Corkboard of Curiosities have done it again! Click on the image below to read a lovely explainer on what taphonomy is.
Image by Corkboard of Curiosities
... would we mammals be 'scurrying' at the feet of our dinosaurian masters?
Prof. Jonathan Losos recently gave a talk (summarised in this article by Cameron Hill) and stated that it is arrogant to assume that humanity is the pinnacle of evolution, and somehow inevitable over a long enough evolutionary time scale. Which I completely agree with.
But the assertion that, if the Cretaceous-Paleogene (K-Pg) mass extinction hadn't happened, meaning that non-avian dinosaurs weren't wiped out 65 million years ago, that they would still be ruling today? I'm not so sure.
What if certain groups of mammals had opportunities to out-compete non-avian dinosaurs? (Yes, those opportunities usually come around when mass extinctions occur and niches open up for the taking). However, there is evidence that non-avian dinosaurs were already on the decline before the K-Pg mass extinction event (see here, here, here, and here). Perhaps new niches would have opened up for mammal groups even without an asteroid crashing landing in the Yucatán Peninsula. Or any other group of animals, for that matter. New research proposes that it was the avian dinosaurs (birds) ability to eat seeds that allowed them to survive the K-Pg extinction. If the non-avian dinosaurs were declining anyway, would avian dinosaurs still have taken this seed-y niche?
It comes down to how we identify faunal turnover in the fossil record, and how we understand the causes for changes in the 'dominant' clade. Mass extinctions are commonly invoked to mark the end of one clade's reign and the start of another - from synapsids (often known as 'mammal-like reptiles') dominating the Permian then suffering mass extinction at the Permian-Triassic boundary, after which pseudosuchian diversity increased throughout the Triassic until the Triassic-Jurassic extinction event. Then, dinosauria took over newly created niches and ruled the rest of the Mesozoic until the K-Pg event, where synapsids (in the form of mammals) once again took the reins.
If non-avian dinosaurs had survived the K-Pg extinction event, how sure can we be that they would still be around today? I don't think we can say for certain that another extinction event wouldn't have happened between 65 million years and now. Perhaps the pseudosuchians (in the form of crocodiles) would have taken over once again. I think it's reasonable to propose that continental drift and ice ages would have inevitably occurred as they did, regardless of what animals were alive. Physics (and geography) will do what it wants to do, after all. Would non-avian dinosaurs, even with their proto-feathery fluff, have survived ice ages or 'ice house' conditions? They had survived a period of global cooling at the Jurassic-Cretaceous boundary, but it was not technically an ice age. What about the pseudosuchians? Furry mammals didn't appear to do too badly in our evolutionary history, but they were already in dominant niches prior to various ice ages.
One thing is for sure: I one-hundred percent agree with Prof. Losos that humanity, or even bipedalism in any animal, is not inevitable in Earth's evolutionary history.
Lest we forget this horrifying vision of an alternate Earth, ruled by humanoid-dinosaurs or 'dinosauroids'. This would not have happened. I hope.
Image by the Canadian Museum of Nature, Ottowa, Canada.
They've done it again! The fabulous creators at Corkboard of Curiosities has a very clear and succinct run down of cladistics - how we determine which groups of animals are more closely related to one another. Head over there to find out how!
Image by Nate Carroll and Tammi Heneveld
What does a palaeontology student do on a typical work day? And what about a non-typical day? Head over to UQ's new blog, Small Change, and find out! Hint: it involves a little bit of reading papers, a little bit of lab work, with a sprinkle of lunch-time Twitter perusal.
Soapbox Science is coming to Australia for the first time!
As a part of National Science Week 2016, Soapbox Science will take place in Brisbane where leading female researchers will talk about their scientific projects and why they love science.
Soapbox Science is a public speaking and outreach event aimed at encouraging girls and women to take up careers in science. You can hear all about why these scientists love their jobs, ask questions about their research, and see that women belong in the sciences just as much as men do.
I will be speaking at this years Soapbox Science event at King George Square in Brisbane, on the 20th August between 1-4 pm. My talk title (coming as no surprise to long time readers of this blog) is: “Fossil forensics: how taphonomy helps us understand the death and decay of dinosaurs”. Keep an eye out for updates between now and August!
New feathery evidence for North American dinosaurs: it appears that Ornithomimus was covered with feathers everywhere except for its lower legs.
An artists impression of Ornithomimus - note the lack of feathers on the hind limb, akin to modern day ostriches. Image from van der Reest et al (2015), reconstruction by Julius Csotonyi.
What interested me about this paper by van der Reest et al (2015) was the lack of leg feathers found.
If this feathery absence isn't taphonomic (i.e. leg feathers were present in life, but not preserved with the fossil), then perhaps their absence paves the way for another type of leg covering... perhaps, podotheca?
I've written about podotheca - the scales on the lower leg and foot seen in modern birds and reptiles - a couple of times on this blog (both on hypothesised podotheca in a coelurosaurian theropod fossil, and preserved podotheca impressions with a non-coelurosaurian theropod fossil).
In those prior studies, podotheca were proposed to be present in not only the lineage that led to modern day birds (coelurosaurs), but also theropod lineages that do not include modern birds (non-coelurosaurs). As Ornithomimus is a coelurosaur, the presence of podotheca would at least bolster the idea that this feature was present in the ancestors of modern birds.
The study by van der Reest et al (2015) doesn't hypothesise about whether there was a podotheca-like covering on the hind limbs of Ornithomimus. But it does point out the presence of both feathers across the body and skin webs attached to the upper leg, which are features also seen in modern day birds.
They do, however, suggest that the lack of feathers on the lower legs may be related to thermoregulation - a way for the animal to keep cool - which has been noted as the reason why modern ostriches, emus, and cassowaries have sparse or no leg and neck plumage.
If Ornithomimus did have podotheca on its hind limbs, the artist's reconstruction in the paper, and shown above, indicates what it would have looked like in life. In any case, let's hope for more solid evidence of podotheca in future Ornithomimus specimens.
van der Reest, A. J., Wolfe, A. P., Currie, P. J. 2015. A densely feathered ornithomimid (Dinosauria: Theropoda) from the Upper Cretaceous Dinosaur Park Formation, Alberta, Canada. Cretaceous Research, 58: 108–117.
How have I only just recently heard about the palaeontology themed comic, Corkboard of Curiosities? Given my obsession with both palaeontology and cabinets of curiosity... I'll blame my lack of awareness on working too hard on my PhD.
Now, enjoy their primer on Pterosaurs: how they aren't dinosaurs, and they certainly didn't have bat-like wings, and more! And click this link to go to the Corkboard of Curiosities website and enjoy more of their palaeontological comics.
Images via Corkboard of Curiosities
Here's what has been making headlines this week (28th September - 4th October):
New experiments prove that colour can be fossilised
Colour preservation has been found in fossil feathers before (in the form of structures called melanosomes), but this is the first time they have been shown to potentially preserve in other soft tissues. The journal paper can be found here (paywalled).
Dinosaurs with little heads and giant bodies: why did sauropods get so big?
Being gigantic has its advantages: you're harder to eat, tend to live longer, and can regulate internal body temperature with much more ease. But if you grow a gigantically long neck, you can't have a gigantic head attached at the end.
Palaeolatitude calculator - how far has your continent drifted?
If you travelled back in time, but moved with the land your currently standing on (thanks continental drift!), where would you end up? Click anywhere on the map, and you can how far that location has moved over the course of 200 million years! The journal paper backing this up can be found here (open access).
Maiasaura life history determined from 50 slices of bone, the largest study of its kind
A new study of Maiasaura, the "good mother lizard", indicates they grew to 2.3 tonnes over eight years, reached sexual maturity in its third year, and had similar bone structure to modern large warm-blooded mammals. The researchers plan to learn even more about Maiasaura over the coming years thanks to 'The Maiasaura Life History Project'. The journal paper can be found here (paywalled).
TRIGGER WARNING: Depression
Some caveats to begin with:
Everyone experiences depression differently, and to different degrees. I’m describing my (abbreviated) personal journey through my depression. This will not be the same for everyone, and is not The Answer™, just one answer. But I hope it will be useful to someone going through depression, or a friend or loved one who wants to know how depression may feel.
PhD programs can be stressful. If you didn’t know that, now you do. It is fantastic that people discuss how they’re feeling about their PhD workloads and how stressed they may or may not be, using Twitter hashtags such as #phdlife.
The issue comes with normalisation - thinking that it’s ok to always feel stressed during your PhD - and then just living with the stress.
Don’t get me wrong - in small doses, stress is a great motivator. A problem arises when those feelings of stress persist even when there isn’t, for example, a looming deadline. And then it can lead to depression, limiting your ability to deal with any upcoming deadline at all.
When stress isn't motivating, but crippling. Image by Loading Artist.
And therein lies the problem. I had great supervisors, and an interesting project, so I counted myself as one of the lucky ones. I also had a fantastic, supportive partner (and still do!). Stress was a ‘normal’ part of the PhD, so what did I have to worry about?
There were days where I just couldn’t get out of bed. I wished that the day would remain on ‘pause’ until I decided I was ready to get up and face the world. Even though my PhD was progressing nicely, I still felt stressed and sad.
I couldn't concentrate on reading a paper for more than 2 minutes before my vision blurred for no apparent reason. I couldn't write a sentence without having three other trains of thought (relevant or not) interrupting it. I’d also find myself walking to or from my office and feel the sudden urge to sprint down the corridor. But I had no energy to do anything of the like.
But I figured that I mustn’t really have depression, because what do I have to be depressed about? Perhaps I had just spontaneously become scatterbrained.
Over a period of a few months, things got worse. My morning sleep-ins became longer, I sniped at my partner, I still felt sad and always felt like crying. Even my favourite computer and console games felt boring.
I figured that yes, maybe now I do have depression. But only a little bit. Just a light case.
Turns out, this doesn't work. Also, you should definitely read this article+comic by Allie Brosh about how depression affected her. Image by Hyperbole and a Half.
I didn’t see a doctor about how depressed I felt for a long time because, again, I thought it was a natural part of the PhD process. It wasn’t coming out of nowhere, as it does for some, but from a definable stressor. I likened it to someone repeatedly hitting their head against a wall: their head hurts, they know why it hurts, so wouldn’t it be silly of them to take some painkillers and merrily continue on their head-smacking ways?
My doctor nodded when I described this scenario, and said, “Are you going to stop doing your PhD?” I said no, the PhD program was fine, I was just stressed and depressed for no apparent reason.
“So”, she replied, “Why don't you medicate yourself while you continue the PhD, and when you’re finished, if you want to, you can slowly come off the medication?”
And there was the seemingly obvious answer. If the cause of my depression was the PhD, I needed to take some antidepressants to continue the program. If it wasn’t the PhD, but the beginning of clinical depression, then I would have refused medication for the entire PhD program for no reason.
Here was a new option: finish the PhD program WHILST AT THE SAME TIME feeling better about myself and the world in general.
I have to remind myself that, sometimes, maybe, doctors just might know what they're talking about.
Image from KnowYourMeme.com.
(A side note: when you have an upswing in mood, and everything is feeling a bit better with the world, go see your doctor. This may seem counterintuitive - after all, you’re feeling better - but now is the time you’ll be motivated enough and able enough to step outside and talk to someone about how you’re feeling. If you wait until you are at your worst, you may not feel able to talk to the doctor about what your going through and just put off the potential diagnosis and help.)
This is the way I personally feel about antidepressants (besides complicated issues of overprescription): if the medical community has spent millions of dollars and decades of research into helping people with depression, why not take advantage of their hard work? Why suffer in a time where you have options to feel better?
I know that not all cases of depression can be easily fixed with medication. In my case, it did work. Some people need to try different types of medication, or find that the medication only takes some of the depression away.
But if you are on the road to some kind of recovery, please don’t feel guilty about the time you’ve lost. You were unable to work during that time, just like with many other illnesses. But when you feel better, capitalise on it. Use this time to talk to your supervisors, get a clear idea of your tasks, and create plans to get work done.
This doesn’t mean you should work yourself into the ground to make up for 'lost time'. It means you should work efficiently and at your normal pace, to keep that good feeling going for as long as possible. Also explore whether you can extend your PhD program deadlines, or go part-time for a little bit (if you are able) for more time to get back on your feet.
And read ALL the papers! Images by Hyperbole and a Half.
I still suffer from periods of depression. But those depressive periods are much shorter and much less emotionally exhaustive than before. And I can bounce back to the pure enjoyment of research much, much quicker.
Now, I’m off to read about fossil preservation in deltas and estuaries, and tonight will play video games I’ve actually been looking forward to!
A huge thank you to my Twitter friends for reaching out and showing support. You guys rock!
A key tenant of palaeontology is that soft tissue and DNA cannot be preserved in fossil bones; they’re much too old, and any soft tissue that survived microbial decay (the skin of mummies, for example) would have been mineralised. This is why, sadly, we cannot ever clone a dinosaur. But how long does it take soft tissue to decay? And more specifically, how long does blood last in the bones of a dead animal?
A new paper has just been published on the taphonomy of blood in decomposing human bones (Cappella et al., 2015). In it, the authors collected human bone samples from ‘fresh’ cadavers (no more than 24 hrs post-mortem), from those same cadavers each week for the next 7 weeks, from a ’putrified’ carcass (48-72 hours post-mortem), from 20 year old bones, and one sample from a 400 year old bone. One ‘fresh’ cadaver also had bone samples taken and frozen, boiled, or macerated (placed in fresh water). These bone samples were then examined in thin section under a microscope to see if any trace of blood could be found.
The authors found that they could identify blood in the ‘fresh’ bone, but it was nearly impossible to identify red blood cells in bones older than 2 weeks post-mortem. They confirmed that boiling and macerating bone is a very efficient ‘cleaning’ method with very little blood remaining, whereas blood was preserved well and easy to observe in frozen bone. Some more refined analysis (using immunohistochemistry) made it possible to identify red blood cells older bone samples (up to 15-20 years post-mortem), yet the amounts present were very small - found in only 10% of the bone pore space. However, no red blood cells could be detected in the 400 year old bone either by microscopy or immunohistochemistry.
Graph showing the percentage of red blood cells and other blood components seen in frozen, boiled, macerated, putrefied, modern and ancient skeleton bone samples. The blue line indicates blood seen in thin section, the red line indicates blood seen using immunohistochemistry. From Cappella et al (2015).
The authors suggest that those who have reported seeing soft tissue in fossil bones are most likely mistaken in their interpretation. This finding is especially pertinent to palaeontology, as Schweitzer et al (2007) claimed to have found soft tissue preserved in 65 mya Triceratops horridus bone (MOR 699), 68-65 mya Tyrannosaurus rex bone (MOR 1125, MOR 555, FMNH-PR-2081), and 78 mya Brachylophosaurus canadensis bone (MOR 794). Given the results of this latest study by Cappella et al. (2015), these interpretations of dinosaur soft tissue preservation appear to be highly unlikely.
Cappella, A., Bertoglio, B., Castoldi, E., Maderna, E., Di Giancamillo, A., Domeneghini, C., Andreola, S., Cattaneo, C. 2015. The taphonomy of blood components in decomposing bone and its relevance to physical anthropology. American Journal of Physical Anthropology, doi: 10.1002/ajpa.22830.
Schweitzer, M. H., Wittmeyer, J. L., Horner, J. R. 2007. Soft tissue and cellular preservation in vertebrate skeletal elements from the Cretaceous to the present. Proceedings of the Royal Society B: Biological Sciences. 274 (1607):183-197. doi:10.1098/rspb.2006.3705. 274:183–197.
About the author
Syme is a PhD candidate at The University of Queensland, studying the taphonomy (preservation state) of fossil non-avian dinosaurs, crocodiles and fish from
the Winton Formation, Queensland, Australia. Think forensic science or CSI for fossils, and you're on the right track!
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