Monday, September 7, 2015

Masiakasaurus Proposed as a Fossorial Animal Hunting Specialist

And now for a change of pace from serrated tongued terror birds and bonesaw theropods to a new look at Masiakasaurus knopfleri in terms of its lifestyle. This is an idea of mine that I have been kicking around for a while so time to dust it off and present it. It's a bit of a stop-gap until I wade back into talking about ziphodont cutlery.

Masiakaraurus knopfleri credit James St. Johns. CC2.0 

When I look at how an extinct animal likely lived I use a blending of three criteria:

1) Is there a reasonable analogue available? or at least a composite analogue?

2) Is the lifestyle feasible with regards to the local ecology/environment this animal likely lived in? i.e. maybe dedicated piscivory is not the best idea in a semi-arid habitat.

3) Are there any substantiating osteological/biomechanical clues in the skeleton? Trace fossils? Gut contents?

So with Masiakasaurus we have an interesting little character. It's actually the most well known noasaurid. In fact it is one of the better known theropods at this point. Now because Masiakasaurus knopfleri is a relatively recent addition to the theropod canon it gives us a good glimpse of how the suggestion of a lifestyle, then becomes repeated, and then becomes unquestioned. It is in fact a picture perfect view of how dogma arises.

used w/permission credit Luis Rey
And for Masiakasaurus the lifestyle that is most heavily repeated is the fishing one. Why is this?

Well first of all let's review why the dental design is so weird in this guy. The anterior end of the jaw is characterized by the procumbent dentition and lack of serrations which grade back into more typical laterally compressed serrated teeth towards the back.  Carrano, Sampson & Forster 2002 interpreted this heterodont pattern as indicative of the animal having the ability to grasp at small prey items which could be further minced in the rear teeth. They muse that "One possibility is that Masiakasaurus was insectivorous or piscivorous, using its anterior teeth for acquiring small, whole prey items and its posterior teeth for maceration."

Evolving from this simple suggestion you can clearly trace the insertion of this view as the dominant one with regards to how Masiakasaurus lived. But given that it has really never been fully tested (although Jaime Headden questioned it) is there any merit to dedicated piscivory in Masiakasaurus?

Is fishing Masiakasaurus really just a knee jerk reaction - "Ughhh it's doing something different with those teeth... ummm.... fish!!"

I am going to endorse theirs and others suggestions that the anterior teeth did indeed seize relatively small, single prey items and the posterior teeth did indeed help slice prey items too big to swallow whole. But I don't think that these prey items were commonly fish - which were likely not that common in semiarid Late Cretaceous Madagascar - but that its most common prey was the various likely fossorial animals it shared its island home with.

I hypothesis it was a fossorial animal hunting specialist.

Is there anything in the skeleton of this animal that could substantiate this claim?

from Carrano et al. 2011
If we start working our way back from the head we can see that the neck, at least for a theropod, is relatively straight. And there is an anatomical reason for this. From Carrano 2002: "The posterior cervical vertebrae of Masiakasaurus lack any elevation of the anterior face over the posterior face, suggesting that the base of the neck was relatively straight. They differ from those of coelophysids in being taller and wider relative to their length, bearing larger epipophyses, and having antero-posteriorily shorter neural spines."

To translate the vertebrae did not form the classic sigmoidal "S" shaped neck of theropods. Masiakasaurus was not optimized to achieve the kind of strike that herons do when fishing. Additionally  the relatively short vertebrae (taller and wider relative to length) is incongruent with the relatively long vertebrae of azdharchids, herons, and Tanystropheus - all likely strikers of small prey.

Quetlzalcoatlus sp. Jaime Headden CC3.0
Tanystropheus longobardicus. CC3.0 credit Ghedoghedo
Great Blue Heron. Ardea herodias
So for three tetrapod lineages that - certainly in the case of the heron but most likely in the other two -strike at small prey with their neck in a downward motion and all of which feature very elongated cervical vertebrae, Masiakasaurus does not line up well with.

Additionally from Carrano et al. 2002: "Like abelisaurids and most other basal theropods (but unlike coelurosaurs), the cervical centra zygapophyseal facets are not "flexed" and exposed anteriorly. The three cervicals from the Late Cretaceous Lameta Group of India ascribed to Laevisuchus indicus (Huene & Matley, 1933) are similar to those of Masiakasaurus in most respects, as is the cervical neural arch of Noasaurus. All three display short, anteriorly-placed neural spines, and postzygapophyses that are swept back strongly posteriorily."

What this means, in my shotgun blast translation, is that all that stuff that stuff that sticks out off the cervical centra - the neural spines, the zygapophyses - it is all swept back to streamline the whole contour of the cervical osteology. Almost as if the animal wanted to have any potential obstructions diminished that would impinge it from sticking its neck into tight spots - like deep into a burrow for instance. Furthermore this adaptation might be congruent in other noasaurids hinting at potential similar function and ecology across this group.

An interesting transition occurs when we move from the cervical vertebrae into the dorsal (i.e. torso) vertebrae. Carrano et al. (2011) take note of the interesting transition in this theropod and that it differs from the pattern in most theropods: "The tenth cervical vertebra (C10) lies at or near the cervicodrosal transition, although this can be difficult to define in theropods. Its unusually long proportions indicate that Masiakasaurus was characterized by antero-posteriorly lengthened centra thoughtout the presacral vertebra column. This is unlike the condition in most theropods, where the cervicodorsal transition is marked by one or two anteroposteriorly short vertebrae."

Masiakasaurus is breaking all the rules... but why?

Gone are the short vertebrae of the cervical region instead (from Carrano et al. 2002): "They are spool shaped, weakly amphicoelus, and lack foramina. Unlike the dorsals of Majungatholus, the centra are not shortened but remain anteroposteriorly elongate (approximately twice as long as either as either wide or tall), as in most coelophysids, smaller theropods, and Elaphrosaurus."

When vertebrae are amphicoelus that means both surfaces of a vertebrae are concave and there is good potential for mobility in several directions. This feature, combined with the relatively longer vertebrae, speak to a relatively mobile trunk region. Which is an interesting contrast to the relatively stiffer neck region. Its almost as if the animal needs the ability for its trunk to squeeze and squirm around in tight places - like into a burrow.


So if the anterior of the body is, as I am suggesting built to get into tight spaces i.e. burrows we should also expect to see some interesting adaptations in the pectoral girdle.

From Carrano et al. 2011: "The scapula and coracoid show an unusual morphology that finds some complacement among other members of Ceratosauria. When articulated, the scapulocoracoid is mediolaterally curved and presents an enormous area for muscle attachment anterior and ventral to the glenoid."


So we have some buffed arms... potentially for digging maybe? However despite the indication of a robust pectoral girdle the morphological theme of trying to "streamline" the bauplan - which I argue is to better access burrows - is persistent.

From Carrano et al. 2011:

"The scapula has a curved blade that reflects the shape of the underlying rib cage, and is broad relative to its length as in coelophysoids as well as other ceratoraurs."

Tranlation: the shoulder blade closely hugs to and mimics the contour of the rib cage. The ecological inference I argue is to diminish obstacles when pummeling into burrows.

"The glenoid has a pronounced anterodorsal rim, as in Ceratosaurus and Majungasarus. In posterior view the scapular portion of the glenoid is D-shaped, and substantially taller dorsoventrally than wide mediolaterally. Its ventral margin along the coracoid suture is oriented obliquely rather than horizontally."

Again the glenoid, or shoulder socket, is showing adaptations to diminish lateral projections and make the anterior of the animals body as flush and streamlined as possible. All useful traits to facilitate entry into tight spaces i.e. burrows.

from Carrano et al. 2011


From Carrano et al. 2011:

"The coracoid is expansive and oval, with long axis oriented anteroposteriorly (fig 18a above). It is much broader than the same element in basal theropods such as Dilophosaurus and Coelophysis, more closely resembling the condition in Elaphrosaurus. Limusaruus, and abelisaurids (although it is more anteroposteriorly elongate than in the latter). The posteroventral process is blunt, projecting only slightly beyond the posteriormost part of the glenoid. It is extremely thin mediolaterally, more so than in almost any other theropod, and lacks the characteristic medial concavity."

Did you pick up on that? The corarcoid, though large, is orientated in a front to back direction but the authors note that it is relatively more elongate than other ceratosaurs. The posteroventral process - a process implies a ridge of bone - is blunt. Not only is it blunted it it is extremely shallow mediolaterally, which means it is thin going from the midline of the body out away from the body - more so than any other theropod the authors mention. Both the bluntness and thiness speak to further diminishing any lateral projection that might diminish fitting the anterior of the body into tight spaces.

Let's look at the humerus now (from Carrono et al 2011):

"Overall it is concave curved medially but nearly straight in the anteroposterior plane. The deltapectoral crest is proportionally short, extending down only about one-third of the total shaft length. The distal condyles, although slightly damaged, are clearly flattened proximodistally as in abelisauruds, Ceratosaurus and Elaphrosaurus. Both the entepicondyle and ectepicondyle are located along the narrow margins close to the distal end, but are indistinctly developed in this specimen."

credit Carrano et al. 2011
Now, for our purposes here the most illustrative picture is B, the posterior view - which means you are looking at the humerus from the rear. What you want to notice is that the humerus curves medially- or inwards - from top to bottom. This exquisitely follows the trend that I have been noting all along of lateral projecting bits of anatomy are brought as close in line with the body to precent blocakage into tight spaces. Furthermore the authors note that the condyles - the rugose attachments at the distal end of the humerus - are undeveloped. This feature further streamlines and narrows the anterior aspect of this animal.

But despite these anatomical concessions to diminish lateral projections the pectoral girdle was robust, undiminished and likely very mobile From Carrano et al. 2011:

"No reduction in functionality is evident from the preserved remains. In contrast, the morphology of the humeral head and the expanded muscle origination areas on the ventral pectoral girdle suggest that mobility was significant and perhaps enhanced over the primitive theropod condition."

The morphology of the manual phalanges is interesting - might be useful to compare their morphology with the phalanges of animals that dig....

credit Carrano et al. 2011
Looking at the manual unguals we see they are relatively short and mediolaterally compressed. They do look a little blunt to be optimized for seizing prey. Could be indicative of some capability in digging.

credit Carrano et al. 2002
Moving towards the pelvic area this trend continues.

On the pubic boot (Carranno et al. 2002):

"The distal end is enlarged into a relatively small, rounded "boot" that projects posteriorly form the main shaft axis.... In most other theropods the boot is either small, lobular and unremarkable (coelophysisds), enlarged anteroposteriorly (allosauroids), or lacks an inset (most coelurosaurs)."

Admittedly not the most compelling piece of evidence so far but it is interesting to note the divergence from other theropods and that the "boot" projects posteriorly - again to diminish bony protuberances that might block passage into burrows.

credit Carrano et al. 2002 
Looking at the femur Carrano et al note:

"The femoral shaft is bowed strongly anteriorly and more subtly medially (fig 14)."

credit Carrano et al. 2002

This medial bowing is best seen in B - looking at the femur posteriorly (from the rear). It is quite evident that it bows medially and this feature is consistent with the trend I have been noting of potential laterally projecting bony features being brought close to the body medially. All of which is consistent with a body plan designed to exploit fossorial creatures.




Does this suggested lifestyle make sense within the paleoecology of where it lived? I must state that here things get a little equivocal as pinpointing true fossorial adaptations in the presumed prey base that I suggest Masiakasaurus exploited is currently lacking.

While evidence of dedicated fossorial specialists that lived with Masiakasaurus is equivocal (but that may change) there are a lot of promising candidates. These are animals that - even if they don't actively burrow themselves - they certainly fall within a size range of animals that frequently use other animals burrows, abandoned or otherwise. Especially in hot arid land with various terrestrial crocs and predatory theropods on the surface.

Simosuchus clarki, the pug nosed notosuchian. credit Gordon E. Robertson CC3.0
Vintana sertichi credit Lucille Betti-Nash (c)
Beelzebufo ampinga. credit Nobu Tamura(spinops.blogspot.com)  CC3.0
Araripesuchus patagonicus. remains of the same genus have
been recovered from Madagascar. credit Gabriel Lio. CC3.0

A diverse fauna of snakes also inhabited Madagascar in the Late Cretaceous. Madstoia madagascariensis is the largest at close to 8 meters and, although no skull is known, was likely a macrophagous predator. Kalyophis, which shows some weakly developed aquatic adaptations.  Menarana, which has been suggested to be fossorial. There is a paper online here if you want to read up on them.

Again I am not going to get into the nitty-gritty of were these guys really fossorial. Chances are in a hot arid climate, with predatory crocs and theropods roaming about, and at their size range they likely were. It is certainly a more tenable and viable food base than fish for which I can find no reference to in the Maeverano formation. Furthermore I am not excluding fish (or scavenging, insectivory) as part of their diet. Indeed exploitation of lungfish coiled up in their burrows during the dry season is a very viable option.

Canis simensis. credit Harri J. CC2.0
And finally I propose Masiakasaurus most analogous to: the Ethiopian Wolf (Canis simensis). This canid of the Ethiopian highlands primarily hunts burrowing rodents - especially big-headed mole rats. And it has specialization in its jaw indicative of this lifestyle with an elongated head, long jaw, widely spaced and slightly procumbent dentition.

Ethiopian Wolf. credti Paul Gervais

credit Jaime A. Headden The Strange Case of Dr. Masiaka & Mr. Vicious CC3.0

Duane Nash
Ethiopian Wolf credit Rod Waddington (lolz) CC2.0


So to wrap it up:

The unique and compelling skeletal morphology including; relatively straight neck due to short vertebrae; unique transition to long, flexible dorsal vertebrae from short, stiff neck vertebrae at cervical/dorsal juncture; streamlining of vertebral processes, pectoral and pelvic girdles; potential adaptations for digging in manual unguals/phalanges, mobile pectoral girdle & muscle attachments; medial bowing in of femur & humerus; and long noted procumbent dentition.

A possible diverse and abundant fossorial prey base.

A likely viable and useful modern analogy in the form of the Ethiopian wolf.

All speak to a tenable interpretation of Masiakasaurus knopfleri as a fossorial animal hunting specialist.

Further analysis and discovery of other noasaurid material may show similar adaptations potentially illuminating a Gondwanan radiation of fossorial hunting specialist. Fossorial notosuchians and mammals diversifying at the time may have fostered these specializations.


Can you dig it?



special thanks to Andrea Cau for providing pdfs of papers

Papers

Carrano, Mathew T., Loewen, Mark A., & Sertich, Joseph J.W. (2011) New materials of Masiakasaurus knopfleri, Sampson, Carrano, and Forster. 2001 and implications for the morphology of the noasauridae (theropoda: ceratosauria). Smithsonia Contributions to Paleobiology number 95

Carrano, Mathew T., Sampson, Scott D., & Forster, Catherine A. (2002) The osteology of Masiakasaurus Knopfleri, a small abelisaurid from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 22(3) Sep 2002 510-534

Sampson, Scott D., Carrano, Mathew T., & Forster, Catherine A. (2001) A bizarre predatory dinosaur from the Late Cretaceous of Madagascar. Nature vol 409. January




"A Long habit of not thinking a thing wrong, gives it a superficial appearance of being right, and raises at first a formidable outcry in defense of custom". Thomas Paine

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26 comments:

davidmaas said...

I really enjoy the way you build up your arguments.
Then... tada! Great stuff.

Thomas Holtz said...

Agree with the assessment. Also even more so for the unpublished Niger noasaurid. Indeed, when Sereno presented it at SVP I made precisely the "noasaurid as fossorially-feeding canid" analogy.

Duane Nash said...

Thanks for comments.

@davidmaas thanks a lot, I do try to give a little flair to the presentation.

@Thomas Holtz nice to see convergence in thought. Since the fishing idea was always just a suggestion - as was insect eating and even fruit eating - and never fully explored I thought it interesting how artistic depictions & popular thought really seized upon fish eating. As I mentioned, because this is a fairly recent dinosaur we can accurately trace this development from suggestion - to portrayal - to acceptance. Again, not necessarily acceptance on the part of dedicated researchers but in the popular interpretation en masse.

Duane Nash said...

Also Dr. Holtz if you are still reading these comments would love to have you comment on my previous posts in this series on theropods. Even if still undecided.

khalil beiting said...

Yet another great article. I never really bought into the whole piscivore Masiakasaurus idea. It's envirenment alone couldn't have supported a specialist like that. That and all the strange anatomical features show that it couldn't have been a fish specialist (besides burrowing lungfish of course). And I also like how you added feathers to your Masiakasaurus picture. I've always wondered why you never really added feathers to most of your Dinosars. Is it just because it's tedious to draw, you just don't like feathers, or because you have another theory up your sleave?

Duane Nash said...

I tend to leave big dinos lacking in feathers that live in hot environments - just like big mammals in hot environments. And the presence of feathers in all lineages is still equivocal. I'm still waiting on any kind of suggestion of integument on sauropods/hadrosaurs/large ornithopods/ankylosaurs etc etc. It's open for interpretation. I might be wrong about leaving big theropods mainly naked - in fact feathers can shield against heat and cold. It's partially a personal aesthetic to tell you the truth. And yeah I do have a little bit of an alternative theory on why some lineages might have been naked - even in cold/temperate climes - and did just fine anyways ;*)

Then again I have never really done a review of how many large mammal fossils preserve traces of hair/integument...

But feathers/integument is a whole wormhole to go down really beyond the scope of this post.

PHoovy said...

Again, amazing theory, im starting to wonder if simosuchus osteoderms would be of use if it was trying to defend itself inside a burrow against a hungry masiakasaurus.

Also, this is a bit off-topic with your post, have you thought about creating a twitter page for your blog? Not sure if it would be of any good, but you never know!

khalil beiting said...

I personally give feathers to all my Dinosaurs since feathers are most certainly ancestral to Ornithodira, and possibly Archosauria. I don't give them all giant floofy coats of feathers, but I give them some form of feathering none the less. I personally think that most if not all Theropods had large amounts of extensive feathering. Same thing goes with most small to medium sized Ornithischians. The main reason why warm weather species didn't have extensive coverings of feathers is because of the fact that all they really do is just eat all day long, and don't often move. Since they don't spend to much time wasting energy and tiring themselves out, they wouldn't need a built in cooling/heating system like feathers. Theropods on the other hand need extensive amounts of feathers to better control their body temperature since they waste so much energy on hunting/chasing prey. This also is really tiring, so that could easily raise their body temperature. I'd actually like to go more in depth with this, but I actually accidentaily dleted my first comment that went very in depth, so now I'm to tired to write it all over again :/. On the matter of naked non Theropods, even then they still had feathers. We know from Hadrosaurs that they were primarily covered in avian scales, but that doesn't leave out the possibility of very light stretches if feathers, similiar to the amounting of hair on elephants. There is also the matter of juveniles (especially in altricial species). Due to their small body size, they would probably have a hard time regulating their body temperatures, unlike their massive adult counterparts, so having an adult hadrosaur (or even a Sauropod) being equally as feathered as a modern day hairy elephant, yet still having a relatively fluffy juvenile stage isn't too speculative. There is also of course cold and even temperate envrenments. I don't really have to say much on this subject, but you can understand how warm weather Rhinoceros and Elephants can still have very insulated polar and even temperate weather cousins. There is also the matter of the Sumatran Rhinoceros. I know that hairs and feathers act very different from one another, but the Sumatran Rhinoceros is a good example of how being in a hot envirenment doesn't mean you have to be naked. The main reason why it has so much hair is because all of that hair can keep mud on it's body, and it can use this mud as both sun screen and bug repelant. This could be very effective for many mediumm to even large sized species of Dinosaurs, and if a "wooly" species of hairy mammal can live in a tropical enivernment, than I think a feathered Dinosaur could fair even better. There is also the case of attraction/signaling/recognition/intimidation/communication/etc. in the case of having feathers. Things like manes, beards, moustaches (that is suprisingly a thing in modern day birds), tail tufts, quills, etc. would be perfect for all of the reasons listed above. I could talk all day about this, but I'm getting tired, plus I want to see what you think of all of this.

khalil beiting said...

Oh, I forgot to mention in the 4th sentence, I was talking about herbivores. My mistake.

Duane Nash said...

@PHoovy and twitter. Yeah I don't want to do twitter. Not because I don't think it useful, just because I think with my personal neural circuitry it would get very distracting, too much potential for "twitter" wars, I don't like the character limit blah blah. I stay active on fb, G+ (chirp... chirp... chirp), deviantart, youtube channel, and try and stay on top of the comments here.

@khalil beiting - all valid points! seasonal coats is an option too... we have much to learn. And who knows - with global warming and Antarctica/high arctic grounds opening up for fossil prospecting maybe we will get that feather coated hadrosaur, sauropod, ankylosaur etc etc.

khalil beiting said...

Do you think you could ever do a post about feathers on non Coelurosaurian Dinosaurs? Many people on the internet have trouble with this aspect of Dinosaur, and even Ornithodiran anatomy, physiology, evoltuion, etc. I personally don't have any issues with it, but many other people do.

Albertonykus said...

Dr. Holtz beat me to mentioning Sereno's undescribed noasaurid. In conjunction with that, this idea sounds very plausible indeed.

Bk Jeong said...

This makes way too much sense....

Bk Jeong said...

About the feather thing: Fur and feathers have different insulating properties. Mammals are a bad analogy in this case. Feathers keep temperature stable, not warm. Therefore it actually makes more sense for a giant theropod to have feathers to PREVENT overheating.

khalil beiting said...

@Bk Jeong That's what I meant, it's just that I showed the example of the Sumatran Rhino to point out that even "wooly" haired mammals that are bad at keeping cool are still prevelent in tropical envirenments. If something that can barely keep cool in a tropical envirenment due to it's insulation can easily survive, than I think that an animal who has insulation that prevents from over heating can fair even better when in a tropical envirenment. I also forgot to mention the fact that it is much more easy to preserve hardened avian scales than bare skin, so technically speaking, Hadrosaurs and even Sauropods could have been very feathered, it's just that we only have the remains of the more "scaley" Dinosaurs due to fossil bias. For all we know, Hadrosaurs and Sauropods could be incredibly feathered for things like attraction and communication, but since those species lived in places that can't fossilize remains well, or the fact that they just didn't have easily preserved scales, we just don't know. This type of thinking is actually one of the things that make me really have a burning passion for paleontology.
http://i1.kym-cdn.com/entries/icons/original/000/013/034/yeahsciencebitch.PNG

Duane Nash said...

@khalil beiting & Bk jeong... points taken regarding feathers and heat shielding. I may well be wrong in usually going with little feathering in large theropods BUT my reasoning is this. I think large theropods spent a lot of their time bathing and wallowing in mud wallows/bodies of water in hot environments - like the majority of their day. If I look at large tropical herbivores - or even pigs, tigers, bears, hyenas - in hot environments they just love to wallow. If it wasn't for that tiresome chore of consuming vast quantities of fodder I think elephants/rhinos/other large herbivores would spend all their time lounging in the water if they could, they just seem to enjoy it so much. Massive theropods would likely have a lot more free time on their hands - being carnivores and all - to enjoy a wallow, maybe even the majority of their day. When it cools off in the evening that is when they go do their active business. Additionally if you just spend all your time at the water hole there is a constant supply of potential prey making its way towards you. And if you are not wallowing you are sequestered away in some shady hollow relaxing until the cooler evening hours.

And then the problem of insulation is solved as dried mud aka adobe has excellent thermal insulating qualities.

Furthermore their massive jaw/more stout necks seem ill equipped for pruning chores compared to smaller theropods. Also the parasite issue. If they were thickly feathered it was probably very coarse/bristly/or even matted/dread locked in appearance not well maintained plumages as is often depicted.

But yeah I probably won't do a post on feathers/integument because there is a lot of stuff out there in the blogosphere on that by people honestly better qualified/more researched on that subject than myself. Plus I have a backlog of stuff I want to get to. ANd finally, although I am flattered that you want me to write a piece on the topic of feathers in non-coelurosaurian dinosaurs - I don't do requests. Not trying to be a prick. It's just that it is one of my personal mandates for this blog to write about what I want to write about and am passionate about at that moment. And I think that this is important to keep in mind for any creative/intellectual pursuit is that the person you should most try to please is yourself. If others come along with you that's great. If not, oh well. Otherwise if you start trying to do work just to please other people it ends up losing integrity and sounding contrived in my opinion. I hope that explains my feelings on the issue, and again I am flattered by the request.

That is not to say I don't have ideas on the subject that I might get to in the (distant) future.

Thanks for comments and I think Bk Jeong was responding to my analogy on mammals and not yours khalil.

khalil beiting said...

The whole mud thing is understandable, but it's not like they would just lose something as valuable as feathers just to sit in the mud. They could very well have just waded in water or just hid underneath a tree to get away from the sun/heat if they didn't want to get dirty. All ground dwelling birds still have large amounts of feathers and live in hot envirenments, but they never lost them just to bathe in the mud. Even species that don't/didn't have to sit over the eggs didn't lose their feathers. Feathers can do SO many things that are beneficial to an animal. Communication, camouflage, intimidation, attraction, mimicry, incubation, stealth, sound, distraction, snowshoes (doesn't neccesarily have to do anything with mud, but you know what I mean), protection from the sun, protection from the weather, protection from attack (this really only works for small sized animals/animals with weak bites), water carrying, heating/cooling the body and can sometimes evolve to be water proof. All these factors are so beneficial, I don't think an animal would give all that up just to have a quick mud bath. I do understand how the mud bath is beneficial to an animal's survival in a hot envirenment, but the 1-2 benefits that it gives doesn't out way over a dozen other benefits.

And yeah, that's completely understandable how you don't take requests. I've tried to force myself to draw/study things that I had no interest in, or even things that I wan't thinking about currently, and because I had no interest in doing so I never really pured my heart out into it. And no, you don't sound like a prick for saying that ;).

Oh and my bad for responding to Bk Jeong's comment that was directly stated to me.

khalil beiting said...

*wasn't directly stated to me.

Anonymous said...

Just want to point out ratites as a relevant, modern comparison, especially emu and ostrich. The emu especially does very well in both extremely hot and cold environments. The emu also has a fondness for water (and by extension mud) regardless of its feathers, so losing them is unnecessary to engage in this behaviour. Particularly hot and arid environments don't seem like they'd have an excess of mud readily available anyway. The simpler feather design due to not needing to fly also makes their upkeep far less demanding than in flighted birds, as well as possible adaptations that reduce/remove the need for manual maintenance (I thought the powder in parrot feathers has some function like this or something?). I would also imagine that the camouflage benefit of breaking up their outline, especially for a large theropod, would be a strongly positive factor preventing their loss.

khalil beiting said...

Thanks for bringing that up sir or madam (or alien). Btw, you mentioned emus as a good comaprison since they fair well in both hot and cold envirenments. Do they sometimes live in colder envirenments or can they just perform well in it? Also, elephant birds come to mind. They were in the weight range of some Rhinoceros/other mammalian megafauna yet they still had large amounts of feathers.

Stevie Moore said...

Great Article. I'd not ever considered if of Masiakasaurus in particular, but did always ponder that, "there must have been numerous small animals, whether mammalian or reptilian, to support a food web and surely predators would take advantage of that food source then as they do today. I would agree that the tooth and mouth designs don't follow the typical trend of piscivory, however, Just to Revisit specialization in environments, I wouldn't discount there being an option for heavy piscivory or even obligate piscivory in dry and arid desert environments. It may be less common a niche to fill with less food matter than in a wetland or coastal environment, but I would point to the Nile Delta as an extant example of a biotope wherein the general environment is hot, dry, and desert-ish but with the river as a water source, there are many specialized aquatic animals (Hippo) as well as aquatic prey including fish. In the Nile you have all sorts of avian Piscivores, not to mention crocodilians and monitor lizards that may feed on fish as well. Large walking catfish, Toads that can construct cocoons for themselves, and lungfish as you mention Duane could all be nice food sources for an animal with the ability to access them. The fact that much of the land was of desert environment wouldn't eliminate the possibility of Wetland-River or Flooding types of environments such as in Modern Egypt and Botswana.

Anonymous said...

Hey Khalil I'm not sure whether emus deliberately enter cold territory in their natural Australia, though I do know parts of Australia experience snowfall. Deserts with sparse vegetation often experience severe temperature fluctuations which I suspect emus need to deal with. I looked extensively into emu husbandry for a time and all reports show that they care little for what the worst weather seems able to throw at them (I live in the UK). This includes zoo husbandry guides, to the point where the minimum shelter suggested is basically a small doorless barn and even then they tend to sit out in harsh stormy rain or snow and let it pile up on them. They seem pretty indifferent to it.
Latter half of this video has some juveniles frolicking in snow: https://www.youtube.com/watch?v=vjy6bDy7DWY

Not sure where I read it now but I did read that the emus dense coat helps protect against heat as only the tips of the feathers are a dark colour, thus excessive heat from the sun concentrates here and aware from the skin. Nifty adaptation assuming this is accurate.

khalil beiting said...

Thanks for the info ^^. Never really knew how "stubborn" emus could be when it comes to shelter. I guess those feathers really do come in handy in bad weather. Also, do you know wether or not Emus take large amounts of care for their chicks? I always heard that ratites like emus and especially megapodes are highly precocial. I even heard that some megapodes are so precocial that they just hatch looking like adults and just walk away after birth. I know emus are megapodes, but they are closely related, so I just assumed they were both precocial. Thanks.

Anonymous said...

The male emu incubates the eggs. The young are precocial but guided and guarded (but not directly fed) by the father for a period of time. The juveniles are eventually left to themselves but tend to remain as a loose group for some time further before dispersing more as they mature.

Anonymous said...

@Duane

Have you ever thought about publishing this argument as an actual article? The argument certainly seems sound enough that it should be seriously considered, and having it in article format (even in something like PeerJ) would make it more difficult for anyone to take your observations and try to pass them off as original research, as happened with Mickey Mortimer and that oviraptorosaur.

Duane Nash said...

@anonymous above. you are probably right. Someone could just steal this. Would they have the gall? I do have actual working paleo people stop by in my comments as shown above but then again so does Mickey. This dilemma is on me. Partially I am a bit lazy and don't have so much time on my hands. I also don't like a lot of the whole game of publications where they tend to suck the life out of writing, insist on a totally dry format. There also seems to be a bit of resistance - for practical reasons - to accept self published/blogging material as valid credible material.

I would totally be ok with someone contacting me to collaborate on a paper and putting me down as a coauthor if they wanted to take this idea and go through the details of putting it in proper format, editing, citation etc etc.

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