Felid field work (part 1)

As part of the ongoing felid research grant I am involved in for my postdoc, we have been studying felid scaling. The literature shows that cats maintain the same standing posture at all body sizes (whether small or big), but we wanted to find out what the felids are doing whilst under steady state locomotion (walking, trotting or galloping/running at a constant speed). John and colleagues had collected some data previously from domestic cat, ocelot, caracal, serval, leopard, and tigers from Amazing Animals, and a couple of locations in the USA. However, with the 40ish species of felids, this covers only a tiny diversity of those. As such, we managed to put together a BSc project at the Royal Veterinary College (RVC) for a student in the bioveterinary sciences degree programme to go collect some more data and analyse the "historical" dataset.

We first went to Colchester Zoo last year (2015) to see if we could work with their felid collection. Having done a recon. of the site we figured we could work easily with their tigers and cheetah. But we needed a platform to put the forceplate within allowing the cats to walk steadily (not up or down hill or up/down steps).

Force plate platform

Platform setup showing how I put together the platform, with and undercut on one side allowing the cables to exit so the cats didn't chew on them. Red is the forceplate

So I designed what was a very simple system for the Colchester enclosures. Basically layers of marine plywood stacked on top of each other and secured together. Fortunately they were the same thickness of our forceplate, so I was able design it so that we could sneak the cables out one side so the cats wouldn't chew on them. The first platform was built, and shipped by courier to Colchester. Somehow during the trip (all of 2hrs up the road), the forceplate platform turned into a box of books... or at least that is what was delivered to Colchester. Due to this, we had to rebuild the platform and try again so we got delayed by almost a month, but finally it got there.

Platform (II) with plate installed. Cables were run out the left (my right in picture) and buried under wood 

Data collection
So we had two days with the tigers and cheetah collecting data, although in truth the data collection only lasts an hour or two as we don't want to stress the cats.

Setting up the forceplate whilst being watched by the test subjects

One thing that we would come to quickly learn, is that scaredy-cat works as a description for most species of felids. The tigers were initially less than happy to go onto the plates, even with food bribes.

The tigers would scrape the food back off the platform/plate and eat it. I have to say I was impressed by their dexterity and picking up food with a paw to get to their mouths, but it didn't help the data collection. We got them moving across the plate, but not how we wanted:

Eventually, after much coaxing, we did get them to walk over the plate. We (the incredibly helpful keepers) even managed to get them to manage a trot from time to time.

Tiger with right front foot on the plate (marked by the grey duct tape in the middle)

Luckily Jack the cheetah was much easier. He has an area that he regularly paces when he is off exhibit between being fed and being let back out. As such we stuck out platform right there. We had the funny realisation though that after the first go, we needed to stick a log on the side nearest the fence otherwise Jack would continually walk down the side and not on the plate.

Jack being a beautiful test subject with a nice right front foot on the plate

Results
Whilst we do not have a full set of results to show you, I thought it would be useful to show what the output of forceplate is for those of you who don't know:

Force trace from one of the trials for a tiger

For walking felids what we get is a more or less m-shaped major peak in forces corresponding to the vertical force. The first peak of the m is caused by the foot impacting the ground and the second peak caused as the animal pushes off the ground. The front-back force trace tends to look like a sin-x graph (although the one above is messy). This is again as the foot impacts the ground it causes a deceleration force (negative), before transitioning to an acceleratory one (positive). The remaining line is the mediolateral forces (side to side). This force is generally minor but is linked to any number of joint rotational forces (e.g. pronation/supination). These forces and shapes of the traces all change depending on the speed of the animal (with the m becoming n shaped at running speeds). Combined with the video data we are able to calculate running speeds and posture (or at least joint angles) and see how they change across an animal at different speeds, as well as across different species/body sizes.

End of part 1
So two days of work, we had a lot of data and a very busy student. Unfortunately due to the delays, we were unable to do anymore in 2015. However, that is not the end, and part two has actually just finished now so will appear imminently on the blog. It includes a lot more pretty pictures of exotic cats, as well as more successes, and some terrible failures.

Underwhelming fish fossil of the year

The title is a bold claim, particularly for so early in the year. This fossil is obviously not a big flashy dinosaur, it is two tiny bits of tooth plates from a Cretaceous fish. However, it has special meaning for me for two reasons. Firstly, I am on a quest to publish on all groups of vertebrates (not actively pursuing but it would be nice to do) and this will cross of teleosts (the bony rayed fishes - most of the things you count as fish today) along with dinosaurs, marine reptiles, and mammals (these groupings may also get more specific as I get further along too). Secondly, and more exciting for me, is these fossils are the first I've found myself that have been published:
http://onlinelibrary.wiley.com/doi/10.1002/spp2.1040/full (if you want a .pdf email me)

A bit of background, the fossil is from the Kallamedu formation of SE India. The area has been published on a fair bit as it is one of the largest Cretaceous exposures of fossil bearing strata in India. That being said it is still remarkably poorly represented in publishing when compared to the North and Central regions known for the intertrappean layers where small pockets of material lay between the massive Deccan trap eruptions layers. These areas are interesting for the sheer size of the erupted material as it covers an area the size of Texas twice over, and to a depth of up to 2km in places. The eruption has also been implicated by some for climactic events that led to the demise of the dinosaurs (either with or because of the meteor that hit Mexico).

I digress again, back to the site in the Kallamedu. The fossils found in the formation are typical of Gondwanan locales of similar late Cretaceous age, with teeth of crocodilians, abelisaurid and troodontids dinosaurs, bones of titanosaur sauropods, bothremydid turtles, and fish scales. The sediment is a mix of clays and sandstones and has been interpreted as a fluvial/deltaic region with occasional marine influence. Thus it may not come as a surprise you find fish teeth in it, however the type of teeth is what makes them interesting.

After much ado:

From Halliday et al., 2016 - Photographs in lateral, occlusal, and apical views of specimens DGUF/145 (left) and DGUF/146 (right). Scale bar = 1cm.

So there you have it, two tiny pieces of tooth plates, both barely more than a centimetre in size. They aren't just any standard tooth plate, they are what are called pharyngeal toothplates. In fish that feed on shells and hard objects, they develop what is functionally a second set of jaws in their throats designed to crush. It is these teeth that help determine which group they belong too. The size and apparent replacement pattern meant we took it a step further and CT scanned these specimens.

From Halliday et al., 2016 - CT scans of DGUF/145 (A) and DGUF/146 (B) in lateral (1), occlusal (2), and apical (3) views. The bony matrix has been digitally removed to illustrate the stacking of the teeth. Convex teeth are organized in vertical stacks; each stack is arranged in a row offset from adjacent rows. The apical surface of the teeth shows no foramen housing a pulp cavity, as is also true for NHM-UK 38814.

From the CT scans we can see the teeth are small, rounded on the occlusal (top) surface, covex on the apical (bottom) side, and arranged in nice linear columns. All of these are important for not just figuring out the group of fish that they belong to (Phyllodontidae), but also narrow it down to probably Egertonia sp.. It's tough to be more specific as we lack any more material from the fish, although there are living relatives (bonefish and ladyfish) which give us an insight into probably biology (shell and crustacean crushing, shallow salt water fish), and they have similar teeth although they are stacked alternatively.

The most interesting thing to derive from two otherwise minute underwhelming fossils is that the fish is otherwise unknown from India in the Cretaceous. The taxa has only ever been found once before in the Cretaceous, although indeterminate fossils belonging to the family have been found across Eurasia from this time. The only other definitive occurrence is from Madagascar showing the close links these two regions maintained in terms of what animals were there despite the fact that Madagascar and India were joined until about 85 million years ago (about 20 million years earlier than these fossils). Keep an eye out for another paper by Halliday et al., that is following hot on the heels of this one (mainly as it was reliant on this publishing before it could be) addressing the faunal similarities between these areas.

Anyway, that's all from me on my underwhelming fish fossil. I thought I could give you a lovingly crafted drawing of what part the fossils come from on a fish (see the entertaining blog from which this one post derives inspiration https://blogs.ucl.ac.uk/museums/tag/underwhelming-fossil-fish-of-the-month/), but could not do it justice. So instead here is a picture of a black drum showing off its crazy throat teeth that do look superficially similarly (but I can tell you they are very different indeed):

A black drum (Pogonias cromis) showing off its smiles, inside and out. From http://img.photobucket.com/albums/v464/Vetcraft/drumJune52008008_zps2af54b6d.jpg

My year in review

So it is that time of year, where everyone is putting up their exciting top finds and top science stories, and thought that I could do the same for my academic year. I won't over big it up, as the review won't be too exciting, but a fun way for me to link together my blog posts and papers, and put things into perspective of where I'm heading for 2016.

As it turns out 2015 was the first calendar year of my postdoc (although Feb 2014-Feb 2015 was the first full year). The year started off really well in India, where we were in the field on the 1st of January (we had been there for a few days by this point).

The artistic New Years messages in front of many houses in Tamil Nadu

After another 10 or so days in the field, we'd found bits of dinosaurs, sharks, ichthyosaurs, ammonites, sea urchins, belemnites, turtles, and fish. A good field season if you asked me.

When back from the holidays I got the stark reminder of how difficult it is balancing work and social life as an academic. Something I remain very envious of all of my friends who have successfully managed it. I instead buried myself in work and very rapidly had my first manuscript of my postdoc submitted and in review on felid body mass evolution. Before Easter had rolled around I was also at a very advanced stage of revision with a paper on ornithomimosaur cranial reconstructions, and had submitted a long running paper on finite element validation in an ostrich cranium. I had also helped put together a small display in the UCL Grant Museum for their Strange Creatures exhibit showing how palaeontologists and biomechanists work together to understand what dinosaurs looked like, and how they moved.

I was also lucky enough to be involved in some field work with felids at Colchester Zoo, where we had a forceplate in enclosures with their tigers and cheetah. This was part of a BSc project looking at forces exerted by cat species on the ground at various speeds, and how limb posture changes with gaits in different sized felids. As this is ongoing research that we are hoping to add to I will save that for another time. It was lots of fun but worrying when my supervisor scampers away when she first saw the tiger behind me without saying a word...

The shock moment when a tiger says hello!

June was a great month for my publications, as both the cat body mass paper and ornithomimosaur crania papers were accepted. We finished up all the dissections from the various cat species by the end of June, having had a bit of a delay with missing data and vertebral column issues whilst figuring out the best way to analyse all of the data in regressions. Thankfully we fixed those issues and those manuscripts were getting written.

Tiger dissection. If you want to see the photogrammetry click here.

In July, John went to Los Angeles and we acquired some stunning scans of two extinct felids fom the La Brea Tar Pits: Panthera atrox (North American lion); and Smilodon fatalis (the commonly known, although equally misnamed, sabre tooth tiger).

In August/September I was off on field work again, this time in Argentina. It was an amazing place, with lots of fossil finds ranging from dinosaurs, to mammals, fish, frogs, crocs(?).

The rock formations were spectacular, even if you aren't a trained geologist or palaeontologist

I spent the end of the summer reconstructing the P. atrox skeleton, resulting in the most complete reconstruction of a single individual of the species (the rest, as with S. fatalis, are composites of several individuals).

Panthera atrox skull

The resulting skeleton allowed estitmates for the body mass, and using the scaling equations for the muscles (how muscles scale with body mass) for all extant felids I was able to reconstruct the muscles for P. atrox. A sneaky side project meant that I also extracted the endocast for the specimen, allowing the first digital brain, and endosseous reconstruction.

In October my ostrich validation paper came out meeting my minimum estimate for number of publciations for the year (was hoping 3-5 based on ongoing projects at the start of the year). The joyous SVP was also upon us again for the year. Dallas was a good conference, and I presented the dissection data, as well as the reconstructions to a good reception as my first invited poster.

November rolled around and the forelimb and hindlimb muscle papers were submitted, and work began on attempting to validate loading cat bones by loading them and measuring the strain patterns. Unfortunately, this would be an ongoing problem through December when I finally gave up with it. Our rig is just too unstable for small scale things.

December led to the submission of the P. atrox brain paper, the submission of a big grant, and also a fun interview with a crew as part of a new ITV and PBS documentary called Story of Cats. Apparently I am now considered a domestic cat expert (or at least the easiest one to get at short notice), which is flattering but always thought it would be dinosaurs first! Continuing the outreach, I was also invited to give a public talk as part of the Animal Showoff (Science Showoff spinoff) at the Grant Museum, which was a load of fun. I also finally got to get on to the Smilodon reconstructions, so that has been a fun holiday project. Paper-wise, the hindlimb paper came back out of review with relatively minor corrections, as did a collaboration on vertebral column morphology in cats. More excitingly, and in a beautiful wrapping up of 2015, a collaboration on a fish fossil from India was accepted for publication. It is my first fossil find that is being published on, and have already written the blog for that whenever it comes out fully.

So 2015 is pretty much done and dusted, what's lined up for 2016?
1) Building on the 3 papers this year, I'm hoping there will be 4-5 first author papers (3 are already in review/revision, 2 in prep), and equal numbers of co-authored ones (1 accepted, 1 with minor corrections already, 2 to be submitted).
2) More zoo visits for experiments in Jan/Feb which will hopefully lead to a fun blog post with pics and videos.
3) Off to Argentina in March for some more fieldwork in different areas that will hopefully yield more fossils, and maybe something new to add to my Indian find?
4) The rest of the year will be getting the FE validation done (we've got leads to possibly use another setup), and then hopefully computer modelling of the musculoskeletal models.
5) September brings about the biggest and scariest (potentially) change of the year, as I will be out of my current contract. The big grant that I am named on, and a job application will be out, but due to the joys of academia, I may still be stuck and searching for the next big research project. If you do know of any, please let me know!

Thanks for reading the blog, and hope everyone had a good 2015, and has a great 2016!