Spotlight: Tyrannosaurus rex

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Tyrannosaurus rex
“Tyrant reptile king”

Specimen Name: Regina (female)
Specimen Height: 4.12 m
Specimen Length: 12.02 m
Specimen Weight: 8.11 tonnes

Tyrannosaurus rex — a name “irresistible to the tongue” (according to Robert Bakker) — has been famous from the start. This animal captured the imagination of the public from the very start. An early-1900s New York Times paper describes it as “the king of kings in the domain of animal life.” And now, T. rex remains among the most popular dinosaurs to enthusiasts and laypeople alike; it ranks highly among other favorites such as TriceratopsBrontosaurusVelociraptor, and Stegosaurus. As such, it is also one of the most scrutinized dinosaurs to interest groups. Was it a scavenger? Was it an active hunter? Was it endothermic? Was it ectothermic? Was there a middle ground? Were the arms useless? What was its bite force? How fast could it run? Could it even run?

Many of these questions have close answers, but I rest my case that Tyrannosaurus is still heavily argued over more than a century after its discovery.

Paleontologists have made strides during that century of study, evolving our perception of Tyrannosaurus from a slow kangaroo-posed reptile to a (relatively) agile and rather birdlike predator. Recently, tyrannosaur integument (skin covering — i.e. bare skin, feathers, scales, keratin plates, and so on) has started to become a topic of interest. The uncovering of Yutyrannus — a tyrannosauroid* from China covered from head-to-tail with feathery down — set an interesting precedence in artistically restoring large tyrannosauroids. However, developments made by Bell et al. suggest that the possible feather “real estate” for Tyrannosaurus rex proper is less substantial than previously thought. Fossilized scale impressions from Tyrannosaurus rex and other related large tyrannosaurs carry the implication that these taxa were predominantly scaly. The paper does not suggest large tyrannosaurs lacked feathers. The authors do suggest that, if feathers were present on the animal, they’d be most likely placed on the dorsal side of the body (the “top”).

This was the first time that scale impressions of Tyrannosaurus & co. were formally described in scientific literature. Paleo artist Mark Witton presents a supplementary argument for adaptive integument (carrying further from one of Bell et al.’s proposals that scales in advanced tyrannosaurs were derived from early tyrannosauroid feather covering) where tyrannosaur taxa integument could change on a population-by-population or even within the same individual over time. The Bell paper is still under tough scrutiny by paleo enthusiasts and professionals everywhere. As one block of text in a sea of comments suggested, “It’s not that T. rex couldn’t be feathered. It’s just the likelihood of scales has increased.”

*Tyrannosauroidea is a taxonomic grouping one step above Tyrannosauridae.

Artist Notes:

Hooooooooo-boy.

This was a tough dinosaur to get through. Not because it was particularly challenging (I’m confident enough with tetanuran theropods to freehand most of ’em), but rather I was unsure of how it’d be received. I was pleasantly surprised to have this animal be my most popular on my Instagram account.

This version of Regina takes some major departures from previous incarnations, the most obvious of which is the lack of a protofeather coat. She does have filaments on her body (top of the neck and on the arms). She also sports a yellow-olive-tan pelt as opposed to my bread-and-butter brown and white. The blue highlight around the eye was a last-minute addition; it’s also unintentionally reminiscent of Jurassic World‘s Baryonyx artwork. I swear it’s a coincidence; great minds think alike.

Regina has a fairly tall keratin “crest” on her snout. This is influenced by ancestral tyrannosauroids such as Guanlong, which had crests with a bony core (not entirely dissimilar to Dilophosaurus). Evidence of vascular structures along the top of the head supports the existence of some type of keratin structure. Another feature I added was taken from Daspletosaurus. Carr et al. published some writing involving facial scales that were analogous to crocodilians.

This is also the first animal I’ve restored with reflective lighting/shading (I refer to both, collectively, as “dynamic overlays”) with greens, blues, and yellows representing where light from the ground, sky, and sun would be hitting the animal from all angles. The effect is subtle, but present.

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Spotlight: Brachiosaurus altithorax

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Brachiosaurus altithorax — High-chested arm reptile

Specimen Name: Eclipse (female)
Specimen Height: 14.2 m
Specimen Length: 20.1 m (neck erect)
Specimen Weight:  33.2 tonnes

B. altithorax is currently the only valid species of Brachiosaurus. Most restorations seen in media (Jurassic Park films, etc.) are modelled after a similar brachiosaurid hailing from Africa — Giraffatitan brancai. Initially assumed to be a species of Brachiosaurus, compounding analyses of G. brancai dating as far back as the late 1980s have pointed to reassign the, at the time, “Brachiosaurus brancai” as its own standalone genus. The differences between the two taxa were described, in-depth, by Michael P. Taylor in 2009. Some characters that would be easiest to see in a side-by-side comparison of two living specimens would be:

  • B. altithorax having semi-splayed forelimbs due to more mass carried in the front half of the animal
  • B. altithorax having a longer+taller tail
  • G. brancai having a more “gracile” appearance, whereas B. altithorax would be the more visually-massive/”robust” animal

(You can read more in the link above, if interested.)

Other synapomorphies (traits scientists use to identify related species from a common ancestor) within B. altithorax and G. brancai that were originally thought to be only characteristic of the genus Brachiosaurus have also been found to be more widely-distributed amongst similar sauropods, meaning that as the pool of discoveries expanded, the traits that supposedly unified B. altithorax and G. brancai together became less and less unique across the spectrum. Extinct animals are kind of a mess when it comes to taxonomy since they’re, well, dead.

Brachiosaurus specimens have been found in the Morrison Formation in the midwestern USA. Here, they have proven to be one of the rarer dinosaurs found in this locale (sharing similar distributions to other uncommon sauropods such as Barosaurus). The reason for this is unknown. Other contemporary sauropods such as Apatosaurus, Camarasaurus, and Diplodocus are much more common finds. With relatively scant material (and an incomplete skull), not much is known about this species of brachiosaur.

However, one of the more interesting things about the holotype (the “example”/”base” individual) B. altithorax is that it’s likely not fully grown. Taylor describes the coracoid (a process near the shoulder blade) as not fused, indicating immaturity and the possibility of much greater growth, had it survived to adulthood. Projections already place Brachiosaurus near the 12-15-meter mark in height, but with this finding in conjunction to more evidence of rather extreme gigantism in some other sauropods (ApatosaurusBarosaurus) can push the limits even further.

Artist Notes:

Brachiosaurus is my favorite dinosaur of all-time. I typically have “tiers” of favorite dinosaurs (love ’em, like ’em, hate ’em), but the top of the pyramid is this gal. Its supposed rarity in the floodplains of Jurassic USA would’ve made it quite the treat to see in a hypothetical paleo-safari setting. As such, I tried to make the animal much more distinctive than my older restoration made in January:

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(Don’t get me wrong, I still love her colors. They’ll be repurposed for another sauropod.)

Besides the color adjustments, I also had the legs “mesh” better with the body with added skin and muscle attachments (particularly for the hind limbs). A row of spines down the dorsal is also a prominent new feature. I’ve retained some quills on the head and tail, but removed them from the arms in favor of large tubercles. Brachiosaurids are Titanosauriformes, whose members have quite variable integument. Saltasaurus, while not directly related/descended from B. altithorax by any means, had protective bony plates within the skin. It’s not unreasonable that other Titanosauriformes would have similar deterrents to predators.

June is also #PrideMonth. I’ve taken the liberty to include grey, white, black, and purple onto the new brach to represent motifs from the demisexual flag. You can deduce the reason why if you add 2 and 2.