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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—did 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 “tinamou caecum” I found the answer, here (free pdf link):

“at 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.”

The caeca in question.

OK buddy, those are the little lumpy buds I saw. Bunches of grapes—exactly.

And later:

“The 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’ s tip.”

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.

Hi, sorry for the social media spam but this is important to me: I got EU money to study dinosaur movement and we made a website for the project. There will be some fun stuff posted there and nowhere else, such as new palaeo-art that we commissioned specifically for this project. Oh, and science, too! Five years of science!

So please have a look at it now that it is live!

https://dawndinos.com/

I love our logo (by Andrew Bourne) so I will spray paint it everywhere I can.

Work from the DAWNDINOS project won’t be featured here much, so either watch that new website or me on other social media to find out what’s up!

And coming up on John’s Freezer: another episode of “Better Know A Muscle”! Yeah, baby!

Uh oh, a “why?” 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 (“ostriches evolved two kneecaps because…”). 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 “how?” 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 “jogging”). That was “just” (Kyle may laugh at the “just”– it wasn’t trivial) taking some vectors out of an existing simulation and adding them into a detailed 3D model. We’ve done similar things before with a horse foot’s 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 “what if?” and that can help you understand “how?” or even “why?” questions that experiments alone cannot address. Ostriches aren’t 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 “jogging”.

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’s results in light of modern theory about how tissues respond to loading regimes. That “mechanobiology” theory, specifically “tissue differentiation”, 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’s 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’s 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’s not a bad match overall for the first (“real”; common to all living birds) patella, located on top of the upper knee (femur). It’s 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, “Being 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’s reactions when I tell them I study ostrich knees.

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!

A thread that has run through my various rants on this blog, usually more implicitly than explicitly, has been blame. Who or what is to blame for something undesirable? Blame is another name for causation (of a negative outcome). As conscious beings we’re drawn to find that causation and attribute it to agents, be they gods/spirits/the universe, governments, corporations, CEOs, supervisors, friends or ourselves. In my mid-forties I’ve become better at watching myself for situations involving blame/causation and pause when entering them, because everyone’s unconscious bias often is to seek very simple scenarios of blame. But, much as we’re trained as scientists to find parsimonious conclusions, Occam’s razor can balance a very complex scenario on its knife-edge when reality is indeed very complex. And the point of this post is to explore how that complexity is often very real, but that needn’t be stifling. That’s probably bloody obvious to everyone but maybe the exploration will be interesting—or at least, for me, cathartic.

Stomach-Churning Rating: 0/10- or blame me. I’m at best an amateur philosopher and psychologist!

I feel that a big part of my job as a responsible human, adult, parent, supervisor, colleague, scientist, etc. is to blame myself when I deserve it. “Responsible” encompasses that ability to attribute blame/causation correctly. I find that blaming myself comes easier now that I’m battle-scarred and wiser for it, and I am more able to watch for excessive self-blame and paralytic pummelling than I was when I was younger. Low self esteem makes it easier to find the simple solution that you’re entirely to blame, or that simply someone else is. Excessive self confidence/power makes it easier to deny personal culpability or hunker down until it blows over. Balance is hardest– and I fail all the time.

I’ve been in many situations, ranging from the more micro-scale (smaller, embarrassing/silly events) to more traumatic (e.g. long-term arguments, correction/retraction of papers), in which I’ve had to consider blame or something like it. Foremost in my mind are my health problems and personal relationships. I’ve explored some of those here before and there are others I’d love to write about publicly but, no.

Yet lately it seems that blame is everywhere; the “blame culture” we hear about. Watch the news and virtually every story is about blame. Blame is a symptom of an angry world. It can be informative (or even a fun game) to think over who/what is not blamed in those stories (a simpler narrative is convenient, or propaganda and/or paranoia). We should be looking inwards at those we don’t want to blame, too.

There are many ways to confront the issue of blame. On one side we can say “don’t sweat the small stuff—and it’s all small stuff”. I hate that shit. “Happy happy joy joy” and all that; Voltaire rotates in his crypt. To me, that attitude also means “existence is meaningless” and “we are utterly powerless and blameless”, which is in contradiction to my experience and philosophy. On another side we can try to micromanage everything around us (small and big stuff), dissecting all the levels of blame in every situation, and we’d go/be insane. A middle ground approach within this spectrum, as usual, is best. Don’t be ashamed of that blame; it’s a thing we can tame.

Purpose and meaning in existence are chosen based on the direction we want our life to go (and how our successors look back on it postmortem). We place blame on those causative agents that push us away from that vector, and credit those that aid us. The more neutral agents are harder to grasp (e.g. the indifference of the universe to our existence). Purpose comes from our consciousness — to me they are the same; although our purpose leaves a legacy that persists after consciousness departs. Consciousness arises gradually from the spectrum of life – a virus is somewhat alive but closer to a rock than we are in terms of its “purpose” (more mechanical, less choices to make), then as evolution added nervous systems and other bits to life, more choices and complexity piled on. Purpose could be said to exist throughout that spectrum, from “instinct” to “choice”, all of which involve some causation — and chance. Vast oversimplification here, yes, but please stay with me. I’m getting there.

To avoid the extreme ends of the blame spectrum, we have to pick our battles and choose what is right or wrong in our world view. Lately I’ve watched smaller-scale events like United’s awful treatment of a passenger (and inability to de-escalate, then terrible PR handling) and huge global events like the resurgence of anti-intellectualism/populism or the clusterf*@$ in Syria, and blame inevitably comes to mind. Those who had more power AND responsibility to amend these situations, like CEOs or politicians, often deserve more blame. But the more complex story is that blame can be spread around these situations, much as they rightly anger us.

On an even smaller scale, close to my own profession and direct experience, I read a story by a PhD supervisor that largely blamed their student for falling silent (“supervisor phobia”) and then having problems with their degree, while the supervisor “was too busy to notice for another six months.” That seemed to exhibit gross irresponsibility for apportionment of blame in a messy situation: the old-fashioned legacy of authoritative, hierarchical scientific culture when people ranging from the university, department, colleagues, supervisor and student were to blame. It’s also a learning opportunity for many of us, to see how a bad situation evolved and think about what could have been done differently—indeed, differently from what one participant judges post hoc.

The red flag of a silent student/staff member could mean many things: the person might be intimidated about poor progress– or they might have self-esteem sharing what is actually good progress, they might be totally inactive (too little training? Hard technical problems stopping them?), or more. The point is that time is vital and acting too late probably will only worsen the problem, adding more blame to the supervisor and upper echelons.

The overall, common-sense approach I’ve cultivated with figuring ways out of hard situations at work and elsewhere is to (1) watch for (potential) problems, (2) think them through – allowing for the conclusion to be that the situation is complex and requires a nuanced approach (e.g. openly accepting one’s own culpability, maybe not yet pointing fingers at others deserving blame), and then (3) take action to try to resolve them. “The system” (e.g. rules and regulations) may be part of the problem but it can also be part of the solution. Although the system’s carrot is far more pleasant to use than the stick, they are there for reasons, to be applied with empathy and patience. Being human, we can run out of those latter two things and their fuel levels need monitoring.

The hope is that, finally, action leads eventually to a better outcome with a lesson mutually learned and, eventually, greater peace of mind as we reconcile our worldview with reality. The distinct possibility, though, is that we can’t fix everything and sometimes we have to try to find contentment in an imperfect world. Some causes are mysterious and we might have to settle for that mystery. Or we can spiral into paranoia and conspiracy theories; all the rage today; which can be simple scenarios of blame or very elaborate ones. These scenarios deserve their own rational inspection for personal biases that lead toward them, and the desire for easy answers.

But we can still blame the fucked up shit, and that can be therapeutic. Even if we hold onto blame, we can forgive it. Maybe this holiday weekend is a good time to forgive someone that is blamed.

A Confuciusornis fossil; not the one from our study but prettier (more complete).

Today almost three years of collaboration come together in a publication that is a fun departure from my normal research, but also makes sense in light of it. Professor Baoyu Jiang from Nanjing University in China has been being working on the taphonomy of the Early Cretaceous Jehol biota from northeastern China (Manchuria) for a while, and he found a lovely Confuciusornis (early bird) fossil; one of thousands of them; from the volcanic pyroclastic flow-based lake deposits there.

Although at first glance the skeletal remains of that fossil are not fabulous compared with some other Confuciusornis, what makes this one lovely is that, on peering at it with multiple microscopic and other imaging techniques, he (and me, and a China-UK collaboration that grew over the years) found striking evidence of very well-preserved fossil soft tissues. Our paper reporting on these findings has gone live in Nature Communications so I can blog about it now.

Reference: Jiang, B., Zhao, T., Regnault, S., Edwards, N.P., Kohn, S.C., Li, Z., Wogelius, R.A., Benton, M., Hutchinson, J.R. 2017. Cellular preservation of musculoskeletal specializations in the Cretaceous bird Confuciusornis. Nature Communications 8:14779. doi: 10.1038/NCOMMS14779

Stomach-Churning Rating: 3/10; gooey, but fossil gooey, except for some colourful, gastrically-tolerable histology of bird tissue.

Front view of the ankle/foot of our specimen.

Back view of the ankle/foot of our specimen.

What has been fun about this collaboration is that, for one, it fits in perfectly with my prior work. Ever since my PhD thesis I’d been wondering about odd bones in the legs of birds, including a very puzzling and very, very neglected bit of bone called the tarsal sesamoid, on the outside of the upper end of the ankle joint. Furthermore, a tunnel of tissue called the tibial cartilage sits next to that sesamoid bone, and then across the ankle joint there is a bony prominence with grooves and tunnels that vary highly among bird species; that is called the hypotarsus. These structures are all known in living birds and, to a degree, in extinct fossil cousins. Our specimen seems to reveal an earlier stage in how these little features of bird ankles originated, which we concluded to be a step along the transition to the more crouched legs that modern birds have.

This study has also challenged me to broaden my horizons as a scientist. Although this was a big collaboration and thus we had several specialists to apply supercharged technological techniques to our fossil, I had to learn something about what all that meant. My kind colleagues helped me learn more about tissue histology, scanning electron microscopy, synchrotron mapping, FTIR and mass spectrometry and more. I won’t go through all of these techniques but there are some pretty pictures sprinkled here and in the paper, and a lot more detail in the paper for those who want the gory techno-detail. Basically we threw the kitchen sink of science at the fossil to crack open some of its secrets, and what we found inside was nifty.

Scanning electron micrograph image of probable tendon or ligament fibres (arrow) in cross-section, from near the ankle joint.

We found preserved cells and other parts of connective tissues including tendons and/or ligaments, fibrocartilage (the tougher kind) and articular cartilage (the softer joint-padding kind). That’s great, although not unique, but the kitchen sink also flushed out even more reductionist data: those tissues included some organic residues, including what appear to be bits of proteins (amino acids); particularly the collagen that makes up tendons.

Fibrocartilage (“fc”) from the ankle joint region.

Hopefully we’re right, and we included as much of the data as we could manage so that others can look at our findings. The specimen is crushed into nearly two dimensions, like all Jehol biota organisms, so its anatomy was hard to interpret but we think we got it right. All of the other kitchen-sinky tools have their own nuances and pitfalls but we did our best with a superb team of experts. We’ve had to wait 125 million years to uncover this specimen and a few more years to find out if we’ve looked at the right way is no greater test of patience.

I thank my coauthors, especially Baoyu Jiang for the kind invitation to participate and the very fun experience of collaborating. I think I’ll remember this study for a long time because, for me, it takes a step beyond just describing Another Case of Jaw-Dropping Fossilization (can you hear the hipsters recounting the excitement and cynicism of the 1990s when this all was dawning? I was there and maybe now I’m one of them). By combining all of those methods we learned new things about the palaeobiology of birds and the evolution of traits within birds. Confuciusornis, not shockingly, had ankles that should have functioned in ways intermediate between those of bog-standard non-avian theropods and modern birds.

Same anatomical regions in an extant bird as in the main fossil specimen. Left distal tibiotarsus (TT; below) and proximal tarsometatarsus (TMT; above) from an adult helmeted guineafowl (Numida meleagris) after formalin fixation. (from our paper’s Supp Info)

I’m hopeful that more synthesis of molecular/cellular, imaging, biomechanical and other tools (not to mention good old palaeontology and anatomy!) can wash away some more of this mystery. And it was fun to be a part of a study that adds to overwhelming evidence that was heretical ~25 years ago: some hardy biomolecules such as collagen and keratin can survive hundreds of millions of years, not just thousands. Pioneers such as Prof. Mary Schweitzer led the original charge that made reporting on discoveries like ours much easier today.

I know how the birds fly, how the fishes swim, how animals run. But there is the Dragon. I cannot tell how it mounts on the winds through the clouds and flies through heaven. Today I have seen the Dragon.“– Confucius, ca. 500 BCE.

Let’s finish with some images of a living bird’s ankle region, by co-author and PhD student Sophie Regnault. We considered these for inclusion in the paper but they didn’t fit quite right. I love them anyway so here they are:

Patchwork of histology slide images, from a guineafowl’s ankle (as per photo above). The numbered squares correspond to zoomed-in images below. The tibiotarsus is on the proximal end (bottom left); the tarsometatarsus is on the distal end (right side); and the enigmatic tarsal sesamoid is at the top. Magnification: 20x overall.

Region 1. nice (fibro)cartilage-bone inferface at ligament insertion.

Region 2: longitudinal slice through ligaments connecting the tibiotarsus to the tarsometatarsus across the ankle joint.

Region 3: front (bottom) of the tibiotarsus/upper ankle.

Region 4: tendon fibres in longitudinal section; on the back of the tibiotarsus. Some show mineralization into ossified tendons (“metaplasia”); another curious feature of modern birds.

Region 5: muscle attachment to the back of the upper tarsometatarsus bone. Small sesamoid fragment visible.

The early, hippo-like mammal Coryphodon. I didn’t know it had a patella but it does. From Yale Peabody Museum.

I’m not shy about my fondness for the patella (kneecap) of tetrapod vertebrates, and neither are the other members of RVC’s “Team Patella”. We’ve had a fun 3+ years studying these neglected bones, and today we’ve published a new study of them. Our attention has turned from our prior studies of bird and lepidosaur kneecaps to mammalian ones. Again, we’ve laid the groundwork for a lot of future work by focusing on (1) basic anatomy and (2) evolutionary history of these sesamoid bones, with a lot of synthesis of existing knowledge from the literature; including development and genetics. This particular paper is a sizeable monograph of the state of play in the perusal of patellae in placental and other synapsids. Here’s what we did and found, focusing mostly on bony (ossified) patellae because that allowed us to bring the fossil record better to bear on the problem.

Reference: Samuels, M., Regnault, S., Hutchinson, J.R. 2016. Evolution of the patellar sesamoid bone in mammals. PeerJ 5:e3103 https://doi.org/10.7717/peerj.3103

Stomach-Churning Rating: 1/10; bones and more bones.

The short version of the story is that mammals evolved bony kneecaps about five times, with marsupials gaining and losing them (maybe multiple times) whereas monotremes (platypus and echidna) and placentals (us and other mammals) didn’t do much once they gained them, and a couple of other fossil groups evolved patellae in apparent isolation.

Evolution of the patella in mammals: broad overview from our paper. Click to zoom in.

The marsupial case is the most fascinating one because they may have started with a fibrocartilaginous “patelloid” and then ossified that, then reduced it to a “patelloid” again and again or maybe even regained it. There needs to be a lot more study of this group to see if the standard tale that “just bandicoots and a few other oddballs have a bony patella” is true for the Metatheria (marsupials + extinct kin). And more study of the development of patellae in this group could help establish whether they truly do “regress” into fibrocartilage when they are “lost” in evolution, or if other, more flexible patterns exist, or even if some of the cases of apparent “loss” of a bony patella are actually instances of delayed ossification that only becomes evident in older adults. Our paper largely punts on these issues because of an absence of sufficient data, but we hope that it is inspiration for others to help carry the flag forward for this mystery.

The higgledy-piggledy evolution of a patella in Metatheria, including marsupials. Click to zoom in.

Some bats, too, do funky things with their kneecaps, analogous to the marsupial “patelloid” pattern, and that chiropteran pattern also is not well understood. Why do some bats such as Pteropus fruit bats “lose” their kneecaps whereas others don’t, and why do some bats and other species (e.g. various primates) seem to have an extra thing near their kneecaps often called a “suprapatella”? Kneecap geeks need to know.

The short-nosed bandicoot (marsupial) Isoodon, showing a nice bony patella as typifies this group. From Yale Peabody Museum.

Otherwise, once mammals evolved kneecaps they tended to keep them unless they lost their hindlimbs entirely (or nearly so). Witness the chunky patellae of early whales such as Pakicetus and join us in wondering why those chunks persisted. The evolutionary persistence of blocky bits of bone in the knees of various aquatic animals, especially foot-propelled diving birds, may help answer why, as the hindlimbs surely still played roles in swimming early in cetacean evolution. Ditto for sea cows (Sirenia) and other groups.

Early whale Ambulocetus, showing hefty kneecaps.

But I’m still left wondering why so many groups of land vertebrates (and aquatic ones, too) never turned parts of their knee extensor tendons into bone. We know a bit about the benefits of doing that, to add leverage to those joints that enables the knee muscles to act with dynamic gearing (becoming more forceful “low gear” or more speedy “high gear” in function). Non-avian (and most early avian/avialan) dinosaurs, crocodiles, turtles, amphibians, early mammal relatives, and almost all other known extinct lineages except for those noted above got by just fine without kneecaps, it seems, even in cases where a naïve biomechanist would expect them to be very handy, such as in giant dinosaurs.

A quoll, Dasyurus, with what is probably a fibrocartilaginous “patelloid”. From Yale Peabody Museum.

However, tendons don’t turn to bone unless the right stresses and strains are placed upon them, so maybe kneecaps are a “spandrel” or “exaptation” of sorts, to abuse Gould’s ghost, whose adaptive importance is overemphasized. Maybe that adaptive myopia overshadows a deeper ontogenetic story, of how tissues respond to their history of mechanical loading environment. It has been speculated that maybe (non-marsupial) mammals have broadly “genetically assimilated” their kneecaps, fixing them into semi-permanence in their genetic-developmental programmes, whereas in contrast the few studies of birds indicate more responsiveness and thus less assimilation/fixation. That “evo-devo-mechanics” story is what now fascinates me most and we’ve poked at this question a bit now, with some updates to come- watch this space! Regardless, whether an animal has a bony vs. more squishy soft tissue patella must have consequences for how the knee joint and muscles are loaded, so this kind of question is important.

Giant marsupial Diprotodon (at NHM London); to my knowledge, not known to have had kneecaps- why?

In the meantime, enjoy our latest contribution if it interests you. This paper came about when first author Dr. Mark Samuels emailed me in 2012, saying he’d read some of my old papers on the avian musculoskeletal system and was curious about the evolution of patellae in various lineages. Unlike many doctors and vets I’ve run into, he was deeply fascinated by the evolutionary and fossil components of patellae and how those relate to development, genetics and disorders of patellae. We got talking, found that we were kindred kneecap-spirits, and a collaboration serendipitously spun off from that, soon adding in Sophie. It was a blast!

‘Full fathom five thy father lies, of his bones are coral made. Those are pearls that were his eyes. Nothing of him that doth fade, but doth suffer a sea-change into something rich and strange.’

(Shakespeare’s The Tempest Act 1, Scene 2)

Stomach-Churning Rating: 1/10- this time, tame images.

Five years have passed on this blog now, and this year with them passed Freezersaurus (soon to leave RVC’s campus; sob!). Indeed, the blog has changed, via the tempests I’ve weathered in my own life, which I lamented in last year’s summary. Regardless, the blog has been visited this year more than in any prior year, with >101,000 visits– thanks!

This year I’ll keep my annual retrospective shorter than usual, as I’m feeling healthier and more energetic but less self-indulgent.

I still got to have fun, like this ComicCon in NOLA. So, some self-indulgence.

I still got to have fun, like this ComicCon in NOLA. So, some self-indulgence.

I began the past year by blogging about why I blog, and how I feel that in a way I (and others) have long been blogging even if it wasn’t called that, and how I don’t see science communication such as blogging or tweeting as something distinct from science itself. Reading back on that post, I find some themes there that emerge again and again throughout this year’s posts, such as valuing diversity (in its diverse forms) and curiosity.

Like this? So much more is here!

Like this you do? So much more here there is!

Never tired of elephant feet will I be!

Those introspective posts included one that is very close to my heart, about how I notice my own decline (some of it since reversed, but some still lingering) and feel grief. It wasn’t long after that post that I wrote more about my experience as an epileptic; what it’s like to have a seizure. Another, more science-focused (but still very human) one laid out my views on what my team’s principles are. Then I returned a few posts later with some reflection on how time passes (too quickly!) and with it come publications (I reviewed some of my team’s latest), among other changes as a person living as an academic. I wrote then that “I suspect I’ll look back on 2016 and see it as transformative, but it hasn’t been an easy year either, to say the least.” Yep. Spot on. I’ve started a big new grant which has been a huge challenge, and I’ve rediscovered my health and some of my old self with it, rekindling some passion and hope. Later, on USA’s Thanksgiving, I typed in some musings about my appreciation for diversity in the human world. Again, with thoughts of disturbing recent political/social trends weighing heavily on me, I celebrated how the Women’s March inspired me, and how that relates to the importance of curiosity and empathy.

He ain't goin' nowhere.

He ain’t goin’ nowhere.

But there was plenty of time here to talk about freezers and anatomy and research, too! We published a paper that I think I’ll long regard as one of our better ones, on using dynamic computer simulations to study how ostriches control their walking and running gaits with their muscles. Throughout 2016, we worked hard to get our anatomical research out there to the public in person. So I posted about our presentations at the Cheltenham Science Festival (including a public cheetah dissection, which was a huge hit!), and “Team Cat” did a dissection of another cheetah (all zoo mortalities) at the RVC for a well-attended joint event with UCL/Grant Museum on “Wild Cats Uncovered: movement evolves“. UCL’s PhD student (soon Dr.) Marcela Randau wrote a great guest post about our paper on how size and ecology relate to the shapes of backbones in cats, which tied in nicely with those big cat dissection presentations. I also ruminated about how scientists balance testing big questions vs. getting very accurate data, using the big question (in my and others’ research) about how much more slowly big animals can move relative to smaller ones as an example. As a final anatomical post this blog-year, I wrote about the biceps muscle, and people seemed to like that, so I will do more of those.

Whale humeral epiphysis (joint) turned into a sculpture with walrus ivory teeth, at Point Vicente Museum, LA.

Whale humeral epiphysis (joint) turned into a sculpture with walrus ivory teeth, at Point Vicente Museum, LA.

In addition to being open about my (and my team’s) thoughts, experiences, dissections and publications, we put a lot of effort this year into making our scientific and anatomical data public. My blog posts about our huuuuuge open datasets on crocodile and tuatara 3D scans exemplify a deluge of data that is going to keep coming out. We’re going to push very hard on this, including an effort to release old data from prior publications of mine. I’m thrilled that we can finally deliver on these things; it is a great feeling!

Yale Peabody Museum specimen YPM57100: ilium (hip bone) and vertebrae of the Triassic archosaur Poposaurus. More about this later!

Yale Peabody Museum specimen YPM57100: right ilium (hip bone) and vertebrae of the Triassic archosaur Poposaurus. More about this later!

We enter year 6 of this blog with a new (temporary, maybe) freezer, which we failed to reach a conclusion on naming. I’m sure you’re on tenterhooks awaiting the final decision. I have a bunch of ideas for some blog posts to come soon (really fun anatomical papers en route), and I always welcome guest posts so let me know if you want to do one! In the meantime, I sprinkled some images from my 2016-7 travels here in this post. With good health comes more ability to go do fun things that I’ve put off while recovering, so hopefully 2017-8 will provide some new images to share.

A sunny Sceloporus fence lizard seen in LA.

A sunny Sceloporus fence lizard seen in LA. Meanwhile, the UK awaits some sunshine…

I doth not protest too much, methinks– there have been some good times this past year, and ides of March be damned, I look forward to sharing more science here for year 6!