The Fathered Pterosaur

In my previous posts I did talked about the origin of the filamentous structures in Ornithodira, the ones I nicknamed stem-feathers since I did believe they could be homologous but was not sure if those structures could be called feathers. And a couple days ago we got the answer for this question in the form of a new paper by Yang et al.(in press.) presenting us to two little feathered pterosaurs.

Using varied methods the authors analyzed the raw morphology, ultrastructure and the chemical composition of the filaments; leading them to the conclusion that this similarity probably confirms the homology of those structures. The do talk a bit about the original function of those structures being insulation (the one I did support in previous posts), use as sensory organs, enhance camouflage and making the animals more streamlined.

This paper support the ideas I did present in previous posts, the small bodied basal homeothermic Ornithodirans would probably need some form of insulation so they would not suffer the risk dying of hypothermia; we knew about the homeothermic characteristic and now we know they were feathered what we only need is a study modeling the climate of Southern Gondwana to see if it was necessary for their survival.
This will also open space for new discussions about when and why many dinosaur groups like sauropods, thyreophorans, hadrosauriforms and large theropods lost most if not all this form f integument. For the subject of paleoart it does open many possibilities of depictions of feathery structures in non-conventional groups like some fuzzy tufts on the head of sauropods.

Now knowing that feathers are ancestral to at least Ornithodira, and those are not only simple filaments but very complex branched structures, it opens the space for the question: "Are feathers an even more basal trait?"
We know for some time that crocodilian osteoderms B-keratin is similar to the one of ornithodiran filaments, also since modern pseudosuchians common characteristics with other "reptiles" like petiolethermy are a secondary acquisition could the "scaly/osteodermic" also is a secondary character and basal members might have been feathery/fuzzy as well?

As many times in science answering a question brings up many more, and this will be the scenery after Yang et al, (in press.), we answer the question is feathers are an ancestral trait for dinosaurs only to open space for the question if it is an ancestral trait of Archosauria. 2018 was not the most vibrant year of paleontology but ending the year with this new amazing paper is very nice and may be a good sign for 2K19.

References:

YANG, Zixiao et al. Pterosaur integumentary structures with complex feather-like branching. Nature Ecology & Evolution, v. 3, n. 1, p. 24, 2019.
DALLA VALLE, Luisa et al. β‐keratins of the crocodilian epidermis: composition, structure, and phylogenetic relationships. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, v. 312, n. 1, p. 42-57, 2009.

Erratum of the post: SVP-2018 and the Evolution of Stem-Feathers

A note on  my last post about the evolution of stem-feathers; as I did said in the post I was not present in SVP so all my information about the presentations there were outstretched from people present at the event, so that post might have suffered from a misunderstanding of my part or a misquotation of my sources. And that actually happened.

In the section about Lovelace et al. paper I affirmed he did said that Coelophysis would need some form of insulation to survive in Chinle, and it would die from hypothermia if not. That was a misunderstanding of my part based on a misquotation I read, Lovelace never said it would need insulation to survive, it would benefit from being insulated nothing else.

What that means for my discussion and final point?

The part where I did argue that if Coelophysis would need insulation to survive much smaller animals like basal ornithodirans would need it as well; independent if living in more topical region*; lacks support now. We are back to the "steam-feathers might or not be a basal trait of Ornithodira" point; we lack evidence to solidly support or deny if filamentous structures would be present in the basalmost members of that clade. (*That is wrong as well; topic for another post).

What we know is that pseudosuchians and avemetatarsalians both had high-metabolisms and were probably "warm-blooded"; hence the LCA of Archosauria would likely be as well.

SVP-2018 and the Evolution of Stem-Feathers

01-Recalling an old text:

To kick of this discussion I'm going to write a breath summary of a post I made still in my Deviant Art with the title "Are ornithischians filaments feathers?"

Instead of actually tackling the subject of the post heads on I usually dodged the main point, doing it right now, and I did it there as well in that post, instead of talking if ornithischians filaments were or not feathers I focused on the evolution of Avemetatarsalia.

In there I treated the LCA of both lineages as being a "cold blooded" animal that later evolved "warm bloodedness" somewhere around the base of the ornithodiran node. Starting from this premise I connected the evolution of "warm bloodedness" with the smaller size of basal ornithodirans (compared to aphanosaurians and pseudosuchians); but this reduction in size together with an increase in metabolic rates would be contradictory since it is easier for smaller animals to lose their body heat. So this condition seen in basal ornithodirans would be strange and nonsense, unless those animals had a way to insulate their bodies and prevent this head from escaping.

Therefore I concluded that feather-like filaments (stem-feathers) were an ancestral trait for Ornithodira evolving together with "warm bloodedness", while "cold blooded" was the most likely the ancestral condition of Archosauria.

02-New Data:

However I missed some stuff there, at the moment I was not aware we had histology analysis of Teleocrater, the results showing an animal with a high metabolism comparable to those of silesaurids, though slower than pterosaurs and traditional dinosaurs. If I knew that in the moment, proposing an answer for the ancestor metabolism of archosaurians would be harder and we would have had a scenario with many possible alternative answers.

In addition to this SVP-2018 brought us some new information on the metabolism of basal archosaurians:

• The first one being "High variations in growth duration and growth rates in the early ancestors of Crocodylia" by Werning and Turner (page 238 of the abstract book)
• The second one being "Deep-time application of linked microclimate and biophysical models constrains the thermal ecology of two Late Triassic dinosaurs (Coelophysis, Plateosaurus)" by Lovelace et al. (page 172)

Starting by Werning's paper, they made and studied histological slides of many groups of basal pseudosuchians (phytosaurs, aetosaurs, shovosaurids, "rauisuchians", basal crocodylomorphs and crocodyliformes). The result pointed that most of the basal lineages had a high metabolism more akin to those of avemetatarsalians than those of modern crocodiles (Crocodylia). More so, the metabolism of small basal crocodylomorphs and crocodyliformes was sometimes comparable with dinosaurs of the same size, meaning they were likely "warm blooded" animals.

Into Lovelace now, the most relevant part of his work for this discussion is not what he presents in the abstract but rather some thing he said in his SVP lecture*. They made a modeling analysis of Chinle Formation and focused on how Coelophysis and Plateosaurus would react to the environment, results found out that Coelophysis could not survive without insulation, partially "feathered" Coelophysis would have a better chance to survive, with the only way the animal could be healthy was if it was fully "feathered".

*Information obtained from tweets by Paleontologist Robert Gay (Link 01)

03-Discussion:

Now that we know the metabolism of a good number of lineages of both sides of Archosauria, we can say that almost surly the LCA of Archosauria was indeed homoeothermic, all the lineages studied so far were shown to have been homoeothermic giving a strong support to this idea. By consequence this refutes my old hypothesis that homeothermia evolved together with filamentous integument in the base of Ornithodira.

Resumed phylogenetic tree of Archosauria: underlined in red means the clade was "warm blooded", underlined in gray/silver means we are not sure about the clade metabolism. (We will have information on Aetosauria when the paper comes out).

Even though the prat about homeothermy has fallen I think more than ever we have support for stem-feathers being ancestral trait of at least Ornithodira. Lovelace et al. suggest that even larger animals like Coelophysis could die from hypothermia without insulation, so it is reasonable to assume* the even smaller basal ornithodirans like Scleromochlus, Lagerpetids and Marasuchus would die from hypothermia as well if not insulated. This supports my idea that stem-feathers would need to show up before these animals could suffer the size reduction we see at the base of Ornithodira without dying from heat loss.

*Obviously this is more complex since Ornithodira origin seems to have occurred in the Tropical Pangaea Belt, while the study was conducted for Chinle that was located further north in a (probably) temperate region. But I still thing the hypothermia idea would be valid since even if living in a hotter environment and having a lower metabolism then Coelophysis those guys would have a much inferior mass.

04-Concluding:

Combining all this new information with previous knowledge show us that basal archosaurs were more active and had higher metabolic rates then we did expect; being more comparable to mammals than modern reptiles (Linnaean sensu, minus birds) only latter being reverted to pecilothermy in modern crocodiles. The highly derived ornithodirans would probably need some form of stem-feathers for insulation otherwise they would die from heat-loss, hence "feathers" would probably be an ancestral trait of Dinosauria (fanboys gonna crie).

I also wanna note that I was not present at SVP and did not attended the lectures/presentations of these works, and all this information used in here is "outsourced" so there may have been some confusion and misinterpretation of my part at some part of this. We will still have to wait for the final paper to come out to be 100% sure that this here is

Note: I used the terms "warm blooded" and "cold blooded" in here because I don't know if the metabolism of these animals fits into endothermy and/or homeothermy; so not to spread missinformation I opted to use the popular name in quotation marks cause those cover the general idea.

Read the erratum post: https://apaleontologystudentblog.blogspot.com/2018/12/erratum-of-post-svp-2018-and-evolution.html

References:

Link 01: https://twitter.com/paleorob/status/1052668072195047424
Link 02: https://twitter.com/paleorob/status/1052585584907059202
SVP-2018 abstract book
Nesbitt, Sterling J., et al. "The anatomy of Teleocrater rhadinus, an early avemetatarsalian from the lower portion of the Lifua Member of the Manda Beds (Middle Triassic)." Journal of Vertebrate Paleontology 37.sup1 (2017): 142-177.

"Amphicoelias" fragillimus and the Knowledge of Armchair Paleontologists

   There could not have had a better paper to kick of the first content post of this blog than the present Dr. Kenneth Carpenter gave us last Sunday when redescribing "Amphicoelias" fragillimus and naming a new genus to make it separate from the type species of the genus. Not only that but he also formally publishes something many of us in the internet have been saying in the last 4 years, "A." fragillimus is a basal rebbachisaurid.

01-The Birth of Rebbamphi:

The first person to suggest "Amphicoelias" fragillimus  might have been a rebbachisaurid rather than a diplodocid was Andrea Cau, Italian Theropod specialist, in his Blog in 2012 (link N°-01). He did not entered in much detail there but shows that "A." fragillimus was in a polytomy at the base of Diplodocoidea and they had similar characters regarding the neural arches and lamination of the vertebrae, so it might have been a basal rebbachisaurid. In the end he just said it was just a provocation, though if true it would be more reasonable than the diplodocid-like size estimates.

02-Popularization of Rebbamphi:
 
Though Cau was the first to propose such possibility the guy that actually popularized the idea of Rebbamphi was Zachary Armstrong (aka: Zach Armstrong), an independent paleoblogger, in a journal posted in his Deviant Art in March of 2014 (link N°-02). There he presents a reconstruction of a fragillimus vertebra with the unknown parts being filled by Rebbachisaurus and Limaysaurus rather than a diplodocid like Diplodocus as was usually done, and show the know bits were indeed more similar to those of rebbachisaurids than the more derived diplodocids.

In a similar way to Cau, Armstrong showed that the neural arch of "A." fragillimus is actually similar to the one of rebbachisaurids than to diplodocids, looking especially like Limaysaurus. He also notes that if it was a  rebbachisaurid-like animal, we could explain the fragility of the specimen being in fact a result of the pneumaticity of the skeleton; very common on rebbachisaurids. His size estimate for the animal was around 28.6 meter long.

*Also it is very nice that Carpenter did recognize Armstrong suggested this 4 years ago.

03-Carpenter's paper:

Finally we get to Dr. Carpenter's paper, during the first part of the paper he focuses on the history of the specimen and in the latter segments (past Systematic Paleontology) he focuses on giving the species a redescription and the biogeographic and evolutionary implications for Rebbachisauridae and Diplodocoidea (if his hypothesis that "A." fragillimus actually was correct).

But the most important part is in the middle of the paper (pages 7-11) where he presents the arguments behind his hypothesis; and those were the same ones used by Cau and Armstrong:

• Neural arch morphology
• The fragility of the specimen may be caused by the fact that rebbachisaurids have highly pneumatic skeleton.
• I honestly did not understand very well one of them, but I think it is the same thing Cau said about lamination of the vertebrae

In the end the 3 researches suggested/got to this same conclusion independently, and what is especially important (and reason why I choose this as the subject of my first post) is that Armstrong does not have an academic degree in biology/geology. However he did nailed that "A." fragillimus could have actually represented a rebbachisaurid instead of another kind of diplodocoid and used the same arguments that now were used by Carpenter to support his hypothesis.

What can we learn with this? That we cannot immediately discard anyone opinion because he/she does not have an academic degree for paleontology, the real basis of a scientific opinion is not the curriculum behind the author of it, but actually the solidness of its arguments. Finally it proves that there are many talented "armchair" paleontologists hanging around in DeviantArt, Discord or in various blogs in the internet; and it's worth at least giving a chance to their opinions as they may actually be correct.

I could not have asked for a better subject for the inauguration post of this blog; now that you are aware of this story you may give my page a try and listen to my opinions because some of us armchair/self-thought paleontologists do actually know our stuff.

Link N°-01:
https://theropoda.blogspot.com/2012/01/amphicoelias-fragillimus-e-un.htm
Link N°-02:
https://www.deviantart.com/palaeozoologist/journal/Was-Amphicoelias-a-rebbachisaur-440611550

Introduction Par 03 - Proposal, Objectives and Methodology

   Now that you know who I am and what motivates and inspire me it is time to finish this introduction series by making clear the proposal for this blog; which goals I intend to achieve with this project and how I'll do it.

01-The Proposal:

   I intend in making this a new space for what I was doing for a long time in other platforms; discussing, commenting and gave my opinion on recently published papers; though I used to do it mostly for adding a bonus to my curriculum and now my focus is to create paleontology related contempt to mostly catch the attention of younger paleontology enthusiasts from high school students to fresh biology/geology ones and try to inspire them in some why to follow this passion as their career; just like I did.

02-Objectives and Methodology:

• 1° Objective = As spoiled above; attract attention of young paleontology enthusiasts and try to convince to follow career on it (if it is their passion, course).
• Methodology = Writing posts on recently published papers; discussing the data, results and hypothesis presented.

• 2° Objective = Generate bonus curricular material for myself.
• Methodology = The post I'll be writing here will be proof I always was interested in working in paleontology and that I know my stuff. I hope this will be a differential in my curriculum from other students helps to tip the balance in my favor in the future when someone evaluates my curriculum.

   I could make some final considerations, but I already wrote too much in 3 post and I guess there is nothing special I should say. Just stay tuned for new posts coming soon.

Introduction Part 02 - Motivations and Inspirations

Continuing with the introduction process of this blog this post will focus on my motivations and inspirations for this project; without wasting much time:

01-Motivations:

   The "paleontology lab" of my institutions is very small; it technically does not exist and fossils are housed together with the sedimentology and mineralogy collections of the university. I heard quite a few  colleagues saying they wanted to work with paleontology but gave up because of the size of the laboratory and lack of perspective for the future. This seems to be a recurring theme in other universities, even those with big labs and world-class researchers, with few graduation students choosing paleontology as their research area.

   I imagine this is not exclusive to Brazil and in many other places people gave up on working with science based on lack of perspective for future/success. And this is one of the prime motivations I'm launching this project, reach the maximum number of people especially young paleontology enthusiasts and try inspiring then to follow a career on the area (hence why this is in English not in Portuguese).

   Because of this, I proposed earlier in the year to my boss if she could let me teach and assume some classes about paleontology, with the objective of trying to pass my passion to those students and  understand the value of our work and want to preserve the rich Brazilian fossiliferous record. I still have yet to lesson my first class but together with my boss we gave a small speech and convinced 6 students to follow and have an experience working with us, giving me even more support and desire for making this blog.
   Summarizing I wanna make people valorize the field of paleontology and inspire some to work in the are, I'll only have access to 30-40 students each semester doing this only in college but the internet can spread this message to a larger level, reason for the existence of this blog.

02-Inspirations:

   The idea of making a blog/page for scientific talk is not unprecedented; there is Witton's Blog; Motimer's Theropod Database; Cau's Theropoda; Wedel's, Taylor's and Naish's SVP-PW or Naish Tetrapod Zoology. All of those have their importance and are the inspiration for the layout and content of this blog; but not direct inspiration for me to make move and inaugurate this page. This honor goes to some of my professors that by their work and are my inspiration for this work:

• Camila Neves Silva: my adviser/supervisor/boss (I don't know the correct terminology) for the opportunity of working with her and giving me all the support I need for starting this kind of project. Coincidentally we both got convinced that we need more work done in education about paleontology independently, I hope our work in class can indeed catch more to our boat.

• Roberto Juinio Pedroso Dias: he ministered to me the Protozoa subject; lets be honest it is not the most exciting subject for someone that loves dinosaurs. But he is so in love with his work and me me also like Protozoans (I still prefer my dinosaurs). You proved to me that a good and passionate teacher can have a large positive influence in his students, you are my inspiration for teaching and hence one of the main inspiration for this work.

• Larisse Faroni Perez: though we work with very different subjects (she works with polychaetes) she is my career inspiration. She studied this group since her graduation and with dedication during years she presented the best student work in International Polychaetes Conference in 2016 getting recognition of all researches she admire since her graduation. I wanna be just like you when "I grow up"; when I get the same honer in SVP-202X I promise I'll remember of you. (Hope we can be friends now)

You are kind of the "parents" of this project so I wanna at least have a part of it dedicated to saying thanks to you.

Introduction Part 01 - Me, and how I got here

   People say the first step is the hardest; so imagine writing the post to kick of the blog I intend on using for a scientific outreach project for at least the rest of my college graduation; yeah it is pretty hard, so I'll be going with a safe bet in:

Hello readers,

   Before I introduce you to this blog and the project I intend on developing here, I need to introduce  introduce myself; my name is André de Oliveira and in summary I'm a 19 year old Biology college student in Universidade Federal de Juiz de Fora, Brazil.
   Since I was a kid I always was fascinated with dinosaurs and other extinct fauna, and as expected, the interest faded during most of my teenagehood. Only coming back in late 2014 because of the recent discoveries of the time about Spinosaurus and Deinocheirus that made me go and look stuff on the internet and that made my passion for those creatures to bloom once more.
   During 2015 and 16 I mostly followed the subject from far away with quite a passive approach, checking into new species I looked up at some blogs or Wikipedia, but nothing very deep. But while looking for pictures of various species I entered frequently in contact with the DeviantArt paleontology community till one day (September 29 2016) I decided to create my own page there. This was the "start of my paleontology internet career". For most of 2016 and 17 I was just there enjoying the art till I decided to start posting some of my drawings, positive reception of members of the community made me keep posting those consistently.
   During the second semester of 2017, I was doing a subject/course in college named "Topics on Geology and Paleontology" and in the end of the semester I decided to show some of my work to my professor. She was quite supersized and invited me to help her at her lab and work in a project with her (where I'm still working).

   In February, I needed to make a trip to São Paulo and driven by such success in my institution I decided to visit the paleontology lab of São Paulo University. There I talked with Dr. Max Langer and show what I was doing, he was not impressed, and said to me something around the line of “You are still very fresh and barely finished your first graduation year; when you reach the penultimate year of college come back here and if you are still interested I can help you”.
   To be honest this was not the answer I expected to hear; for the rest of that day I was quite miserable, on the ground and even questioned if that was the career I intended on following for my life. But as some say "successful people are those who rise up after they fell", so I needed to rise up once more.
   The next day I reevaluated my work and saw I was drawing too much but producing very few technical paleontology contempt. Realizing so I changed what I was doing; I stooped drawing constantly and transformed my DA into a mini blog where I made reviews and commented recent papers and sometimes congresses abstracts and resumes.

   I liked that work and felt it was much more in line with a graduation student than my old gallery with mostly drawings. However, I always felt Deviant Art was not the right place to do such; I had a blog in a platform supposed to be an art gallery. Because of such I am here today inaugurating this blog and transfusing that work into a more appropriate platform.

   This is just a brief story of myself so everyone can understand how I got here and the origins of this project. The rest of the introduction: proposal, objectives, motivation and my inspirations for this project are in the other posts of this Introduction series.