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Posts Tagged ‘boids’

I had a spare hour in Cambridge this weekend so I dared the crowds in the revamped UMZC’s upper floor. In my prior visit and post I’d experienced and described the lower floor, which is almost exclusively mammals. This “new” floor has everything else that is zoological (animal/Metazoa) and again is organized in an evolutionary context. And here is my photo tour as promised!

Inviting, soft lighting perfuses the exhibits from the entryway onwards.

All images can be clicked to mu-zoom in on them.

Stomach-Churning Rating: 5/10 for spirit animals, by which I mean dissected/ghostly pale whole specimens of animals in preservative fluids.

The exhibits are on a square balcony overlooking the lower floor, so you can get some nice views. It does make the balcony crowded when the museum is busy, so take that in mind if visiting. Strollers on this upper floor could be really difficult. But the ceiling is very tall so it is not cramped in a 3D sense. The lower floor is more spacious.

Like phylogenies? You got em! Tucked away at the beginning of each major group; not occupying huge valuable space or glaringly obvious like AMNH in NYC but still noticeable and useful. To me, it strikes a good balance; gives the necessary evolutionary context for the displayed specimens/taxa.

Introductory panels explain how names are given to specimens, how specimens are preserved and more.

The exhibits give due focus to research that the UMZC is doing or has been famous for. Hey I recognize that 3D tetrapod image in the lower left! ūüôā

There is ample coverage of diversity throughout Metazoa but my camera tended to be drawn to the Vertebrata. Except in some instances like these.

Some larger chelicerates.

Some smaller, shadowy sea scorpion (eurypterid) fossils.

Watch here for more about ophiuroids (brittlestars) in not too long!

A BIG fish brain! Interesting!
Before I go through specimens in evolutionary “sequence”, I will feature another thing i really liked: lots of dissected spirit-specimens that show off cool anatomy/evolution/adaptation (and technical skills in anatomical preparation). Mostly heads; mostly fish.

Salps and other tunicates! Our closest non-vertebrate relatives- and some insight into how our head and gut came to be.

Salp-reflection.

Lamprey head: not hard to spot the commonalities with the salps; but now into Vertebrata.

Hagfish head: as a fellow cyclostome/agnathan, much like a lamprey but never forget the slime glands!

Shark head. Big fat jaws; all the better to bite prey with!

Lungfish (Protopterus) head showing the big crushing tooth plates (above).

Sturgeon vertebrae: tweak some agnathan/shark bits and here you are.

Worm (annelid) anatomy model, displaying some differences from/similarities to Vertebrata. (e.g. ventral vs. dorsal nerve cord; segmentation)

Dissected flipper from a small whale/other cetacean. Still five fingers, but other specializations make it work underwater.

Wonderful diversity of tooth and jaw forms in sharks, rays and relatives. I like this display a lot.

More of the above, but disparate fossil forms!

On with the evolutionary context! Woven throughout the displays of modern animals are numerous fossils, like these lovely placoderms (lineage interposed between agnathans, sharks and other jawed fish).

Goblin shark head.

I seem to always forget what ray-finned fish this is (I want to say wolffish? Quick Googling suggests maybe I am right), but see it often and like its impressive bitey-ness.

Bichir and snakefish; early ray-finned fish radiations.

Armoured and similar fish today.

Armoured fish of the past; some convergent evolution within ray-fins.

Convergence- and homology- of amphibious nature in fish is another evolutionary pattern exemplified here.

Gorgeous fossils of ray-finned fish lineages that arose after the Permian extinctions, then went extinct later in the Triassic.

Note the loooooong snout on this cornetfish but the actual jaws are just at the tip.

Flying fish– those ray-fins are versatile.

Diversity of unusual ray-finned fish, including deep-water and bottom-dwelling forms.

Can you find the low-slung jaws of a dory?

Recent and fossil perch lineage fish.

It’s hard to get far into talking about evolution without bringing up the adaptive radiation of east African cichlid fish, and UMZC researchers are keen on this topic too.

Lobe-fins! Everybody dance!

Rhizodonts & kin: reasons to get out of Devonian-Carboniferous waters.

A Cretaceous fossil coelacanth (skull); not extremely different from living ones’.

Let’s admire some fossil and modern lungfish skulls, shall we? Big platey things¬† (here, mainly looking at the palate) with lots of fusions of tiny bones on the skull roof.

Eusthenopteron fossils aren’t that uncommon but they are still great to see; and very important, because…

OK let’s stop messing around. The UMZC has one of the best displays of fossil stem-tetrapods in the world! And it should.

Another look at the pretty Acanthostega models.

Acanthostega vs. primate forelimb: so like us.

Ichthyostega parts keep Acanthostega company.

A closer look at the “Mr. Magic” Ichthyostega specimen, which takes some unpacking but is incredibly informative and was a mainstay of our 2012 model. Back of skull, left forelimb, and thorax (from left to right here).

Eucritta, another stem-tetrapod.

Closer look at Eucritta‘s skull.

Weird stem-tetrapod Crassigyrinus, which we’re still trying to figure out. It’s a fabulous specimen in terms of completeness, but messy “roadkill” with too many damn bones.

The large skull of Crassigyrinus, in right side view.

Early temnospondyl (true amphibian-line) skulls and neck.

Nectrideans or the boomerangs of the Palaeozoic.

Cool fossil frogs.

Giant Japanese salamander!

Fire salamanders: not as colourful as the real thing, but here revealing their reproductive cycle in beautiful detail.

Closeup of oviduct in above.

Sexual dimorphism in Leptodactylus frogs: the males have bulging upper arms to (I am assuming) help them hold onto females during amplexus (grasping in mating competitions).

Did I forget that Leptodactylus has big flanges on the humerus in males, to support those muscles? Seems so.

An early stem-amniote, Limnoscelis (close to mammals/reptiles divergence); cast.

Grand sea turtle skeleton.

One of my faves on display: a real pareiasaurian reptile skeleton, and you can get a good 3D look around it.

Details on above pareiasaurian.

Mammals are downstairs, but we’re reminded that they fit into tetrapod/amniote evolution nonetheless.

Let there be reptiles! And it was good.

Herps so good.  (slow worm, Gila monster, glass lizard)

A curator is Dr Jason Head so you bet Titanoboa is featured!

Crocodylia: impressive specimens chosen here.

It ain’t a museum without a statuesque ratite skeleton. (There are ~no non-avian dinosaurs here– for those, go to the Sedgwick Museum across the street, which has no shortage!)

Avian diversity takes off.

Glad to see a tinamou make an appearance. They get neglected too often in museums- uncommon and often seemingly unimpressive, but I’m a fan.

I still do not understand hoatzins; the “cuckoo” gone cuckoo.

Dodo parts (and Great Auk) near the entrance.

Wow. What an oilbird taxidermy display! :-O

There we have it. Phew! That’s a lot! And I left out a lot of inverts. This upper floor is stuffed with specimens; easier there because the specimens are smaller on average than on the lower floor. Little text-heavy signage is around. I give a thumbs-up to that– let people revel in the natural glory of what their eyes show them, and give them nuggets of info to leave them wanting more so they go find out.

Now it’s in your hands– go find out yourself how lovely this museum is! I’ve just given a taste.

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An epiphysean Sispyhean task today: solve this mystery that has been bothering me for >15 years. It’s about bird knees. Read on.

Stomach-Churning Rating: 1/10- bones and brief words. Nothing to worry about.

Here is an ostrich. I was interviewing undergrads the other day and looked up to see it, then thought something like: “Oh yeah, that little bit of bone really bothers me. I cannot figure it out.” What little bit of bone?

Right leg, side view, ostrich…

This little bit of bone. Zooming in on that ostrich’s knee:

Who am I? (femur above; tibiotarsus below; “PTE” is the crest of bone with the white arrow on it)

The little bit of bone is not talked about much in the scientific literature on bird knees. But we know it’s there and it is part of the composite bone called the tibiotarsus (ancestral tibia, this bit of bone, and the proximal tarsal [ankle] bones on the other end; the astragalus and calcaneum of earlier dinosaurs).

What is it? We call it something like the proximal tibial epiphysis (PTE for short, here). An epiphysis is an end of a bone that fuses up with the shaft during growth, around the time of skeletal maturity; ultimately ending longitudinal (length-wise) growth of that bone. Mammals almost ubiquitously have them. So do lizards and tuataras. And some fossil relatives. Not much else– except birds, in this particular region (the two ends of the tibiotarsus; also in the foot region; the tarsometatarsus; which also has its share of mysteries such as the hypotarsus; I won’t go there today).¬†You can see the PTE in mostly cartilaginous form if you take apart a chicken drumstick.

This PTE, like other well-behaving epiphyses, fuses with the tibiotarsus in mature birds, forming one bone. But the young ostrich’s knee above shows the PTE nicely; and other living birds show more or less the same thing.

It begs for explanations. I’ve talked about it in a few of my papers. But I’ve always punted on what it really means– does it have anything to do with the patella (they appear at similar times in evolution; we know that much, roughly)? Where does it come from, developmentally? (we sort of know that but more work is needed in different species and in high resolution) When did it evolve? What does it tell us? Why is it there in living birds and almost no other extinct birds/other dinosaurs? Does it have anything to do with why birds, during their evolution, seem to gradually increase the fusion of skeletal elements or ossify new ones (tendons, kneecaps, etc)? Why here and not in the femur or several other long bones of birds? How much do these PTEs vary between (or within) bird species?

This is the challenge in the post’s title. I present to you: solve this puzzle. Developmentally, biomechanically, evolutionarily, genetically, whatever– why does this PTE happen? There are hints– e.g. this paper proposes why growth rates of long bones favour the formation of “secondary centres of ossification” like this. But I’m unable to satisfy myself with any solutions I can find. Maybe you can complete The Bird Knee Challenge?

Have a go at it in the Comments below! There are plenty of papers or even a grant or something involved in sorting out this single mystery; one of the many basic mysteries about animal anatomy.

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Putting my morphologist hat back on today, I had an opportunity to dissect an Elegant-crested tinamou (Eudromia elegans) for the second time in my life. The last time was during my PhD work ~20 years ago. In today’s dissection I was struck by another reminder of how studying anatomy is a lifelong learning experience and sometimes it’s really fun and amazing even when it’s stinky.

Tinamou foot. I did know that tinamous don’t have a hallux; big “perching toe” (1st/”big toe” in us); true of ratites/palaeognaths more generally. Unlike a chicken or many other birds. Just the three main toes (2, 3 and 4) are here.

Stomach-Churning Rating: 7/10; you gotta have guts to learn about intestine-churning stuff.

Tinamous are neat little partridge-like ground birds but they are not close cousins of partridges or guineafowl at all. Their closest cousins are other ratites/palaeognaths such as ostriches and kiwis. And hence they are found in South America, especially Patagonia in Argentina. I’ve seen them there, much to my enjoyment.

Said tinamou.

What struck me today was that, as I delved into the digestive system of this bird, I saw features that were unfamiliar to me even after having dissected many species of birds from many lineages. The intestinal region was very lumpy, with little bud-like pockets full of dense droppings. Furthermore, on separating the tubes of the small and large intestines I realized that most of the intestinal volume itself was caecum (normally a modest side-pocket near the juncture of the small and large intestines). Indeed, that caecum was caeca (plural): it had two massive horns; it was a double-caecum, feeding back into the short rectum and cloaca. Birds have variable caeca and it is typical to see subdivision into two parts, but I’d never seen it to this degree.

Oh why not, here’s the gizzard/stomach showing its grinding pebbles and bits of food, plus the strong outer muscle layers (pink) for driving that grinding. Small intestine heads toward the bottom of the image. Yes, we do need a better dissection light…

I had to question my anatomical knowledge at this point, wondering if I was identifying things incorrectly‚ÄĒdid I really screw up somehow and these were other organs, like giant ovaries? But no, they were clearly full of faecal matter; they were digestive organs. I finished the dissection, still puzzled, and hit the literature. Right away, Google-Scholaring for ‚Äútinamou caecum‚ÄĚ I found the answer, here (free pdf link):

‚Äúat least one species (Elegant Crested Tinamou, [Eudromia elegans]), the ceca contain multiple sacculations, resulting in structures that look much like two bunches of fused grapes.‚ÄĚ

The caeca in question.

OK buddy, those are the little lumpy buds I saw. Bunches of grapes‚ÄĒexactly.

And later:

‚ÄúThe paired ceca of the Elegant Crested Tinamou are extraordinary and probably unique within Aves (Fig. 3): long and wide (12.5-13.0 X 2.2- 2.5 cm; Wetmore 1926) and internally honeycombed by many small diverticula. These outpocketings gradually diminish in size and organization from the base to the tip of the organ, apically showing a more spiral form of internal ridges like ratite ceca. Externally, the basal diverticula protrude from the ceca as pointed lobes, gradually becoming flatter but still clearly apparent toward the organ‚Äô s tip.‚ÄĚ

Whoa! I never knew that! So I happened to be dissecting a bird, fairly common in its homeland, that has a really bizarre and singular form of caeca/ceca! That hit my morphologist sweet-spot so I was very pleased and decided to share with you. It is one of those many examples of times when you quickly go from confusion to illumination as a scientist, emerging with a neat fact about animal biology. And journal articles help you get there!

The bare “brood patch” on the back end of the tinamou’s belly; a nicely hotspot for keeping eggs warm. Perhaps for brooding bad puns, too.

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Uh oh, a ‚Äúwhy?‚ÄĚ question in biology! There are many potential, and not mutually exclusive, answers to such questions. Ultimately there is a historical, evolutionary answer that underpins it all (‚Äúostriches evolved two kneecaps because‚Ķ‚ÄĚ). But we like ostrich knees and their funky double-kneecaps (patellae; singular = patella) so we wanted to know why they get so funky. One level of addressing that question is more like a ‚Äúhow?‚ÄĚ they have them. So we started there, with what on the surface is a simple analysis. And we published that paper this week, with all of the supporting data (CT, MRI, FEA).

Stomach-Churning Rating: 6/10 because there is a gooey image of a real dissection later in the post, not just tidy 3D graphics.

First author Kyle Chadwick was my research technician for 2 years on our sesamoid evolution grant, and we reported earlier on the detailed 3D anatomy of ostrich knees (this was all part of his MRes degree with me, done in parallel with his technician post). Here, in the new paper with Sandra Shefelbine and Andy Pitsillides, we took that 3D anatomy and subjected it to some biomechanical analysis in two main steps.

Ostrich (right) knee bones. The patellae are the two knobbly bits in the knee.

First, we used our previous biomechanical simulation data from an adult ostrich (from our paper by Rankin et al.) to estimate the in vivo forces that the knee muscles exert onto the patellar region during moderately large loading in running (not maximal speed running, but ‚Äújogging‚ÄĚ). That was ‚Äújust‚ÄĚ (Kyle may laugh at the ‚Äújust‚ÄĚ– it wasn‚Äôt trivial) taking some vectors out of an existing simulation and adding them into a detailed 3D model. We‚Äôve done similar things before with a horse foot‚Äôs bones (and plenty more to come!), but here we had essentially all of the soft tissues, too.

Ostrich knee with muscles as 3D objects.

Second, the 3D model that the muscular forces were applied to was a finite element model: i.e., the original 3D anatomical model broken up into a mesh, whose voxels each had specific properties, such as resistance to shape change under loading in different directions. The response of that model to the loads (a finite element analysis; FEA) gave us details on the stresses (force/area) and strains (deformations from original shape) in each voxel and overall in anatomical regions.

Finite element model setup for our study. If you do FEA, you care about these things. If not, it’s a pretty, sciencey picture.

The great thing about a computer/theoretical model is that you can ask ‚Äúwhat if?‚ÄĚ and that can help you understand ‚Äúhow?‚ÄĚ or even ‚Äúwhy?‚ÄĚ questions that experiments alone cannot address. Ostriches aren‚Äôt born with fully formed bony kneecaps; indeed those patellae seem to mature fairly late in development, perhaps well after hatching. We need to know more about how the patellae form but they clearly end up inside the patellar (knee extensor) tendon that crosses the knee. So we modelled our adult ostrich without bony patellae; just with a homogeneous patellar tendon (using the real anatomy of that tendon with the bony bits replaced by tendon); and subjected it to the loading environment for ‚Äújogging‚ÄĚ.

The right knee of an ostrich hatchling. The patellae have yet to form; indeed there is little bone around the knee region at all, yet.

We then inspected our FEA‚Äôs results in light of modern theory about how tissues respond to loading regimes. That ‚Äúmechanobiology‚ÄĚ theory, specifically ‚Äútissue differentiation‚ÄĚ, postulates that tendon will tend to turn into fibrocartilage if it is subjected to high compression (squishing) and shear (pushing). Then, the fibrocartilage might eventually be reworked into bone as it drops the compression and shear levels. So, according to that theory (and all else being equal; also ignoring the complex intermediate states that would happen in reality), the real ostrich‚Äôs kneecaps should be located in the same positions where the FEA, under the moderately large loads we applied, predicts the homogeneous tendon to have high compression and shear. But did the real anatomy match the mechanical environment and tissue differentiation theory‚Äôs predictions?

Tissue differentiation diagram displaying the theoretical pathways for transformation of tissues. If tendon (red) experiences high shear (going up the y-axis) and high compression (going toward the left), it should turn into fibrocartilage (purple). Transformation into bone (diagonally to the bottom right) would reduce the shear and compression.

Well, sort of. The image below takes some unpacking but you should be able to pick out the red areas on the bottom row where the patellae actually are, and the yellow shaded regions around some of those patellar regions are where the compression and shear regimes are indeed high and overlapping the actual patellar regions. The upper two rows show the levels of compression (or tension; pulling) and shear, but the bottom row gets the point across. It‚Äôs not a bad match overall for the first (‚Äúreal‚ÄĚ; common to all living birds) patella, located on top of the upper knee (femur). It‚Äôs not a good match overall for the second (unique to ostriches) patella, located below the first one (and attached to the tibia bone).

FEA results! (click to embiggen)

Kyle says, ‚ÄúBeing a part of this project was exciting because of the application of engineering concepts to interesting biological (including evolutionary) questions. Also, it never gets old seeing people‚Äôs reactions when I tell them I study ostrich knees.‚ÄĚ

The study had a lot of nuances and assumptions. We only looked at one instant in slow running and only at one adult ostrich, not at the full development of ostrich anatomy and loading. That’s harder. We started simple. The tissue differentiation theory is used more for fracture healing than for sesamoid bone formation but there’s some reason to suspect that similar mechanisms are at play in both. And there’s much more; if you want the gory details see the paper.

So did we solve why, or how, ostriches have two kneecaps? We felt that the mechanical environment of our FEA was a good theoretical explanation of where the first patella forms. We originally expected the second patella, which evolved more recently and might be more mechanically sensitive as a result, to be a better match than the first one, but it was the opposite. C’est la science!

Enough models, let’s have some reality! I warned you this post would get messy, and here it is. Left leg (skinned) of an ostrich showing the muscles around the knee. The patellar region would be in the gloved hand of the lucky individual shown.

This study, for me, was a fun experience in moving toward more fusion of “evo-devo” and biomechanical analyses, a research goal of mine lately– but there’s still a ways to go with the “how?” and “why?” questions even about ostrich kneecaps.

We felt that the best conclusion supported by our analyses was that, rather than have homogeneous stresses and strains throughout their knee tissues (e.g. the patellar tendon), ostriches have a lot of regional diversity in how those tissues are loaded (in the condition we modelled, which is adequately representative of some athletic exertion). Look at the complex FEA coloured results above again, the top two rows: there are a lot of different shades of compression/tension and shear; not homogeneous strains. That diversity of regional loading sets those tissues up for potential transformation throughout growth and development. And thus ONE of the reasons why ostriches might have two kneecaps is that the heterogeneous loading of their knee tendon favours formation of heterogeneous tissue types.

Another, compatible, explanation is that these different tissues might have consequences for how the muscles, tendon and joint operate in movement behaviours. In due time there will be more about that. In the meantime, enjoy the paper if this post makes you want to know more about the amaaaaaazing knees of ostriches!

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I have an impression that there is a large disparity between how the public views museums and how scientists who use museums view them. Presumably there are survey data on public attitudes, but surely the common impression is¬†that museums mainly exist to exhibit cool stuff and educate/entertain the public. Yet, furthermore, I bet that many members of the public don’t really understand the nature of museum collections (how and why they are curated and studied) or what those collections even look like. As a researcher who tends to do heavily¬†specimen-oriented and often museum-based research, I thought I’d take the opportunity to describe my experience at one museum collection recently. This visit was fairly representative of what it’s like, as a scientist, to visit a museum with the purpose of using its collection for research, rather than mingling with the public to oggle the exhibits — although I did a little of that at the end of the day…

Stomach-Churning Rating: 4/10; mostly bones except a jar of preserved critters, but also some funky bone pathologies! Darwin hurls once, totally blowing chunks, but only in text.

Early camel is sitting down on the job at the NHMLA.

Early camel is sitting down on the job at the NHMLA.

About two weeks ago, I had the pleasure to spend a fast-paced day in the Ornithology collection of the Natural History Museum of Los Angeles County (NHMLA or LACM). I arranged the visit (you have to be a credible researcher to get access; luckily I seemed to be that!) via email, took an Uber car to the museum, and was quickly cut loose in the collection. I was hosted by the Collections Manager Kimball Garrett, who is an avid birder (adept at citizen science, too!) and a longtime LA native.

Amongst museum curators and collections managers (there can be a distinction between the two but here I’ll refer to them all as “curators”), there is a wide array of attitudes toward and practices with museum collections, regarding how the curators balance their varied duties of not only making the museum collection accessible to researchers (via behind-scenes studies) and the public (via exhibits and behind-scenes tours etc.), but also curation (maintaining a record of what they have in their collection, adding to it, and keeping the specimen in good condition), research, admin, teaching and other duties.

Most curators I’ve known, like Kimball, are passionate about all of these things, and very generous with their time to help scientists make the most of the collection during their visit, offering hospitality and cutting through the bureaucracy as much as possible to ensure that the science gets done. There are those few curators that aren’t great hosts because they’ve had a bad day or a bad attitude (e.g. obsession with paperwork and finding obstacles to accessing specimens for research; or just not responding to communication), but they are few and far between in my experience.

Regardless, the curator is the critical human being that keeps the wheels of specimen-based museum research rolling, and I am appreciative of how deeply dedicated and efficient most curators are. Indeed, I enjoy meeting and chatting with them because they tend not only to be fun people but also incredibly knowledgeable about their collection, museum, and area of expertise. Sadly, this trip was so time-constrained that I didn’t get much time at all for socializing. I had about five hours to get work done so I plunged on in!

Images, as always, can be clicked to emu-biggen them. Thanks to the NHMLA for access!

My initial look down the halls of the osteology storage. Rolling cabinets (on the right) are a typical sight.

My initial look down the halls of the osteology storage. Rolling cabinets (on the right) are a typical sight.

Freezers ahoy!

Freezers ahoy! With Batman watching over them.

A jar of bats? Why not? Batman approves.

A jar of bats? Why not? Batman approves.

The curator cleared a space on a table for me to set bones on. Then the anatomizing and photographing began!

The curator cleared a space on a table for me to set bones on. Then the anatomizing and photographing began!

On entering a museum collection, one quickly gets a sense of its “personality” and the culture of the museum itself, which emerges¬†from the curator, the collection’s history, and the museum’s priorities. There are fun human¬†touches like the ones in the photos below, interspersed between the stinking carcasses awaiting skeletonization, the crumbling bone specimens¬†on tables that need repair or new ID tags, or the rows upon rows of coffee cups ready to fuel the staff’s labours.

Yet another reason why Darwin kicks ass.

Yet another reason why Darwin kicks ass. And fine curator-humour!

Ironic bird pic posted on the wall.

Ironic bird pic posted on the wall.

Below a typical wall-hanging of a bovid skull, an atypical display of a clutch of marshmallow peeps. Contest to see whether the mammalian or pseudo-avian specimens last longest?

Below a typical wall-hanging of a bovid skull, an atypical display of a clutch of marshmallow peeps. Contest to see whether the mammalian or pseudo-avian specimens last longest?

The NHMLA’s collection is a world-class one, which I why I chose it as the example for this post. When I entered the collection, I got that staggering sense of awe that I love feeling, to look down the halls of cabinets full of skeletonized specimens of birds and be overwhelmed by the vast scientific resource it represents, and the effort it has taken to create and maintain it. Imagine entering a library in which every book had the librarian’s hand in writing and printing it, and that those books’ contents were largely mysteries to humanity, only some of which you could investigate during your visit. Museum collections exist to fuel generations of scientific inquiry in this way. Their possibilities are endless. And that is why I love visiting them, because every trip is an adventure into the unknown– you do not know what you will find. Like these random encounters I had in the collection’s shelves:

Sectioned moa thigh bones, showing thick walls and spars of trabecular bone criss-crossing the marrow cavities.

Sectioned moa thigh bones, showing thick walls and spars of trabecular bone criss-crossing the marrow cavities.

My gut reaction was that this is a moa wishbone (furcula)- not often seen! It is definitely not a shoulder girdle (scapulocoracoid), which would be larger and more robust, and have a proper shoulder joint. It could, though, be a small odd rib, I suppose.

My gut reaction was that this is a moa wishbone (furcula)- not often seen! It is definitely not a shoulder girdle (scapulocoracoid), which would be larger and more robust, and have a proper shoulder joint. It could, though, be a small odd rib, I suppose. EDIT: Think again, John! See 1st comment below, and follow-ups. I seem to be totally wrong and the ID of scapulocoracoid is right.

A cigar box makes an excellent improvised container for moa toe bones- why not?

A cigar box makes an excellent improvised container for moa toe bones- why not?

Moa feet: all the moa to love!

Moa feet: all the moa to love!

May the skull of the magpie goose (Anseranas semipalmata) haunt your nightmares.

May the skull of the magpie goose (Anseranas semipalmata) haunt your nightmares.

Double-owie: headed shank (tibiotarsus) bone of a magpie goose (Anseranas semipalmata). No mystery why this guy died: vet staff at the zoo tried to fix a major bone fracture, and it had time to heal (frothy bone formation) but presumably succumbed to these injuries/infection.

Healed shank (tibiotarsus) bone of the same magpie goose as above. It had its own nightmares! No mystery why this guy died: vet staff at the zoo tried to fix a major bone fracture (bracing it with tubes and metal spars), and it had time to heal (see the frothy bone formation) but presumably succumbed to these injuries/infection.

Kiwi (Apteryx australis mantelli) hand, showing feather attachments and remnant of finger(s).

Kiwi (Apteryx australis mantelli) hand, showing feather attachments and remnant of finger(s).

Now that I’m in the collection shelves area, it brings me to this trip and my purpose for it! I wanted to look at some “basal birds” for our ongoing patella (kneecap) evolution project, to check which species (or individuals, such as juveniles/adults) have patellae. Every museum visit as a scientist is fundamentally about testing whether what you think you know about nature is correct or not. We’d published on how the patella evolved in birds, but mysteries remain about which species definitely had a patella or how it develops. Museum collections often have the depth and breath of individual variation and taxonomic coverage to be able to address¬†such mysteries, and every museum collection has different strengths that can test those ideas in different, often surprising, ways. So I ventured off to see what the NHMLA would teach me.

Shelves full of boxes, begging to be opened- but unlike Pandora's box, they release joyous science!

Shelves full of boxes, begging to be opened- but unlike Pandora’s box, they release joyous science!

Boxes of kiwis, oh frabjous day! A nice sample size like this for a "rare" (to Northern hemispherites) bird is a pleasure to see.

Boxes of kiwis, oh frabjous day! A nice sample size like this for a “rare” (to Northern hemispherites) bird is a pleasure to see.

Well, in my blitz through this museum collection¬†I didn’t see a single damn patella!

As that kneecap bone is infamously seldom preserved in nice clean museum specimens, this did not surprise me. So I took serendipity by the horns to check some of my ideas about how the limb joints in birds in general develop and evolve. One thing I’ve been educating myself about with my freezer specimens and with museum visits (plus the scientific literature) is how the ends (epiphyses) of the limb bones form in different species of land vertebrates (tetrapods). There are complex patterns linked with evolution, biomechanics and development that still need to be understood.

Left side view of the pelvis of a very mature, HUGE Casuarius casuarius (cassowary). The space between the ilium (upper flat bone) and ischium (elongate bone on middle right side) has begun to be closed by a mineralization of the membrane that spanned those bones in life. A side effect of maturity, most likely. But cool- I've never seen this in a ratite bird before, that I can recall.

Left side view of the pelvis of a very mature, HUGE Casuarius casuarius (cassowary). The space between the ilium (upper flat bone) and ischium (elongate bone on middle right side) has begun to be closed by a mineralization of the membrane that spanned those bones in life. A side effect of maturity, most likely. But cool- I’ve never seen this in a ratite bird before, that I can recall.

Hatchling ostrich thigh bones (femora), showing the un-ossified ends that in life would be occupied by thick cartilage.

Hatchling ostrich thigh bones (femora), showing the pitted, un-ossified ends that in life would be occupied by thick cartilage.

A more adult ostrich's femora, with more ossified ends and thinner cartilages.

A more adult ostrich’s femora, with more ossified ends and thinner cartilages.

Rhea pennata (Darwin's rhea) femora (thigh bones), left (top) one with major pathology on the knee end; overgrown bone. Owie!

Rhea pennata (Darwin’s rhea) femora; right¬†(top) one with a major pathology on the knee end; overgrown bone (osteoarthritis?). Owie!

Also very-unfused knee joints of a Darwin's rhea. Cool Y-shape!

Also very-unfused knee joints of a Darwin’s rhea hatchling. Cool Y-shape!

In birds, most of the bones don’t have anything that truly could be called an epiphysis– the bone ends are capped with thick cartilage that only gradually becomes bone as the birds get older, and even old-ish birds can still have a lot of cartilage¬†(see photos above)– no “secondary centre” (true epiphysis) of bone mineralization ever forms inside that cartilage. However,¬†there are two curious apparent¬†exceptions to this absence of true epiphyses in avian¬†limbs:

(1) in the knee joint, something like an epiphysis forms on the upper end of the tibia (shank bone) and fuses during growth (shown below). Sometimes that unfused epiphysis is confused with a patella, as our recent paper discussed; in any case, where that “epiphysis” came from in avian evolution is unclear.¬†But also:

(2) in the ankle joint, several bones on both sides (shank and foot) of the joint fuse to the long-bones of the limbs, acting like epiphyses. It is well documented by the fossil record of non-avian and avian dinosaurs that these were the tarsals: at least five different bones (astragalus, calcaneum and distal tarsals) were individual bones for millions of years in various dinosaurs, then these all fused to form the “epiphyses” of the shank and foot, eventually completing this gradual fusion within the bird lineage. Modern birds obliterate the boundaries between these five or more bones as they grow.

These are worthwhile questions to pursue because they show us (1) how odd, little-explored features of the avian skeleton came to be; and (2) potentially more generally why limb bones develop the many ways they do in vertebrates, and how they might develop incorrectly — or heal if damaged.

Images below from the NHMLA collections show how this is the case. Fortunately(?) for me, they supported how I thought the “epiphyses” of avian limbs develop/evolved; there were no big surprises. But I still learned neat details about how this happens in individual species or lineages, especially for the knee joint.

Juvenile kiwi's shank (tibiotarsus) bones viewed from the top (proximal) ends, showing the bubbly nubbins of bone (very bottom of each bone image) that are the "cranial tibial epiphyses" often mistaken for patellae.

Juvenile kiwi’s shank (tibiotarsus) bones viewed from the top (proximal) ends, showing the bubbly nubbins of bone (very bottom of each bone image; lighter region) that are the “cranial tibial epiphyses” often mistaken for patellae.

Subadult kiwi's tibiotarsi in same view as above, showing the epiphyses fusing onto the tibiae.

Subadult kiwi’s tibiotarsi in same view as above, showing the smooth triangular epiphyses fusing onto the tibiae.

Adult kiwi's tibiotarsi (sorry, blurry photo) in which all fusion is complete.

Adult kiwi’s tibiotarsi (sorry, blurry photo) in which all fusion is complete.

Looking down at the top/ankle end of the tarsometatarsal (sole) bones in a hatchling ostrich: the three bones are separate and hollow, where "cartilage cones" would have filled them in.

Looking down at the top/ankle end of the tarsometatarsal (sole) bones in a hatchling ostrich: the three bones are separate and hollow, where “cartilage cones” would have filled them in. The left and right bones have different amounts of ossification; not unusual in such a young bird.

Ossified tendons (little spurs of long, thin bone) on the soles of the feet (tarsometatarsal bones) of a brush-turkey (Alectura lathami)- seldom described in this unusual galliform bird or its close relatives, and thus nice to see. These would be parts of the toe-flexor tendons.

Ossified tendons (little spurs of long, thin bone) on the soles of the feet (tarsometatarsal bones) of a brush-turkey (Alectura lathami)- seldom described in this unusual galliform bird or its close relatives, and thus nice to see. These would be parts of the toe-flexor tendons. Another nice thing about these two tarsometatarsus specimens is that their fusion is basically complete- each is one single bone unit, as in normal adult birds, rather than five or more.

My visit to the NHMLA bird bone collection was a lot of fun, because I got to do what I love: opening box after box of bone specimens, with bated breath wondering what would be inside. In this case, familiarity was inside, but my knowledge of avian bone development and evolution still improved. I got to look at a lot of ostriches, rheas, cassowaries and kiwis, more than I’d seen in one museum before, and that broadened my sample of young, juvenile and adult animals that I’d seen for these species. Their knees and ankles all grew in grossly similar ways, supporting this assumption in my prior work and building my confidence in published ideas. It’s always good to check such things.¬†Each box opened takes some careful observation and cross-checking against all the facts and ideas swirling around in your head. You take notes, scale photos, measurements, do comparisons between specimens, and just explore; letting your curiosity run unleashed as you assemble knowledge, Tetris-like, in your mind.

And I had a lot of fun because a museum collection visit is like swimming in anatomy. You’re surrounded by more specimens than you could ever fully comprehend. Sometimes you run across an odd specimen whose anatomy tells you something about its life, like pathologies such as the terrible fractured magpie goose leg shown above. Or you see some curatorial touch that makes you chuckle at an apparent inside joke or mutter respect for their careful organization in tending their charges. That feeling of pulling open a museum drawer or box lid and peering inside is like few others in science — there might be disappointment inside (e.g. “Crap, that specimen sucks!”), boredom (“Oh. Another one of these!?”) or the joy of discovery (“Holy *@$¬£,¬†I’ve never seen that before!”). My first scientific publication¬†(in 1998)¬†came from rummaging through the UCMP museum collections as a grad student and spotting an obscure pelvic bone that turned out to be highly diagnostic for the equally obscure clade of bird-like dinosaurs called alvarezsaurids. I happened to open that drawer with the alvarezsaurid specimen at the right time, shortly after the first ever specimen of that dinosaur had been described in the literature (~1994). Before then, no one could have identified what that bone was!

There is time for hours of quiet introspection during museum collection studies, immersed in this wealth of anatomical resources and isolated in a silent, climate-controlled tomb-like hall. It is relaxing and overwhelming at the same time. Especially in my case with just five hours to survey numerous species, you have to budget your time and think efficiently. It’s a unique challenge to explore a museum collection as a researcher. If you don’t learn something — especially in a good museum collection — you’re doing it wrong. In this time of tight finances and trends to close museums or stow away precious collections, it is important to vocally celebrate¬†what a vast treasure museum collections are, and how the people that maintain them are vital stewards of those treasures.

I set the cat amongst the pigeons by also visiting the Page Museum at the La Brea Tar Pits in LA, to study fossil cats-- like this American lion (Panthera atrox) code-named "Fluffy", that we CT scanned during my LA visit-- more about that later!

I set the cat amongst the pigeons by also visiting the Page Museum at the La Brea Tar Pits in LA, to study fossil cats– like this American lion (Panthera atrox), code-named “Fluffy”, that we CT scanned during my LA visit– more about that later!

EDIT: I hurried this post off during my free time today, and still feel I didn’t fully capture the deep, complex feelings I have regarding museum collections and the delight I get from studying them. Other freezerinos, please add your thoughts in the Comments below!

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This week was a great week for me and giant dinosaurs in many ways, so I’m sharing that experience via photos and a bit of backstory. I hope you like it.

Stomach-Churning Rating: 1/10. Big birds and bones but no barfing.

First, I attended the filming of a new documentary, “T. rex Autopsy” (due for release on 7 June on NatGeo TV, just in time to steal the thunder of get you excited for Jurassic World), on the edge of London. I’m allowed to post these two photos of it. Expect much, much more information later– and I think you will like that information when it comes! Not quite a 50′ tall bird, but… So. Damn. Cool.

trex-autopsy2

trex-autopsy1

Second, my team and I dissected a big animal I’ve mentioned here before. For various reasons, I won’t/can’t post images or details of it right now, but I hope to soon. It’s not a dinosaur, but it was giant as its kind goes, so I’m wedging it in here.

Third, and this is the main impetus for my¬†post, I finally got to see the giant chicken! No, not this one that I recall from my childhood…

hoboken

But this one! A 50’/13m tall chicken made by teacher Ben Frimet’s team of students and teachers at the City of London Academy!

Shortly after my first encounter.

Shortly after my first encounter. I’m still in a state of awed shock. And shadow.

The megachicken¬†was unveiled at a¬†“Chickenfest” event celebrating the sculpture’s completion. Chickenfest also prominently involved members of the “Chicken Coop” team who have drawn together scientists, humanities scholars, artists and more to investigate “Cultural &¬†Scientific Perceptions of Human-Chicken Interactions” — more details here. Their theme helped unite the event’s various displays and lectures as well as some of the City of London Academy’s teaching topics, which inspired students to look at chickens from many angles. The event was so fun and truly integrative that it had me clucking with joy, but the anatomically accurate giant chicken art piece stole the show (as intended).¬†Enjoy the photo tour below.

Giant Chicken 5

Pelvic/thigh region! (no patella, but hey)

Giant Chicken 6

Great views from up to 3 storeys around it.

Giant Chicken 3 Giant Chicken 4 Giant Chicken 7 Giant Chicken 8 Giant Chicken 9

Little chickens made of fast-food forks and stuff.

Little chickens made of fast-food forks and stuff. Very clever.

Chicken bones

One of our research chickens, a 30-day-old broiler, skeletonized by the Chicken Coop team and brought to the event. Chunky and funky!

Our RVC chicken research team (postdocs/fellows Drs. Heather Paxton, Jeffery Rankin, Diego Pereira-Neves) presented a stall with motion capture and chicken bones, like this fun identification display.

Our RVC chicken research team (postdocs/fellows Drs. Heather Paxton, Jeffery Rankin, Diego Pereira Neves) presented a stall with motion capture demos and chicken bones, like this fun identification display.

What will happen to that giant chicken art piece? This is yet to be determined, and was the question asked of the lecture panel (including me, who gave a lame answer involving King’s Cross’s birdcage). It was unanimous that it must not be destroyed– as long as it does not go on a destructive rampage through London…

One of my favourite films of my teenage years, Beastmaster, lends me a phrase I’ll throw out here like a razor-edged boomerang-thing: “Life is a circle. We will meet again.” And so, at the Chickenfest event, past and present worlds collided. I happened to be there presenting a talk just before Luis Rey. Almost exactly 13 years ago, Luis had done this classic T. rex vs. giant chicken race for my¬†“T. rex was not a fast runner” paper in Nature. He likewise has blogged about the Chickenfest event, so check that out!

T. rex vs. chicken race, by Luis Rey

Coincidentally, there was ANOTHER 50′ tall bird placed not far from that giant chicken in southeast London this week, for a very different reason- a huge Norwegian Blue parrot in celebration of the Monty Python reunion! And I’ve been a Monty Python fan since age ~11, so that rocks my world two times over.

IMAGE: FLICKR USER TAYLOR HERRING

IMAGE: FLICKR USER TAYLOR HERRING

Two giant birds in London in one week. It doesn’t get any better than that– unless there were three such birds– if I missed one, chime in in the Comments!

(Edit: British friends tell me I must refer to an Alan Partridge skit here, so I am doing so. I know when to do as I’m told.)

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

‚ô¨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‚ô™

(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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