actorartathleteauthorbizcrimecrosspostcustomerservicedirectoredufoodgaminghealthjournalistmedicalmilmodpostmunimusicnewsworthynonprofitotherphilpolretailscispecialisedspecializedtechtourismtravelunique

Request[AMA Request] Anyone who committed a horrible crime as a child.

Mar 20th 2018 by CivilizedPsycho • 13 Questions • 92 Points

I am part of an international team that studies Archaeopteryx with microtomography using synchrotron light. Archaeopteryx is a feathered dinosaur from the Late Jurassic of Bavaria in Germany. We just found out that the cross cuts of its wing bones look remarkably like those of modern birds and interpreted this as evidence for active flight. However, we also recalled that the skeleton of Archaeopteryx was not equipped with the advanced flight adaptations that all present-day flying birds share. Furthermore, the recent years have uncovered evidence for various previously unrecognised aerial strategies that were adopted by early bird-like dinosaurs. This led us to the conclusion that Archaeopteryx, which remains among the oldest of them, must have represented one of many such evolutionary experiments of dinosaurian flight that ultimately went extinct, leaving only the flight of living birds today. Tomography in general - and synchrotron microtomography in particular - continues to unlock new possibilities for non-destructive and three-dimensional visualisation of important fossils. This promises much for the future of studying the past!

I said a few words on Science Friday and enjoyed a good talk with Dave from Palaeocast just now.

Proof

EDIT: Thank you all very much for having joined me here to talk about Archaeopteryx! I will have to return to finishing my preparations for my defence later this week but hope to have sufficiently addressed your interesting questions!

Q:

Well i certainly didnt do anything that extreme but maybe this will fit.

1) i was about 9 or 10. I saw this older kid who i wasnt on the best of terms with, was sitting on a picnic bench so i went home and grabbed a hammer and some nails. Snuck up on him and nailed his hand to the bench, i then procedded to beat him with the hammer for a few more minutes and left.

2) too young to be charged at the time, i ended up on a few different medications and in therapy and some other stuff. I had a history of acting out violently like this for much of my childhood.

3) yes, though after a few whacks of the hammer i kinda blacked out.

4) #2 applies a fair bit to here i would say. Kinda hard to say though, the rest of my family had its share of problems and alot of my memory around this time "hazy" at best.

5) im doing alright these days. Though when i was in my early twenties i sold crack and stuff and later became a crackhead for a couple years.

A:

Hi Dennis, I also like bones! I practice orthopedic surgery - many patients suffer degenerative conditions around their joints, but they differ in weight bearing and non-weight bearing joints (ie- knee vs. shoulder). Both get arthritis, but for different reasons. When deciding if a particular species could fly, do you look for degenerative bony sequela related to the stresses of attempted/achieved flight?


Q:

My first instinct was to respond "Jesus Christ" and then I realized how wrong that was.

Do you feel any regret from that incident? Did you make amends? Do you still feel violent?

A:

Hello fellow bone enthusiast! Limb bones evolve to cope with the stresses and demands they are subjected to and can even remodel themselves to a certain degree during life, depending on how they are used. We did not find signs of degeneration but really aimed at interpreting these evolutionary and adaptive modifications in comparison with understood archosaurs to explain what they signify.


Q:

Based on a quick Google search it seems like this species was bipedal: given that the shoulder ortholog would be non weight bearing, I would imagine that the stresses would either be related to flight with the “wing” in full abduction, or lack of flight with the joint in adduction; did you find reciprocal changes in joint morphology suggestive of either?

A:

Because our parameters are expressed in the middle of the bone shaft, we have not considered the humeral articulation with the glenoid yet. As you know, the shoulder girdle does not articulate rigidly with the axial skeleton, and it was displaced in most specimens of Archaeopteryx. It is therefore quite difficult to reliably reconstruct its orientation with respect to the rest of the skeleton, which has important implications for the mobility of the shoulder joint itself. Furthermore, we know that Archaeopteryx descends from a group of non-flying dinosaurs with relatively large arms and hands, which were presumably used quite intensively as well. Considering this, untangling all these influences towards specifying the exact function(s) of the forelimbs is far from straightforward.


Q:

How do I become a bone enthusiasts like you? I wish to learn the way of the bone

A:

Bone enthusiast is not something that you become, it is something that becomes you ;)! Familiarising yourself with the varieties and all the interesting little details of bone is a good start. If it captures you then, there is no way back!


Q:

How on Earth did you manage to get a PhD on Archaeopteryx? Extremely high GPA?

A:

I was at the right place at the right time! I had started working on scans of Nothosaurus under the supervision of Paul Tafforeau. He was also conducting several quite successful tests on Archaeopteryx and he invited me on board!


Q:

So Lucky! I went straight to google for Nothosaur, I see you did both Nothosaur AND Archaeopteryx! http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0188509 Any advice for a future PhD student who would like to work in paleontology? Is it all just luck?

A:

In order to exploit luck, you have to be prepared to recognise it! My advice would be to start getting involved with research as soon as you can. This may seem intimidating at first, but it is actually very accessible if you start contributing to studies led by more experienced people. Along the line your own experience, knowledge, and confidence will grow, and you will start to see possibilities for new or underappreciated research. This is the moment you will feel comfortable putting your very own studies together in a team of supportive experts. This, my friend, is one of the most rewarding endeavors we fossil enthusiasts can pursue. Good luck with the voyage!


Q:

Hi Dennis, how large was the dinosaur sample you brought to the ESRF?

A:

Assuming you are not asking me about the modern dinosaurs, birds, it was actually quite limited. Because we were able to get a lot of information from literature, we "only" needed to scan three specimens of Archaeopteryx, two bones from Compsognathus, and an ulna of a dromaeosaurid.


Q:

But was it a full Archaeopteryx, or only a part? Was it embedded in something?

A:

All fossils of Archaeopteryx are preserved in and on thin limestone plates. This was a particular challenge for tomography to overcome, but the expertise of the ESRF managed to circumvent this problem. We scanned particular parts of two nearly-complete Archaeopteryx specimens and one that is only represented by a right arm skeleton. This specimen is appropriately referred to as the "Chicken Wing" (especially the arm looks very bird-like on first glance!).


Q:

Has there been similar work done on other similarly adapted dinosaurs (e.g. micro raptor) and what are the results and how are they patterned?

A:

Not yet, and unfortunately such material was not available to us during this study either. Nevertheless, I am also very curious to see what the addition of such taxa could tell us. One problem is that most of the relevant Chinese material is even more crushed than that of Archaeopteryx. This makes reliable retrodistortion a lot more challenging but I would definitely be happy to give it a try if I receive the opportunity.


Q:

I understand. I hope you'll get the opportunity to try.

To follow up, how many similarly adapted dinosaurs are currently known and how would you predict (based on skeletal morphology, or feather morphology in the case of micro raptor) that these would compare to your results concerning Archaeopteryx?

A:

The most similar to Archaeopteryx is Jeholornis from the Cretaceous of China. This dinosaur resembles Archaeopteryx in more ways than one, including an inferred preference for running around, but had fewer teeth, more strongly fused hand bones, and a shoulder that allowed for more upward mobility of the wing. We therefore think it was a better flyer than Archaeopteryx although it was still not particularly well-equipped for the flight stroke of modern birds. Jixiangornis shows a slightly improved flight apparatus still but also retains the long "dinosaurian" tail. Virtually all other flying dinosaurs we know today, including birds, have a tail consisting exclusively of feathers.


Q:

Being a person that professionally studies dinosaurs, what are the big pet peeves you have based on how dinosaurs are portrayed in pop culture/the media?

A:

What an interesting question! Although I generally welcome any and all attention for extinct life that may invite people into the fascinating field of palaeontology, I must admit that I cringe whenever I hear somebody with authority and a hidden agenda say that dinosaurs really support whichever non-scientific doctrine he or she adheres to. This is especially dangerous when it comes to educating children, since they may not be able to start looking into fossils independently until it is too late for them to choose for a scholarly path that may have brought them where they wished to be.


Q:

Hi, Dennis! I work with museum collections and I'm finally taking paleontology and the professor I work with closely did a study on Deinonychus' (specifically Deinonychus antirrhopus) forelimb function and morphology and how it might be important for the development of avian flight.

Is there a laymens terms way you could explain the relationship between Archaeopteryx and Deinonychus? He uses Archaeopteryx as a comparative example often to support his research and it's a little over my head in hand morphologies of therapods

Edit: I would also like to know what museums or institutions you've researched at to study Archaeopteryx?

A:

How very interesting! Archaeopteryx and Deinonychus are both members of the dinosaur group named "Paraves" or "near-birds". Within that group, Deinonychus falls within the dromaeosaurs (also called "raptors"), whereas Archaeopteryx is part of the other group, the "Avialiae".

Your professor's example is indeed very relevant, since it was exactly that line of reasoning that brought Prof. Ostrom in the 1970's to conclusion that a century-long old theory which had received little attention but is accepted today, namely that birds are dinosaurs, may actually be true!

If you look at the wrist of Deinonychus, you will find that the hand connects to the arm with a half-moon-shaped bone, which is also called exactly that (semi-lunate carpal). This bone allowed Deinonychus to sweep its hand to the side, which we ourselves cannot do. Archaeopteryx also had this bone, and in modern birds it is preserved as a similarly-shaped portion of a fused bone: the carpometacarpus. Exactly this anatomical aspect allows birds to fold their wings along their sides and over their back. Because it is present in both the raptors and the Avialiae, we suspect it was also present in the shared ancestor of those groups.

Edit: I would also like to know what museums or institutions you've researched at to study Archaeopteryx

My PhD project is officially accommodated within Palacký University in Olomouc (Czech Republic) but I have probably spend a little bit more time at the European Synchrotron Radiation Facility because they have the best arrangements for studying these large data sets. Furthermore, my team has close relations with several museums and institutes in Germany that house Archaeopteryx specimens and/or are involved in Archaeopteryx research themselves.


Q:

Hi Dennis, how exactly does a synchrotron work in relation to your research?

A:

A synchrotron is a particle accelerator in which electrons move around in a long circular tube, the storage ring, at high speeds. This produces synchrotron radiation that is released by electrons forced to circle its storage ring. Such so-called synchrotron light has certain properties that make it very suitable for a particular tomographical technique that rely on a phase shift created by differences in the rock rather than differential absorption by different materials in the rock and is capable of achieving much better contrast and detail in three-dimensional data sets than most conventional tomographical techniques. This is very important for palaeontology since the contrast between rock and fossil bone (which has essentially been converted to rock as well during fossilisation) is notoriously low in tomographical data. Using this technique was vital for non-destructively obtaining the reliable and high-quality imagery required for conducting the presented study.


Q:

What kind of costs are associated with a synchrotron scan of samples like this? How long does the scanning take?

A:

The European Synchrotron Radiation Facility is based in France but shared by its member countries that all chip in to have a wide range of research opportunities available for their scientists. Research proposals from teams within these member countries are evaluated and the most promising studies will be granted beamtime to conduct the presented study. If a project is granted then the researchers themselves do not have to pay extra; such research is covered by the membership fees of their country. Besides proposed research there is also some in-house research being conducted, for example when a planned experiment is cancelled at the last moment. Although experimentation time is not cheap if you would have to pay for it straight up, the synchrotron is running 24/7, so using beamtime that would not be used otherwise does not amount to significant additional costs.

Scanning time depends strongly on the size and nature of the sample that you wish to scan. Making individual scans of small samples may only take about 10 minutes. However, obtaining good scans from larger samples (which is done by stitching numerous individual scans together) with a challenging composition can require acquisition times of 20 hours or more!