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/
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.
My infographic terror continues to spread!
This time, prompted by nothing in particular (he lied) is the question of ontogenetic metaplastic transformation.
Let's talk about #Pachycephalosaurus. #Dinosaur #Ontogeny #Paleontology Bri'is #Palaeontology #SciArt #metaplasia
This time, prompted by nothing in particular (he lied) is the question of ontogenetic metaplastic transformation.
Let's talk about #Pachycephalosaurus. #Dinosaur #Ontogeny #Paleontology Bri'is #Palaeontology #SciArt #metaplasia
November 9, 2025 at 5:49 AM
My infographic terror continues to spread!
This time, prompted by nothing in particular (he lied) is the question of ontogenetic metaplastic transformation.
Let's talk about #Pachycephalosaurus. #Dinosaur #Ontogeny #Paleontology Bri'is #Palaeontology #SciArt #metaplasia
This time, prompted by nothing in particular (he lied) is the question of ontogenetic metaplastic transformation.
Let's talk about #Pachycephalosaurus. #Dinosaur #Ontogeny #Paleontology Bri'is #Palaeontology #SciArt #metaplasia
Why do people do this?
An ornithischian, perhaps a thescelosaurid or maybe an elasmarian, with what I'm unlovingly and unflatteringly calling "Skeksi face," with all due apologies to Brian Froud and the Henson Company.
#sciart, actually. No, really.
An ornithischian, perhaps a thescelosaurid or maybe an elasmarian, with what I'm unlovingly and unflatteringly calling "Skeksi face," with all due apologies to Brian Froud and the Henson Company.
#sciart, actually. No, really.
November 8, 2025 at 2:46 AM
Why do people do this?
An ornithischian, perhaps a thescelosaurid or maybe an elasmarian, with what I'm unlovingly and unflatteringly calling "Skeksi face," with all due apologies to Brian Froud and the Henson Company.
#sciart, actually. No, really.
An ornithischian, perhaps a thescelosaurid or maybe an elasmarian, with what I'm unlovingly and unflatteringly calling "Skeksi face," with all due apologies to Brian Froud and the Henson Company.
#sciart, actually. No, really.
Quick sketch of Nanotyrannus lethaeus, based on Jane, ~45 minutes (slowed down towards the end because my cat likes to climb onto my lap when I'm using my drawing monitor.)
#SciArt #Tyrannosaurus #Nanotyrannus #theropod #dinosaur #not-a-juvenile #bigger-arms
#SciArt #Tyrannosaurus #Nanotyrannus #theropod #dinosaur #not-a-juvenile #bigger-arms
November 2, 2025 at 3:39 AM
Quick sketch of Nanotyrannus lethaeus, based on Jane, ~45 minutes (slowed down towards the end because my cat likes to climb onto my lap when I'm using my drawing monitor.)
#SciArt #Tyrannosaurus #Nanotyrannus #theropod #dinosaur #not-a-juvenile #bigger-arms
#SciArt #Tyrannosaurus #Nanotyrannus #theropod #dinosaur #not-a-juvenile #bigger-arms
Pure evil can only be fought with pure intent. Fascism, and all other forms of authoritarianism, tend towards the corruption of whatever intangible central portion a person might name for themselves, without temper or give.
Evil begets evil, and good can never serve it.
Evil begets evil, and good can never serve it.
October 20, 2025 at 6:00 AM
Pure evil can only be fought with pure intent. Fascism, and all other forms of authoritarianism, tend towards the corruption of whatever intangible central portion a person might name for themselves, without temper or give.
Evil begets evil, and good can never serve it.
Evil begets evil, and good can never serve it.
I can't stop looking at this thing. I bashed together a side view of the skull of Zavacephale rinpoche Tsogtbataar et al. 2025.
This comes to us via Nature (a tabloid, and paywalled, ugh) --
www.nature.com/articles/s41...
This comes to us via Nature (a tabloid, and paywalled, ugh) --
www.nature.com/articles/s41...
![Reorganization of a diagram of the skull and lower jaw of MPC-D 100/1209 (Mongolian Paleontological Center, in Ulaanbataar, Mongolia; Dinosauria collection, 100/1209), holotype and adult specimen of Zavacephale rinpoche ("precious" original skull, from Tibetan zava [origin] and rinpoche [precious one, referencing the jewel-like shape of the dome.) The earliest (chronologically) pachycephalosaur.
Figure depicts the skull overlayed with colors referencing a variety of lateral surface bones of the skull (top), the mandible (middle two, with the medial surface of the same inverted for comparison), and then a sagittal and transverse CT section through the same mandible, showing a large anterior caniniform dentary tooth preceeded by an even smaller one (this figure is also reversed for comparison).](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:dqvmeinobi5kf2xabxmmmncf/bafkreihhjyaixweafliqxpapt6rrrcj4tmghjdmanqivsqjp4pvtz5by3q@jpeg)
September 19, 2025 at 1:12 AM
I can't stop looking at this thing. I bashed together a side view of the skull of Zavacephale rinpoche Tsogtbataar et al. 2025.
This comes to us via Nature (a tabloid, and paywalled, ugh) --
www.nature.com/articles/s41...
This comes to us via Nature (a tabloid, and paywalled, ugh) --
www.nature.com/articles/s41...
With mud sadness, I hear of the recent passing of Rinchen Barsbold (or Barsbold Rinchen, as it were), the first in the wave of Mongolian paleontologists to secure the future of Mongolian specimens to their own country. Anatomist, describer, namer.
GIN 100/02 (or MGP-D 100/42) shown.
GIN 100/02 (or MGP-D 100/42) shown.
August 29, 2025 at 6:14 PM
With mud sadness, I hear of the recent passing of Rinchen Barsbold (or Barsbold Rinchen, as it were), the first in the wave of Mongolian paleontologists to secure the future of Mongolian specimens to their own country. Anatomist, describer, namer.
GIN 100/02 (or MGP-D 100/42) shown.
GIN 100/02 (or MGP-D 100/42) shown.
High cervicodorsal spines indicate a raised head support system on a quadruped, similar to mammals.
I mean, look at this thing:
I mean, look at this thing:
August 27, 2025 at 10:05 PM
High cervicodorsal spines indicate a raised head support system on a quadruped, similar to mammals.
I mean, look at this thing:
I mean, look at this thing:
My read of the relevant papers suggest that even when there's a gap, it's likely due to disarticulation. When reconstructed, the gap is subsumed.
Here's Crush on Terrestrisuchus, which diminishes any gap between zeugopodium and autopodium, but leaves a small gap at the end of the ulnare.
Here's Crush on Terrestrisuchus, which diminishes any gap between zeugopodium and autopodium, but leaves a small gap at the end of the ulnare.
August 14, 2025 at 5:58 PM
My read of the relevant papers suggest that even when there's a gap, it's likely due to disarticulation. When reconstructed, the gap is subsumed.
Here's Crush on Terrestrisuchus, which diminishes any gap between zeugopodium and autopodium, but leaves a small gap at the end of the ulnare.
Here's Crush on Terrestrisuchus, which diminishes any gap between zeugopodium and autopodium, but leaves a small gap at the end of the ulnare.
#SCiArt #drepanosaurs
The pectoral and pelvic girdles of Megalancosaurus suggest aquatic behavior, in that they are similar to sauropterygians like elasmosaurs. The bodies are long and tubular, very wide -- possibly wider than shown. The tail, unseen, is flattened, but very stiff.
The pectoral and pelvic girdles of Megalancosaurus suggest aquatic behavior, in that they are similar to sauropterygians like elasmosaurs. The bodies are long and tubular, very wide -- possibly wider than shown. The tail, unseen, is flattened, but very stiff.
August 12, 2025 at 4:08 AM
#SCiArt #drepanosaurs
The pectoral and pelvic girdles of Megalancosaurus suggest aquatic behavior, in that they are similar to sauropterygians like elasmosaurs. The bodies are long and tubular, very wide -- possibly wider than shown. The tail, unseen, is flattened, but very stiff.
The pectoral and pelvic girdles of Megalancosaurus suggest aquatic behavior, in that they are similar to sauropterygians like elasmosaurs. The bodies are long and tubular, very wide -- possibly wider than shown. The tail, unseen, is flattened, but very stiff.
In the end, there's simply no consensus. I had intended to continue this thread talking about hindlimbs, but it's less important.
Terrestrial pointing does not mean exclusively ground-bound; Drepanosaurus was likely fossorial, most of the others likely favored ground-to-trees.
More evidence awaits
Terrestrial pointing does not mean exclusively ground-bound; Drepanosaurus was likely fossorial, most of the others likely favored ground-to-trees.
More evidence awaits
August 9, 2025 at 9:40 AM
In the end, there's simply no consensus. I had intended to continue this thread talking about hindlimbs, but it's less important.
Terrestrial pointing does not mean exclusively ground-bound; Drepanosaurus was likely fossorial, most of the others likely favored ground-to-trees.
More evidence awaits
Terrestrial pointing does not mean exclusively ground-bound; Drepanosaurus was likely fossorial, most of the others likely favored ground-to-trees.
More evidence awaits
Drepanosaurs show a host of arboreal traits: Megalancosaurus has possible opposable pollex, the tail has a "fifth foot" claw at the end and curls, the crania are oddly bird-like suggesting arboreally predatory features. These can also aid in scansorial behaviors.
August 9, 2025 at 9:24 AM
Drepanosaurs show a host of arboreal traits: Megalancosaurus has possible opposable pollex, the tail has a "fifth foot" claw at the end and curls, the crania are oddly bird-like suggesting arboreally predatory features. These can also aid in scansorial behaviors.
I can't help but compare Drepanosaurus with its unusually stout forelimb and giant claw to alvaresaurs -- although, of course, there are distinctions. Always distinctions.
August 9, 2025 at 9:00 AM
I can't help but compare Drepanosaurus with its unusually stout forelimb and giant claw to alvaresaurs -- although, of course, there are distinctions. Always distinctions.
In Drepanosaurus, however, the humerus is short and bowed, lacks the S-shaped twist, and even the humeral head is sub-spherical, neatly fitted tightly into its glenoid unlike most lizards. This suggests the glenoid is fairly deep in this taxon, and also affording it high mobility.
August 9, 2025 at 8:23 AM
In Drepanosaurus, however, the humerus is short and bowed, lacks the S-shaped twist, and even the humeral head is sub-spherical, neatly fitted tightly into its glenoid unlike most lizards. This suggests the glenoid is fairly deep in this taxon, and also affording it high mobility.
My reconstructions of Megalancosaurus shows a sprawling, posteriorly deflected humerus as a concession to uncertainty in how to present this argument.
I admit it's a bit cowardly to not make the limb erect.
I admit it's a bit cowardly to not make the limb erect.
August 9, 2025 at 8:16 AM
My reconstructions of Megalancosaurus shows a sprawling, posteriorly deflected humerus as a concession to uncertainty in how to present this argument.
I admit it's a bit cowardly to not make the limb erect.
I admit it's a bit cowardly to not make the limb erect.
If the humerus, crushed in most specimens, is indicative of one thing, what of the rest?
The glenoid of the shoulder should face partially or entirely ventrally to allow strong humeral adduction (towards the body). However, in drepanosaurs, the glenoid faces laterally in almost all specimens.
The glenoid of the shoulder should face partially or entirely ventrally to allow strong humeral adduction (towards the body). However, in drepanosaurs, the glenoid faces laterally in almost all specimens.
August 9, 2025 at 8:07 AM
If the humerus, crushed in most specimens, is indicative of one thing, what of the rest?
The glenoid of the shoulder should face partially or entirely ventrally to allow strong humeral adduction (towards the body). However, in drepanosaurs, the glenoid faces laterally in almost all specimens.
The glenoid of the shoulder should face partially or entirely ventrally to allow strong humeral adduction (towards the body). However, in drepanosaurs, the glenoid faces laterally in almost all specimens.
This S-curve allows high leverage at a variety of angles, while the same would not be possible for drepanosaurs.
Even chameleons have such a splayed, S-shaped humerus, even if the manus and pes are held under the body.
Even chameleons have such a splayed, S-shaped humerus, even if the manus and pes are held under the body.
August 9, 2025 at 7:58 AM
This S-curve allows high leverage at a variety of angles, while the same would not be possible for drepanosaurs.
Even chameleons have such a splayed, S-shaped humerus, even if the manus and pes are held under the body.
Even chameleons have such a splayed, S-shaped humerus, even if the manus and pes are held under the body.
The humerus in most drepanosauromorphans is elongated, slender, and straight. In typical sprawling forelimbs, the humerus has a twist in the middle and a strong curvature, forming an S where the proximal end is reflected backwards and the distal end, for the elbow, forwards.
August 9, 2025 at 7:50 AM
The humerus in most drepanosauromorphans is elongated, slender, and straight. In typical sprawling forelimbs, the humerus has a twist in the middle and a strong curvature, forming an S where the proximal end is reflected backwards and the distal end, for the elbow, forwards.
In the case of Megalancosaurus, it's split down the middle of an otherwise flattened, crushed specimen. Further, the scapular glenoid, partially shared with the coracoid, faces laterally. I'd posit for this, the humerus should face laterally. The only problem is ... the humerus.
August 9, 2025 at 7:48 AM
In the case of Megalancosaurus, it's split down the middle of an otherwise flattened, crushed specimen. Further, the scapular glenoid, partially shared with the coracoid, faces laterally. I'd posit for this, the humerus should face laterally. The only problem is ... the humerus.
We'll get the ugly nitty-gritty out of the way, first: "Why aren't the forelimbs splayed?"
To be honest, it's a difficult question: the scpaulocoracoid and humerus in almost all drepanosauromorph taxa are either crushed or distorted in other ways.
To be honest, it's a difficult question: the scpaulocoracoid and humerus in almost all drepanosauromorph taxa are either crushed or distorted in other ways.
August 9, 2025 at 7:44 AM
We'll get the ugly nitty-gritty out of the way, first: "Why aren't the forelimbs splayed?"
To be honest, it's a difficult question: the scpaulocoracoid and humerus in almost all drepanosauromorph taxa are either crushed or distorted in other ways.
To be honest, it's a difficult question: the scpaulocoracoid and humerus in almost all drepanosauromorph taxa are either crushed or distorted in other ways.
#FossilFriday #SciArt
A quick and dirty example of the different forelimb morphologies in Drepanosauromorpha.
A: Hypuronector limnaios
B: Megalancosaurus preonensis
C: Drepanosaurus unguicaudatus
🧵 below
A quick and dirty example of the different forelimb morphologies in Drepanosauromorpha.
A: Hypuronector limnaios
B: Megalancosaurus preonensis
C: Drepanosaurus unguicaudatus
🧵 below
August 9, 2025 at 7:39 AM
#FossilFriday #SciArt
A quick and dirty example of the different forelimb morphologies in Drepanosauromorpha.
A: Hypuronector limnaios
B: Megalancosaurus preonensis
C: Drepanosaurus unguicaudatus
🧵 below
A quick and dirty example of the different forelimb morphologies in Drepanosauromorpha.
A: Hypuronector limnaios
B: Megalancosaurus preonensis
C: Drepanosaurus unguicaudatus
🧵 below
This time, the "plumes" are the right size, they're not splayed out, and you can sorta get a sense that Longisquama's got a BIGGER RACK than Mirasaura does.
For comparison, the generally strange drepanosaur Megalancosaurus preonensis is attached.
For comparison, the generally strange drepanosaur Megalancosaurus preonensis is attached.
August 2, 2025 at 8:19 AM
This time, the "plumes" are the right size, they're not splayed out, and you can sorta get a sense that Longisquama's got a BIGGER RACK than Mirasaura does.
For comparison, the generally strange drepanosaur Megalancosaurus preonensis is attached.
For comparison, the generally strange drepanosaur Megalancosaurus preonensis is attached.
Oh, but this wasn't enough.
A new paper by Spiekman et al. now propose Longisquama is a drepanosauromorph --or simiosaur, whatever -- and this comes it more peculiarites. It makes other things MAKE SENSE, too. Those RIBS.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura
A new paper by Spiekman et al. now propose Longisquama is a drepanosauromorph --or simiosaur, whatever -- and this comes it more peculiarites. It makes other things MAKE SENSE, too. Those RIBS.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura
August 2, 2025 at 8:15 AM
Oh, but this wasn't enough.
A new paper by Spiekman et al. now propose Longisquama is a drepanosauromorph --or simiosaur, whatever -- and this comes it more peculiarites. It makes other things MAKE SENSE, too. Those RIBS.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura
A new paper by Spiekman et al. now propose Longisquama is a drepanosauromorph --or simiosaur, whatever -- and this comes it more peculiarites. It makes other things MAKE SENSE, too. Those RIBS.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura
The second came shortly after the publication of Buchwitz and Voigt in 2012 who described all the impressions of these peculiar midline dermal appendages.
This one's a lot better, and it fixes some issues with the first.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura
This one's a lot better, and it fixes some issues with the first.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura
August 2, 2025 at 8:12 AM
The second came shortly after the publication of Buchwitz and Voigt in 2012 who described all the impressions of these peculiar midline dermal appendages.
This one's a lot better, and it fixes some issues with the first.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura
This one's a lot better, and it fixes some issues with the first.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura
It occurred to me to update my Longisquama skeletal reconstruction with recent findings of close relation to drepanosaurs.
The first one was dozens ans dozens of years ago, rendered from bad photographs. It's really bad.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura
The first one was dozens ans dozens of years ago, rendered from bad photographs. It's really bad.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura
August 2, 2025 at 8:08 AM
It occurred to me to update my Longisquama skeletal reconstruction with recent findings of close relation to drepanosaurs.
The first one was dozens ans dozens of years ago, rendered from bad photographs. It's really bad.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura
The first one was dozens ans dozens of years ago, rendered from bad photographs. It's really bad.
#drepanosaurs #sciart #skeletal_reconstruction #longisquama #mirasaura