Jaime Headden

My accessible email is my name as seen above this post, at Gmail.

- Nanotyrannus lancensis -

I love the smile.

I'm not sure I would do much a good job mentoring, but you're welcome to share with me here, if you message me personally. I'll try to offer what I can, but I can't really critique the art.

A Tyrannosaurus rex looks upon the viewer inquisitive A bright green eye fixates as we gaze back. Its garb in wooded brown and trimmed in milky cream, a thickened face of armored gold, lined in sky's blue. What colors does it have seem hardly to matter to it. Perhaps it doesn't see us as either threat or food. We are mere denizens in its eye.

Now, I'm not saying this is how I'd do it, but prompted by nothing other than my own curiosity, a sketch of #Tyrannosaurus for Saturday.

#SciArt and #SciComm

Draw for yourself, and speculate. It's actually been a bit freeing to think that I can draw whatever I want, to nudge along the fantastical side of the axis a bit.

One of the reasons I don't relly post the progress of my own paleoart that often, and for this subject I have plenty or at least sketches, is that I don't want progress and "thinking about" pieces to come off as authortitative, as if I have a right to decide.

I tend to the opposite, rather!

There were so many big paleo publications made this year, especially in the last few months. First sauropod with gut content, nanotyrannus X2, new hadrosaur mummies, new pterosaur in vomit. You think any more big things will come before the year ends????

Butt.

I'm not actually prompting anyone to do *anything*. More like ... have this conversation?

But I get the exhaustion of a constant and piecemeal change over time. But I look at it as us having these rows over minutiae, while reminding myself it's actually about scientific process, curiosity, art.

The vascular grooves do cross the rim of the AOF in Jane, however, without a tapering off. The "rim" might just be something of a functional support for the skull, rather than an occlusion of the dermal structure.

The vascular grooves are there on all tyrant maxillae, but not overlapping the AOF. Albertosaurus/Gorgosaurus have something a "rim" to the AOF that is smooth, and the maxilla isn't as intricately textured. More glabular, "hummocky."

Caveat lector:

I have made a number of reconstructions of my own, all without following my own advice, hardly to present them as natural depictions or qualitatively authoritative. Most of THAT effort goes into "guides" like these infographics.

The coward in me balks any further.

I don't come to this interpretation lightly; this is me trying to follow the science, while still trying to draw my leather-faced, RJ Palmer-designed Tyrannosaurus that more clearly mirrors modern "living animal" depictions. But the truth is, tyrants, like ceratopsians, were likely "horn-faced."

The maxillary features imply something radical:

Like edentulous pterosaurs and ceratopsids, in which a network of grooves reaches the AOF or parietal fossa then taper off, it's likely they support a cornified sheet which surpasses the bone margin, leaving no other trace behind.

These identifications were based on a broad interpretation and certain assumptions built from a lack of direct examination. They're aslo very, VERY macro. Microstructure will present better details.

"Light vascular skin" is glabular, being fatty and thick, without muscle attachment.

ANOTHER infographic, this time breaking down AMNH 5027 facial bone structures into their base patterns, and thus the osteological correlates that are inferred from these textures. 1: Oral epithelium 2: Light, vascular skin 3: Squamous dermis 4: Muscular attachment 5: Cartilaginous attachment 6: Pneumatic vasculature 7: Lightly cornified skin 8: Highly cornified skin 9: Cornified sheets

Some years ago, spurred by discussions back on Facebook, I made this infographic based on the same image I used at the top of this thread (from Osborn 1912, improperly citing the person who uploaded the image to Wikipedia, but thanks for doing that).

There's issues with this, including terms.

These ridges aren't "hummocks" but extensively grooved, and the pattern and arrange of those those grooves suggest something that has been recently proposed for ceratopsians, but long assumed for pachycephalosaurid domes: that the facial skeleton was covered by large keratinized sheets. Horny-faces.

As for what those features might represent, Witton (personally and in print) referred to them as "hummocks," llikening the ridges between pits to the rounded, lumpy surface of squamate skulls to theorize that they were covered by large, singular (vaguely turtle-like) scales.

Longrich and Saitta (2024) used the lack of pits to distinguish BMNP 2002.4.1 (Jane, now holotype of Nanotyrannus lethaeus) from T. rex. That's now notable these structures are.

www.mdpi.com/2813-6284/2/...

I digress.

AMNH 5027 isn't the only Tyrannosaurus maxilla to have these features, either the grooves, which are present on every skull I've seen, but the large pits. FMNH PR 2081 (Sue) has them; CM 9380 has them.

We're allowed to play the creator of our own worlds, and to directly walk away from models of inference. We should simply be clear when we do so. The less grounded our art becomes, the more fantastical it gets. Be honest with that.

It's a model, built on inference, developed from living animals and the variety of facial structures they develop, from the Gila monster's cranial armor "shield," croc faces, birds' beaks, rhino horns, musk ox head butting, claws, antlers, etc.

But there's some unknowns, and that's ... fine?

The paper and follow-up studies looking at how dermis, bone, and other integumental structures interact has been more or less lauded and poorly received by the paleoart community for reasons I can only guess at:

That it seems to "tie one's hands" when it comes to creative depictions.

That paper is freely available from OUM (Witmer Lab) here:

people.ohio.edu/witmerl/Down...

This is based on Tobin Hieronymous's PhD work, studying why and how horns, beaks, scales, etc., do or do not leave traces on bone. It's also the basis of various issues of contention, built on "inferrence."

This skull presents the details of the surface vascularity and ridges that Mark Witton some time ago referred to as "hummocky," a phrase used to describe the dermal skull roof of squamates by Hieronymous et al. when working out facial anatomy of rhino noses and bird's beaks, applied to ceratopsids.

File:Tyrannosaurus rex AMNH 5027 skull.png - Wikimedia Commons

This skull is more of less complete and relatively undistorted, and has been the basis for depictions of the animal since Obsorn described in 1912, making it the most famous dinosaur in the world.

commons.wikimedia.org/wiki/File:Ty...

Infographic explanation The same image across the top is a crop of the maxilla and nasal of Tyrannosaurus rex (AMNH 5027), the first being a crop from Osborn 1912 (plate, digitally made available by the AMNH). It's separated into A, B, C, with the latter two faded and overlain with tracings and sketches, describing fine vascular features (in B) and large "pits" (in C). Below it, is the inset text: "Tyrannosaurus rex AMNH 5027 (maxilla). Osteological correlates to a dense, keratinized facial dermis inferred from low and high-relief structures (large "pits") and extensive vascular grooves surrounding antorbital fossa." Image sup-parts D includes a key for E-H, describing layers of bone and integument (dermis, scales, cornified structures), described various hues of red, orange, and yellow. From bottom up, bone in black, deep dermis in orange (where Sharpey's fibres are most common), yellow in the middle for the meso and epidermis, red for the cornified epidermis, and dark red for scales, which sometimes have bony cores in crocodilians and lizards. Bottom right are E-H, showing various thicknesses and bone "texture" related to relief of structures. E: glabular, labile, or squamous skin. This is shown with a thick dermis and vague correlation between bone and scale placement. F: ridged and corrugated bone is related to a thicker, sometimes cornified (keratinized) epidermis. G: canaliculate or grooves bone texture is associated with more extensive cornified dermis, related to increased vascularization and reduced meso and deep dermis depth. H: high-relief corrugated with secondary grooves, depicted strongly ridged bone with grooves incised into them, an exagerration of G.

#FossilFriday and #SciArt

The maxilla of various Tyrannosaurus specimens (perhaps or not "rex") have several peculiar, and possibly diagnostic, surface features relating to their integument (skin, horn, whatnot).

We begin with, and perhaps best with, AMNH 5027, the "archetypal" T. rex skull.

I get that. Based on my reading, it's not something that's going to be discernible at the macro level. One of the models suggested that squamate skulls have an undulating, lumpy surface underlying scales, which have a dense, keratinized skin. So that's a clue, but it's not perfect.

I think it's healthy to be skeptical, so I've been very low-key in some places on this. Obviously, I'm "pro-ost.corr." when it comes to reconstruction, but given there are unknowns still, some flexibility with actual reconstruction (I was pushing fleshy structures pachy domes!), we have room.