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Archive for the ‘Frozen Mammals’ Category

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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Sick feet, pig feet, boo hoo, in pain you are
Not well heeled; fate sealed, oh no, inflamed they are
And when your trotter’s on the floor
You’re nearly a good boar
Almost a porker

(corrupted from Pink Floyd’s “Pigs (Three Different Ones)” track #3 from the Animals concept album (1977). A song with quite a history- check out some more about it.)

It could happen...

It could happen…

Concept albums often weave back and forth between themes in a non-linear story, returning to refrains and leitmotifs to create their narrative weft and warp. This Freezermas, I’ve already woven in two legs and four legs, cats and other beasts, x-rays and more. Today, I tie in another thread, which extends throughout the blog, but especially into yesterday’s post. This post is about feet and health again. But it is also solely about pigs, which are cool animals whose biomechanics are surprisingly little studied.

It’s a shorter post (in contrast to the 11-17 minute Pink Floyd cousin song); a drum solo if you will; with just three images representing three big pigs and their funky feats of footedness, and the three days left in Freezermas. One image is about ongoing research; the other two about bizarre cases that kinda freak me out (enough to want to know more about them).

Stomach-Churning Rating: 4/10, not for gore but for surreality; things that should not be. Especially the 2nd picture.

pig gif

Above: X-ray GIF (may take a while to load) from our 3D XROMM analyses of foot biomechanics, here showing a pig studied by Dr. Olga Panagiotopoulou (also RVC Fellow Jeff Rankin; and Prof. Steve Gatesy at Brown University). With data like these, we not only can measure how the tiny bones move, but also get better estimates of the loads on the soft tissues within those feet. Those loads should relate to the risks of musculoskeletal injury or disease. This GIF is just a teaser for some fantastic 3D images we’re producing. The pig’s feet were normal. The odd little spheres on them are skin-adhered markers that let us compare how external estimates of skeletal motion compare to actual motion; normally this is a big source of error.

I know little about this case, posted on Reddit (link here), except that the overgrown, grossly deformed toes/hooves of this pig are like nothing I've seen before! This almost gave me nightmares. Poor chicken-footed pig!

I know little about this case (seems to trace back to an original Brazilian news story), posted on Reddit (link here), except that the overgrown, grossly deformed toes/hooves of this pig are like nothing I’ve seen before! This almost gave me nightmares. Poor chicken-footed pig. Foot deformities of this kind in pigs don’t seem to be as much of a problem as in cattle or horses; from the limited literature I’ve seen on this, they seem to have more problems with the soft tissues of their feet, such as  abscesses or inflammation of the digital cushion (padding) of the trotter.

Another crazy case; but this one I was able to track down more about after reading the Reddit post here. The Getty images page says: This photo dated November 24, 2011 shows a Chinese farmer showing off his prize swine, which he named 'Strong Pig', as the disabled animal keeps its 30kgs of body suspended in midair, in Mengcheng, east China's Anhui province. The pig has become an internet sensation around China due to its ability to walk around balancing on its two front legs. TOPSHOTS CHINA OUT AFP PHOTO (Photo credit should read STR/AFP/Getty Images)

Another crazy case; but this one I was able to track down more about after reading the Reddit post here. This news image page says:
“This photo dated November 24, 2011 shows a Chinese farmer showing off his prize swine, which he named ‘Strong Pig’, as the disabled animal keeps its 30kgs of body suspended in midair, in Mengcheng, east China’s Anhui province. The pig has become an internet sensation around China due to its ability to walk around balancing on its two front legs. TOPSHOTS CHINA OUT AFP PHOTO (Photo credit should read STR/AFP/Getty Images)”

Bipedal pigs– two legs good again? I guess so. Well done, Strong Pig. Well done.

Bipedal ability in injured/deformed/spooked quadrupeds is not so unusual- in addition to trained macaques and rats that have been scientifically studied, there are plenty of examples out there on the internet of videos/GIFs of bipedal cats, dogs, and so on… Post your favourites below. Hooray for the marvelous plasticity of the locomotor system! As Pink Floyd famously wrote, “Any fool knows a dog needs a home, a shelter from bipedal pigs.” (or something like that)

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Why should you care
If you have to trim my hooves?
I’ve got to move with good feet
Or be put down fast.
I know I should trot
But my old vet she cares a lot.
And I’m still living on stone
Even though these feet won’t last.

(mutated from The Who, “Cut My Hair“, Quadrophenia… from the heyday of concept albums and grandiose rock!)

Talkin' bout my osteitis?

Talkin’ bout my osteitis

Day Four of Freezermas. Four posts to go. I can see through time… Hence the silly title for today’s concept album track. Quadrupedophilia did not have a good ring to it, anyway.

Stomach-Churning Rating: 4/10. Reasonably tame; bones and hooves. Some pathologies of those, but not gory.

If Quadrophenia was the story of a man with four personalities (metaphor for the four band members), then quadrupedopheniaphilia is the story of how diverse forms of four-legged animals have lots of problems because of our exploitation of them, which leaves a crisis to resolve: Who are we? Are we caring enough to fix a bad situation we’ve created for our four-legged ungulate comrades?

Four legs good, two legs bad? Not really. I featured ostriches earlier this week and two legs are indeed pretty good. Four-legged cats are great, too. But four-footed big beasties with deformed hooves: those are bad all around. That leads to today’s topic…

But hey, happy 205th funkin’ birthday Charles freakin’ Robert Darwin!

Charles Darwin on his horse “Tommy” in 1868- from the Darwin Correspondence Project, https://www.darwinproject.ac.uk/darwins-photographic-portraits

Today’s post concerns a phenomenon that (Western) civilization has wrought with large hoofed mammals, and evolution is a big part of it (as well as biomechanics and anatomy) . Cynical perspective, with some truth to it: We’ve evolved larger and heavier animals to either do harder and harder work on tough surfaces like concrete floors and tarmac roads, or to stand around while we gawk at them or wait for them to get fat and tasty. Either way, the outcome should come as no surprise: their feet, the interface of that hard ground and their body, eventually start falling apart.

I’ve posted about this several times with respect to rhinos and elephants (here and here and here and here and here), but this post hits closer to home: what goes wrong with the humble hoof of our friend the horse, cow, sheep or other ungulate. It’s where the rubberkeratin hits the road. Ungulates have not evolved to live on dirty, wet concrete floors; to be obese and inactive; or to have hooves that don’t get worn down. So they suffer when they do encounter those modern conditions.

“No foot no horse,” they say, and it’s so true- once the feet start to go (due to hoof overgrowth or cracks, abscesses or other trouble), it’s hard to reverse the pathologies that ensue (arthritis, osteomyelitis, infections, fractures, etc.) and the animals start going lame, then other limbs (supporting greater loads than the affected limb) start to go, too, sometimes.

Jerry the obese, untrimmed-hoof-bearing horse.

Jerry the obese, untrimmed-hoof-bearing horse. “Turkish slippers” is an apt description. DM has more here.

We can do plenty about these problems, and the title track above explains one of them: trimming hooves. Hooves often get overgrown, and if animals are tame enough (requires training!) or are sedated (risky!), hoof care experts (farriers) can rasp/file/saw them down to a more acceptable conformation. If we don’t, and the animals don’t do the trimming themselves by digging or walking around or living on varied surfaces, then the feet can suffer. But there’s still not much evidence for most common species kept in captivity by humans that indicates what the best methods are for avoiding or fixing foot problems.

What we’ve been trying to do at the RVC is use our expertise in evolution, anatomy and biomechanics to find new ways to prevent, detect, monitor or reverse these foot problems. We had BBSRC grant funding from 2009-2012 to do this, and the work continues, as it behooves us to do… Past posts have described some of this research, which spun off into other benefits like re-discovering/illuminating the false sixth toes of elephants. We’re working with several zoos in the UK to apply some of the lessons we’re learning to their animals and management practices.

Above: Thunderous hoof impacts with nasty vibrations, and large forces concentrated on small areas, seem to contribute to foot problems in hoofed mammals. From our recent work published in PLOS ONE.

Foot health check on a white rhino at a UK zoo. Photo by Ann & Steve Toon, http://www.toonphoto.com/

Foot health check on a white rhino at a UK zoo; one of the animals we’ve worked with. Photo by Ann & Steve Toon, http://www.toonphoto.com/

If it works, it’s the most satisfying outcome my research will have ever had, and it will prevent my freezers from filling up with foot-influenced mortality victims.

Again, I’ll tell this tale mainly in photos. First, by showing some cool variations evolved in the feet of hoofed mammals (artiodactyls and perissodactyls; mostly even/odd-toed ungulates of the cow/sheep and horse lineages, respectively). Second, by showing some pretty amazing and shocking images of how “normal” hooves go all wonky.

Two ways to evolve a splayed hoof for crossing soft ground: 2 toes that are flexible and linked to big pads (camel), and 2 main toes that allow some extra support from 2 side toes when needed (elk). At Univ. Mus. Zoology- Cambridge.

Two ways to evolve a splayed hoof for crossing soft ground: 2 toes that are flexible and linked to big pads (camel), and 2 main toes that allow some extra support from 2 side toes when needed (elk). At Univ. Mus. Zoology- Cambridge.

Diversity of camelid foot forms: big clunky, soft Old World camel feet and dainty, sharp highland New World camelids.

Diversity of camelid foot forms: big clunky, soft Old World camel feet and dainty, sharp highland New World camelids. [Image source uncertain]

Moschus, Siberian musk deer with remarkable splayed hooves/claws; aiding it in crossing snowy or swampy ground. At Univ. Mus. Zoology- Cambridge.

Moschus, Siberian musk deer with remarkable splayed hooves/claws; aiding it in crossing snowy or swampy ground. At Univ. Mus. Zoology- Cambridge.

Tragulus, or mouse-deer, with freaky long "splint bones" (evolutionarily reduced sole bones or metatarsals) and dainty hooved feet. At Univ. Mus. Zoology- Cambridge.

Tragulus, or mouse-deer, with freaky long “splint bones” (evolutionarily reduced sole bones or metatarsals) and dainty hooved feet. At Univ. Mus. Zoology- Cambridge.

Overgrown giraffe hooves. An all-too-common problem, and one we're tacking with gusto lately, thanks to PhD student Chris Basu's NERC-funded giraffe project!

Overgrown giraffe hooves. An all-too-common problem, and one we’re tacking with gusto lately, thanks to PhD student Chris Basu’s NERC-funded giraffe project!

Wayyyyyyyyy overgrown hooves of a ?sheep, from the RVC's pathology collection.

Wayyyyyyyyy overgrown hooves of a ?sheep, from the RVC’s pathology collection.

Craaaaaaazy overgrown ?cow hooves, from the RVC's pathology collection.

Craaaaaaazy overgrown ?sheep hooves, from the RVC’s pathology collection.

If we understand how foot form, function and pathology relate in diverse living hoofed mammals, we can start to piece together how extinct ones lived and evolved- like this giant rhinoceros! At IVPP museum in Beijing.

If we understand how foot form, function and pathology relate in diverse living hoofed mammals, we can start to piece together how extinct ones lived and evolved- like this giant rhinoceros! At IVPP museum in Beijing.

So, what do we do now? If we love our diverse hoofed quadrupeds, we need to exert that quadrupedopheniaphilia and take better care of them. Finding out how to do that is where science comes in. I’d call that a bargain. The best hooves ever had?

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Freezermas continues with track 3 of our rockin’ anatomy concept album! The number of the beast today is 5 (five days to go in Freezermas!), and I will deviate from the rock/metal theme to embrace the other side of the tracks: hip hop and rap. The Beastie Boys and I go way back: their “Licensed to Ill” album was the second cassette tape I bought (I remember proudly showing it off in Geometry class, circa 1986/7), and still ranks as one of my favourite albums ever. Everyone should own a copy of that, and of this next album…

The Five Felids, featuring KC

If only MCA were still alive to do this follow-up album…

The Beastie Boys’ superb, old school rap NYC-style (and themed) “To The Five Boroughs” (2004) satisfies my search for a #5-themed concept album/song. No track has that title, so I’m going with this one, “Triple Trouble” (song 3; day 3 of Freezermas… c’mon this is all just an excuse for me to talk about music I like and celebrate the concept album/freezers anyway!), as an introduction to a collaborative cat (felid) project we’ve started; and to continue the felid theme from Sunday (also be sure to check out the Snow Leopard dissection I posted on earlier!):

If You If You 
Wanna Know Wanna Know 
The real deal about the cats
Well let me tell you 
We’re felid funded ya’ll 
We’re gonna bring you some mad facts

(yes, that’s painful, I know… be relieved, I tried working some rap jargon into this post’s text but it just looked wack)

Dodgy-looking bagged-up skinned jaguar (bag-uar?) after delivery from Scotland.

Dodgy-looking bagged-up skinned jaguar (bag-uar?) after delivery from Scotland.

Anjali Goswami at University College London, myself, and Stephanie Pierce have teamed up to join the former’s skills in mammalian evolution, morphometrics, evo-devo and more together with our RVC team’s talents in biomechanics, evolution and modelling, and to apply them to resolving some key questions in felid evolution. We’ve hired a great postdoc from Bristol’s PhD programme, soon-to-be-Dr. Andrew Cuff, to do a lot of the experimental/modelling work, and then we have the marvellous Marcela Randau as a PhD student to tackle more of the morphometrics/evo-devo questions, which we’ll then tie together, as our Leverhulme Trust grant’s abstract explains:

“In studying the evolution of vertebrate locomotion, the focus for centuries has been on limb evolution. Despite significant evolutionary and developmental correlations among the limbs, vertebrae, and girdles, no biomechanical studies have examined the entire postcranial skeleton or explicitly considered the genetic and developmental processes that underly morphological variation, which are captured in phenotypic correlations. We propose to conduct experimental and geometric morphometric analyses of living and fossil cats, including the only large, crouching mammals, to study the evolution of locomotion, the mechanical consequences of size-related morphological evolution, and the evolution of correlations (modularity) in the postcranial musculoskeletal system.”

Above: snow leopard (headless) reconstructed and taken for a spin

Our study will integrate some prior studies from Anjali’s group, on modularity for example, and from my group, on the apparent lack of postural change with increasing size in felids (most other birds and mammals get more straight-legged as size increases, to aid in support, cats don’t– paper forthcoming). How does the neglected vertebral column fit into these limb-focused ideas? We’ll find out!

And it’s all very freezer-based research, using a growing stock of specimens that we’ve collected from zoo/park mortalities, many of which are kindly being supplied by Dr. Andrew Kitchener from the National Museums Scotland. We’ll be scanning, dissecting, measuring and modelling them and then returning the skeletons to be curated as museum specimens. This page features five sets of felid specimens involved in the research. We’ll be presenting plenty more about this research on this blog and elsewhere as it continues!

Above: ocelot from Freezermas day 1, now in 3D!

The Bag-o-Cats: whole specimens of a black-footed cat (Felis nigripes), juvenile cheetah, and juvenile snow leopard. I think. Sometimes you get a bag-o-cats and are not sure.

The Bag-o-Cats: x-ray CT slice showing whole specimens of a black-footed cat (Felis nigripes), juvenile cheetah, and juvenile snow leopard. I think. Sometimes you get a bag-o-cats and are not sure.

Panthera atrox (large American lion) from the NHM in LA. Oh yes we'll be applying our insights to strange extinct cats, too!

Panthera atrox (large American lion; “Naegele’s giant jaguar”) from the NHM in LA. Oh yes we’ll be applying our insights to strange extinct cats, too!

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So in my last post I promised to put up the videos of my cat biomechanics footage online (cut scene from “The Secret Life of the Cat” documentary). Here I deliver on that promise.

Note that all this footage was filmed at 250 frames/second, so it is 10 times faster than conventional UK/EU (PAL format) video and thus it plays 10x slower if replayed at PAL format speeds. Hence it is often called “slo-mo”/slow motion video. However, most experts would call it high speed video due to the high frame rate that gives us higher temporal resolution, ideal for studying fast movements.

It was cold that day; indeed the Colchester Zoo area where we filmed the tiger videos below had been snowed in earlier; so the posting of these videos on my freezer-based blog is DEFINITELY apropos.

First, the cat (named Ricochet, not Rocket, I now recall; I’m sure you’re all ineffably outraged at this mistake in my prior post) that we filmed to show how a standard; if rather shy; cat walks:

Second, here I am goofing off. High speed video is so fun! OK actually I was testing the video camera to ensure it worked; we only got one chance with each of 2 tigers. As you can imagine it’s not easy to get a tiger back in its indoor enclosure when it’s nice and sunny outside! So my gear needed to work, and it did, despite the cameraman’s bum being in the shot here:

Third, a tiger whom we filmed at Colchester Zoo. It nonchalantly strolled out of its indoor enclosure upon release. No drama. It was a bit unnerved by our presence but took its time.

Finally, this is the video that we were really hoping for with the tiger; a dramatic turn and gallop out of the “tiger chute” into its main enclosure:

Pretty nice! And thanks to the magic of blogging, you get to see it, rather than having it banished forever to the purgatorial cutting room floor!

Here are some parting shots of the male tiger happily checking out his snowy paddock upon release, and then…

Tiger outdoors

I turned around and he was checking me out; I was just on the other side of the fence. That was a fun surprise! Some close-up time with a curious tiger.2013-03-12 12.38.13

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…a daily picture of anatomy! And today it is six picture-facts; doo-raa-dee! ♫

Welcome back againagain, and again (gasp, pant)– and again (exhausted howl) to Freezermas

And Happy World Pangolin Day!

Stomach-Churning Rating: 4/10; pretty tame images of anatomy today– but 9/10 if you consider how vile a practice it is to eat pangolins.

Much like rhinoceroses are, pangolins (“scaly anteaters”) are threatened with extinction across Africa and Asia largely because tradition holds that they have magical skin. It comes down to that. It’s simply pathetic.

Pangolin in Borneo

Sunda pangolin, Manis javanica; from Wikipedia. It’s not a pig in a convenient artichoke-like wrapper. It’s a precious, rare creature.

To make matters worse, pangolins are smaller than rhinos and covered in the tough armour that makes them so desirable, and hence they are more portable and easy to hide. They also are thought to taste delicious — or just have the social cachet that it is a sign of affluence to be able to afford to eat them — to some people, especially from some southeast Asian cultures. Habitat loss/growing populations/deforestation/climate change aren’t helping, either.

Around 60,000 pangolins were illegally smuggled or otherwise slaughtered for human uses in 2012 worldwide; contrasting with 668 rhinos in South Africa that year (perhaps 2,000 worldwide?); so the scale of the problem is immense. Smaller-bodied pangolins will be more numerous in the wild than large, wide-roaming rhinos, but the drain on those numbers is obviously not sustainable. Sometimes pangolins are smuggled alive, a cruel practice that delivers them fresh but in a poor welfare state at the point of sale, compounding the urgency to turn the tide of exploitation.

Please take the time today to lend your hand to a good conservation group. Learn about the crisis facing pangolins (e.g. this recent article; and this video) and speak out about it. Of course, don’t eat pangolins, either.

Let’s not let humanity fail in its moral imperative of stewardship.

Pangolin body and skeleton

My photo of a pangolin body and skeleton, from the University of Cambridge Museum of Zoology’s exhibits.

In celebration of World Pangolin Day, for today’s Freezermas we have six impressive facts about pangolin anatomy. Much like rhinos, these are animals we don’t know as well as we should. I’ve never had one in my freezers, and would feel a bit weird if I did, since I find them so adorable, but they do have fascinating anatomy, natural history and evolutionary heritage. All the more reason to preserve them as they should be: alive and with the freedom they deserve.


Pangolin Fact 1: Pangolins have highly modified skulls with myrmecophagous adaptations-- these are specializations for eating arthropods (especially ants/termites): toothless, tubular snout, reduced mandibles, and more– shown below.

Pangolin skull x-ray

X-ray of Malayan pangolin (Manis javanica) skull in side(1) and top(2) views, modified from Endo et al., 1998. The small arrow denotes the V-shaped, splint-like mandible, and the large arrow is directed at the jaw joint (zygomatic process on the temporal bone). The zygomatic arch, crossing from the jaw joint toward the front of the upper jaw (maxilla), is incomplete, so there is no bony bridge across the cheek as in many mammals. The large masseter and temporalis muscles run across this region, forming a more flexible, muscular cheek involved in feeding. Some nice labelled skull photos are here.

EDIT: Aaagh! Of course I should have checked Digimorph, which has a kickass CT scan/movie of the skull. Play with that; hours of anatomy-tainment!


Pangolin Fact 2: Pangolins have long tongues whose attachment extends way across the breastbone.

Pangolin tongue dissection

Tongue anatomy of a Malayan pangolin, from Prapong et al., 2009. This shows the chest region in ventral view (head is to the right side), with the main body of the sternum removed. A indicates muscles forming a sac around the tongue base; B is where the tongue finally inserts on the sternum/xiphoid processes; C is the ribcage; D is the xiphisternal joint (middle of the sternum parts).

Your tongue, even Gene Simmons‘s, just extends a little ways down your chin. It is, however,  a common misconception that a pangolin’s tongue is longer than the animal. It can’t be longer than the distance between its sternal origin and the tip of the snout, so it might extend up to 40cm out of the mouth when fully extended in a large pangolin. Around 1988, there was the scientific misconception that the tongue extended way back to the pelvis (hips) or stomach. This is not true according to the latest literature I’ve read (e.g. in caption above), but is widespread in pangolin information on the internet. If someone has secondary confirmation of this either way, I’d love to see some concrete evidence.

EDIT: This image of a dissected pangolin fetus indicates a quite long tongue, maybe even long enough to attach near the pelvis, although that site agrees that there is no pelvic attachment. The latter site also depicts a fascinating cartilaginous sheath for the tongue. The misinformation about pangolin tongues does make me wonder: perhaps there is a lot of diversity in tongue attachments/lengths among the 8 pangolin species? Who knows.


Pangolin Fact 3: Pangolins have toughened, keratinized stomach linings.

Pangolin stomach histology

Click to embigitate. Histology of the stomach lining in Manis tricuspis (modified from Ofusori et al., 2008), showing layers of keratinized stratified squamous epithelium (thick stomach lining). These layers seems to act as a protective coating against the rasping, chitinous exoskeletons of the ants and termites that are consumed, helping to reduce the risk of ulcers while reportedly eating up to 200,000 ants/per night. There is also an increased preponderance of elastic and collagenous fibers in layers of the stomach, helping it to expand to enclose many ants from one feeding.


Pangolin Fact(ish) 4: Pangolins are not closely related to other ant-eating living mammals, but to carnivores.

Eurotamandua fossil

Eurotamandua; a possible fossil relative of pangolins from the early Eocene (Messel, Germany); image from Wikipedia.

Together, the eight living pangolin species are remnants of the group Pholidota, which has a respectable fossil record– particularly considering that they lack teeth, which are often such a diagnostic feature for mammalian fossils. Controversy persisted for many years about whether they were related to anteaters, sloths and armadillos (Xenarthra) within the group Edentata, along with possibly aardvarks (Tubulidentata) and other digging and/or myrmecophagous animals. There has also been controversy about some fossil mammals and their relationships, including Eurotamandua (above) and the Palaeonodonta– the latter seems to be approaching a consensus, though, as an extinct sister group to Pholidota.

Nonetheless, the main features that were once thought to unite ant-eating mammals as close relatives now seem to be a prime example of convergent evolution. Xenarthans are definitely closely related to each other, but aardvarks are afrotherians (closer related to hyraxes and elephants), and pangolins seem not to be closely related to either of those groups.

More conclusively, with the addition of genetic data, it has emerged that Pholidota is most closely related to Carnivora (mongooses, dogs, cats, bears, pinnipeds, etc.) among living mammals. A good example of this conclusion is the very recent paper by O’Leary et al. in Science. Furthermore, this image shows a nice example of such a phylogenetic result. This relationship with Carnivora raises fascinating questions about the tempo and mode of the evolution of all their digging/ant-eating specializations- when, where and how did they become so much like other ant-eating mammals?


Pangolin Fact 5: Pangolins have many digging (fossorial) and climbing (scansorial) adaptations, especially in their forelimbs.

Pangolin hindfeet Feet of anteating mammals

Click to embignify. Above (modified from Gaudin et al., 2006): stippled drawings of hind feet of (left) the Eocene fossil pangolin Cryptomanis and (right) Manis; Below: line drawings of front feet (from Humphrey, 1869) showing the convergent evolution of digging/climbing hands in (left to right) pangolins, an anteater (2-toed; Myrmecophaga), Ai (3-toed sloth; Bradypus) and Unau (2-toed sloth; Choloepus).

A striking feature of pangolin claw bones (unguals); evident above; is their characteristic fissured anatomy (split ends), which even the fossils have. This probably is how they develop strong, keratinous digging claws that remain anchored to those bony claw cores. If you look really closely, you may be able to see the fused scaphoid and lunar (scapholunar) bones of the wrist in the manus of Manis. Cryptomanis (above left) had more climbing specializations than living pangolins; is this how pangolins first evolved, and then later added more ant-eating features? This makes sense in terms of their phylogeny (above), as they are related to primitively climbing carnivores.

Other possibly digging/climbing-related features characteristic of pangolins include the loss of a coracoid process on the pectoral girdle, and curious enrolled zygapophyses (joints) on the lumbar (lower back) vertebrae — the functional significance of the latter feature is almost unstudied, but is reminscent of the complex xenarthrous vertebrae that gave Xenarthra their name (see above and this past post). A nice photo of a pangolin ribcage/vertebrae is here. There is an exceptional page on pangolins and their once-thought-to-be-close relatives among Xenarthra here, with lots of anatomical detail.

A feature that first got me scientifically curious about pangolins in my research is the presence of “predigits“- prepollex and prehallux- in their hands and feet (“prh” in upper left two figures). Many mammals have these, and some have expanded them into larger structures like the “sixth toes of elephants” (hence my interest), but precious little is known about their evolution or function in many other groups.


Pangolin Fact 6: Pangolin skin armour, like rhinoceros horns, is just modified skin (hair/epidermis) keratin; shaped into imbricating scales.

Pangolin scales closeup Coat of pangolin scales

That apocryphally “magic skin”. Images from Wikipedia: closeup above, and below it a suit of armour made from those scales–  coated in gold and given to King George III in 1820.

These scales, the double-edge sword of pangolins (both protecting them in nature and making them desirable in part of the human world for silly reasons), form as pangolins grow. In the fetus they are still soft, making fetuses more of a delicacy in some Asian cultures. Much like the stomach lining described above, the skin is formed from keratinized, stratified squamous epithelium– much more densely formed than in our skin, but more like in our fingernails. Asian pangolins, unlike African species, may have some more normal hairs beneath the scales, too.

There is no convincing evidence that the scales are any more healthy to eat, in any form, than your own fingernails, dead skin, or hair. Given the ready availability of the latter to any humans, we’re all wearing, and growing, our own goldmine…

I’ve barely dug into the fascinating biology of pangolins. I haven’t talked about their bipedal locomotion, much as it fascinates me, because we know next to nothing about that. I’m not aware of good scientific studies on their prehensile tail, either. A great page on pangolin biology, with a focus on reproduction and anatomy, is here. A lovely illustration and discussion of the convergent evolution between anteaters and pangolins is here. Awesome photos and facts are here. More about pangolins’ plight here, and very thoroughly here.

If you have favourite links to more material, or want to provide more information or especially questions, don’t hold back and experience painful pang(olin)s of remorse– chime in in the comments below!

Happy World Pangolin Day! Visit these great pages, please! Here, here and hereAnd…

Happy Freezermas! Sing it: “On the sixth day of Freezermas, this blo-og gave to me: one tibiotarsus, two silly Darwins, three muscle layers, four gory heartsfive doggie models a-and six facts of pangolin anatomy!” ♪

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…a daily picture of anatomy! And today it is four pictures; da-da-dee! ♫

Welcome back again, again to Freezermas! 

Today I’m shimmying down your interwebz with a late delivery. I’ve promised before to show how we clean up our nasty gooey skeletons to preserve them for future research to use. This is the intended final destination of all critters that are tenants of my freezers– the freezer is just a lovely holiday home, but bony heaven is the end result. I’ve accumulated a little museum of the bones of exotic animals I’ve studied, using these cleaned specimens. Here is how I do that preservation– there are four basic steps, and I’ll show them in four photos.

Stomach-Churning Rating: 8/10; first just dry bones, but then some gooey bones and by the end we ratchet it up to bloody organs.

Step 1) We get the deceased animal from various zoos and other EU sources, CT/MRI scan it, and dissect it. That’s what most of this blog focuses on, so I won’t show that. But I will show the end result, and then how I get to that:

ele-rhino-bones

Those are some elephant and rhino bones, some of which you saw on the 2nd day of Freezermas. Elephant bones are super greasy; it’s almost impossible to get rid of that brown grease visible in this photo (upper LH side) without making the bones brittle and over-bleached. The bones of the whiter white rhino on the right show what I’m usually aiming for. How do I get this done? Well, here’s an example for an elephant shank:

Cookin' up elephant shank

I take the elephant shank and make soup.  (above) An Asian elephant’s patella, tibia and fibula were dissected, frozen for many years (queued up for cleaning; much freezer burn occurred on this specimen— it was jerky-fied), and then thawed. I put large specimens in this Rose cooker unit, which is a big ham cooker with a heater unit at the bottom. My baby, a Rapidaire MKV 5-ham unit is shown; oooh, ahhh!

The Rose cooker is filled up with tap water and been set it at around 60-90C. Then I let it cook away! A brothy soup develops, and sometimes it smells rather nice (my favourite aroma is giraffe leg). Sometimes… it’s not so nice. We check it every few hours to top up the water and remove stray tissue, and then change the water every day or so.

An elephant shank like this will take 2-3 days of cooking, longer if only switched on during work hours. The key thing is not to let it cook dry, which happened once with a faulty Rose cooker that did not do its normal auto-shutoff when the water ran low… showing up to work to encounter some fire trucks and unhappy college Health & Safety rep is not a good way to start your day, trust me!

This step is only slightly different for smaller (<30cm) specimens. Rather than the Rose cooker, we use the lovingly named “Croc Crock”, which isn’t visually impressive but you can see it here. As the name indicates, we’ve mainly used it for small crocodiles, and it is a crock pot. (a helpful thing is to add some detergent to the water for these small specimens; then bleaching isn’t so necessary)

Step 2) Then I empty out the water through the bottom spout, do the very nasty job of cleaning out the fat and other tissue that has accumulated (think 20 gallons of goo), hose off the bone, and set it in a ~10% bleach solution for at least a day, or up to a week or so for an elephant bone. Once it’s cleared up, I leave it out to dry (for big elephant bones, copious amounts of grease may be emerging for a few weeks). And then…

Elephant shank bones

Step 3) I varnish the dry bones with a clear varnish, and let them dry. Here is how that elephant shank turned out. Pretty good! Finally, they get to join their friends:

The bone shelves

Step 4) The prepared bones are labelled, given a number/name that I file in a world class comprehensive electronic database (cough, get on that John, cough!), and they become part of my humble mini-museum, shown above. Voila! The chef’s job is finished. Let science be served!

Happy Freezermas! Sing it: “On the fourth day of Freezermas, this blo-og gave to me: one tibiotarsus, two Darwin pictures, three muscle layers, a-a-and four steps of bone cookery!” ♪

Oh it’s Valentine’s day, so, err, have a heart today. Have four, actually!

giraffe heart - 1 white-rhino-heart-Perez Windfall-ele 054

chicken-heart

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I’m not sure if this is a new tradition at this blog or not (probably not), but hey let’s give it a name: an Anatomy Vignette. Just something curious I notice during my research that deserves more than just a tweet. I borrowed some bones from the University of Cambridge Museum of Zoology (whom I love, because they have great exhibits and are very research-friendly) to CT scan for some projects. I noticed this:

femur-path

And I thought “Ouch! That’s nasty, dude.” (the holes in the bone just above the knee joint– these should just be a roughened area where the adductor muscles and other leg muscles attach)

So I was interested to see the CT scan images to find out how these possibly osteomyelitic lesions continued into the bone. They’re really pervasive, continuing into the marrow cavity quite far up the femur, as this shows (good CT-viewing practice to match up what you are seeing in the photo above with this movie):

I would be surprised if this was not the reason this animal died (presumably being euthanased at a UK zoo). There would have been extensive infection and pain resulting from this bony disease. How did it originate? Who knows. Maybe the animal strained a muscle and bacteria got inside, or maybe there was a fall or other injury. Hard to tell.

Oh, and also note the lack of a true marrow cavity in hippos, which is true for all the long bones. The “cavity” is filled in with cancellous bone. Same with rhinos, elephants, and many other species… science doesn’t entirely know why but this feature surely does help support the body on land, and grants at least some extra negative buoyancy in water; at a cost of some extra weight to lug around, of course.

And so ends this Anatomy Vignette.

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I have a lot to be thankful for as a scientist, including a great, steady set of blog readers interested in my freezer and its sundry tenants. And now and then I get a fun surprise, like Redditors stumbling across my posts and ramping up my blog views by a factor of 10-20 fold. So this weekend I did (and am still doing at this moment) an “Ask Me Anything” (AMA) on Reddit, by suggestion, and I just crossed 1000 Twitter followers. So I figure I should give some thanks.

And I will give those thanks in a way that I can only do on this blog. With kickass pictures of incredible animal anatomy! Much as I started this blog with giraffes, I will return to them now. And I will let the pictures, with brief captions, tell the tale. These photos are from a dissection our team did quite a few years ago, on an adult giraffe that died suddenly in a local zoo. I forget who snapped these photos– my thanks to them anyway, as I didn’t take them but it was someone from our team.

Stomach-Churning Rating: a 7/10 or even 8/10, depending on your fortitude. Blood, a freshly dead animal, guts, brains, and more.  So before we go further, while you brace yourself if need be, a pic to liven things up. Here I am with my cat (taken a few years ago, too), wishing you Happy Holidays — and much fortitude.

Away we go!

TOSHIBA Exif JPEG

Left side of the neck. Purplish-blue vessel is the jugular vein, shown next.

Left side of the neck. Purplish-blue vessel toward the bottom/eft is the jugular vein, shown next. Nuchal ligament, shown further below, is toward the top.

The jugular vein, opened to show the valves, which prevent blood from flowing back down the neck.

The jugular vein, opened to show the valves (little pockets), which prevent blood from flowing back down the neck.

Cross-section of trachea (windpipe). A narrow tube should give less dead space to move in/out with each breath, so it makes sense for such a huge, long-necked animal to have such a thin trachea.

Cross-section of trachea (windpipe). A narrow tube should give less dead space to move in/out with each breath, so it makes sense for such a huge, long-necked animal to have such a thin trachea.

The nuchal ligament, which runs along the spine and helps hold up that long neck.

The nuchal ligament, which runs along the spine and helps hold up that long neck.

The big heart, needed to pump blood up that long neck to the head.

The big heart, needed to pump blood up that long neck to the head. Compare with the elephant and rhino hearts posted here before.

Left shoulder and ribcage, muscles peeled back.

Left shoulder and ribcage, muscles of the triceps peeled back. Shoulder blade (scapula) visible. The neck extends up to the left corner.

Left side of chest, rumen showing through behind ribcage.

Left side of chest, rumen (fermenting tank) showing through behind ribcage. Forelimb has been entirely removed here.

The left cheek's teeth-- and check out the spines on the inside of the cheek! Keratinous growths to aid in chewing, food movement, digestion etc. These extend into the stomach, too! Amazed me first time I saw them, in an okapi (giraffe cousin).

The left cheek’s teeth (molars)– and check out the spines on the inside of the cheek! They are keratinous growths to aid in chewing, food movement, digestion, protection against thorns, etc. These extend into the stomach, too! These amazed me the first time I saw them, in an okapi (giraffe cousin).

The brain.

The brain, in bottom view. Olfactory nerves leading to the nostrils near the top (whitish), and optic chiasm for the eyes (“X” shape behind the olfactory nerves) are visible, then the medulla oblongata, smallish cerebellum and the spinal cord. For a human brain diagrammed and labelled in similar view, see here.

Like rhinos, elephants and many other large mammals, giraffes (especially in captivity) are vulnerable to foot/hoof pathologies, such as this very skewed/divergent pair of nails. This can lead to them walking very abnormally, getting infections or arthritis and other problems, so it is very serious.

Like rhinos, elephants and many other large mammals, giraffes (especially in captivity) are vulnerable to foot/hoof pathologies, such as this very skewed/divergent pair of nails on the right front foot. This can lead to them walking very abnormally, getting infections or arthritis and other problems, so it is very serious.

The tapetum; reflective coating of the eye that can aid in night vision and protect the eye a bit. Gorgeous!
The tapetum lucidum; reflective coating of the eye that can aid in night vision and protect the eye a bit. Gorgeous!

Hope to see you again here soon!

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Well, I’ve been pretty busy with grant-writing and other stuff lately, so I’ve been neglecting my beloved blog. Here is a little sequel to my Animal Inside Out exhibit review, from my 2nd visit there, yesterday. I had previously missed the “3-headed camel” that is in one corner of the great hall (the Diplodocus one overlooked by Darwin). Because that is outside the special exhibit, there are no issues with taking photos, although I must apologize that as usual I just had my mobile phone’s camera. So here you go– a camel anatomy extravaganza. Too bad I didn’t do this on Hump Day

(beefy reward at end for those who view all the pics)

Front view.

Side view.

Back right view. Naughty boy trying to grab the guts. It’s not a petting zoo, kid!

Back view. Kid nearly has snatched some precious entrails.

Front right view.

Cranial view of forelimb. Now I’m starting to get pretty interested in documenting the muscle anatomy for my own records. These AIO displays really do clearly show the myology.

Nice view of right triceps, latisssimus, carpal extensors/flexors, etc.

Guts, glorious guts! Beautifully sectioned stomach, showing “pseudoruminant” three-chambered structure and smaller compartments within.

Right hindlimb, rear/side view. Great view of semimembranosus/tendinosus, biceps femoris, superficial gluteal, tensor fasciae latae?

Left distal hindlimb, side view, emphasizing (toward bottom right) calcaneal “Achilles” tendon, and possibly a slip of the very reduced plantaris muscle? Also distal tendon of hamstrings prominently visible, with belly toward top of image (dark).

Left forelimb, showing elbow region with triceps/anconeus, more carpal flexors/extensors.

Great exhibit. No bullshit.

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