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Posts Tagged ‘dissection’

Who needs “Ice Road Truckers” when you have the “John’s Freezer” team on the road with fossils, amphibians, felids and 3D phenotype fun? No one, that’s who. We’re rocking the Cheltenham Science Festival for our first time (as a group), and pulling out all the stops by presenting two events! Here’s the skinny on them, with updates as the week proceeds.

Stomach-Churning Rating: 2/10 for now (just bones), but it could change once the cheetah dissection is under way… 8/10 bloody cheetah bits but only at the end (updated)

Right now, Lauren Sumner-Rooney (of “Anatomy To You” and other fame) is on-site with a rotating team of others from our lab, in the “Free Activity Tents” area of the Imperial Gardens/Square, inside a marquee where we’ll be showing off our NERC-funded tetrapod research all week. This “First Steps” event features not only our past and present work with Jenny Clack, Stephanie Pierce, Julia Molnar and others on Ichthyostega & its “fishapod” mates, but also our “scampering salamanders” research in Spain, Germany and England. I’ve blogged a lot about all that, and won’t repeat it here, but you can see a 3D-printed Ichthyostega skeleton, view the skeleton in a virtual reality 3D environment, see related specimens and engage in kid-friendly activities, and talk to our team about this and other related research.

Ichthyostega 3D printed backbone is born!

Ichthyostega 3D printed backbone is born!

The central themes of that event are how bone structure relates to function and how we can use such information, along with experimental measurements and computer models of real salamanders, to reconstruct how extinct animals might have behaved as well as how swimming animals became walking ones. How did fins transform into limbs and what did that mean for how vertebrates made the evolutionary transition onto land? If you know my team’s work, that encapsulates our general approach to many other problems in evolutionary biomechanics (e.g. how did avian bipedalism evolve?). Added benefits are that you too can explore this theme in a hands-on way, and you can talk with us about it in person. That continues all week (i.e. until Saturday evening); I’ll be around from Thursday afternoon onwards, too. Kids of all ages are welcome!

Ichthyostega 3D print taking shape!

Ichthyostega 3D print taking shape!

Then, on Saturday for our second free event we join forces with Ben Garrod (master of primate evolution, the secrets of bones, and “Attenborough and the Giant Dinosaur”) and RVC’s forensic pathologist Alexander Stoll as well as Sophie Regnault (“sesamoid street” PhD student w/me). As the “Large Animal Dissection” title hints, it’s not the right kind of gig to bring small kids to. There will be blood and stuff— we’ll be dissecting a cheetah together from 10am-4pm. This will involve walking through all the major organ systems, giving evolutionary anecdotes, and plenty more, with an aim to understand how the magnificent adaptations of cheetahs evolved—but also to investigate what problem(s) this animal faced that led to its sad demise. By the day’s end, there will just be a skeleton left. Get a front row seat early for this event, which serendipitously ties into “Team Cat”’s Leverhulme Trust-funded research project (we wanted a big animal and it just happened to be a cheetah; I had hoped for a giant croc or a shark or something but can’t complain!).

Ichthyostega 3D print is ready!

Ichthyostega 3D print is ready!

If you miss these events, please do cry bitter tears of regret. But don’t despair, there will be another “big cat dissection” in the London area in ~November (watch here for details), and plenty more fossil tetrapod stuff to come, plus a LOT more dinosaurs on the horizon!

Guess the bones! (photo by Zoe Self)

Guess the bones! (photo by Zoe Self)

And please come back to this blog post for more pics and stories as the week carries on… For hashtag afficionados, you can follow the fun on Twitter etc. at #firststepsCSF16. What a world we live in!

Update 1: While you’re here, check out our Youtube playlists of tetrapod-related videos:

Lobe-finned fishes

Ichthyostega‘s awesome anatomy

Tetrapod evolution: Tiktaalik to salamanders!

Update 2: Photos of our main stand (about tetrapod evolution)

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Our poster/banner display looks nice.

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Our tent brings in some punters.

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Our bones excite people young and old, sighted and blind.

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Fun with stickers and lab t-shirts.

And…

Update 3: Cheetah meat & greet
Ben, Alex, Sophie and I tackled the cheetah dissection today and it went GREAT! Much better than I’d optimistically expected. Rain didn’t scare the crowds off and neither did the gore, which there was some of (gelatinous spinal cords, lumpy tumors and at least one flying tiny bit of cheetah flesh that landed on a good-natured audience member!). Photos will tell the tale:

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Peek-a-boo!

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Sophie and Alex help us get set up in our tent.

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Our initial rough schedule- although we ended up improvising more after lunch.

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Dissectors assemble!

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The beast revealed. It was skinned by the museum that loaned it to us.

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Alex showing his talent: removing the viscera in one piece from end to end, starting with the tongue.

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Impressive finding of a surgical fixture (plate and wires) on the tibia, which had been used to hold the shattered bone back together long enough for it to heal. Added to the kidney disease and liver-spleen-lung cancer, this cheetah was in the sorriest shape of any cadaver I’ve seen yet.

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Cheetah coming to pieces: (from bottom) lumbar/pelvic region, hindlimb, thorax, forelimb and other bits.

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Dr Adam Rutherford, an eye expert, did a nice dissection of the cheetah’s eye, here showing the tapetum lucidum (reflective membrane), which shows up as light blue colour. Its small size befits the not-very-nocturnal habits of cheetahs.

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The lens of the cheetah’s eye. Now cloudy because of dehydration and crystalization, but still fascinating to see.

Want to see more images and the enthusiastic responses from the audience (we got some great feedback)? Check out Twitter’s #cheltscifest feed, or more simply my Storify condensation of the cheetah-related tweets here.

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Happy Darwin Day from the frozen tundra sunny but muddy, frosty lands of England! I bring you limb muscles as peace offerings on this auspicious day. Lots of limb muscles. And a new theme for future blog posts to follow up on: starting off my “Better Know A Muscle” (nod to Stephen Colbert; alternative link) series. My BKAM series intends to walk through the evolutionary history of the coolest (skeletal/striated) muscles. Chuck Darwin would not enjoy the inevitable blood in this photo-tour, but hopefully he’d like the evolution. Off we go, in search of better knowledge via an evolutionary perspective!

There is, inarguably, no cooler muscle than M. caudofemoralis longus, or CFL for short. It includes the largest limb muscles of any land animal, and it’s a strange muscle that confused anatomists for many years– was it a muscle of the body (an axial or “extrinsic” limb muscle, directly related to the segmented vertebral column) or of the limbs (an “abaxial” muscle, developing with the other limb muscles from specific regions of the paraxial mesoderm/myotome, not branching off from the axial muscles)? Developmental biologists and anatomists answered that conclusively over the past century: the CFL is a limb muscle, not some muscle that lost its way from the vertebral column and ended up stranded on the hindlimb.

The CFL is also a muscle that we know a fair amount about in terms of its fossil record and function, as you may know if you’re a dinosaur fan, and as I will quickly review later. We know enough about it that we can even dare to speculate if organisms on other planets would have it. Well, sort of…

Stomach-Churning Rating: 8/10. Lots of meaty, bloody, gooey goodness, on and on, for numerous species. This is an anatomy post for those with an appetite for raw morphology.

Let’s start from a strong (and non-gooey) vantage point, to which we shall return. The CFL in crocodiles and most other groups is (and long was) a large muscle extending from much of the front half or so of the tail to the back of the femur (thigh bone), as shown here:

Julia Molnar's fabulous illustration of Alligator's limb muscles, from our 2014 paper in Journal of Anatomy.

Julia Molnar’s fabulous illustration of Alligator‘s limb muscles, from our 2014 paper in Journal of Anatomy. Note the CFL in blue at the bottom right.

As the drawing shows, the CFL has a friend: the CFB. The CFB is a shorter, stumpier version of the CFL restricted to the tail’s base, near the hip. The “B” in its name means “brevis”, or runty. It gets much less respect than its friend the CFL. Pity the poor CFB.

But look closer at the CFL in the drawing above and you’ll see a thin blue tendon extending past the knee to the outer side of the lower leg. This is the famed(?) “tendon of Sutton“, or secondary tendon of the CFL. So the CFL has two insertions, one on the femur and one (indirectly) onto the shank. More about that later.

Together, we can talk about these two muscles (CFL and CFB) as the caudofemoralis (CF) group, and the name is nice because it describes how they run from the tail (“caudo”) to the femur (“femoralis”). Mammal anatomists were late to this party and gave mammal muscles stupidly unhelpful names like “gluteus” or “vastus” or “babalooey”. Thanks.

But enough abstract drawings, even if they rock, and enough nomenclature. Here is the whopping big CFL muscle of a real crocodile:

Huge Nile crocodile, but a relatively small CFL.

Huge Nile crocodile, but a relatively small CFL.

Bigger crocs have smaller legs and muscles.

Bigger crocs have smaller legs and thus smaller leg muscles, relatively speaking. CFL at the top, curving to the left.

The giant Nile croc's CFL muscle removed for measurements.

The giant Nile croc’s CFL muscle removed for measurements. 2.35 kg of muscle! Not shabby for a 278 kg animal.

However, maybe crocodile and other archosaur CFL muscles are not “average” for leggy vertebrates? We can’t tell unless we take an evolutionary tack to the question.

Where did the CFL come from, you may ask? Ahh, that is shrouded in the fin-limb transition‘s mysteries. Living amphibians such as salamanders have at least one CF muscle, so a clear predecessor to the CFL (and maybe CFB) was present before reptiles scampered onto the scene.

But going further back through the CF muscles’ history, into lobe-finned fish, becomes very hard because those fish (today) have so few fin muscles that, in our distant fishy ancestors, would have given rise eventually to the CF and other muscle groups. With many land animals having 30+ hindlimb muscles, and fish having 2-8 or so, there obviously was an increase in the number of muscles as limbs evolved from fins. And because a limb has to do lots of difficult three-dimensional things on land while coping with gravity, more muscles to enable that complex control surely were needed.

OK, so there were CF muscles early in tetrapod history, presumably, anchored on that big, round fleshy tail that they evolved from their thin, finned fishy one — but what happened next? Lizards give us some clues, and their CFL muscles aren’t all that different from crocodiles, so the CFL’s massive size and secondary “tendon of Sutton” seems to be a reptile thing, at least.

Courtesy of Emma Schachner, a large varanid lizard's very freshly preserved CFL and other hindlimb muscles.

Courtesy of Emma Schachner, a large varanid lizard’s very freshly preserved CFL and other hindlimb muscles.

Courtesy of Emma Schachner, zoomed in on the tendons and insertions of the CFL muscle and others.

Courtesy of Emma Schachner, zoomed in on the tendons and insertions of the CFL muscle and others. Beautiful anatomy there!

Looking up at the belly of a basilisk lizard and its dissected right leg, with the end of the CFL labelled.

Looking up at the belly of a basilisk lizard and its dissected right leg, with the end of the CFL labelled. It’s not ideally dissected here, but it is present.

An unspecified iguanid(?) lizard, probably a juvenile Iguana iguana, dissected and showing its CFL muscle at its end. The muscle would extemd about halfway down the tail, though.

An unspecified iguanid(?) lizard, probably a juvenile Iguana iguana, dissected to reveal its CFL muscle near its attachment to the femur. The muscle would extend further, about halfway down the tail, though.

Let’s return to crocodiles, for one because they are so flippin’ cool, and for another because they give a segue into archosaurs, especially dinosaurs, and thence birds:

A moderate-sized (45kg) Nile crocodile with its CFL muscle proudly displayed.

A moderate-sized (45kg) Nile crocodile with its CFL muscle proudly displayed. Note the healthy sheath of fat (cut here) around the CFL.

American alligator's CFL dominates the photo. Photo by Vivian Allen.

American alligator’s CFL dominates the photo [by Vivian Allen].

Black caiman, Melanosuchus, showing off its CFL muscle (pink "steak" in the middle of the tail near the leg).

Black caiman, Melanosuchus, showing off its CFL muscle (pink “steak” in the middle of the tail near the leg), underneath all that dark armour and fatty superficial musculature.

A closer look at the black caiman's thigh and CFL muscle.

A closer look at the black caiman’s thigh and CFL muscle.

Like I hinted above, crocodiles (and the anatomy of the CFL they share with lizards and some other tetrapods) open a window into the evolution of unusual tail-to-thigh muscles and locomotor behaviours in tetrapod vertebrates.

Thanks in large part to Steve Gatesy’s groundbreaking work in the 1990s on the CFL muscle, we understand now how it works in living reptiles like crocodiles. It mainly serves to retract the femur (extend the hip joint), drawing the leg backwards. This also helps support the weight of the animal while the foot is on the ground, and power the animal forwards. So we call the CFL a “stance phase muscle”, referring to how it mainly plays a role during ground contact and resisting gravity, rather than swinging the leg forwards (protracting the limb; i.e. as a “swing phase muscle”).

The “tendon of Sutton” probably helps to begin retracting the shank once the thigh has moved forward enough, facilitating the switch from stance to swing phase, but someone really needs to study that question more someday.

And thanks again to that same body of work by Gatesy (and some others too), we also understand how the CFL’s anatomy relates to the underlying anatomy of the skeleton. There is a large space for the CFL to originate from on the bottom of the tail vertebrae, and a honking big crest (the fourth trochanter) on the femur in most reptiles that serves as the major attachment point, from which the thin “tendon of Sutton” extends down past the knee.

Femur bones (left side) from an adult ostrich (Left) and Nile crocodile (Right).

Femur bones (left side; rear view) from an adult ostrich (left) and Nile crocodile (right). Appropriate scale bar is appropriate. The fourth trochanter for the CFL is visible in the crocodile almost midway down the femur. Little is left of it in the ostrich but there is a bumpy little muscle scar in almost the same region as the fourth trochanter, and this is where the same muscle (often called the CFC; but it is basically just a small CFL) attaches.

That relationship of the CFL’s muscular anatomy and the underlying skeleton’s anatomy helps us a lot! Now we can begin to look at extinct relatives of crocodiles; members of the archosaur group that includes dinosaurs (which today we consider to include birds, too), and things get even more interesting! The “tendon of Sutton”, hinted at by a “pendant” part of the fourth trochanter that points down toward the knee, seems to go away multiple times within dinosaurs. Bye bye! Then plenty more happens:

A large duckbill dinosaur's left leg, with a red line drawn in showing roughly where the CFL would be running, to end up at the fourth trochanter. Many Mesozoic dinosaurs have skeletal anatomy that indicates a similar CFL muscle.

A large duckbill dinosaur’s left leg, with a red line drawn in showing roughly where the CFL would be running, to end up at the fourth trochanter. Many Mesozoic dinosaurs have skeletal anatomy that indicates a similar CFL muscle.

We can even go so far as to reconstruct the 3D anatomy of the CFL in a dinosaur such as T. rex ("Sue" specimen here; from Julia Molnar's awesome illustration in our 2011 paper), with a fair degree of confidence.

We can even go so far as to reconstruct the 3D anatomy of the CFL in a dinosaur such as T. rex (“Sue” specimen here; from Julia Molnar’s awesome illustration as part of our 2011 paper), with a fair degree of confidence. >180kg steak, anyone?

As we approach birds along the dinosaur lineage, the tail gets smaller and so does the fourth trochanter and thus so must the CFL muscle, until we’re left with just a little flap of muscle, at best. In concert, the hindlimbs get more crouched, the forelimbs get larger, flight evolves and voila! An explosion of modern bird species!

Ozburt (72)

Left femur of an ostrich in side view (hip is toward the right side) showing many muscles that attach around the knee (on the left), then the thin strap of CF muscle (barely visible; 2nd from the right) clinging near the midshaft of the femur.

Another adult ostrich's CF muscle complex, removed for study.

Another adult ostrich’s CF muscle complex, removed for study. Not enough ostrich myology for you yet? Plenty more in this old post! Or this one! Or this one… hey maybe I need to write less about ostriches? The CF muscle complex looks beefy but it’s no bigger than any other of the main hindlimb muscles, unlike the CFL in a crocodile or lizard, which puts everything else to shame!

STILL not enough ostrich for you yet? Take a tour of the major hindlimb muscles in this video:

And check out the limited mobility of the hip joint/femur here. No need for much femur motion when you’re not using your hip muscles as much to drive you forwards:

But I must move on… to the remainder of avian diversity! In just a few photos… Although the CF muscles are lost in numerous bird species, they tend to hang around and just remain a long, thin, unprepossessing muscle:

Chicken's right leg in side view. CFC (equivalent of CFL) muscle outlined and labelled.

Chicken’s right leg in side view. CFC muscle (equivalent of CFL; the ancestral CFB is confusingly called the CFP in birds, as it entirely resides on the pelvis) outlined and labelled.

A jay (species?) dissected to show some of the major leg muscles, including the CF. Photo by Vivian Allen.

A jay (species? I forget) dissected to show some of the major leg muscles, including the CFL-equivalent muscle; again, smallish. [Photo by Vivian Allen]

Finally, what’s up with mammals‘ tail-to-thigh CF-y muscles? Not much. Again, as in birds: smaller tail and/or femur, smaller CF muscles. Mammals instead depend more on their hamstring and gluteal muscles to support and propel themselves forward.

But many mammals do still have something that is either called the M. caudofemoralis or is likely the same thing, albeit almost always fairly modest in size. This evolutionary reduction of the CF muscle along the mammal (synapsid) lineage hasn’t gotten nearly as much attention as that given to the dinosaur/bird lineage’s CFL. Somebody should give it a thoroughly modern phylogenetic what-for! Science the shit outta that caudofemoralis…

Yet, oddly, to give one apparent counter-example, cats (felids) have, probably secondarily, beefed up their CF muscle a bit:

Cats have a pretty large CF muscle in general, and this jaguar is no exception! But mammals still tend to have fairly wimpy tails and thus CF muscles, or they even lose them (e.g. us?).

Cats have a pretty large CF muscle in general, and this jaguar is no exception! But mammals still tend to have fairly wimpy tails and thus CF muscles, or they even lose them (e.g. us?). [photo by Andrew Cuff, I think]

In summary, here’s what happened (click to embeefen):

Better Know A Muscle: The Evolution of M. caudofemoralis (longus)

Better Know A Muscle: the evolution of M. caudofemoralis (longus).

I hope you enjoyed the first BKAM episode!
I am willing to hear requests for future ones… M. pectoralis (major/profundus) is a serious contender.

P.S. It was Freezermas this week! I forgot to mention that. But this post counts as my Freezermas post for 2016; it’s all I can manage. Old Freezermas posts are here.

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Tonight is the debut of the ballyhooed BBC1 programme “Attenborough and the Giant Dinosaur“, featuring Sir David and The Titanosaur-With-No-Name, at 6:30pm. Furthermore, this week I presided over a showing of “T. rex Autopsy” to our RVC undergrad Zoological Society, with a very enjoyable Q&A afterwards. So it seemed timely for me to do a post about a theme that links these two documentaries that I helped with, my own research, and science communication and palaeontological research more generally. But first let’s get this out of the way:

It was great.

It was great. I could gush more but that’s not what this post is about.

Stomach-Churning Rating: ~7/10; mainly the elephant leg dissection that’s not far below, which is a bit messy.

For the titanosaur documentary with Sir David, and the incomparable Ben Garrod as well, we had an old elephant “friend” of mine (subject of many biomechanics studies we’d done) walk across a pressure pad to demonstrate how the elephant locomotion works and some of the basic similarities with how a giant sauropod dinosaur might walk:

A broader feature of that documentary, which elephants are linked into, is how we can use the skeleton to reconstruct some general aspects of the soft tissue anatomy, and thereby the physiology or even behaviour, of a giant titanosaur. Which brings me to this post’s subject: We dig up dinosaurs all the time, but what about digging into dinosaurs and using what’s preserved to reconstruct what isn’t? 

The "G-suit" compressive stocking that the fascia wrapped around elephant, and other large mammals, creates, and the underlying, interwoven muscles and tendons (hindlimb of a young Asian elephant).

Some of the “G-suit” compressive stocking that the fascia wrapped around elephant, and other large mammals, creates, and the underlying, interwoven muscles and tendons (hindlimb of a young Asian elephant that sadly died in captivity). Did some larger dinosaurs have something like this? I’d expect so.

Another view, more superficially, of that G-suit/stocking under the thick, tight skin of an elephant's leg.

Another view, more superficially, of that G-suit/stocking under the thick, tight skin of an elephant’s leg. You’ll hear more about this in the Attenborough show…

Once the documentary airs, I may be able to share some more images from it showing what they did for the titanosaur, but this BBC photo gives a good idea.

Once the documentary airs, I may be able to share some more images from it showing what they did for the titanosaur, but this BBC photo gives a good idea. Here, blood vessels and other tissues surrounding the skeleton. How would a titanosaur pump blood around its body? A good question.

I’ve covered the science behind these reconstructions before, along with the art (in numerous posts, actually). Here I want to inspect how it’s communicated through the media: what are good (and not so good?) ways to cover it, especially now that displaying raw anatomy is more tolerable on TV and other media? I’m not writing about Thanksgiving dinner dinosaur dissections; not really; or in technical terms how we build a dinosaur to dissect/depict internally (digitally or physically).

I wanted to focus more on the end product; the imagery or even physical object; and how it conveys what we think we know about dinosaur anatomy. I’ll do that via examples, using photos of dinosaur anatomy that I’ve collected over the years from museums or other media. There won’t be any profound points or long musings; it’s mainly a photo blog:

What your (inner?) child most needs is a dinosaur to dissect yourself! Why not a T. rex toy like this?

What your (inner?) child most needs is a dinosaur to dissect yourself! Why not a T. rex toy like this?

I could quibble, but for the price they did a good job.

For the price (~$30 in USA), the 4D Vision dinosaurs deliver a pretty good bargain, and the anatomy is satisfactory. I’ve been collecting this series. I could quibble, but hey: it’s a dinosaur you get to build/dissect yourself, and with many major organs in reasonable positions! Not so easy to put/keep together, but it’s fine. I would not pay a ton for it, though.

Poster of Velociraptor's anatomy I've had since grad school, adorning my office. For ~1996, it's damn good, mostly... (placeholder photos until I get to the office tomorrow and take better ones!)

Poster of Velociraptor’s anatomy I’ve had since grad school, adorning my office. For ~1996 (no feathers; “zombie hands“), it’s damn good, mostly… Closer views below (sorry, photo quality is crap– taking photos of wall poster turned out to be harder than I expected! Bad lighting.) :

Closeup of the leg muscles- hey, not bad!

Closeup of the leg muscles- hey, not bad! Pretty much the right muscles in the right places more or less, and plausible proportions. No air sacs in the torso, but again, this is mid-1990’s science shown. BUT…

I was happy with this poster until I got it home and read this final bit of text... Oh, America! You silly place.

I was happy with this poster until I got it home from the western-USA museum I bought it at and read this final bit of text… Oh, America! You silly place. (And unfortunately, these dinosaurs are not from the very end of the Cretaceous anyway, so “global catastrophe” is not implicated.)

Ornithomimid in Barcelona natural history museum. This was unexpected and got me excited when I first saw it.

Ornithomimid in Barcelona natural history museum. This was unexpected and got me excited when I first saw it.

Looking down onto the opened torso of the Barcelona ornithomimid. Strikingly realistic!

Looking down onto the opened torso of the Barcelona ornithomimid. Strikingly realistic! Breastbone, heart, liver, intestines; not unreasonable positions and sizes. No feathers, but again hey– this was made in the earlier days.

Skinned Albertosaurus from the Drexel Academy of Sciences. I forget where I got this pic but I like the display.

Albertosaurus from the Drexel Academy of Sciences. I forget where I got this pic but I like the display– this is an impressive full-scale physical model. The transition from skeleton-only on the left to skinned in the middle to fully-fleshed and popping out atcha on the right is clever.

?T. rex? leg, photo that I took ages ago as a PhD student, if memory serves. Can anyone remind me where this was? California Academy of Sciences?

?T. rex? leg, photo that I took ages ago as a PhD student, if memory serves. Can anyone remind me where this was? California Academy of Sciences? I am embarrassed that I cannot recall. I remember geeking out about it. It has a toy-ish look, but I reckon they had to build this to withstand kids touching it.

Perhaps the best example I've seen in a museum: the AMNH's sauropod with internal organs and their functions projected onto it. Bravo!

Perhaps the best dino-dissection example I’ve seen in a museum: the AMNH’s sauropod Mamenchisaurus with internal organs and their functions projected onto it, in the “World’s Largest Dinosaurs” exhibit. Bravo! I stood and watched it for quite a while.

This is far from comprehensive– just several kinds of imagery that I mostly like. There’s the tension between showing too much realism, which science simply can’t back up, and being too cartoonish, losing the viewer’s immersion in the time-travelling fantasy. I do, however, like other kinds of more abstract, schematic depictions of dinosaur anatomy that simplify the details to focus on the basics of what organs should have been where and how they may have worked, such as this depiction from T. rex Autopsy, which also took the other extreme favouring ultra-realism (but with physical models, not so much with the CGI):

AIr flow through a T. rex: simplified but clear.

Air flow through a T. rex: simplified but clear. CGI used to explain, not abused. The real air sac anatomy would be too complex to show. You may see something similar with the titanosaur show.

That’s enough for now. I’ve stuck with relatively recent examples; of course in my particular field I also think back to Romer’s wonderful 1920’s drawings, which I covered in this post.

So, blog readers, help me out here: what examples of dinosaur internal, squishy anatomy from museums, documentaries or other not-entirely-done-by-nitpicky-scientists venues do you like, or not like so much? What works for you, or at least is memorable in some way?

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Goat morphology is cool! (from work with local artist)

I posted the above photo once before, but didn’t explain any of the fun details of artist-designer Thomas Thwaites‘s visit to the RVC to dissect a goat with us. Now his show has just finished in London, celebrating the end of his project and the near-completion of his book about his experience trying to live life as a goat. This week, I went to his east side gallery and had some time to chat with Thomas about his transhuman experiences. Because the project has a strong biomechanics, anatomy, art and science theme to it, I’m posting a photo-blog post about all of that. It’s goat to be seen to be believed! I for one wouldn’t mind being a goat right now; I could use a break from my decrepit body…

Stomach-Churning Rating: Too late, there’s the goat pic above and more like it below. I’d give those a 8/10; no kidding. The puns make it worse, too.

The context

The context. Thomas never did get to gallop (sorry, spoiler!) but he did manage a trot, and some other capricious behaviours. I forgot to ask him if he’d tried the Goat Simulator. I have; it’s good for an hour of fun hircosity.

Starting the dissection at the RVC.

Starting the dissection at the RVC, to get inside a goat.

Hide.

Hide.

Fore- and hindlimbs.

Fore- and hindlimbs; comparative design for inspiring prosthetics.

Dissections!

Dissections on display!

Prototype goat-suits. Their mobility was too limited.

Prototype goat-suits. Their mobility was too limited.

The prototype in the foreground could not move without falling down.

The prototype in the foreground could not move without falling down.

Goat-suit shots.

Inhabited-goat-suit shots.

The Goat-Suit: custom made prothetics, a helmet, and some form-fitting casts.

The final Goat-Suit: custom prosthetics, a helmet, and some form-fitting casts.

Thomas Thwaites with the goat-suit.

Thomas Thwaites with the goat-suit.

The forelimb prosthesis. I was worried it would hurt his wrists but apparently it transferred the loads mainly to the forearms.

The forelimb prosthesis. I was worried it would hurt his wrists but apparently it transferred the loads mainly to the forearms. It was made by a prosthetics clinic up in Salford.

Showroom

Photos from rambling around the Swiss Alps in the goat-suit with goats.

Trip-trap-trip-trap...

Trip-trap-trip-trap… (but no trolls)

Goat-suit in action!

Goat-suit in action! With Goat-Pro camera, I see.

Acceptance?

Acceptance?

And the goat that we had dissected, skeletonized at RVC and re-articulated by Thomas:

Do goats wish they were human?

Do goats wish they were human?

What are you looking at?

What are you looking at?

Close-up of goat head.

Close-up of goat head and shoulders.

Goat hooves-on-hips

Goat hooves-on-hips; a gruff pose.

So like us.

So like us.

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Deck the ‘Nets With PeerJ Papers— please sing along!

♬Deck the ‘nets with PeerJ papers,
Fa la la la la, la la la la.
‘Tis the day to show our labours,
Fa la la la la, la la la la.

Downloads free; CC-BY license,
Fa la la, la la la, la la la.
Read the extant ratite science,
Fa la la la la, la la la la.

See the emu legs before you
Fa la la la la, la la la la.
Muscles allometric’ly grew.
Fa la la la la, la la la la.

Follow the evolvin’ kneecaps
Fa la la la la, la la la la.
While we dish out ratite recaps 
Fa la la la la, la la la la.

Soon ostrich patellar printing
Fa la la la la, la la la la.
Hail anat’my, don’t be squinting
Fa la la la la, la la la la.

Dissections done all together
Fa la la la la, la la la la.
Heedless of the flying feathers,
Fa la la la la, la la la la♪

(alternate rockin’ instrumental version)

Stomach-Churning Rating: 5/10: cheesy songs vs. fatty chunks of tissue; there are no better Crimbo treats!

Today is a special day for palaeognath publications, principally pertaining to the plethora of published PeerJ papers (well, three of them anyway) released today, featuring my team’s research! An early Crimbo comes this year in the form of three related studies of hind limb anatomy, development, evolution and biomechanics in those flightless feathered freaks of evolutionary whimsy, the ratites! And since the papers are all published online in PeerJ (gold open access), they are free for anyone with internet access to download and use with due credit. These papers include some stunning images of morphology and histology, evolutionary diagrams, and a special treat to be revealed below. Here I’ll summarize the papers we have written together (with thanks to Leverhulme Trust funding!):

1) Lamas, L., Main, R.P., Hutchinson, J.R. 2014. Ontogenetic scaling patterns and functional anatomy of the pelvic limb musculature in emus (Dromaius novaehollandiae). PeerJ 2:e716 http://dx.doi.org/10.7717/peerj.716 

My final year PhD student and “emu whisperer” Luis Lamas has published his first paper with co-supervisor Russ Main and I. Our paper beautifully illustrates the gross anatomy of the leg muscles of emus, and then uses exhaustive measurements (about 6524 of them, all done manually!) of muscle architecture (masses, lengths, etc.) to show how each of the 34 muscles and their tendons grew across a more than tenfold range of body mass (from 6 weeks to 18 months of age). We learned that these muscles get relatively, not just absolutely, larger as emus grow, and their force-generating ability increases almost as strongly, whereas their tendons tend to grow less quickly. As a result, baby emus have only about 22% of their body mass as leg muscles, vs. about 30% in adults. However, baby emus still are extremely athletic, more so than adults and perhaps even “overbuilt” in some ways.

This pattern of rapidly growing, enlarged leg muscles seems to be a general, ancestral pattern for living bird species, reflecting the precocial (more independent, less nest-bound), cursorial (long-legged, running-adapted) natural history and anatomy, considering other studies of ostriches, rheas, chickens and other species close to the root of the avian family tree. But because emus, like other ratites, invest more of their body mass into leg muscles, they can carry out this precocial growth strategy to a greater extreme than flying birds, trading flight prowess away for enhanced running ability. This paper adds another important dataset to the oft-neglected area of “ontogenetic scaling” of the musculoskeletal system, or how the locomotor apparatus adapts to size-/age-related functional/developmental demands as it grows. Luis did a huge amount of work for this paper, leading arduous dissections and analysis of a complex dataset.

Superficial layer of leg muscles in an emu, in right side view.

Superficial layer of leg muscles in an emu, in right side view. Click any image here to emu-biggen. The ILPO and IC are like human rectus femoris (“quads”); ILFB like our biceps femoris (“hams”); FL, GM and GL much like our fibularis longus and gastrocnemius (calf) muscles, but much much bigger! Or, perhaps FL stands for fa la la la la?

Data for an extra set of emus studied by coauthor Russ Main in the USA, which grew their muscles similarly to our UK group. The exponents (y-axis) show how much more strongly the muscles grown than isometry (maintaining the same relative size), which is the dotted line at 1.0.

Data for an extra set of emus studied by coauthor Russ Main in the USA, which grew their muscles similarly to our UK group. The exponents (y-axis) show how much more strongly the muscles grew than isometry (maintaining the same relative size), which is the dotted line at 1. The numbers above each data point are the # of individuals measured. Muscle names are partly above; the rest are in the paper. If you want to know them, we might have been separated at birth!

2) Regnault, S., Pitsillides, A.A., Hutchinson, J.R. 2014. Structure, ontogeny and evolution of the patellar tendon in emus (Dromaius novaehollandiae) and other palaeognath birds. PeerJ 2:e711 http://dx.doi.org/10.7717/peerj.711

My second year PhD student Sophie Regnault (guest-blogger here before with her rhino feet post) has released her first PhD paper, on the evolution of kneecaps (patellae) in birds, with a focus on the strangeness of the region that should contain the patella in emus. This is a great new collaboration combining her expertise in all aspects of the research with coauthor Prof. Andy Pitsillides‘s on tissue histology and mine on evolution and morphology. This work stems from my own research fellowship on the evolution of the patella in birds, but Sophie has taken it in a bold new direction. First, we realized that emus don’t have a patella– they just keep that region of the knee extensor (~human quadriceps muscle) tendon as a fatty, fibrous tissue throughout growth, showing no signs of forming a bony patella like other birds do. This still blows my mind! Why they do this, we can only speculate meekly about so far. Then, we surveyed other ratites and related birds to see just how unusual the condition in emus was. We discovered, by mapping the form of the patella across an avian family tree, that this fatty tendon seems to be a thing that some ratites (emus, cassowaries and probably the extinct giant moas) do, whereas ostriches go the opposite direction and develop a giant double-boned kneecap in each knee (see below), whereas some other relatives like tinamous and kiwis develop a more “normal”, simple flake-like bit of bone, which is likely the state that the most recent common ancestor of all living birds had.

There’s a lot in this paper for anatomists, biomechanists, palaeontologists, ornithologists, evo-devo folks and more… plenty of food for thought. The paper hearkens back to my 2002 study of the evolution of leg tendons in tetrapods on the lineage that led to birds. In that study I sort of punted on the question of how a patella evolved in birds, because I didn’t quite understand that wonderful little sesamoid bone. And now, 12 years later, we do understand it, at least within the deepest branches of living birds. What happened further up the tree, in later branches, remains a big open subject. It’s clear there were some remarkable changes, such as enormous patellae in diving birds (which the Cretaceous Hesperornis did to an extreme) or losses in other birds (e.g., by some accounts, puffins… I am skeptical)– but curiously, patellae that are not lost in some other birds that you might expect (e.g., the very non-leggy hummingbirds).

Fatty knee extensor tendon of emus, lacking a patella. The fatty tissue is split into superficial (Sup) and deep regions, with a pad corresponding to the fat pad in other birds continuous with it and the knee joint meniscus (cushioning pad). The triceps femoris (knee extensor) muscle group inserts right into the fatty tendon, continuing over it. A is a schematic; B is a dissection.

Fatty knee extensor tendon of an emu, showing the absence of a patella. The fatty tissue is split into superficial (Sup) and deep regions, with a pad corresponding to the fat pad in other birds continuous with it and the knee joint meniscus (cushioning pad). The triceps femoris (knee extensor) muscle group inserts right into the fatty tendon, continuing on over it. A is a schematic; B is a dissection.

Sectioning of a Southern Cassowary's knee extensor tendon, showing: A Similar section  as in the emu image above. revealing similar regions and fibrous tissue (arrow), with no patella, just fat; and B, with collagen fibre bundles (col), fat cells (a), and cartilage-like tissue (open arrows) labelled.

Sectioning of a Southern Cassowary’s knee extensor tendon, showing: A, Similar section as in the emu image above. revealing similar regions and fibrous tissue (arrow), with no patella, just fat; and B, With collagen fibre bundles (col), fat cells (a), and cartilage-like tissue (open arrows) labelled.

Evolution of patellar form in birds. White branches indicate no patella, blue is a small flake of bone for a patella, green is something bigger, yellow is a double-patella in ostriches, and grey is uncertain. Note the uncertainty and convergent evolution of the patella in ratite birds, which is remarkable but fits well with their likely convergent evolution of flightlessness and running adaptations.

Evolution of patellar form in birds. White branches indicate no patella, blue is a small flake of bone for a patella, green is something bigger, yellow is a double-patella in ostriches, black is a gigantic spar of bone in extinct Hesperornis and relatives, and grey is uncertain. Note the uncertainty and convergent evolution of the patella in ratite birds (Struthio down to Apteryx), which is remarkable but fits well with their likely convergent evolution of flightlessness and running adaptations.

3) Chadwick, K.P., Regnault, S., Allen, V., Hutchinson, J.R. 2014. Three-dimensional anatomy of the ostrich (Struthio camelus) knee joint. PeerJ 2:e706 http://dx.doi.org/10.7717/peerj.706

Finally, Kyle Chadwick came from the USA to do a technician post and also part-time Masters degree with me on our sesamoid grant, and proved himself so apt at research that he published a paper just ~3 months into that work! Vivian Allen (now a postdoc on our sesamoid bone grant) joined us in this work, along with Sophie Regnault. We conceived of this paper as fulfilling a need to explain how the major tissues of the knee joint in ostriches, which surround the double-patella noted above, all relate to each other and especially to the patellae. We CT and MRI scanned several ostrich knees and Kyle made a 3D model of a representative subject’s anatomy, which agrees well with the scattered reports of ostrich knee/patellar morphology in the literature but clarifies the complex relationships of all the key organs for the first time.

This ostrich knee model also takes Kyle on an important first step in his Masters research, which is analyzing how this morphology would interact with the potential loads on the patellae. Sesamoid bones like the patella are famously responsive to mechanical loads, so by studying this interaction in ostrich knees, along with other studies of various species with and without patellae, we hope to use to understand why some species evolved patellae (some birds, mammals and lizards; multiple times) and why some never did (most other species, including amphibians, turtles, crocodiles and dinosaurs). And, excitingly for those of you paying attention, this paper includes links to STL format 3D graphics so you can print your own ostrich knees, and a 3D pdf so you can interactively inspect the anatomy yourself!

(A) X-ray of an ostrich knee in side view, and (B) labelled schematic of the same.

Ostrich knee in side view: A, X-ray, and (B) labelled schematic.

3D model of an ostrich knee, showing: A, view looking down onto the top of the tibia (shank), with the major collateral ligaments (CL), and B, view looking straight at the front of the knee joint, with major organs of interest near the patella, sans muscles.

3D model of an ostrich knee, showing: A, View looking down onto the top of the tibia (shank), with the major collateral ligaments (CL), and B, View looking straight at the front of the knee joint, with major organs of interest near the patella, sans muscles.

You can view all the peer review history of the papers if you want, and that prompts me to comment that, as usual at PeerJ (full disclosure: I’m an associate editor but that brings me £0 conflict of interest), the peer review quality was as rigorous at a typical specialist journal, and faster reviewing+editing+production than any other journal I’ve experienced. Publishing there truly is fun!

Merry Christmas and Happy Holidays — and good Ratite-tidings to all!

And stay tuned- the New Year will bring at least three more papers from us on this subject of ratite locomotion and musculoskeletal anatomy!

♬Should auld palaeognathans be forgot, 
And never brought for scans? 
Should publications be soon sought, 
For auld ratite fans!♪

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It has been a long time since we had some Mystery Anatomy fun here, so I am cutting loose with a double-barrelled blast of images– dive for cover!

I’m also giving out a Crimbo present as a bigger post, on a special day coming soon, count on that. This is just an advent snack.

Stomach-Churning Rating: 2/10 and 7/10: digital body and glistening, snotty.

Mystery Anatomy 2014same rules as before; remember that the scoreboard has been reset.

Identify (1) the animal shown in the four-panel top images (CT scan/reconstruction), and (2) the DIFFERENT animal (and/or the main central, pink structure) shown in the big, gooey bottom image (Dissection). No special rules. Potential for double points!

And someone will get these, I am sure. This might be the final round of 2014’s Mystery Anatomy game.

Difficulty: Plenty.

Mystery CT 14

Mystery CT 14

Mystery Anatomy 15

Mystery Anatomy 15

Go forth!

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I’ve described our “Walking the Cat Back” Leverhulme Trust-funded project with Dr. Anjali Goswami and colleagues before, but today we really got stuck into it. We’re dissecting a 46kg male Snow Leopard (Panthera uncia) as the first “data point” (actually several hundred data points, but anyway, first individual) in our study of how limb and back muscles change with size in felids. No April Fools’ pranks here; real science-as-it-happens.

Stomach-Churning Rating: 7/10 for skinned leopard and globs of fat. Much worse in person, hence the downgrading from what could be a higher score. Don’t click the photos to emkitten them if you don’t want to see the details.

This leopard is the same one that Veterinary Forensics blogged about. It died in a UK cat conservation/recovery centre. Today is simply a short post, but it is the first in what will surely be a continued series of posts on felid postcranial anatomy and musculoskeletal biomechanics by our felid research team, with bits of natural history and evolution thrown in when we can manage. As befits one of my curt “Anatomy Vignette” posts, pictures will tell the story.

Skinned and mostly de-fatted snow leopard, with fat piled up on the lower left hand corner near the hind feet. Here we are identifying and then removing and measuring the individual muscles. Project postdoc Andrew Cuff is hard at work on the forelimb while I'm mucking around with the hindlimb.

Skinned and mostly de-fatted snow leopard, with fat piled up on the lower left hand corner near the hind feet. Here we are identifying and then removing and measuring the individual muscles. Project postdoc Andrew Cuff is hard at work on the forelimb while I’m mucking around with the hindlimb. The fat here is about 3kg subcutaneous fat, so around 6.5% of body mass. And as the cat has been around for a while, that fat has gone a bit rancid and that is not nice. Not nice at all, no… Usually smells do not bother me, but this took some adjustment. Fortunately, the muscles are still OK, and work is coming along well.

UCL PhD student Marcela Randau,, carving up our cat's limb muscles. As usual in comparative biomechanics, we measure the "architecture"- parameters of the muscle that relate in a somewhat straightforward fashion to function.

UCL PhD student Marcela Randau, carving up our cat’s limb muscles. As usual in comparative biomechanics, we measure the “architecture”- parameters of the muscle that relate in a somewhat straightforward fashion to function. This muscular architecture includes things like muscle mass, the lengths of the fibers (fascicles) that make up the muscles, and the angle of the fascicles to the muscle’s line of action. These parameters correlate reasonably well with the force and power that the muscle can develop, and its working range of length change. Other posts here have discussed this more, but by measuring the architecture of many muscles in many felids of different sizes, we can determine how felids large and small adapt their anatomy to support their bodies and move their limbs. This will help to solve some lingering mysteries about the odd ways that cats move and how their movement changes with body size.

This research is being driven forward mainly by Andrew and Marcela, shown above, so I wanted to introduce them and our odoriferous fat cat. Upcoming dissections: 1-2 more snow leopards, tiger, various lions, ocelot, black-footed cat, leopard, and a bunch of moggies, and whatever else comes our way. All were EU zoo/park mortalities (there are a LOT of big cats out there!).

EDIT: Had to add a photo of the CLAWS! Whoa dude.

CLAWS

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