proud of it and the work our team did together to produce it. Now it is also yours. And all 3200ish words of this lengthy blog post are, as well!

Last but not least, enjoy the wonderful digital painting that Luis Rey did for this paper (another of my team’s many failed attempts to get on the cover of a journal!); he has now blogged about it, too!

Dinosaur posture and body shape evolving up the evolutionary tree, with example taxa depicted.

Dinosaur posture and body shape evolving up the evolutionary tree, with example taxa depicted. By Luis Rey.


News stories about this paper will be added below as they come out, featuring our favourites:

1) NERC’s Planet Earth, by Harriet Jarlett: “Dinosaur body shape changed the way birds stand

2) Ed Yong on Phenomena: “Crouching  bird, hidden dinosaur

3) Charles Choi on Live Science: “Crouching bird, hidden evolutionary purpose?

4) Brian Handwerk on Nat Geo Daily News: “Birds’ “Crouching” Gait Born in Dinosaur Ancestors

5) Jennifer Viegas on Discovery News: “Heavier dino arms led evolution to birds

6) Puneet Kollipara on Science News: “Birds may have had to crouch before they could fly

And some superb videos- we’re really happy with these:

1) Nature’s “Crouching Turkey, Hidden Dragon

2) Reuters TV’s “3D study shows forelimb enlargement key to evolution of dinosaurs into birds

Synopsis: Decent coverage, but negligible coverage in the general press; just science-specialist media, more or less. I think the story was judged to be too complex/esoteric for the general public. You’d think dinosaurs, evolution, computers plus physics would be an “easy sell” but it was not, and I don’t think we made any big errors “selling” it. Interesting– I continue to learn more about how unpredictable the media can be.

Regardless, the paper has had a great response from scientist colleagues/science afficionados, which was the target audience anyway. I’m very pleased with it, too– it’s one of my team’s best papers in my ~18 year career.

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frontcover

The Unfeathered Bird book by Katrina van Grouw proclaims immediately in its Introduction that it “is not an anatomy of birds.”  True– it is far more than that, and it would be a shame if it had just been a dry, technical avian osteology reference book. It is a unique blend of art and science- particularly avian anatomy, evolution, taxonomy, natural history and more. The Unfeathered Bird is written for a general audience; birders/twitchers or just natural history buffs would be ideal targets of its unfettered passion for all things avian. A 12-year-old who is very keen on animals could enjoy it, and it may ignite the flames of ornithological excitement in many young or older readers. I am glad it was not called “The Naked Bird” as that would have caused some serious misconceptions (badum-tish!). The book is dripping with illustrations (at least one every two pages, often more). Almost all of the illustrations (except some paintings in the style of the cover) are in the same brownish sketch style that, like much of the book, evokes a bygone era of dark wooden cabinets and shadowed halls packed with skeletons, with nary an interactive graphics display, animatronic dinosaur or hyperdetailed cladogram in sight. It feels like an homage to the Victorian naturalists’ joy for anatomical detail conveyed through painstakingly detailed woodcuts. And while many still think of feathers as “the defining feature of birds,” enough about feathers already. Seriously. This is a book is about what lies beneath, and how all that non-fluffy stuff is important for birds’ lives, too.

(image-intense post; all can be clicked to embiggritate)

Katrina with peacock feather headdress? (back cover pic and rear view of same skeleton)

Katrina with peacock feather headdress? (back cover pic and rear view of same skeleton)

Katrina with front cover framed pic and the peacock skeleton that went with it.

Katrina with front cover framed pic and the peacock skeleton that went with it.

The Introduction continues to explain that the book is truly about how the external anatomy of birds is linked to the bony anatomy, which might remind astute readers of modern approaches like the extant phylogenetic bracket. The rest of the book uses both skeletal and unfeathered, quasi-myological illustrations to get this point across vividly. The explanatory text is written at a basic enough level for the average reader and is just the right length, with interesting anecdotes and natural history facts that even the expert reader will find interesting or even inspirational (e.g. possibly a goldmine for research ideas). First there is a 26 page “Basic” section with an introduction to avian osteology, with bountiful sketches to illustrate key organs and text explaining how it all fits together in the fully accoutered bird. The decision to use classical Linnean taxonomy (defunct or re-arranged taxa from the Systema Naturae like Accipitres, Picae, Anseres, Grallae, Gallinae and Passeres; which are the six “Specific” chapters in the second section of the book) was a good one- it enhances the classical feel of the tome and gives the author a great opportunity to discuss convergent evolution and how that misled past ornithologists.

But for me, the book is most pleasurable for the visualizations and the passion for all things birdy that weaves through them and the accompanying text. The removal of feathers, or even all soft tissues, from bird bodies (posed in naturalistic behaviours) that van Grouw renders in her illustrations shows birds in a new light, emphasizing the strangeness and diversity that lie beneath. The author begins the book with a touching Acknowledgments section in which her husband Hein van Grouw, curator of birds at the Natural History Museum’s Tring collection, features very prominently, making it clear that the book was a team operation and comes from the heart after a 25-year journey. This gives the book a special warmth that is preserved throughout the remainder- although the illustrations are of flayed bodies or boiled / beetle-macerated skeletons, the tone is nothing less than an earnest love for birds of all kinds, and a zest for portraying those feelings to the reader in sketches and prose. It is a joyous celebration, not a somber litany, of the wonder of birds that can be gleaned from dead bodies. There is so much powerful, awesome imagery stuffed into those pages that it is hard to summarize. I’ll let five of my favourite images from the book (more are in her gallery and her book’s Facebook page; but even these are just the tip of the icebird) help get this across (used with permission of the author):

Naked kiwi in action.

Naked kiwi in action.

The unscaled bird: guineafowl feet.

The unscaled bird: guineafowl feet.

Deplumed sparrowhawk with dove trophy, exalting in its triumph.

Deplumed sparrowhawk with dove trophy, exalting in its triumph.

Budgerigar has made a friend? Or came to grips with its own mortality?

Budgerigar has made a friend? Or came to grips with its own mortality?

Trumpet Manucode WTF anatomy! Spiraling tracheal coil made me gasp in awe when I saw this image in the book.

Trumpet Manucode’s WTF anatomy! Spiraling tracheal coil made me gasp in awe when I saw this image in the book.

Now I’ll depart from this post just being a book review. I went to the Tring collection to do some research, and arranged my trip so I’d also get to see the debut of a Tring special exhibit featuring The Unfeathered Bird, and also to meet Katrina as well as Hein van Grouw. The placement of the exhibit at Tring is apropos, because Katrina was a curator at the museum until a few years ago and Hein still is. But the inspiration for the work and the specimens used (with a few exceptions, including from other museums) are Katrina’s. She (with Hein’s help) procured bodies of birds to dissect, macerate and sketch for the book over its 25 year fledging period, noting in the Acknowledgments that “no birds were harmed” to do this– do read those acknowledgments, as there are some amusing tales there of how she obtained some specimens.

I was fortunate to be able to take some photos of the exhibit while they set it up, and grabbed some candid images of Katrina and colleagues during that process. The following images show off the exhibit, which is all in one clean, bright, simply adorned room in the Tring that lets Katrina’s framed sketches be the focus. Here are some examples:

Poster advert for the book in the Tring collections.

Poster advert for the book in the Tring collections.

Tring exhibit setup, with Katrina, husband Hein, and helper finishing it up.

Tring exhibit setup, with Katrina, husband Hein, and helper finishing it up.

Tring exhibit now ready.

Tring exhibit now ready.

Tring exhibit case.

Tring exhibit case.

Framed sketches at Tring exhibit.

Framed sketches at Tring exhibit.

Framed sketches at Tring exhibit.

More framed sketches at Tring exhibit.

The exhibit is fun for people who are already Unfeathered Bird fans, and a good way of drawing in new ones. The book is a precious thing that any fan of birds, especially scientists, really needs to have a hard copy of. While it claims not to be an anatomy text, its illustrations provide ample opportunities to use it for that purpose. But really the point of owning all 287-plus pages is to bask in the warmth of true, pure appreciation for classic ornithology, which I found infectious. It is a book by and for bird lovers, but also for those that find the interface of art and science to be fascinating.

I confess I used to hate birds. I found them annoying and boring; all that flitting and twitting and pretentious feathers. “Get over yourselves, already, and calm down too!” was my reaction to them. When I started grad school, I had an open disdain for birds, even moreso than for mammals (OK, except cats). I was a “herp” fan through and through, for most of my life (childhood spent catching anoles in Florida, or stalking frogs in Ohio; during visits to my grandparents). What won me over was studying birds (and eventually mammals, too) as a young scientist, and learning how incredible they are– not just as endpoints in the story of theropod dinosaur evolution, as my thesis focused on, but as amazing animals with spectacular form-function relationships.  The Unfeathered Bird is saturated with that amazement, so we’re birds of an unfeather.

Framed sketch of dodo head at Tring exhibit.

Framed sketch of dodo head at Tring exhibit.

Entirely unfeathered Indian peafowl in matching views.

Entirely unfeathered Indian peafowl in matching views.

Painted Stork and Toco Toucan sketches.

Painted Stork and Great Hornbill sketches.

Red junglefowl, wild ancestor of domestic chickens (and the book ends with several such breeds illustrated),

Red junglefowl, wild ancestor of domestic chickens (and the book ends with several such breeds illustrated).

Katrina told me that she is already deep into writing the next book, whose subject I won’t spoil for you here but maybe we will be lucky enough to have her appear in the Comments and plug it? :) (Her website does say “It was Hein’s stroke of genius to include domestic birds and they’ve provided the inspiration for my next project.” so the cat is out of the bag and amongst the pigeons!) It is great to hear that the book has done quite well sales-wise and critically, such as ~#67 on the Amazon sales list at one point– I hope this paves the way for more such books not only from Katrina, but from others engaged in lateral thinking (and still others) on the boundaries of science-art.

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…a daily picture of anatomy! And today it is two pictures, tra-la-lee!

Welcome back to Freezermas! And HAPPY DARWIN DAY! Last year our whole lab got involved in DD2012, but this blog was just a twinkling in my keyboard back then. This year it was a more mellow, somber occasion for DD2013. But Heinrich Mallison of the dinosaurpalaeo blog took part, and took photos (all credits go to him), and the result kicked ass and took names. Bring it on!

Darwin amidst the bones

Here is Darwin amidst a selection of greatest hits from my bone collection; post-freezer denizens. How many can you identify? Have a go in the comments below. A few should be quite familiar to blog followers… More about these bones later this week. Incidentally, Darwin is standing on a Kistler forceplate. So biomechanics afficionados can geek out about this, too.

An offering to The Master

And here I am hamming it up again. Give it a rest, John! But ’tis merely a humble offering to The Master. I’m sure he’d appreciate it. Any guesses what it is?

Happy Freezermas! Sing it: “On the second day of Freezermas, this blo-og gave to me: one tibiotarsus, a-and two silly pictures with Chucky D!”

(don’t know the song? Try this version)

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To kick off the New Year just right, our tetrapod team has a new paper in Nature, following up on last year’s Ichthyostega not-so-good-at-walking study (also see here). Yet this paper has a more anatomically descriptive — and also an “evo-devo” — twist to it. For brevity, I’ll let our press release tell the story, since I think it does a good job of it (like I always preach scientists should do, we worked with our PR company to write this together, so we’re happy with how the press release came out). In a nutshell, our study used some very fancy synchotron radiation techniques to image the 3D anatomy of the backbone in early land vertebrates. Our findings surprised even us, and ended up turning around palaeontology/comparative anatomy’s view of how the backbone evolved, giving us a new glimpse into our inner tetrapod.

Stick around for the videos at the end, which are the first four supplementary movies from the paper and are rather pretty (there are two more, for imaging/segmenting afficionados, but they are not as pretty or interesting for most of this blog’s readership). The final figure (Figure 1 from our paper) gives some extra visual context.

The paper is:

Pierce, S.E., Ahlberg, P.E., Hutchinson, J.R., Molnar, J.L., Sanchez, S., Tafforeau, P., Clack, J.A. 2013. Vertebral architecture in the earliest stem tetrapods. Nature, published online [here].

I should note that I’m just 3rd author, so I deserve only modest credit. But I helped. Even though no freezers were involved, or harmed, in the process.

Ichy_vertebrae_final_sm-01

Above image: Julia Molnar‘s illustration of Ichthyostega showing anatomical changes of its spine from front to back, with neural arch/spine in pink, twin pleurocentra in yellow, and intercentrum in green. These four parts, three kinds of bones, made up the backbone of the first land vertebrates. These parts evolved in different ways in later animals, but formed one main bone in all living lineages of vertebrates.

RVC PRESS RELEASE:

Scientists reassemble the backbone of life using a particle accelerator

Research published today (Sunday 13 January 2013) in the journal Nature documents, for the first time, the intricate three-dimensional structure of the backbone in the earliest four-legged animals (tetrapods).

The international team of scientists, led by Dr Stephanie E. Pierce from The Royal Veterinary College and Professor Jennifer A. Clack from the University of Cambridge, bombarded 360 million year old early tetrapod fossils with high energy synchrotron radiation. The resulting high resolution X-ray images allowed the researchers to reconstruct the backbones of the extinct animals in exceptional detail.

The backbone, also known as the spine or vertebral column, is a bony structure found in all tetrapods, along with other vertebrates such as fish. It is formed from many elements or vertebrae all connected in a row – from head to tail. Unlike the backbone of living tetrapods (e.g. humans), in which each vertebra is composed of only one bone, early tetrapods had vertebrae made up of multiple parts.

Lead author Dr Pierce says: “For more than 100 years, early tetrapods were thought to have vertebrae composed of three sets of bones – one bone in front, one on top, and a pair behind. But, by peering inside the fossils using synchrotron X-rays we have discovered that this traditional view literally got it back-to-front.”

For the analysis, the European Synchrotron Radiation Facility (ESRF) in France, where the three fossil fragments were scanned with X-rays, used a new protocol to reveal tiny details of the fossil bones buried deep inside the rock matrix.

Using this new technology, the team of scientists discovered that what was thought to be the first bone – known as the intercentrum – is actually the last in the series. And, although this might seem like a trivial oversight, this re-arrangement in vertebral structure has over-arching ramifications for the functional evolution of the tetrapod backbone. (see here for a now out-of-date image from Wikipedia)

Dr. Pierce explains: “By understanding how each of the bones fit together we can begin to explore the mobility of the spine and test how it may have transferred forces between the limbs during the early stages of land movement”.

But, the findings didn’t end there. One of the animals – known as Ichthyostega – was also found to have an assortment of hitherto unknown skeletal features including a string of bones extending down the middle of its chest.

Professor Clack says: “These chest bones turned out to be the earliest evolutionary attempt to produce a bony sternum.  Such a structure would have strengthened the ribcage of Ichthyostega, permitting it to support its body weight on its chest while moving about on land.”

This unexpected discovery supports recent work done by the same authors that showed Ichthyostega probably moved by dragging itself across flat ground using synchronous ‘crutching’ motions of its front legs – much like that of a mudskipper or seal.

Dr Pierce adds: “The results of this study force us to re-write the textbook on backbone evolution in the earliest limbed animals.”

The next step, the researchers say, is to understand how the backbone aided locomotion in these early tetrapods using sophisticated biomechanical analysis.

The study was funded by the Natural Environment Research Council.

Additional support was provided by the European Research Council and the ESRF, of which the Science and Technology Facilities Council (STFC) is the UK shareholder.

MOVIES:

These are rotating images of the anatomy, colour-coded, of the four species of early tetrapod that we examined for this study. Each shows the same basic pattern of having a “reverse rhachitomous” (pleurocentra in the front, intercentrum in the back; trying to think of a mullet joke…) anatomy. This is opposite the pattern that essentially all studies since famed evolutionary biologist/palaeontologist Edward Drinker Cope coined the term “rhachitomous” in 1878 have portrayed these and related animals as having. And this realization forces a re-examination of how the backbone structures first evolved in tetrapods and which parts (intercentra? pleurocentra? And where?) formed the spines of later animals.

For once, as authors we all felt that this finding really deserved the painfully hackneyed “rewrite the textbooks” label. It changes a lot of what we thought we knew about this classic evolutionary transition of anatomy. Check a vertebrate palaeontology/comparative anatomy textbook and you’ll likely find rhachitomous vertebrae and/or changes of pleurocentra vs. intercentra told in a way that we now are pretty sure is wrong.

You can also see the “sternebrae” (sternal elements; parts of the sternum that evolved independently in later land animals) in the first movie.  This, to my knowledge, is by far the oldest such evidence. I know of ossified sternal plates in Early Permian mesosaurs like Stereosternum, but nothing earlier although perhaps in some synapsid I don’t know, or a basal diapsid of some kind? Chime in in the comments if you know of something I missed. Regardless, the sternebrae in Ichthyostega have nothing to do directly with those convergently evolved in lissamphibians, lepidosaurs, synapsids and archosaurs, although there may be some parallel developmental mechanisms involved and at least similar dermal tissues recruited into ossification patterns. Even so, these sternebrae are further evidence of how that taxon, at least, was beginning to make forays onto land, as they’d have helped it to support its belly on land and breathe.

The segmented PPC-SRµCT of Ichthyostega stensioi MGUH VP 6115 spinning in yaw and roll.

The segmented PPC-SRµCT of Ichthyostega eigili MGUH VP 29017a spinning in yaw and roll.

The segmented PPC-SRµCT of Acanthostega gunnari MGUH f.n. 1227 spinning in yaw.

The segmented µCT of Pederpes finneyae GLAHMS 100815 spinning in yaw.

FIGURE:

Figure 1_Pierce et al

Above: (a,b) How we used to think the vertebrae were composed in early tetrapods like Ichthyostega. (c) How we found that Ichthyostega‘s posterior thoracic vertebrae actually tend to look. (d) Ichthyostega‘s anterior lumbar vertebral morphology. (e) Acanthostega according to Coates’s important description. (f) Our revision of the anatomy of Acanthostega (anterior dorsal). (g) Our new interpretation of Pederpes‘s morphology, from a posterior dorsal. Focus on the yellow vs. green elements. In a,b and e they are in different positions (reversed) compared with our new versions in c,d,f,g.

To put the above figure and movies into broader context, check this Wikipedia image. We think the red/pink bones (pleurocentra) are in the wrong place relative to the blue ones (intercentrum); the ones currently there in this image actually belong to the vertebral unit behind that one, so the pleurocentra should be moved to the front (left end) of each unit. But also look down toward the bottom of the figure. Some of those vertebrae may need to have their blue/pink bits re-examined and interpreted, too. Is it turtles intercentra all the way down?

There you have it! Welcome to your new, revised, irradiated, reverse-rhachitomous inner tetrapod’s vertebrae. Propagation phase-contrast X-ray synchrotron microtomography FTW!!!!

Science media articles arising from this study–

I like to keep track of media stories covering our research, using this blog, so here are some of the stories about this paper. It’s funny… this was one of the most broadly important papers I’ve ever been on, but the coverage was relatively scant. It was too technical. We knew that would be a problem, and really had a hard time putting into words why the study was so surprising even to us! Most writers wanted the “how did the animals move?” angle, which was not what the study was about. I still feel that this angle was not even needed; the study (and again I take minimal credit for it) is exciting without it. To comparative anatomy and evo-devo specialists, anyway. Well, that’s science for you; sometimes it is just too hard to explain its value to the outside world, even when you feel its importance in your very spine… And the press coverage was not terrible by any means; no sour grapes from me. Regardless, we’re glad it has been well received by specialist researcher colleagues we’ve spoken to, and that matters a lot.

NERC’s Planet Earth (nice story from our funder)- “Scientists had fossil backbone backwards”

BBC online (the only story aside from NERC’s that did more than read the press release) “Tetrapod anatomy: Backbone back-to-front in early animals”

Discovery News online- “First Land Animals Shuffled Like Seals” (good, but is sort of mixing up our this study, our 2012 one and Ahlberg et al’s 2005 seal-analogue study; latter two were more about movement. As often happens, a lot of other media stories basically copied this one’s headline/angle.)

Discover 80beats- “Paleontologists Use 3-D Models to Rewrite Evolution” (also in “top stories”)

Popsci- “Particle Accelerator Reveals That First Land Animals Walked Like Seals”

Daily FMail (nice pics)- “Astonishing 3D images reveal the first four-legged land animals in amazing detail – and overturn a century of research” (wins longest headline award)

Red Orbit- “Study Reveals First Ever Images Of Early Tetrapod Backbone And How It Helped In Land Evolution”

Examiner.com- “X-ray study rewrites tetrapod backbone evolution (Photos)”

Everything Dinosaur- “Ichthyostega Gets a Re-Think”

Business Standard- “Scientists recreate earliest quadraped’s backbone” (Proofread, editors! Quadruped.)

Geekosystem- “Early Land-Dwelling Animals Moved About Like Seals, Probably Didn’t Balance Balls on Their Noses” (scores some pts for humour)

…and the PR-copying, non-spellchecking fail of the week award goes to… Physorg! “Scientists reassemble the backbone of life with a particle acceleratorynchrotron [sic] X-rays”

Warming up the acceleratorynchrotron for our next study… :)

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A vignette from research I’m engaged in with a couple of different projects follows. Below is a photo I took of two humeri (upper arm bones; humerus is singular).

One is from a Black Rhinoceros; Diceros bicornis (modern; specimen #H.6481 from the University Museum of Zoology, Cambridge), which was collected in 1873 in Bogos, Abyssinia by zoologist ?Edward? Gerrard.

The other, larger one is from a giant long-necked and (presumably) hornless rhinocerotoid; Paraceratherium [AKA Indricotherium, Baluchitherium] (extinct of course; specimen #NHMUK PV M 12251 from The Natural History Museum, London); which was collected in 1911 in the Siwalik Hills of India by palaeontologist Forster Cooper. My photo is shown with kind permission of the Natural History Museum, London.

For an idea of scale, the smaller one is 39 cm (just over a foot) long, so about the same length as your humerus, give or take a bit. It comes from an animal that probably weighed around one tonne (1000 kg; 2200 lbs) or so. Look back at the picture, and pause to reflect on the scale. This is one of the largest living land animals right here, and despite that size it is quite an athlete (watch the classic John Wayne chasing-animals-around-Africa film Hatari! if you want elegant proof, or browse Youtube videos of boisterous rhinos).

But any living rhino pales in comparison to the giant Oligocene form, whose humerus is twice the length (~80 cm; almost as long as your entire leg, probably) and quite a bit more robust. The best estimates of mass for such an animal are up to 15-20 tonnes, on a par with the largest mammoths and other elephant relatives. That’s like a ten-rhino rhino! Sure, they all pale somewhat in scale against the largest sauropods (or whales, which cheat by living in water). Yet for my money (warning: subjective value judgement ahead!) a rhinoceros is cooler than any sauropod at the same size, and sauropods are extinct so we have less left to study. (I’m being deliberately provocative for my sauropod researcher friends, but in a loving way)

The scale, and often cramped conditions, make it hard getting a good photo of a Paraceratherium skeleton or reconstruction, but here’s one I took at Tokyo’s Museum of Nature and Science.

Now, of course if you know me, you know I am thinking about how such giant land animals moved. Authors such as Gregory Paul and Per Christiansen have made arguments based on real data, both qualitative anatomy and quantitative bone dimension measurements, that even giant rhinos like Paraceratherium could trot and gallop much like living rhinos do, despite their giant size. They have inferred from the limb joint structure that these giant rhinos were more crouched, were less columnar (vertical-limbed) than living elephants are (although I’ve shown with my team that this characterization of elephants is quite misleading; they get quite un-columnar, rather crouched, as they attain faster speeds). If Paul and Christiansen were correct, it would be remarkable. I can’t definitively show either way, just yet. But I want to see how well this argument holds up with other data and methods, so I’ve been planning to test this idea for a long time. We’ll see how it goes.

Anyway, that was my brief tale of two scales. On one hand we have living “giants” in the form of the five currently remaining species of rhinoceroses, which are quite extraordinary in many ways, albeit in big trouble. On the other hand we have amazing, mysterious uber-giants like Paraceratherium, two or more times the size in linear dimensions and an order of magnitude greater in weight. Both are certainly giants by any measure of size in land animals.

But was the bigger rhino living in a rather different world, even more dominated by gravity than its smaller relative is today? (No, gravity was no different! It was only 30 or so million years ago; relatively recent!) Or did they live in relatively similar worlds of just being “bloody huge and devastatingly powerful, thank you very much”? I find that question really exciting and wondrous to ponder. What do you think?

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A short(ish) post, but to me an important one. As I’ve mentioned here before, and still mean to write a detailed post on, I’m on a 1-year Royal Society Leverhulme Trust senior research fellowship (pause to breathe… long phrase there!) to study the mechanics and evolution of the kneecap (patella) in birds. Knees are very cool, and the patella is one of the coolest parts of the knee. My fellowship is aimed at returning to my roots, i.e. my PhD research on theropod dinosaur hindlimb evolution (anatomical and functional), to focus in great detail on just the patella (this, not this).

The patella is a mysterious structure: a sesamoid bone like I’ve argued elephant predigits are, and probably the best known sesamoid, but still quite enigmatic– especially in non-humans and most particularly in non-mammals. Why did it evolve three different times, at least? What mechanical/developmental environment encourages it to form? Why don’t some species have them? Does the presence of a patella tell us anything about posture, gait, or anything else? Why did no giant dinosaurs evolve patellae?

Anyway, I now have a related PhD studentship that I need a great EU/UK-based student to apply for, and I’m casting a wide net. It’s a very, very freezer-based PhD: imagine cutting up the knees of the frozen zoo of critters that I’ve shown on this blog already, to your heart’s content! And studying fossils, and doing histology (cool imaging techniques with RVC faculty Michael Doube and Andy Pitsillides, along with bone uber-guru Alan Boyde), and conducting experiments with real animals, and computer modelling both experimental and fossil data… this PhD has it all.

Here are the details. If you know anyone in the EU/UK looking for a good PhD that seems to fit the bill very well, send them my way please!

We now return you to your regularly scheduled frozen organisms… and there is a fun post coming tomorrow!

The knee of an emu from my freezer, showing the many muscles and other tissues that connect to or surround the patella. It’s complicated, and that makes for fun science!

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Here is a little vignette for you; a taster of the BBSRC-funded chicken biomechanics project my team has underway in collaboration with Jonathan Codd’s team at Uni Manchester. I did not know about the following situation until a couple of years ago during my former PhD student (now postdoc) Heather Paxton‘s research on chicken mechanics.

Regard this chicken, slit open along the midline to show the viscera. The huge pectoralis muscles (breast meat) have been pushed aside; the right side’s are clumsily outlined (I blame caffeine?) in blue.

Then consider the heart, within the jagged, shamefully and ineptly drawn green circle. I’ll come back to that.

So this broiler chicken took 6 weeks to reach this size, of about 3 kilograms (6.6 lbs). Fifty years ago, before artificial selection was imposed on a MASSIVE scale (many billions of chickens per year worldwide, bred in a complex pyramid scheme of crossed strains), that same chicken strain would have taken 15 weeks to reach a normal slaughter mass of roughly 2 kg (4.4 lbs). The major selection, of course, has been for edible meat, especially that lovely breast muscle’s white meat.

If we look at red junglefowl, to a large degree the “wild type” ancestors of domestic chickens that are native to southeast Asia, the leg muscles take up about 7.7% body mass per leg vs. about 6.3% in the broiler. Just a small decrease, but probably an important one, and something our research focuses a lot on (walking ability, lameness, activity levels etc). But that’s a subject for a future post. In stark contrast, the breast muscles (back to the blue ellipse above)  have gone from 7% to up to 11.6% body mass per wing; a huge change!

Now let’s return to another large muscle, the one within the green circle above; the heart. Not only must the heart, which has become relatively larger by perhaps 25%, pump blood to a body that has enlarged by >50%, but it also must perfuse the giant pectoral muscles, which have enlarged by >65%.

Herein lies the problem… You probably can predict what happens.

Several syndromes may develop, but the one I want to cover here is called deep pectoral myopathy (AKA “Oregon disease” or better yet “green muscle disease”, a very appropriate term as you’ll see below). Basically, the giant pectoralis muscles receive inadequate blood flow from the smallish heart, because the muscles are so big and under so much pressure, creating resistance to flow, and so the muscles begin dying from within. A picture tells the story:

While surely uncomfortable for the birds and hence a welfare problem, it is usually not found until the animals are slaughtered, and then of course the meat is destroyed rather than delivered for human consumption. Because of the welfare problems and loss of meat (i.e. financial loss), the poultry industry is trying to remedy this problem. W’e’re working on aspects of this as well, as part of our study of how the locomotor and ventilatory systems of chickens develop and have evolved.

I am blogging this as a great example of how anatomy can go haywire and become imbalanced when evolutionary selection pressures are intense and highly specific (e.g. almost single-minded human selection for large breast muscle). It is also a conundrum that human society faces: while chicken meat seems more efficient and more ecologically sound than some other meats, and there is growing demand for meat as the human population grows, how do we balance welfare concerns with food security, economics and other factors? And how do we judge when artificial selection has gone too far? I do not present an answer because the answer is not easy, and because my team is still learning about how to answer it.

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Party time! Let the media onslaught begin! We’ve published a paper in Nature on the limb motions of Ichthyostega (and by implication, some other stem tetrapods). Since we did use some crocodile specimens from Freezersaurus (see below) in this study, I figured WIJF could cover it to help celebrate this auspicious event. Briefly. Particularly since we already did a quasi-blog on it, which is here:

http://www.rvc.ac.uk/SML/Research/Stories/TetrapodLimbMotion.cfm

and some juicy fossily images at:

http://www.rvc.ac.uk/SML/Research/Stories/TetrapodImages.cfm

However I want to feature our rockin’ cool animations we did for the paper, to squeeze every last possible drop of science communicationy goodness out of them. So here they are in all their digital glory. Huge credit to Dr. Stephanie Pierce, the brilliant, hardworking postdoc who spearheaded the work including these videos! Dr. Jenny Clack is our coauthor on this study and the sage of Ichthyostega and its relatives- her website is here. Also, a big hurrah for our goddess of artsy science, Julia Molnar, who helped with the videos and other images. Enjoy!

The computer model

The forelimb model

The hindlimb model

We used some of my Nile crocodile collection to do a validation analysis of our joint range of motion (ROM) methods, detailed in the Supplementary info of the paper, which I encourage anyone interested to read since it has loads more interesting stuff and cool pics. We found that a bone-based ROM will always give you a greater ROM than an intact fleshy limb-based ROM. In other words, muscles and ligaments (and articular cartilage, etc.). have a net effect of reducing how far a joint can move. This is not shocking but few studies have ever truly quantitatively checked this with empirical data from whole animals. It is an important consideration for all vert paleo types. Here is a pic of one of the crocodiles from the study, with (A) and without muscles (B; ligaments only):

I’ll close with Julia Molnar’s jaw-droppingly awesome flesh reconstruction from our model. Why Nature wouldn’t use this as a cover pic, I’ll never understand, but I LOVE it! When I first saw it enter my email inbox and then opened it to behold its glory, my squeal of geeky joy was deafening.

(edit: Aha! Fellow Berkeley alum Nick Pyenson’s group made the Nature cover, for their kickass study of rorqual whale anatomy, including a “new” organ! Well, we don’t feel so bad then. Great science– and a win for anatomy!!!)

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