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Posts Tagged ‘integument’

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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Jason Anderson, vertebrate paleontologist and anatomist at the University of Calgary (Canada), shared these two intriguing photos with me, and agreed for me to share them with you. Yay, thanks Jason! Good timing for a badly needed Mystery Dissection post:

What are they (species ID) *AND* from what region of the body?

(they are the same region, same specimen, same animal)

RULE: Your answer must be in the form of a winter holiday song (at least four lines)!

If you’ve been following some of my recent tweets, I’ve been tweeting about the “joys” of increased academic paperwork around holiday-time; e.g. this one:

As always, you can score extra points for creativity.

Remember: the scoreboard is here.

Difficulty: Integumentary

Stomach-Churning Rating: 6/10; if beauty is only skin deep, then ugly is, too?

Here they are…

(more…)

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frontcover

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

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

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

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

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

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

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

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

Naked kiwi in action.

Naked kiwi in action.

The unscaled bird: guineafowl feet.

The unscaled bird: guineafowl feet.

Deplumed sparrowhawk with dove trophy, exalting in its triumph.

Deplumed sparrowhawk with dove trophy, exalting in its triumph.

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

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

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

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

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

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

Poster advert for the book in the Tring collections.

Poster advert for the book in the Tring collections.

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

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

Tring exhibit now ready.

Tring exhibit now ready.

Tring exhibit case.

Tring exhibit case.

Framed sketches at Tring exhibit.

Framed sketches at Tring exhibit.

Framed sketches at Tring exhibit.

More framed sketches at Tring exhibit.

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

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

Framed sketch of dodo head at Tring exhibit.

Framed sketch of dodo head at Tring exhibit.

Entirely unfeathered Indian peafowl in matching views.

Entirely unfeathered Indian peafowl in matching views.

Painted Stork and Toco Toucan sketches.

Painted Stork and Great Hornbill sketches.

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

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

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

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A superficial little post for you today, with a skinny specimen from the freezers. What is it, what/where from, etc; tell me what you know about it!

(upper object, not the ruler…)

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Like other birds, ostriches are fluffy. Too fluffy for some anatomists– so fluffy, it’s hard imagining or estimating what they look like beneath all the feathers. A few years ago, we received an ostrich from a UK farmer. The male bird had been killed by a kick to the neck from another rival, and at the time was supposedly “Britain’s largest ostrich.” As the feathers were valuable to him, the farmer delivered the animal to us whole but plucked. I wanted to dissect it mainly to refresh my memory on ostrich anatomy while developing a biomechanical model of their limbs (see below). Taphonomy expert Jason Moore then buried it for his studies of how bodies decompose.

[Side note: ostriches and other ratites (flightless birds, members of the palaeognath group, whose evolution remains fascinatingly complex) are often brought up as uniquely dinosaur-like. That’s rather misleading; all birds are living dinosaurs, so all birds are descended from an ancestor that was equally ‘dinosaur-like’. What we see of them today is a snapshot that is biased by their recent evolutionary history. During their apparently multiple losses of flight, ratite birds increased in body size and “re-evolved” (or simply enhanced) some traits that were more marked in extinct dinosaurs than in the most recent common ancestor of living birds. Some of those more ‘primitive’ traits may be due to flightlessness, some due to large size, some due to their extreme running specializations; science hasn’t sorted all that out just yet. But the point is, ostriches and other ratites are far from the ancestral form that all birds sprung from, which was probably more like a small, flying tinamou-like animal. Their similarities are due to convergent evolution. And they’re still quite different from something like an “ostrich-mimic” dinosaur- which is a sad misnomer because it’s more that ostriches mimicked (in a naughty teleological sense) ostrich-mimic dinosaurs like Struthiomimus than the other way around; the ornithomimosaurs did it first (Huzzah!). Ratites have just gone back, in some ways but not others (e.g. no long tail or large arms) to a superficially more primitive body form. There have been some wacky ideas to the contrary before, such as the idea that ratites evolved entirely separately from other living birds from different dinosaur stock, but they’re so discredited now by multiple lines of evidence that I won’t glorify them by spending time discussing each. This tangent has gone on too long and must die.]

Anyway, back to the plucked ostrich in question. My first look at it really stunned me. It was a powerful example of just how ‘dinosaurian’ most of the anatomy of living birds is, for reasons noted above. I’d never seen a naked ostrich and now I’ll never look at them the same again. Maybe you won’t, either…

First, some images of the animal once it was brought into our dissection room (which you might recognize from the great Inside Nature’s Giants documentary).

The device near the top of the screen is a digital scale; we were weighing the bird before we cut in…

Close-up view of the hugely muscular legs (each leg is around 25% of the animal’s body weight, and mostly muscle; about 50% more bulky than our legs), and the arms (shown more below).

129 kg weight sans feathers; not bad! That’s about 284 pounds for those folks still mired in the medieval Imperial system of units. 🙂

The swollen, bloody region just below the head (on the left above) is where the mortal blow struck. Ouch!

I love the hands of ratite birds. Yes, those are little claws attached to the three vestigial fingers (thumb/first finger at top, long middle finger, and tiny third finger bound to it). Darren Naish covered some of this in a previous post, and let’s not forget SV-POW’s excellent series of “things to make and do” involving various critters including ostriches.

Ostriches and I go way back. Here I am from my less bald immature postdoctoral days at Stanford University in 2002, dissecting a smaller (female, 65kg) ostrich for some biomechanical modelling (still mostly unpublished; aaargh!).

And yes, I had a third hand back then; later lost during a tragic dissection incident involving a battleaxe and a bottle of tequila. I don’t want to talk about that.

Ostrich packed for transport. Just barely fit in the trunk of my little 1993 Toyota Tercel (R.I.P.)!

Once we complete dissections. we put everything together in some fancy biomechanical computer models (a subject of a future post), resulting in a nice, 3D,  poseable, anatomically-realistic model of the entire limb musculature, shown above. This is a right hindlimb in side view, with the individual muscle paths abstracted as red lines. More about this when it is finally published…

This is just a teaser showing off some of the cool external anatomy of ostriches-in-the-buff, and what we’ve done with the anatomical data we’ve gathered. I’ll do a post later showing what’s inside, which is also pretty amazing. Hope you enjoyed it!

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