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Archive for the ‘Croc-cicles’ Category

Crimbo Crocodylian Capers

Posted in Croc-cicles, Exalting Archosauria, tagged , , , , , , on December 17, 2019| 3 Comments »

Ho ho ho! The vagaries of the scientific publication system today brings forth TWO open access papers on crocodylian functional anatomy, evolution and biomechanics, from my team with others’; including our DAWNDINOS project in part. Get ready to bite down on the science! I’ve loved crocodylians throughout my life– “dacadile” was among my first words, for a beloved stuffed croc toy, and “Alligators All Around” was an early favourite song (it’s still GREAT).

One of the many large adult alligators in St. Augustine, Florida.

Stomach-Churning Rating: 1/10; bones and movies of awesome behaviours.

First, I am so relieved and pleased to finally publish an experimental study I began over 17 years ago. This is my most-delayed paper ever, due to my own perfectionism, overcommitment and failures at funding it more broadly. But published is published and I’m glad to see it out. We collected a large experimental dataset from 15 species of Crocodylia at the St Augustine Alligator Farm Zoological Park (a conservation/education centre) in Florida. (No matter how you species-ify them, that’s a good chunk of diversity; roughly half or more.) This was a non-invasive study of 42 individuals ranging from 0.5 to 43 kg in body mass (hatchlings to adults). Larger adults were too dangerous or too slow to work with. It took 3 years (2002, 2004, 2005) of data collection to assemble this, with some twists and turns (including a close brush with Hurricane Katrina), and then a lot of analysis and reanalysis; and I’d do it all very differently if I did it today but that’s a moot point. So what’s the paper about?

Adorable Siamese crocodile family “cuddling”. Crocs are great parents! IIRC, that is the father shown.

Some Crocodylia (the inclusive modern name for all crocs, caimans, gharials, gators) are known to use what we call asymmetrical gaits: “mammal-like” footfall patterns in which the left and right limbs do not move as mirror images of each other. In particular, these gaits include galloping (rotary or transverse; either way a “4-beat” pattern with left-right hind- followed by right/left forefoot contacts) and bounding or half-bounding (the former being the most extreme, with left-right hind- and then forefoot contacts as synchronous pairs). Often people just say that crocs can “gallop” but this confuses/conflates the issue and omits that they can use these faster bounding gaits. Regardless, we’ve known about these gaits at least since HB Cott’s 1961 photographic documentation of them in Nile crocodiles; and more detailed studies of Australian freshwater and saltwater crocodiles in the 1970s-2000s. But very often, scientists and popular natural history accounts ascribe the asymmetrical gaits to only a few species or young individuals.

“Freshie” croc bounding in the wilds of Australia; credit Kent Vliet.

Osteolaemus dwarf African crocodile getting marked up for study.

That’s where we came in. We had access to a huge collection of captive Crocodylia and a very supportive institution (with coauthors from there as a result). I wanted to know which Crocodylia do use asymmetrical gaits, having a very strong suspicion from the literature that Alligatoroidea, the alligator and caiman lineage, don’t use them, whereas their cousins the “true crocodiles” in Crocodyloidea do. And I wanted to test how body size interacted with this ability, as prior accounts hinted that asymmetrical gaits got lost with increasing size or in adults. Finally, I was interested in what the benefits of asymmetrical gaits were– did they give those that used them marked boosts in performance, especially maximal speed? Answering that would help understand why these gaits are used.

Cuban crocodile Crocodylus rhombifer in preparation. A gorgeous but aggressive species that we handled carefully.

So we walked and ran our subjects across some platforms past video cameras and collected about 184 useful trials or strides of gait across level ground at a wide range of speeds; and a LOT of not-so-useful data (mostly subjects just sitting and pouting). We found that, yes, most Crocodyloidea we studied could bound or gallop; and no Alligatoroidea did. In the latter case, we didn’t use as large a sample of subjects as we could have, partly because it already seemed evident that alligators did not use asymmetrical gaits, and partly because those alligatoroids we did try to coax to move quickly either only used symmetrical gaits (e.g. trotting) or would only sit and fight or hiss. And we found that bigger animals moved at least relatively more slowly and less athletically, and perhaps even more slowly in absolute terms (metres/second).

Most intriguingly to me, it didn’t matter what gait alligatoroids or crocodyloids used. They all could move at roughly similar top speeds if they wanted to; less than 5 m/s or 11 mph. It’s just that crocodyloids tended to use asymmetrical gaits, especially bounding, at top speeds– but not always: some even chose to trot at their top speeds. We don’t know why, and we still don’t know why asymmetrical gaits are chosen but they likely have other benefits such as acceleration and manoeuvrability.

It’s a thrill to finally be able to share the huge dataset, including a gigantic file of videos (with some highlights shown here), with the paper, closing this study at last. It should be very useful to anyone studying Crocodylia or wanting to educate people about locomotion. I’m a bit tired of hearing that galloping is a mammalian behaviour when we know so well that many species of animals do it, or something like it. And it was absolutely thrilling to see five species of Crocodylia bound or gallop when they hadn’t been properly documented to do it before– enough anecdotes, here’s cold hard facts from video on what happens. What remains is a mystery: did Crocodylia have this ability to use asymmetrical gaits as an ancestral trait, as almost everyone assumes (and thus alligators and caimans have lost or essentially never express the ability), or did crocodiles uniquely evolve this ability more recently? I would join most scientists in wagering on the former; and there are good reasons to suspect the ability goes deeper into extinct Crocodylomorpha.

(my favourite video is below!)

Want more cool videos? Try my Youtube channel— or if you want ALL of the videos, go here!

Next, Torsten Scheyer was kind enough to invite me to join his team in studying a fossil I’ve long been fascinated by: the “giant caiman” Purussaurus mirandai, from the Miocene (~6 million years ago?) of Venezuela, in the Urumaco Formation‘s very weird biota. Purussaurus has been known of for >125 years but Torsten’s team noticed that Purussaurus (mirandai) specimens tended to add one of their trunk vertebrae to their hip girdles (sacrum; normally only two vertebrae in Crocodylia but here three), and that the shoulder and hip girdles had unusual bone morphology (straighter, more vertical relative to the body). So they asked me to help interpret these features. And here’s the paper!

Infographic by Torsten Scheyer’s team– click to emcroccen!

Three-vertebra sacrum and other traits of Purussaurus; with living caiman bones for comparison. E (bottom): inwards-facing femur head. (see paper for more info)

It became evident that, together, those odd traits conveyed a signal that the skeleton was transformed to aid in supporting the huge body against gravity. For example, I found it quite interesting how the head of the femur (thigh bone) was oriented more directly into the hip socket in multiple specimens, more like a dinosaur’s hip, and specialised for support and fore-aft motions. I used Haley O’Brien et al’s data to estimate just how big P. mirandai might have been and it came out as perhaps 3000 kg and 8 metres total length; as we’d thought, among the largest Crocodylia (and there are larger Purussaurus known, too).

Reconstruction of Purussaurus and morphology of the girdles. (see paper for more info)

The team also put a cool “evo-devo-biomechanics” spin on the study. It is well known that the regional identities of vertebrae (e.g. neck, trunk, sacrum, tail) are largely determined by Hox (homeobox) regulatory genes, early in development. So changes of vertebral identity intimate changes of genetic controls. Crocodylia don’t normally add a trunk vertebra to their sacrum, and only a few fossil crocodyliforms (extinct cousins) ever did either, but we noticed that some specimens of Crocodylia would at least partially make this transformation in pathological states (below). Hence the controls to make these changes exist and sometimes manifest in living crocs, but it’s probably not an “easy” transformation to achieve. One could speculate that under intense selection, such as that imposed by giant body size and some degree of activity on land, that transformation could more easily get permanently “fixed” in a species.

Palaeosuchus palpebrosus (Cuvier’s dwarf caiman) with pathological partial-three-vertebra-sacrum; and lots more morphology. (see paper for more info)

As a nice tie-in to the asymmetrical gait study above, we can safely infer that the giant Purussaurus wasn’t a fast animal on land, by any means. But its skeleton is consistent with it having found novel ways to maintain the ability to stand and move on land, even if slowly.

Happy holidays! Santa Jaws is watching you– be good!

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Papers Seen In 2017

Posted in Biomechanics, Croc-cicles, Exalting Archosauria, Two-Dog-Night Tetrapods, tagged , , , , , , , , , on November 25, 2017| Leave a Comment »

As 2017 approaches its end, there have been a few papers I’ve been involved in that I thought I’d point out here while I have time. Our DAWNDINOS project has been taking up much of that time and you’ll see much more of that project’s work in 2018, but we just published our first paper from it! And since the other two recent papers involve a similar theme of muscles, appendages and computer models of biomechanics, they’ll feature here too.

Stomach-Churning Rating: 0/10; computer models and other abstractions.

Mussaurus patagonicus was an early sauropodomorph dinosaur from Argentina, and is now widely accepted to be a very close relative of the true (giant, quadrupedal) sauropods. Here is John Conway’s great reconstruction of it:

We have been working with Alejandro Otero and Diego Pol on Mussaurus for many years now, starting with Royal Society International Exchange funds and now supported by my ERC grant “DAWNDINOS”. It features in our grant because it is a decent example of a large sauropodomorph that was probably still bipedal and lived near the Triassic-Jurassic transition (~215mya).

In our new study, we applied one of my team’s typical methods, 3D musculoskeletal modelling, to an adult Mussaurus’s forelimbs. This is a change of topic from the hindlimbs that I’ve myopically focused on before with Tyrannosaurus and Velociraptor [in an obscure paper that I should never have published in a book! pdf link], among other critters my team has tackled (mouse, elephant [still to be finished…], ostrich, horse, Ichthyostega… dozens more to come!). But we also modelled the forelimbs of Crocodylus johnstoni (Australian “freshie”) for a key comparison with a living animal whose anatomy we actually knew, rather than reconstructed.

Mussaurus above; Crocodylus below; forelimb models in various views; muscles are red lines.

The methods for this biomechanical modelling are now standard (I learned them from their creator Prof. Scott Delp during my 2001-2003 postdoc at Stanford): scan bones, connect them with joints, add muscle paths around them, and then use the models to estimate joint ranges of motion and muscle moment arms (leverage) around joints. I have some mixed feelings about developing this approach in our 2005 paper that is now widely used by the few teams that study appendicular function in extinct animals. As a recent review paper noted and I’ve always cautioned, it has a lot of assumptions and problems and one must exercise extreme caution in its design and interpretation. Our new Mussaurus paper continues those ruminations, but I think we made some progress, too.

On to the nuts and bolts of the science (it’s a 60 page paper so this summary will omit a lot!): first, we wanted to know how the forelimb joint ranges of motion in Mussaurus compared with those in Crocodylus and whether our model of Mussaurus might be able to be placed in a quadrupedal pose, with the palms at least somewhat flat (“pronated”) on the ground. Even considering missing joint cartilage, this didn’t seem very plausible in Mussaurus unless one allowed the whole forearm to rotate around its long axis from the elbow joint, which is very speculative—but not impossible in Crocodylus, either. Furthermore, the model didn’t seem to have forelimbs fully adapted yet for a more graviportal, columnar posture. Here’s what the model’s mobility was like:

So Mussaurus, like other early sauropodomorphs such as Plateosaurus, probably wasn’t quadrupedal, and thus quadrupedalism must have evolved very close to in the Sauropoda common ancestor.

Second, we compared the muscle moment arms (individual 3D “muscle actions” for short) in different poses for all of the main forelimb muscles that extend (in various ways and extents) from the pectoral girdle to the thumb, for both animals, to see how muscle actions might differ in Crocodylus (which would be closer to the ancestral state) and Mussaurus. Did muscles transform their actions in relation to bipedalism (or reversal to quadrupedalism) in the latter? Well, it’s complicated but there are a lot of similarities and differences in how the muscles might have functioned; probably reflecting evolutionary ancestry and specialization. What I found most surprising about our results was that the forelimbs didn’t have muscles well-positioned to pronate the forearm/hand, and thus musculoskeletal modelling of those muscles reinforced the conclusions from the joints that quadrupedal locomotion was unlikely. I think that result is fairly robust to the uncertainties, but we’ll see in future work.

You like moment arms? We got moment arms! 15 figures of them, like this! And tables and explanatory text and comparisons with human data and, well, lots!

If you’re really a myology geek, you might find our other conclusions about individual muscle actions to be interesting—e.g. the scapulohumeralis seems to have been a shoulder pronator in Crocodylus vs. supinator in Mussaurus, owing to differences in humeral shape (specialization present in Mussaurus; which maybe originated in early dinosaurs?). Contrastingly, the deltoid muscles acted in the same basic way in both species; presumed to reflect evolutionary conservation. And muuuuuuch more!

Do you want to know more? You can play with our models (it takes some work in OpenSim free software but it’s do-able) by downloading them (Crocodylus; Mussaurus; also available: Tyrannosaurus, Velociraptor!). And there will be MUCH more about Mussaurus coming soon. What is awesome about this dinosaur is that we have essentially complete skeletons from tiny hatchlings (the “mouse lizard” etymology) to ~1 year old juveniles to >1000kg adults. So we can do more than arm-wave about forelimbs!

But that’s not all. Last week we published our third paper on mouse hindlimb biomechanics, using musculoskeletal modelling as well. This one was a collaboration that arose from past PhD student James Charles’s thesis: his model has been in much demand from mouse researchers, and in this case we were invited by University of Virginia biomechanical engineers to join them in using this model to test how muscle fibres (the truly muscle-y, contractile parts of “muscle-tendon units”) change length in walking mice vs. humans. It was a pleasure to re-unite in coauthorship with Prof. Silvia Blemker, who was a coauthor on that 2005 T. rex hindlimb modelling paper which set me on my current dark path.

Mouse and human legs in right side view, going through walking cycles in simulations. Too small? Click to embiggen.

We found that, because mice move their hindlimb joints through smaller arcs than humans do during walking and because human muscles have large moment arms, the hindlimb muscles of humans change length more—mouse muscles change length only about 48% of the amount that typical leg muscles do in humans! This is cool not only from an evolutionary (mouse muscles are probably closer to the ancestral mammalian state) and scaling (smaller animals may use less muscle excursions, to a point, in comparable gaits?) perspective, but it also has clinical relevance.

Simulated stride for mouse and human; with muscles either almost inactive (Act=0.05) or fully active (Act=1). Red curve goes through much bigger excursions (along y-axis) than blue curve), so humans should use bigger % of their muscle fibre lengths in walking. Too small? Click to embiggen.

My coauthors study muscular dystrophy and similar diseases that can involve muscle stiffness and similar biomechanical or neural control problems. Mice are often used as “models” (both in the sense of analogues/study systems for animal trials in developing treatments, and in the sense of computational abstractions) for human diseases. But because mouse muscles don’t work the same as human muscles, especially in regards to length changes in walking, there are concerns that overreliance on mice as human models might cause erroneous conclusions about what treatments work best to reduce muscle stiffness (or response to muscle stretching that causes progressive damage), for example. Thus either mouse model studies need some rethinking sometimes, or other models such as canines might be more effective. Regardless, it was exciting to be involved in a study that seems to deliver the goods on translating basic science to clinical relevance.

Muscle-by-muscle data; most mouse muscles go through smaller excursions; a few go through greater; some are the same as humans’.

Finally, a third recent paper of ours was led by Julia Molnar and Stephanie Pierce (of prior RVC “Team Tetrapod” affiliation), with myself and Rui Diogo. This study tied together a bunch of disparate research strands of our different teams, including musculature and its homologies, the early tetrapod fossil record, muscle reconstruction in fossils, and biomechanics. And again the focus was on forelimbs, or front-appendages anyway; but turning back the clock to the very early history of fishes, especially lobe-finned forms, and trying to piece together how the few pectoral fin muscles of those fish evolved into the many forelimb muscles of true tetrapods from >400mya to much more recent times.

Humerus in ventral view, showing muscle attachments. Extent (green) is unknown in the fossil but the muscle position is clear (arrow).

We considered the homologies for those muscles in extant forms, hypothesized by Diogo, Molnar et al., in light of the fossil record that reveals where those muscles attach(ed), using that reciprocal illumination to reconstruct how forelimb musculature evolved. This parallels almost-as-ancient (well, year 2000) work that I’d done in my PhD on reconstructing hindlimb muscle evolution in early reptiles/archosaurs/dinosaurs/birds. Along the way, we could reconstruct estimates of pectoral muscles in various representative extinct tetrapod(omorph)s.

Disparity of skeletal pectoral appendages to work with from lobe-fins to tetrapods.

Again, it’s a lengthy, detailed study (31 pages) but designed as a review and meta-analysis that introduces readers to the data and ideas and then builds on them in new ways. I feel that this was a synthesis that was badly needed to tie together disparate observations and speculations on what the many, many obvious bumps, squiggles, crests and tuberosities on fossil tetrapods/cousins “mean” in terms of soft tissues. The figures here tell the basic story; Julia, as usual, rocked it with some lovely scientific illustration! Short message: the large number of pectoral limb muscles in living tetrapods probably didn’t evolve until limbs with digits evolved, but that number might go back to the common ancestor of all tetrapods, rather than more recently. BUT there are strong hints that earlier tetrapodomorph “fishapods” had some of those novel muscles already, so it was a more stepwise/gradual pattern of evolution than a simple punctuated event or two.

Colour maps of reconstructed right fin/limb muscles in tetrapodomorph sarcopterygian (~”fishapod”) and tetrapod most recent common ancestors. Some are less ambiguous than others.

That study opens the way to do proper biomechanical studies (like the Mussaurus study) of muscle actions, functions… even locomotor dynamics (like the mouse study)– and ooh, I’ve now tied all three studies together, tidily wrapped up with a scientific bow! There you have it. I’m looking forward to sharing more new science in 2018. We have some big, big plans!

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Release the Croc’in

Posted in Croc-cicles, Exalting Archosauria, tagged , , , , on June 22, 2016| 4 Comments »

Sorry about the title. It’s the best I could do. In case you missed it on our Anatomy to You blog, we unleashed a hefty database of CT (and some MRI) scans of our frozen crocodile cadavers last week, for free public usage. In total, it’s about 34 individuals from 5 species, in 53 databases constituting around 26,000 individual DICOM file format slices of data. This page has a table of what the data/specimens are. I am writing this post to share some more images and ensure that word gets out. We’re thrilled to be able to finally release this first dataset. We have plans to let loose a LOT more such data in the future, for various organisms that we study.

Stomach-Churning Rating: 2/10- be glad that these data don’t come with an olfactory component, especially the five rotten, maggot-ridden Morelet’s croc specimens, which are among the stinkiest things I’ve dealt with.

Crocodiles are no strangers to this blog, of course, as these past links testify. Indeed, most of the crocodile images I’ve blogged with come from specimens that are in this scan dataset. We even released a “celebrity crocodile, “WCROC” or FNC7 in our dataset, which is the 3.7m long Nile croc from “Inside Nature’s Giants”. It broke our CT scanner back in ~2009 but we got the data, except for the torso, and we also got some MRI scans from it, so we’re chuffed.

Above: The only spectacled caiman (Caiman crocodilus); and indeed the only alligatorid; in our dataset. To watch for: stomach contents/gastroliths, and all the damn osteoderms that I did/didn’t segment in this quickly processed file. This specimen had its limbs dissected for one of our studies, so only the right limbs are visible.

There are some more specimens to come- e.g. five baby Nile crocs‘ datasets (“GNC1-5”) are hiding somewhere in our drives and we just need to dig them up. You might also know that we published some scan data for crocodile vertebral columns (including fossils) in our recent paper with Julia Molnar et al. (and related biomechanical data discussed here), and we published all of our anatomical measurements for a huge set of crocodylian species in our papers by Vivian Allen et al. And then I had an enjoyable collaboration with Colleen Farmer and Emma Schachner on the lung anatomy of various crocodylian species, using these same specimens and related scan datasets.

 

Above: rotating Crocodylus moreletii (specimen FMC5 from our database) in a happy colour.

Sharing these kind of huge datasets isn’t so easy. Not only do few websites host them cheaply, and with reasonable file size limits, and limited headaches for what info you have to provide, and with some confidence that the websites/databases will still exist in 5-20 years, but also we were hesitant to release the dataset until we felt that it was nicely curated. Researchers can now visit my lab and study the skeletons (or in some cases, the still-frozen specimens) matched up with the scan data, and known body masses or other metadata. We’re not a museum with dedicated curatorial staff, so that was not trivial to reliably organize, and I still worry that somewhere in the dataset we mis-identified a specimen or something. But we’ve done our best, and I’m happy with that for now.

Above: rotating Osteolaemus tetraspis (specimen FDC2 from our database), which was obviously dissected a bit postmortem before we could scan it, but still shows some cool features like the extensive bony armour and the cute little doglike (to me, anyway) skull. I worked with these animals (live) a bit >10 years ago and came to love them. Compared to some other crocodiles we worked with, they had a pleasant demeanour. Like this guy:

Osteolaemus (resting) set up with motion capture markers for a yet-to-be-published study that we did in 2005 (ugh!). It wasn't harmed by this.

Osteolaemus (resting) set up with motion capture markers for a yet-to-be-published gait study that we did in 2005 (ugh!). It wasn’t harmed by this.

Anyway, as a person who likes to maintain quality in the science we do, I also was hesitant to “just” release the DICOM file data rather than beautiful segmented 3D skeletal (or other tissue) geometry that is ready for 3D printing or animation or other uses, or interactive online tools like Sketchfab. Other labs (e.g. Witmerlab) do these kind of things better than we do and they inspire us to raise our game in the future, but I am sure that we will be forgiven for releasing big datasets without gorgeous visuals and more practical, processed files — this time. 🙂  We agree with many other scientists that sharing data is part of modern, responsible science– and it can be fun, too! Oddly enough, in this case we hadn’t used the CT/MRI data much for our own studies; most of the scans were never fully digitized. We just scan everything we get and figured it was time to share these scans.

Enjoy. If you do something cool with the data that we’ve made accessible, please let us know so we can spread the joy!

And if you’re a researcher headed to ICVM next week, I hope to see you there!

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GUEST POST: Croc backbones through Deep Time

Posted in Croc-cicles, Exalting Archosauria, Guestsicle, tagged , , , , , , , on November 4, 2015| 6 Comments »

Seeking adaptations for running and swimming in the vertebral columns of ancient crocs

A guest post by Dr. Julia Molnar, Howard University, USA (this comes from Julia’s PhD research at RVC with John & colleagues)

Recently, John and I with colleagues Stephanie Pierce, Bhart-Anjan Bhullar, and Alan Turner described morphological and functional changes in the vertebral column with increasing aquatic adaptation in crocodylomorphs (Royal Society Open Science, doi 10.1098/rsos.150439). Our results shed light upon key aspects of the evolutionary history of these under-appreciated archosaurs.

Stomach-Churning Rating: 5/10; a juicy croc torso in one small photo but that’s all.

Phylogenetic relationships of the three crocodylomorph groups in the study and our functional hypotheses about their vertebrae. * Image credits: Hesperosuchus by Smokeybjb, Suchodus by Dmitry Bogdanov (vectorized by T. Michael Keesey) http://creativecommons.org/licenses/by-sa/3.0

Phylogenetic relationships of the three crocodylomorph groups in the study and our functional hypotheses about their vertebrae. * Image credits: Hesperosuchus by Smokeybjb, Suchodus by Dmitry Bogdanov (vectorized by T. Michael Keesey) http://creativecommons.org/licenses/by-sa/3.0

As fascinating as modern crocodiles might be, in many ways they are overshadowed by their extinct, Mesozoic cousins and ancestors. The Triassic, Jurassic, and early Cretaceous periods saw the small, fast, hyper-carnivorous “sphenosuchians,” the giant, flippered marine thalattosuchians, and various oddballs like the duck-billed Anatosuchus and the aptly named Armadillosuchus. As palaeontologists/biomechanists, we looked at this wide variety of ecological specializations in those species, the Crocodylomorpha, and wanted to know, how did they do it?

Of course, we weren’t the first scientists to wonder about the locomotion of crocodylomorphs, but we did have some new tools in our toolbox; specifically, a couple of micro-CT scanners and some sophisticated imaging software. We took CT and micro-CT scans of five fossil crocodylomorphs: two presumably terrestrial early crocodylomorphs (Terrestrisuchus and Protosuchus), three aquatic thalattosuchians (Pelagosaurus, Steneosaurus, and Metriorhynchus) and a semi-aquatic modern crocodile (Crocodylus niloticus). Since we’re still stuck on vertebrae (see, e.g., here; and also here), we digitally separated out the vertebrae to make 3D models of individual joints and took measurements from each vertebra. Finally, we manipulated the virtual joint models to find out how far they could move before the bones bumped into each other or the joints came apart (osteological range of motion, or RoM).

 

Our methods: get fossil, scan fossil, make virtual fossil and play with it.

Our methods: get fossil (NHMUK), scan fossil, make virtual fossil and play with it.

Above: Video of a single virtual inter-vertebral joint from the trunk of Pelagosaurus typus (NHMUK) showing maximum osteological range of motion in the lateral direction (video). Note the very un-modern-croc-like flat surfaces of the vertebral bodies! (modern crocs have a ball-and-socket spinal joint with the socket on the front end)

While this was a lot of fun, what we really wanted to find out was whether, as crocodylomorphs became specialized for different types of locomotion, the shapes of their vertebrae changed similarly to those of mammalian lineages. For example, many terrestrial mammals have a lumbar region that is very flexible dorsoventrally to allow up-and-down movements during bounding and galloping. Did fast-running crocodylomorphs have similar dorsoventral flexibility? And did fast-swimming aquatic crocodylomorphs evolve a stiffer vertebral column like that of whales and dolphins?

Above: Video of how we modelled and took measurements from the early crocodylomorph Terrestrisuchus gracilis (NHMUK).

Our first results were puzzling. The Nile croc had greater RoM in side-to-side motions, which makes sense because crocodiles mostly use more sprawling postures and are semi-aquatic, using quite a bit of side-to-side motions in life. The part that didn’t make sense was that we found pretty much the same thing in all of the fossil crocodylomorphs, including the presumably very terrestrial Terrestrisuchus and Protosuchus. With their long limbs and hinge-like joints, these two are unlikely to have been sprawlers or swimmers!

So we started looking for other parts of the croc that might affect RoM. The obvious candidate was osteoderms, the bony scales that cover the back. We went back to John’s Freezer and got out a nice frozen crocodile to measure the stiffness of its trunk and found that, sure enough, it was a lot stiffer and less mobile without the osteoderms. If the fairly flexible arrangement of osteoderms in crocodiles had this effect on stiffness, it seemed likely that (as previous authors have suggested; Eberhard Frey and Steve Salisbury being foremost amongst them) the rigid, interlocking osteoderms running from head to tail in early crocodylomorphs would really have put the brakes on their ability to move their trunk in certain ways.

Testing stiffness of crocodile trunks to learn the effects of osteoderms, skin, muscles, and ribs. We hung metric weights from the middle of the trunk and measured how much it flexed (Ɵ), then removed bits and repeated.

Testing the stiffness of (Nile) crocodile trunks to learn the effects of osteoderms, skin, muscles, and ribs. We hung metric weights from the middle of the trunk and measured how much it flexed (Ɵ), then removed bits and repeated. Click to em-croccen.

Another cool thing we found was new evidence of convergent evolution to aquatic lifestyles in the spines of thalattosuchians. The more basal thalattosuchians, thought to have been near-shore predators, had stiffness and RoM patterns similar to Crocodylus. But Metriorhynchus, which probably was very good at chasing down fast fish in the open ocean, seems to have had greater stiffness. (The stiffness estimates come from morphometrics and are based on modern crocodiles; see here again, or just read the paper already!) A stiff vertebral column can be useful for a swimmer because it increases the body’s natural frequency of oscillation, and faster oscillation means faster swimming (think tuna, not eel). The same thing seems to have happened in other secondarily aquatic vertebrate lineages such as whales, ichthyosaurs, and mosasaurs.

So, our results were a mixed bag of adaptations particular to crocs and ones that seem like general vertebrate swimming specializations. Crocodylomorphs are important because they are the only group of large vertebrates other than mammals that has secondarily aquatic members and has living members with a reasonably similar body plan, allowing us to test hypotheses in ways that would arguably be impossible for, say, non-avian dinosaurs and birds. The take-home message: crocodylomorphs A) are awesome, and B) can teach us a lot about how vertebrates adapt to different modes of life.

Another take on this story is on our lab website here.

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Worst Day of My Career

Posted in Croc-cicles, Mad Science, Voyages, tagged , , , on August 8, 2014| 10 Comments »

Even nine years later, I still keep thinking back to a day, early in my career as an academic faculty member based in England, that traumatized me. Today I’m going to share my story of that day. I feel ready to share it.

Stomach-Churning Rating: hmm that’s a tough call, but I’ll say 1/10 because it’s just photos of live crocs and such.

This day was part of a research trip that lasted a couple of weeks, and it was in Florida, not England, and little of that trip went well at first. It transpired almost exactly 9 years ago today; around 20 August 2005. I took two 2nd/3rd year undergraduate students and our lab technician with me to Florida, meeting up with Dr. Kent Vliet, an experienced crocodile specialist, to study the biomechanics of crocodile locomotion, a subject I’ve been slowwwwwwly working on since my PhD days (see recent related blog post here). We were funded by an internal grant from my university that was supposed to be seed money to get data to lay groundwork for a future large UK research grant.

Cuban crocodile adult relaxing in a nearby enclosure. Pound-for-pound, a scary croc, but these acted like puppies with their trainers.

Cuban crocodile adult relaxing in a nearby enclosure. Pound-for-pound, a scary croc, but these acted like puppies with their trainers.

I’m interested in why only some crocodylian species, of some sizes and age classes, will do certain kinds of gaits, especially mammal-like gaits such as bounding and galloping. This strongly hints at some kind of size-related biomechanical mechanism that dissuades or prevents larger crocs from getting all jiggy with it. And at large size, with few potential predators to worry about and a largely aquatic ambush predator’s ecology, why would they need to? Crocodiles should undergo major biomechanical changes in tune with their ecological shifts as they grow up. I want to know how the anatomy of crocodiles relates to these changes, and what mechanism underlies their reduction of athletic abilities like bounding. That’s the scientific motivation for working with animals that can detach limbs from your body. (The crocodiles we worked with initially on this trip were small (about 1 meter long) and not very dangerous, but they still would have done some damage if they’d chosen to bite us, and I’ve worked with a few really nasty crocs before.)

Me putting motion capture markers onto an uncooperative young Siamese crocodile.

Me putting motion capture markers onto an uncooperative young Siamese crocodile.

We worked at Gatorland (near Orlando) with some wonderfully trained crocodiles that would even sit in your lap or under your chair, and listened to vocal commands. The cuteness didn’t wear off, but our patience soon did. First, the force platform we’d borrowed (from mentor Rodger Kram’s lab; a ~$10,000 piece of useful gear) and its digital data acquisition system wouldn’t work to let us collect our data. That was very frustrating and even a very helpful local LabView software representative couldn’t solve all our problems. But at least we were able to start trying to collect data after four painstaking days of debugging while curious crocodiles and busy animal handlers waited around for us to get our act together. The stress level of our group was already mounting, and we had limited time plus plenty of real-life bugs (the bitey, itchy kind; including fire ants) and relentless heat to motivate us to get the research done.

Adorable baby Cuban crocodile.

Adorable baby Cuban crocodile.

Then the wonderfully trained crocodiles, as crocodiles will sometimes do, decided that they did not feel like doing more than a slow belly crawl over our force platform, at best. This was not a big surprise and so we patiently tried coaxing them for a couple of sweltering August days. We were working in their caged paddock, which contained a sloping grassy area, a small wooden roofed area, and then at the bottom of the slope was the crocodiles’ pond, where they sat and chilled out when they weren’t being called upon to strut their stuff for science. We didn’t get anything very useful from them, and then the weather forecast started looking ugly.

Hybrid Siamese crocodile in its pond in our enclosure, waiting to be studied.

Hybrid Siamese crocodile in its pond in our enclosure, waiting to be studied.

We’d been watching reports of a tropical storm developing off the southeastern coast of Florida, and crossing our fingers that it would miss us. But it didn’t.

When the storm hit, we were hoping to weather the edge of the storm while we packed up, because we decided we’d done our best but our time had run out and we should move to our next site, the Alligator Farm and Zoological Park in St Augustine, where I’d worked a lot before with other Crocodylia. But the storm caught us off guard, too soon, and too violently.

To give some context to the situation, for the previous several days the local croc handlers had told us stories of how lightning routinely struck this area during storms, and was particularly prone to hitting the fences on the park perimeter, which we were close to. There was a blasted old tree nearby that vultures hung out in, and they related how that blasting had been done by lightning. One trainer had been hit twice by (luckily glancing) blows from lightning hitting the fences and such.

Ominous onlooker.

Ominous onlooker.

The storm came with pounding rain and a lot of lightning, much of it clearly striking nearby- with almost no delay between flashes and thunder, and visible sky-to-ground bolts. We debated taking our forceplate out of the ground near the crocodile pond, because sensitive electrical equipment and rain don’t go well together, but this would take precious time. The forceplate was covered with a tarp to keep the rain off. I decided that, in the interest of safety, we needed to all seek shelter and let the forceplate be.

I’ll never forget the memory of leaving that crocodile enclosure and seeing a terrible sight. The crocodile pond had swiftly flooded and engulfed our forceplate. This flooding also released all the (small) crocodiles which were now happily wandering their enclosure where we’d been sitting and working before.

Another subject awaits science.

Another subject awaits science.

At that point I figured there was no going back. Lightning + deepening floodwater + electrical equipment + crocodiles = not good, so I wagered my team’s safety against our loaned equipment’s, favouring the former.

We sprinted for cars and keepers’ huts, and got split up in the rain and commotion. As the rain calmed down, I ventured out to find the rest of the team. It turned out that amidst the havoc, our intrepid lab technician had marshalled people to go fetch the forceplate out from the flooded paddock, storm notwithstanding. We quickly set to drying it out, and during some tense time over the next day we did several rounds of testing its electronics to see if it would still work. Nope, it was dead. And we still had over a week of time left to do research, but without our most useful device. (A forceplate tells you how hard animals are pushing against the ground, and with other data such as those from our motion analysis cameras, how their limbs and joints function to support them)

We went on to St Augustine and got some decent data using just our cameras, for a wide variety of crocodiles, so the trip wasn’t a total loss. I got trapped by remnants of the storm while in Washington, DC and had to sleep on chairs in Dulles Airport overnight, but I got home, totally wrecked and frazzled from the experience.

That poorly-timed storm was part of a series of powerful storms that would produce Hurricane Katrina several days later, after we’d all left Florida. So we had it relatively easy.

I’m still shaken by the experience- as a tall person who grew up in an area with a lot of dangerous storms, I was already uneasy about lightning, feeling like I had a target on my back. But running from the lightning in that storm, after all the warnings we’d had about its bad history in this area, and how shockingly close the lightning was, leaves me almost phobic about lightning strikes. I’m in awe of lightning and enjoy thunderstorms, which I’ve seen few of since I left Wisconsin in 1995, but I now hate getting caught out in them.

The ill-fated forceplate and experimental area.

The ill-fated forceplate and experimental area.

Moreover, the damage to the forceplate- which we managed to pay to repair and return to my colleague, and the failure of the Gatorland experiments, truly mortified me. I felt horrible and still feel ashamed. I don’t think I could have handled the situation much differently. It was just a shitty situation. That, and I wanted to show our undergrads a good time with research, yet what they ended up seeing was a debacle. I still have the emails I sent back to my research dean to describe what happened in the event, and they bring back the pain and stress now that I re-read them. But then… there’s a special stupid part to this story.

I tried to lighten the mood one night shortly after the storm by taking the team out to dinner, having a few drinks and then getting up to sing karaoke in front of the restaurant. I sang one of my favourite J Geil’s Band tunes– I have a nostalgic weakness for them- the song “Centerfold“. I not only didn’t sing it well (my heart was not in it and my body was shattered), and tried lamely to get the crowd involved (I think no one clapped or sang along), but also in retrospect it was a bad choice of song to be singing with two female undergrads there– I hadn’t thought about the song’s meanings when I chose to sing it, I just enjoyed it as a fun, goofy song that brought me back to innocent days of my youth in the early 1980’s. But it is not an innocent song.

So ironically, today what I feel the most embarrassed about, thinking about that whole trip and the failed experiment, is that karaoke performance. It was incredibly graceless and ill-timed and I don’t think anyone enjoyed it. I needed to unwind; the stress was crushing me; but oh… it was so damn awkward. I think I wanted to show to the team “I’m OK, I can still sing joyfully and have a good time even though we had a disastrous experiment and maybe nearly got electrified or bitten by submerged crocodiles or what-not, so you can relax too; we can move on and enjoy the rest of the trip” but in reality I proved to myself, at least, that I was not OK. And I’m still not OK about that experience. It still makes me cringe. Haunted, it took me many years to feel comfortable singing karaoke again.

It should have been a fun trip. I love working with crocodiles, but Florida is a treacherous place for field work (and many other things). I can’t say I grew stronger from this experience. There is no silver lining. It sucked, and I continually revisit it in my memory trying to find a lesson beyond “choose better times and better songs to sing karaoke with” or “stay away from floods, electricity and deadly beasts.”

So that wins, out of several good options, as the worst day(s) of my career that I can recall. I’ve had worse days in my life, but for uncomfortable science escapades this edges out some other contenders. Whenever I leave the lab to do research, I think of this experience and hope that I don’t see anything worse. It could have been much worse field work.

(Epilogue: the grants we’ve tried to fund for this crocodile gait project all got shot down, so it has lingered and we’ve done research on it gradually since, when we find time and students… And one of the students on this trip went on to do well in research and is finishing a PhD in the Structure & Motion Lab now, so we didn’t entirely scare them off science!)

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Crocodiles in Human Culture: British Museum Part 1

Posted in Croc-cicles, tagged , , on June 7, 2014| 9 Comments »

I visited the British Museum a while ago with my daughter and was struck by some of the animal imagery in the loot on display– particularly, as an archosaurophile, the crocodiles (Crocodylia, crocodylians, etc.; no alligatoroids to show in this post). So I decided to go back and photograph some of them for a blog post about the more obscure and rare animals that sometimes appear in human art and design.

It’s easy to think of horses, lions, dogs, eagles and other familiar, domestic or prized beasts in human decorations. Yet what roles do less common animals play? This post is the first of two on the unsung beasties of human artwork, as represented in the British Museum.

Stomach-Churning Rating: 1/10. Tame art and a dried crocodile skin.

Wherever humans and crocodiles coexist, the primeval appearance and dangerous potential of crocodiles are sure to impress themselves upon our psyche. Hence they will manifest themselves in art. This should especially apply in the early days of a civilization, before we extirpate local crocodiles or exclude them to the hinterlands, or in cases in which crocodylians become revered and protected.

Much of Western culture lacks such an emphasis, because it developed in more temperate climes where crocodiles were long since absent. It’s fun to think about what our culture would be like if it had developed with crocodiles as a prominent aspect, as in Egypt, which is the natural place to begin our tour, featuring mummies of course!

All images can be clicked to emcroccen them.

Small Nile crocodile mummy from >30 B.C, El Hiba, Egypt

Small Nile crocodile mummy from >30 B.C, El Hiba, Egypt

Second small Nile crocodile mummy from >30 B.C, El Hiba, Egypt

Second small Nile crocodile mummy from >30 B.C, El Hiba, Egypt

Those mummies remind me of a recent scientific study that used such mummies to reveal the history of the “cryptic” species Crocodylus suchus, a close relative of the Nile croc C. niloticus, and one that seems to be more threatened.

We proceed on our tour with a box showing an example of shabti, or doll-like funeral offerings of “enchanted” mummified figurines:

This shabti box was for a noble daughter, Neskshons, in Thebes, from around 650 B.C.

This shabti box was for a noble daughter, Neskshons, in Thebes, from around 650 B.C.

A crocodile deity receives the shabti from the departed soul, accompanied by serpent god as well as a more human, ankh-bearing divinity.

A crocodile deity receives the shabti from the departed soul, accompanied by serpent god as well as a more human, ankh-bearing divinity.

Next, some amazingly preserved papyrus scrolls:

This papyrus is from around 900 B.C., with short blurbs about the woman Tentosorkon, part of a new style of funeral provisions in the 22nd Dynasty of Egypt.

This papyrus is from around 900 B.C., with short blurbs about the woman Tentosorkon, part of a new style of funeral provisions in the 22nd Dynasty of Egypt.

Crocodile featured in the story of Tentosorkon.

Crocodile featured in the story of Tentosorkon. What’s it doing? Why is a feathered snake-thing touching its butt? I wish I knew.

The "Litany of Ra", from around 1000 B.C., which is a style like that of the previous 22nd Dynasty papyrus and would have decorated a tomb's wall, dedicated to the lady Mutemwia. Ra, the sun god, is shown in his different manifestations, including a crocodile form, called Sobek-ra: http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Sobek.html

The “Litany of Ra”, from around 1000 B.C., which is a style like that of the previous 22nd Dynasty papyrus and would have decorated a tomb’s wall, dedicated to the lady Mutemwia. Ra, the sun god, is shown in his different manifestations, including a crocodile form, called Sobek-ra (AKA Sebek); a protector and comforter of the dead:

egypt croc 1But crocodiles also feature prominently in other cultures around the world– I was hoping to find some in Thai, South American, or other cultures’ art (especially east/western Africa). However, the museum didn’t exhibit any I could find. I did find these, though, starting with this fantastic Roman armour with a great backstory (and hard to take photos of; argh!):

croc armour caption croc armour 1 croc armour 2 croc armour 3

Roman soldiers in a Sobek cult, running around Egypt while wearing badass armour and getting into all kinds of Bronze Age trouble: I DEMAND TO SEE A SWORD-AND-SANDALS MOVIE FEATURING THIS!

I searched for this next one but did not see it:

A crocodile mask from Mabuiag island near Australia- for some cool details, see this page where the image comes from (I didn’t get to see the original).

There were more tenuous links to crocodiles– surely some dragon images throughout the world relate at least partly to crocodiles, such as this one which seems very crocodylian to me:

A water spirit figure called a belum, from Sarawak, Malaysia, 18/1900s. Belief among the Melanau people was that these dragons would wrap their tails around someone's body to protect or drown them. Possibly inspired by saltwater or Phillipine crocs that they lived near.

A water spirit figure called a belum, from Sarawak, Malaysia, 18/1900s. Belief among the Melanau people was that these dragons would wrap their tails around someone’s body to protect or drown them. Possibly inspired by saltwater or Phillipine crocs that they lived near.

And that’s it- all I managed to find, but not a bad haul from this huge museum.  I looked for the Aztec croc-god Cipactli to no avail. If you have £850 to spare you might like to walk away with this one from the museum. I gladly accept donations of such things to my, err, research.

That’s just one museum’s view of crocodylians’ role in our culture. What crocodile imagery from human art around the world do you fancy?

 

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Croc Meet and Greet

Posted in Croc-cicles, tagged , , on September 24, 2013| 6 Comments »

I love doing sciencey road trips with my team when I can. Last week, we got a treat: four of us got a behind-the-scenes tour of the fairly new Crocodiles of the World facility near Oxford; just over 90 minutes west of our lab, nestled in the pictureseque Cotswolds region. We were not disappointed, so you get to share in the joy! In photo-blog format. Pics can be clicked to emcrocken.

In the midst of an unpreposessing industrial estate lies: AWESOME!

In the midst of an unpreposessing industrial estate lies: AWESOME!

If you want to bone up on your croc species, go here and here. I won’t go into details. This is an eye candy post!

Reasonably accurate description that caught my eye.

Reasonably accurate description that caught my eye. My scientific interest in crocodiles starts here, and with their anatomy/relationship with dinosaurs, but I’ve loved crocs since I was an infant (one of my first words, as I may have written here before, was “dock-a-dile”, for my favourite stuffed animal at the time [R.I.P.]).

Siamese crocodiles. They were apart when we entered, then got snuggly later, as I've often seen this species do.

Siamese crocodiles. The large male is “Hugo.” They were apart when we entered, then got snuggly later, as I’ve often seen this species do. Heavily endangered (<300 in the wild?), so any breeding is a good thing!

The above photo brings me to one of my general points. Crocodiles of the World seems genuinely to be a centre that is breeding crocodiles for conservation purposes (and for education, entertainment and other zoo-like stuff). Essentially every crocodile enclosure had a mated pair, and several were breeding. Such as…

Yes, that is a Dwarf African crocodile, Osteolaemus, and it is a female on her nest-mound. Which means...

Yes, that is a Dwarf African crocodile, Osteolaemus, and indeed it is a female on her nest-mound. Which means…

Eggs of said Osteolaemus.

Eggs of said Osteolaemus.

And babies of said Osteolaemus!

And babies of said Osteolaemus! As if the adults aren’t cute enough with their short snouts and doglike size/appearance! These guys have striking yellow colouration, too. I’d never seen it in person before.

That’s not all!

Male American Alligator warming up. Smaller female partner lives in same enclosure.

Male American Alligator “Albert” warming up. Smaller female partner “Daisy” lives in same enclosure. Plenty of babies from these guys, too! Daisy comes when called by name, and Albert is learning to do so.

~1 meter long juvenile Nile crocodiles, bred at the facility.

~1 meter long juvenile Nile crocodiles, bred at the facility.

But then crocodile morphological diversity (colours, textures) and behaviour is just too cool not to focus on a bit, so here are some highlights from our visit!

Endearing shot of a crocodylian I seldom get to see anywhere: Paleosuchus trigonatus, the Cuvier's Dwarf Caiman. Spiny armoured hide and quite terrestrial; poorly known in many ways. Some more info is here- http://crocodilian.com/paleosuchus/description.html (note its tortured taxonomy)

Endearing shot of a crocodylian I seldom get to see anywhere: Paleosuchus trigonatus, the Schneider’s Dwarf Caiman. Spiny armoured hide and quite terrestrial; poorly known in many ways. Some more info is here (note its tortured taxonomy)

Black caiman, Melanosuchus niger, showing some interest in us.

Black caiman, Melanosuchus niger, showing some interest in us.

Cuban crocodiles cooling off by exposing their mouths.

Cuban crocodiles (Crocodylus rhombifer; pound for pound the most badass croc in my experience; badassitude that this photo captures nicely) cooling off by exposing the well-vascularized soft tissues of the mouth region.

But it’s not just crocs there, either, and some of the highlights were non-croc surprises and memorable encounters:

A surprisingly friendly and tame Water monitor (14 yrs old; does kids parties). Note person for scale.

A surprisingly friendly and tame Water monitor (14 yrs old; does kids parties). Note person for scale. Was about 2 meters long, 20 kg or so.

Business end of nice Water monitor, with tongue engaged.

Business end of nice Water monitor, with tongue engaged.

And we got a nice farewell from an African spur-thigh tortoise (Geochelone sulcata) with an oral fixation (action sequence thereof):

tortoise-nom (1)
tortoise-nom (2)

tortoise-nom (3)
tortoise-nom (4)

tortoise-nom (5)

Chowmp!

If someone visits this facility and leaves without being converted to a croc-lover, they must be from a different planet than me. It is a celebration of crocodiles; the owner, Shaun Foggett, is the real deal. He sold his home and quit his job as a carpenter to care for crocodiles, and it seems to be a great success– about to get greater, as they have plans to move to a new, bigger, proper site! They are seeking funding, so if you can contribute go here.

Right then… UK residents and visitors: you need to go here! Badly! Get off the blog and go now. If it is a Saturday/Sunday (the cramped industrial estate location only allows the public then).

Otherwise just stew and imagine how much fun you could be having checking out crocodiles. I cruelly posted this on a Tuesday to ensure thorough marination of any croc-geeks.

Muhaha!  😉

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“Ultimate Croc Anatomy” Deserves Your Support

Posted in Croc-cicles, tagged , , on January 22, 2013| 9 Comments »

Today I’m doing something a bit unusual for this blog, but which very comfortably fits within its theme. Enough talking about my papers and media appearances and such. Too much self-indulgence, I feel. I want to talk about someone else. And then I will get back to the usual business of this blog: sharing the joy of cool anatomy, with a Mystery Dissection/Image post that is long overdue. Yet first, I wish to share the joy of knowing a cool anatomist– and artist.

One of my great shames as a scientist is that I never cultivated some decent artistic skills that I had as a young boy. And now as an anatomist I feel that my work often suffers from a lack of artistic talent (e.g. the image below, which still makes me hang my head in shame). In addition to scientific know-how, anatomy, when done best, demands the eyes and the hands of an artist. I might have the eyes but I definitely lack the hands. I envy people that have both; Julia Molnar from my team is but one example. And for me, encountering them is always a special delight. What follows is my personal perspective on one of the shining stars in the field.

Right ischium (hip bone) of an adult ostrich in side view, showing some muscle origins and stuff, with a 1cm scale bar. Cringe. My amateurish line drawing. I hate it and wish I'd done better.

Right ischium (hip bone; pelvis/synsacrum) of an adult ostrich in side view, showing some muscle origins and stuff, with a 1cm scale bar. Cringe. My boring, amateurish, pixelly line drawing from a paper on pelvic evolution. I hate it and wish I’d done better.

Mieke Roth is a scientific illustrator from the Netherlands, with a Masters degree from the prestigious and hallowed halls of Wageningen University.  Her homepage has the tagline “Complex processes beautifully revealed”. This is a wonderfully succinct and eloquent way to describe the magic that she is able to conjure with her skills in scientific illustration. Her “Ultimate Croc Anatomy” project will be the greatest weaving of that sorcery yet. That project is described and will be documented on this page, and has an Indiegogo crowdfunding page here. Mieke describes its goals best:

“I will meticulously dissect a Nile crocodile and document it. I will share the dissection in text, illustrations and video via my website. I will process the data I gathered and each time build a new part of the digital crocodile. From there I will adapt the model for illustrations, books, animations and apps.”

I first became a happy victim of the artistic spells that Mieke casts when I saw her blog entry “How to make an octopus,” which you absolutely must read if you have not already or else you’ll be firmly spanked and sent away from this blog with only lumps of coal in your freezer for Freezermas (what’s Freezermas? Find out soon, and in the meantime be nice– or else!). In her post, Mieke didn’t just look up a picture of an octopus somewhere and redraw it in an abstract, schematic, flat and deceptively simplified way. She went and did her own hands-on research by dissecting an octopus, and then described the steps in converting those observations into a brilliantly novel set of digital illustrations that really brought octopus anatomy to life.

Octopus image by Mieke Roth

Octopus image by Mieke Roth

Part of what first mesmerized me is that this whole investigative and creative process was lovingly documented on her blog. In doing this, Mieke played the roles of both scientist and artist, by displaying the mundane-but-wonderful labour she did to come up with her final, gorgeous results, and the passion, dedication, scholarship and originality that make her stand head and shoulders above so many gifted scientific or medical illustrators. This thrilled me at both visceral and intellectual levels. It literally gave me chills to witness how good the final product was. As I write this and look back on that blog again, months later, I still feel the magic.

So then I started browsing around her homepage and became punch-drunk from repeated blows of amazement—again and again and again the quality and novelty and thoroughness leaped off the computer screen. Images of nature that I thought I knew well, such as the growth of a chick into a chicken (really great blog here documenting this with sketches), were conveyed in a way that made me see them as if for the first time, with joy and wonder. In the space of a day, I became a huge Mieke Roth fan.

little_chicken

Young chicken sketched by Mieke Roth

And now Mieke is taking it not just a notch, but a huge step, to spend a year documenting the anatomy of the Nile crocodile—how cool is that!?! As an expert in the postcranial anatomy of the Crocodylia, I can confidently state that the available scientific literature on the subject is patchy in coverage and often poor in quality by modern standards. There are big flashes of excellence here and there, such as Larry Witmer’s and Chris Brochu’s teams’ very thorough work on head and neck anatomy, or Colleen Farmer’s and Emma Schachner’s studies of lung morphology. But then I glance at some scholarly books (to avoid offending, I will not cite them here) that are supposed to be key references on the complete anatomy of Crocodylia and I frankly am left cold. While there is some superb work from the 1800s (Gadow, Fürbringer and others come immediately to mind), it is in the flat, often colourless style which the printing technology of that age imposed upon those great masters of anatomy. And while there is superb work by Romer, a tome on the Chinese alligator and a few others, again they tend to be limited to line drawings or spotty coverage of various anatomical systems. We need a visionary with both the scientific and artistic skill to make a subject that could seem dry or arcane become miraculous and accessible. I think you can guess whom I have in mind.

I can think of no one better suited to the ambitious goals and demands of the Ultimate Croc Anatomy project than Mieke Roth. She combines the attention to anatomical detail of a classical 19th century anatomist with the technical wizardry of a modern digital artist. She will have a supportive team of experts to ensure the content is exceptional and up-to-date. I’ll be one of them (and the crocs will come from my freezer), because of my enthusiasm for  the project, and I’ve been helping to recruit others. So I urge you not just to join in her crowdfunding effort to carry out a very worthy and exciting project that the world can share, but also to share the joy I had in discovering her work by browsing her online collection of awesomeness. I predict that many of you will feel the power of her spell and become Mieke Roth fans, too, if you are not fortunate enough to be one yet.

sq-monkey

Squirrel monkey drawing by Mieke Roth

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Crimbo Comes Early– Crocodiles!

Posted in Croc-cicles, tagged , , , on November 4, 2012| 1 Comment »

A quick report on an exciting event for my team, from this week: We got a box! A big one! With 10 frozen crocodiles.

Stomach-Churning Rating: 5 out of 10. Just 1 picture with some blood.

 

These come from a breeding centre in southern France, and died of natural causes. Here is a little, icy box of five Crocodylus moreletii, a species that has featured here before:

And five young Nile crocodiles (remember WCROC?), one of which seems to have had an uncomfortable encounter with a larger relative:

Science shall blossom from their demise.

The end.

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Studying “WCROC,” a 278 kilogram, 3.7 meter long Nile crocodile!

Posted in Croc-cicles, tagged , , , , on October 15, 2012| 5 Comments »

I stumbled across some old pics, which I thought I’d lost, from the filming/preparations of 4 episodes of Inside Nature’s Giants (Jan-Feb 2009) at the RVC. They form a nice accompaniment to my previous post reflecting on my experience with the show, and the timing is great because I’m about to head to Raleigh, NC to talk about this research at the Society for Vertebrate Paleontology conference.

Stomach-Churning Rating: 4 at first (just a dead animal; and a rather clean one at that), then about halfway through the dissections start and it edges up to a 7 or so.

These pictures are sadly some of the few I have of the whole, intact body of a gorgeous adult Nile crocodile (Crocodylus niloticus) that the Windfall Films team managed to get to the RVC from La Ferme Aux Crocodiles in Pierrelatte, France. (I have scores of pics of the dissected limbs, shown further below) As the title indicates, it was a nice big croc. And as you’d expect, CT scanning and then dissecting it was no tiny feat, and makes a fun story. Story time, then, after an introductory pic!

Dr Samuel Martin, vet from La Ferme Aux Crocodiles, brought the crocodile (and some smaller specimens) over to our Hawkshead campus in late January 2009, and we quickly moved to run the specimen through our CT scanner to preserve some details of its anatomy (example shown at the end of this post) and for potential usage in the show. As the photos below illustrate, this was hard work for several people.

And then, as we were finishing the last CT scans of the specimen, our ageing medical scanner stopped working. And could not be resuscitated. R.I.P., Picker PQ5000 (buy one or two here!). The crocodile, “WCROC” as my team came to designate it, had claimed its final victim. It took about a year for us to get a new one, and that year sucked. It made me appreciate how lucky we are to have a CT scanner just across the parking lot from my office!

Anyway, the day of filming I was hoping to make it in to watch my colleague and friend Dr Greg Erickson help lead the dissection team, but a wicked blizzard blew up, and as I was starting the 31 mile drive south from my home to the RVC I realized, from the queue of cars that seemed to be 31 miles long (and train lines shut down), that this was going to be a snow day. So I turned around and came home. Another victory for WCROC!

The filming proceeded despite heavy snow delaying many of the key players’ arrivals. I got filmed a day or two later for a little section of the show on the limbs and locomotion of crocodiles but sadly this got cut from the main ING show (but did air in the National Geographic version “Raw Anatomy“, in the USA at least).

The limbs had been left largely intact, although some of the dissectors who didn’t know croc anatomy very well had slashed through parts of the pelvis and, in eagerness to reach key parts to demonstrate in the show, some major muscles got shredded. This is no big surprise; crocodiles have a lot of bones all over the place: in their skin (scutes; bony armour), in their bellies (the belly ribs called gastralia), and almost everywhere else, so some brute force is required to get to the gooey bits. Apparently there had been 6 or so people dissecting at once and things got a little carried away. The curse of WCROC continues?

Oh well; that’s just how documentaries go sometimes, especially with a pioneering show like this and the intensely compressed timescales of filming (time is ££!). There can be pulses of chaos. And the show turned out GREAT! (alternative link if latter does not work outside UK)

Let’s have more photos tell the story of the scanning, which also shows off this beautiful animal’s external anatomy:

Anyway, things turned out fine overall for our research. A week or so later (maybe longer; I forget if the specimen was frozen and thawed out for us) we came in to start dissections. We were really excited to measure the limb muscles of such a big crocodile, for comparison to a growth series (babies to adults) of alligators that my former PhD student (now postdoc; Dr.) Vivian Allen had dissected back in 2008. Here he is with a masked co-dissector, displaying their joy for the task at hand:

And let’s not leave out the exhuberance of visiting research fellow Dr. Shin-Ichi Fujiwara! He wanted to inspect the forelimbs for his ongoing studies of limb posture, joint cartilages and locomotor mechanics.

The remaining images show progressive stages of dissection of WCROC, starting from the pectoral (fore-) limbs with a view of the belly (and the giant jaw-closing muscles visible on the left side of image):

Isolated right forelimb, with coracoid (part of shoulder girdle) sticking through:

Assorted forelimb/upper arm (brachial) muscles:

And the triceps (elbow-straightening) muscles; not that big in such a big animal:

…and on to the pelvic limbs and the huge tail:

With a closer look at the HUGE thigh muscle, the famed M. caudofemoralis longus:

And then an isolated right hindlimb:

Thigh muscles, with which I have a peculiar fascination that stems from my PhD research:

And last, the great, paddle-like hind foot!

What a great experience that was! We have fond memories of WCROC, a great documentary from Windfall Films, some nice data– and a lovely skeleton. Perhaps the curse of WCROC is not so bad. Nothing can go wrong now!

Soon Mieke Roth, scientific illustrator from the Netherlands, is coming here to do a similar dissection on more Nile crocodiles at the RVC. As with the octopus she wrote about in September, she will make a 3D model, but with much more detail and with an emphasis on accuracy and accessibility. The end products will be really cool; think of the visible body, 3d models that can be used in teaching, animations, a book and lots more but also a “how did she do that?” blog. To finance this project (that probably will take a year or more) she will use crowd funding. In several weeks there will be more info on how to participate in her fantastic endeavour. For now, see her video with the initial pitch for “Nile Crocodile 2.0“!

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