Jaime Headden
@jaimeheaddenart.bsky.social
qilong.wordpress.com
Technical Science Art | Skeletal Diagrams | weird discussions about narrative and literary analysis | Cats, and two of them
Commissions, Technical work info: https://qilong.wordpress.com/jaime-headden-art/
Technical Science Art | Skeletal Diagrams | weird discussions about narrative and literary analysis | Cats, and two of them
Commissions, Technical work info: https://qilong.wordpress.com/jaime-headden-art/
For me, it was someone asking why GRRM writes his stories as if Westeros is Tudor England, replete with all the same stereotypes and tropes. The general answer is "that's how it was."
This is fantasy, not historical fiction. You can make things "how it was" DIFFERENT. The issue is "believeability."
This is fantasy, not historical fiction. You can make things "how it was" DIFFERENT. The issue is "believeability."
November 12, 2025 at 8:43 AM
For me, it was someone asking why GRRM writes his stories as if Westeros is Tudor England, replete with all the same stereotypes and tropes. The general answer is "that's how it was."
This is fantasy, not historical fiction. You can make things "how it was" DIFFERENT. The issue is "believeability."
This is fantasy, not historical fiction. You can make things "how it was" DIFFERENT. The issue is "believeability."
Post-Postscript:
Do not mind the spelling errors in this thread, or the fictitious "Stegocephale" in the OPENING INFOGRAPHIC that I totally should have caught.......
Do not mind the spelling errors in this thread, or the fictitious "Stegocephale" in the OPENING INFOGRAPHIC that I totally should have caught.......
November 9, 2025 at 11:07 PM
Post-Postscript:
Do not mind the spelling errors in this thread, or the fictitious "Stegocephale" in the OPENING INFOGRAPHIC that I totally should have caught.......
Do not mind the spelling errors in this thread, or the fictitious "Stegocephale" in the OPENING INFOGRAPHIC that I totally should have caught.......
Postscript:
I really, really don't have a stake or a more substantial opinion regarding one direction or the other. I'm tolerant of more clarity on ontogeny and would rather err against taxonomy than for it.
For me, figuring out what the dome looked like in life is more interesting.
I really, really don't have a stake or a more substantial opinion regarding one direction or the other. I'm tolerant of more clarity on ontogeny and would rather err against taxonomy than for it.
For me, figuring out what the dome looked like in life is more interesting.
November 9, 2025 at 6:47 AM
Postscript:
I really, really don't have a stake or a more substantial opinion regarding one direction or the other. I'm tolerant of more clarity on ontogeny and would rather err against taxonomy than for it.
For me, figuring out what the dome looked like in life is more interesting.
I really, really don't have a stake or a more substantial opinion regarding one direction or the other. I'm tolerant of more clarity on ontogeny and would rather err against taxonomy than for it.
For me, figuring out what the dome looked like in life is more interesting.
During ontogeny, animals can and will undergo radical, often completely baffling metamorphosis, just like human personalities (and like them, even in response to trauma!). Surely at some point we'll figure out a fundamental model of bone growth, texture analysis, and healthy skepticism.
...hahahaha
...hahahaha
November 9, 2025 at 6:40 AM
During ontogeny, animals can and will undergo radical, often completely baffling metamorphosis, just like human personalities (and like them, even in response to trauma!). Surely at some point we'll figure out a fundamental model of bone growth, texture analysis, and healthy skepticism.
...hahahaha
...hahahaha
I was really hyped on the Horder/Goodwin train and had little difficulty accepting the model while being healthily skeptical. My skepticism, however, begins to wax as the evidence wears thin. Yet the model that underlies it remains:
November 9, 2025 at 6:37 AM
I was really hyped on the Horder/Goodwin train and had little difficulty accepting the model while being healthily skeptical. My skepticism, however, begins to wax as the evidence wears thin. Yet the model that underlies it remains:
So as I sit here thinking about this, among other things, I wonder about the end-Maastrichtian dinosaur diversity model and thing we're undercounting more than theropods when it comes to revealing that Bloody Mary (aka, the specimen that "proves" Nanotyrannus) is not T. rex, it's all these domes.
November 9, 2025 at 6:36 AM
So as I sit here thinking about this, among other things, I wonder about the end-Maastrichtian dinosaur diversity model and thing we're undercounting more than theropods when it comes to revealing that Bloody Mary (aka, the specimen that "proves" Nanotyrannus) is not T. rex, it's all these domes.
We would have no trouble reconciling Dracorex->Pachycephalosaurus were Stygimoloch not shoving its back-end dome into the mix. It's giant spikes, it's parietal-eating and nasal ignoring, narrow mini-dome head somehow thwarting the "perfect" ontogeny of pachycephalosaurs.
November 9, 2025 at 6:34 AM
We would have no trouble reconciling Dracorex->Pachycephalosaurus were Stygimoloch not shoving its back-end dome into the mix. It's giant spikes, it's parietal-eating and nasal ignoring, narrow mini-dome head somehow thwarting the "perfect" ontogeny of pachycephalosaurs.
The key here isn't the question of whether Horner/Goodwin are wrong;
Or that metaplastic ontogeny is wrong;
Or that metamorphosis is wrong.
It's: What is happening with Stygimoloch? This really is the fundamental pin in the truss.
Or that metaplastic ontogeny is wrong;
Or that metamorphosis is wrong.
It's: What is happening with Stygimoloch? This really is the fundamental pin in the truss.
November 9, 2025 at 6:33 AM
The key here isn't the question of whether Horner/Goodwin are wrong;
Or that metaplastic ontogeny is wrong;
Or that metamorphosis is wrong.
It's: What is happening with Stygimoloch? This really is the fundamental pin in the truss.
Or that metaplastic ontogeny is wrong;
Or that metamorphosis is wrong.
It's: What is happening with Stygimoloch? This really is the fundamental pin in the truss.
Why does Pachycephalosaurus differ? why does the adult, with short, knobby spikes, a full dome, and an EFS, begin from a parietofrontal dome that grows forward?
No---that's begging the question. And it also prompts us to ask: *Does* Pachycephalosaurus differ?
No---that's begging the question. And it also prompts us to ask: *Does* Pachycephalosaurus differ?
November 9, 2025 at 6:28 AM
Why does Pachycephalosaurus differ? why does the adult, with short, knobby spikes, a full dome, and an EFS, begin from a parietofrontal dome that grows forward?
No---that's begging the question. And it also prompts us to ask: *Does* Pachycephalosaurus differ?
No---that's begging the question. And it also prompts us to ask: *Does* Pachycephalosaurus differ?
In thier model, as we see in the image at the top of this thread, the dome growth model arises in a similar process save for one thing:
The dome grows in the opposite direction.
If the model that gives rise to Stegoceras comes from Zavacephale, this presupposes pachy ontogeny.
The dome grows in the opposite direction.
If the model that gives rise to Stegoceras comes from Zavacephale, this presupposes pachy ontogeny.
November 9, 2025 at 6:26 AM
In thier model, as we see in the image at the top of this thread, the dome growth model arises in a similar process save for one thing:
The dome grows in the opposite direction.
If the model that gives rise to Stegoceras comes from Zavacephale, this presupposes pachy ontogeny.
The dome grows in the opposite direction.
If the model that gives rise to Stegoceras comes from Zavacephale, this presupposes pachy ontogeny.
When we applied that model to other taxa, we started seeing something strange: Animals were developing larger, but shrinking other things. And yes, this is also part of the issue with Nanotyrannus->Tyrannosaurus.
They proposed that Dracorex and Stygimoloch were juvenile Pachycephalosaurus.
They proposed that Dracorex and Stygimoloch were juvenile Pachycephalosaurus.
November 9, 2025 at 6:23 AM
When we applied that model to other taxa, we started seeing something strange: Animals were developing larger, but shrinking other things. And yes, this is also part of the issue with Nanotyrannus->Tyrannosaurus.
They proposed that Dracorex and Stygimoloch were juvenile Pachycephalosaurus.
They proposed that Dracorex and Stygimoloch were juvenile Pachycephalosaurus.
And a few others.
Horner and Goodwin also considered Torosaurus an ontogenetic phase in the life cycle of Triceratops, reflecting a reduction in frill length, hole, and shape, as they saw Triceratops "solid" frills as "old" taxa, because of that metaplasia->EFS model.
Horner and Goodwin also considered Torosaurus an ontogenetic phase in the life cycle of Triceratops, reflecting a reduction in frill length, hole, and shape, as they saw Triceratops "solid" frills as "old" taxa, because of that metaplasia->EFS model.
November 9, 2025 at 6:22 AM
And a few others.
Horner and Goodwin also considered Torosaurus an ontogenetic phase in the life cycle of Triceratops, reflecting a reduction in frill length, hole, and shape, as they saw Triceratops "solid" frills as "old" taxa, because of that metaplasia->EFS model.
Horner and Goodwin also considered Torosaurus an ontogenetic phase in the life cycle of Triceratops, reflecting a reduction in frill length, hole, and shape, as they saw Triceratops "solid" frills as "old" taxa, because of that metaplasia->EFS model.
Pachys remodel the entire skull roof in what is probably just a few years of their life. It grows, new vascular channels are formed, the entire internal structure gets massively restructured, and then ... it shrinks?
Well, that's what Horner/Goodwin thought, when they considered this taxon.
Well, that's what Horner/Goodwin thought, when they considered this taxon.
November 9, 2025 at 6:20 AM
Pachys remodel the entire skull roof in what is probably just a few years of their life. It grows, new vascular channels are formed, the entire internal structure gets massively restructured, and then ... it shrinks?
Well, that's what Horner/Goodwin thought, when they considered this taxon.
Well, that's what Horner/Goodwin thought, when they considered this taxon.
We see this as the supratemporal fenestra become narrow slots, close, or get covered over. This is a rather radical transformation, something we might call "ontogenetic metamorphosis." Normally features that are functional and useful remain, even if they get sloshed around in ontogeny.
November 9, 2025 at 6:18 AM
We see this as the supratemporal fenestra become narrow slots, close, or get covered over. This is a rather radical transformation, something we might call "ontogenetic metamorphosis." Normally features that are functional and useful remain, even if they get sloshed around in ontogeny.
But pachy domes are doing this constantly even after supposed sexual maturity, in which the domes continue to expand, incorporating the parietal bones, then the squamosal bones, then the postorbital and lacrimal and prefrontal bones... Eventually, the dome reaches the sides and back. A full helm.
November 9, 2025 at 6:15 AM
But pachy domes are doing this constantly even after supposed sexual maturity, in which the domes continue to expand, incorporating the parietal bones, then the squamosal bones, then the postorbital and lacrimal and prefrontal bones... Eventually, the dome reaches the sides and back. A full helm.
The end of this is an external fundamental system (EFS), a layer of bone in which new bone growth typically *can't* occur (unless injury).
In pachy domes, the bone tissues typically don't develop an EFS until well into adulthood, when the domes become smooth, other than vascular grooves and such.
In pachy domes, the bone tissues typically don't develop an EFS until well into adulthood, when the domes become smooth, other than vascular grooves and such.
November 9, 2025 at 6:12 AM
The end of this is an external fundamental system (EFS), a layer of bone in which new bone growth typically *can't* occur (unless injury).
In pachy domes, the bone tissues typically don't develop an EFS until well into adulthood, when the domes become smooth, other than vascular grooves and such.
In pachy domes, the bone tissues typically don't develop an EFS until well into adulthood, when the domes become smooth, other than vascular grooves and such.
The skulls developed metaplasia. Now, this isn't anything new: all bones during growth undergo metaplastic transformation, the coincidental destruction of old bone with the deposition of new bone, growing over and over, often layer by layer.
November 9, 2025 at 6:10 AM
The skulls developed metaplasia. Now, this isn't anything new: all bones during growth undergo metaplastic transformation, the coincidental destruction of old bone with the deposition of new bone, growing over and over, often layer by layer.
As they develop a dome, it's first fusion between the halves, left and right, followed by fusion between the frontals and nasals. then the skull bulges upwards, and the surface texture starts taking on some unique qualities. This is what Horner and Goodwin, in their various studies, saw:
November 9, 2025 at 6:08 AM
As they develop a dome, it's first fusion between the halves, left and right, followed by fusion between the frontals and nasals. then the skull bulges upwards, and the surface texture starts taking on some unique qualities. This is what Horner and Goodwin, in their various studies, saw:
The skulls start out flat and thick, sometimes bulgy, with a knobly appearance. This we also see in Homalocephale, Wannanosaurus, Zavacephale, Goyocephale. All taxa named from what we can now say are juveniles, or perhaps subadults, but which, unlike Ornatotholus, stick around. Oh, and Dracorex.
November 9, 2025 at 6:06 AM
The skulls start out flat and thick, sometimes bulgy, with a knobly appearance. This we also see in Homalocephale, Wannanosaurus, Zavacephale, Goyocephale. All taxa named from what we can now say are juveniles, or perhaps subadults, but which, unlike Ornatotholus, stick around. Oh, and Dracorex.
The ontrogenetic trajectory is based on some assumptions, so bear with me. It assumes that a large number of skulls with distinct sutural marks and other key features belong to the same animal, regardless of size. That, when they are lined up in increasing size, without variation, describe growth.
November 9, 2025 at 6:04 AM
The ontrogenetic trajectory is based on some assumptions, so bear with me. It assumes that a large number of skulls with distinct sutural marks and other key features belong to the same animal, regardless of size. That, when they are lined up in increasing size, without variation, describe growth.
For the record, that blog was [qilong.wordpress.com/2011/08/26/n...]
New Domes, New Interpretations
Thanks to Bob Sullivan, many of his co-authored publications from the New Mexico Museum of Natural History and Science (NMNHS) Bulletin are now available online (which you can find here). I talked …
qilong.wordpress.com
November 9, 2025 at 6:02 AM
For the record, that blog was [qilong.wordpress.com/2011/08/26/n...]
What about that Stegoceras model?
journals.plos.org/plosone/arti...
I talked about this on my blog way, way ago, back when I was on the hunt for some model or reason to make sense of what we're going to talk about next.
journals.plos.org/plosone/arti...
I talked about this on my blog way, way ago, back when I was on the hunt for some model or reason to make sense of what we're going to talk about next.
Cranial Ontogeny in Stegoceras validum (Dinosauria: Pachycephalosauria): A Quantitative Model of Pachycephalosaur Dome Growth and Variation
Historically, studies of pachycephalosaurs have recognized plesiomorphically flat-headed taxa and apomorphically domed taxa. More recently, it has been suggested that the expression of the frontoparie...
journals.plos.org
November 9, 2025 at 6:01 AM
What about that Stegoceras model?
journals.plos.org/plosone/arti...
I talked about this on my blog way, way ago, back when I was on the hunt for some model or reason to make sense of what we're going to talk about next.
journals.plos.org/plosone/arti...
I talked about this on my blog way, way ago, back when I was on the hunt for some model or reason to make sense of what we're going to talk about next.
More on Zavacephale:
www.nature.com/articles/s41...
An immature and mature skull of the basal pachy Zacephale advance a particular model of dome growth proposed for Stegoceras that arises from the nasofrontal bones, which fuse together as they grow.
www.nature.com/articles/s41...
An immature and mature skull of the basal pachy Zacephale advance a particular model of dome growth proposed for Stegoceras that arises from the nasofrontal bones, which fuse together as they grow.
A domed pachycephalosaur from the early Cretaceous of Mongolia - Nature
The pachycephalosaurian Zavacephale rinpoche, from the Early Cretaceous of Mongolia, provides crucial insights into the early evolution of dome-headed dinosaurs, including the development of the front...
www.nature.com
November 9, 2025 at 5:58 AM
More on Zavacephale:
www.nature.com/articles/s41...
An immature and mature skull of the basal pachy Zacephale advance a particular model of dome growth proposed for Stegoceras that arises from the nasofrontal bones, which fuse together as they grow.
www.nature.com/articles/s41...
An immature and mature skull of the basal pachy Zacephale advance a particular model of dome growth proposed for Stegoceras that arises from the nasofrontal bones, which fuse together as they grow.