Tyrannosaurus Rex Family

One of the most fascinating things I've learned about Tyrannosaurus was its distinct growth stages. For several years after hatching they would have barely grown. The youngest specimen found was two years old and weighed around 60 pounds. Until about age 8-10 it seems they remained quite small. Although a number of theories can be proposed from this information, a popular theory is that they were given a degree of protection and care by their parents. Maybe they were successful small to medium independent predators, or perhaps they hunted in sibling gangs. It also is not known if Tyrannosaurus mated for life. If so, this increases the chances of long-term parenting behavior. Monogamy and childcare are well-documented in modern relatives, so it certainly isn't unprecedented. Personally, I think dedicated nuclear family units are reasonable to depict, and hope we get more clues in the behavior of Tyrannosaurus soon!

Stan (Male Tyrannosaurus rex)

Specimen BHI 3033 is a nearly-complete specimen of Tyrannosaurus rex. Although the specimen has been nicknamed 'Stan', its sex is not currently known, but I have followed convention and depicted Stan as a male, complete with the 'crown' of cornified tissue that I reconstructed on my male tyrants. Stan is notable for having the best-preserved skull of any T. rex, although Sue has the best-preserved overall skeleton. There are several injuries on Stan's skull, likely inflicted by another Tyrannosaurus. In addition, two vertebra in Stan's neck are fused, perhaps another injury sustained during an intraspecific fight. These wounds are healed over, indicating that Stan survived these combats. The sheer number of healed injuries from other tyrannosaurs on his skeleton suggests that this specimen endured several duals throughout his life.

Sue (Female Tyrannosaurus rex)

Specimen FMNH PR 2081 is the largest and best preserved Tyrannosaurus skeleton ever discovered. Nicknamed 'Sue' after the paleontologist who discovered her, Dr. Sue Hendrickson. Like Stan, Sue's sex is not known, but as the specimen's name is Sue and it is often described as female, I've used her as an example of a female T. rex, with duller coloration and less ornamentation than my male rex, represented by Stan. Sue was auctioned for $8.3 million USD, making her the most expensive fossil ever sold. She is a permanent feature the Field Museum in Chicago. Although Sue has many healed injuries and pathologies attesting to a difficult 28 years of life (quite old for a T. rex), her cause of death is not currently known.

My Azhdarchidae

Depicted here are the three largest azhdarchid pterosaurs, from the left: Arambourgiania philadelphiae, Quetzalcoatlus northropi, and Hatzegopteryx thambema. These giant pterosaurs were highly successful towards the end of the Cretaceous period, with their bones being found on several continents. Despite their great size, these animals were capable fliers. Although there has been some disagreement about their diet and lifestyle, the currently-accepted theory is that they were terrestrial hunters that specialized in small to medium-sized game.

Lambeosaurus lateral

Lambeosaurus was a large hadrosaur

Mapusaurus family

Mapusaurus has earned a degree of recognition in the public eye when it was discovered, as the bone bed was discovered with at least seven individuals of varying ages. This has been interpreted as evidence of possible social behavior and perhaps even cooperative hunting. While this may have been a predator trap (some prey animal gets stuck in quicksand and lures predators to a similar fate), other large theropods have shown evidence of living in groups, and this would enable Mapusaurus to tackle some of the enormous sauropods that lived in their environment. If they did hunt in groups, it was most likely analogous to the mob tactics of modern Komodo dragons and crocodilians. That said, there is increasing evidence that dinosaurs had long incubation periods and therefore perhaps increased parental investment, and they may have been more socially complex than is currently understood.

Zephyrosaurus lateral

Zephyrosaurus was a small dinosaur that likely lived in burrows.

Zephyrosaurus schaffi

Zephyrosaurus schaffi was a small herbivorous dinosaur about the size of a coyote or boarder collie that lived in early Cretaceous North America, alongside such dinosaurs as the ferocious predator Deinonychus and the tallest dinosaur yet discovered, Sauroposeidon. Although few fossils of Zephyrosaurus have been discovered, many related species have shown interesting features that can also be reasonably attributed to this little animal. Oryctodromeus, one of its closest relatives, has been found in a burrow with two juveniles, suggesting both a tendency to burrow and long-term parental care. Kulindadromeus, another related genus, is famous in the paleontological community because it was covered in hair-like filaments, yet retained scales on its tail and lower legs. Using related animals to determine the appearance and behavior of Zephyrosaurus isn't perfect (lions and tigers are both Panthera, yet have notably different behaviors and can be easily told apart by viewers), yet it helps paleontologists reasonably hypothesize behavior and gives artists a good foundation to build their reconstructions to be as accurate as possible.

Colored Pencil

4 hours (1 for research and sketches, 3 for final illustration)

Apatosaurus lateral

A bull Apatosaurus louisae

Apatosaurus

A bull Apatosaurus louisae drinking from a lake in the Morrison Basin.

Ceratosaurus lateral

Ceratosaurus was a theropod that lived during the late Jurassic period.

Ceratosaurus nasicornis

My Dromaeosauridae

A collection of the dromaeosaurs that I've illustrated this past year, drawn to scale:

1. Acheroraptor

2. Dakotaraptor

3. Deinonychus

4. Dromaeosaurus

5. Saurornitholestes

6. Velociraptor

7. Utahraptor

Smilodon populator

We Three Kings

Three of the largest predatory dinosaurs: Tyrannosaurus, Carcharodontosaurus, and Spinosaurus

Spinosaurus aegyptiacus

Spinosaurus aegyptiacus was a gigantic theropod dinosaur, growing longer than 50 feet in length and weighing at least 10 tons. It primarily ate fish, although anything near its watery home was considered prey. With hollow bones and a series of air sacks throughout their bodies, most theropods would have floated on the surface of the water like ducks. Not so with Spinosaurus. It's bones were solid and dense, and it would have sunk to the bottom of the water, potentially such that it couldn't technically swim. Short, powerfully-muscled legs would have made it quite swift as it jogged along the bottom of the rivers and estuaries it called home, with its sail acting like a ship's keel to keep it from tipping. All this adds up to a terrifying animal, more than earning its ferocious reputation as the largest predatory dinosaur ever discovered.

Colored Pencil

8 hours (1 for research, 1 for sketches, 6 for final illustration)

Deinonychus antirrhopus (red junglefowl)

With a powerful sense of smell, the ability to break bones, and several anatomical features suggesting endurance over bursts of speed, the idea of Deinonychus filling a similar ecological role as a vulture is not to be ruled out. While its wings were too small to fly, they may have helped make the animal appear larger to dominate a kill. Fossil sites featuring multiple Deinonychus dying together have been used as evidence for pack-hunting behavior, but these sites are also consistent with mob attacks of Komodo dragons and vultures. Consensus has not been reached among paleontologists on the matter of coordinated pack hunting versus mob scavenging (perhaps a bit of both?), so I included two ideas of what a scavenger-leaning Deinonychus may have looked like.

For this reconstruction, I was primarily inspired by the red junglefowl and the lappet-faced vulture.

Deinonychus antirrhopus (cassowary)

Deinonychus may have been more scavenger than active predator. Few animals are exclusively one or the other, but some, like vultures and male lions, use their size to bully smaller predators away from their kills. This reconstruction took inspiration from condors, cassowaries, and turkeys.

Deinonychus antirrhopus (heron)

The habitat that Deinonychus called home was a vast floodplain. For this reconstruction, I looked to birds like the great blue heron and snowy egret for inspiration. While there is no evidence that Deinonychus was a piscivore (fish-eater), there was a group of related species in the southern hemisphere that specialized in hunting fish. This image is the least likely reconstruction, yet it's not out of the question.

Deinonychus antirrhopus (Sinornithosaurus millennia)

Sinornithosaurus millenii, a close relative of Deinonychus, is a fascinating dinosaur. A small dromeosaur (raptor), it has been preserved with a full covering of feathers. Most of the body was covered in hairlike down, but its wings and tail had feathers with filaments branching from a quill. Not as advanced as a bird feather, but it may have been possible for Sinornithosaurus to glide. Not only does this dinosaur provide us with a template for the feathers of other dromeosaurs, recent evidence has shown it preserved with color! Mostly orange and brown, Sinornithosaurus would have been well camouflaged in its forested environment. This is the most conservative of my reconstructions, as it is based on a closely related dinosaur, not a modern bird.

Deinonychus antirrhopus (caracara)

A popular trend by modern paleoartists is to depict raptors as, well... raptors. Birds of prey like hawks and eagles often serve as inspiration for animals like Velociraptor and Deinonychus. AS a nod to this trend, I have included two 'raptor' based reconstructions of Deinonychus. This one is a mixture of the caracara of Central and South America, and the bearded vulture known throughout the Old World.

Deinonychus antirrhopus (great horned owl)

This reconstruction is my personal favorite. It is the one I chose for my full-bodied reconstruction of Deinonychus. For inspiration I chose the great horned owl, along with other owl species. If Deinonychus was a pack hunter, having 'ear tufts' like an owl may have helped them coordinate, much like wolves. This is speculation on my part.

Adult Pachycephalosaurus wyomingensis

For many dinosaurs, each growth stage came with striking characteristics. This has led to a great deal of taxonomic confusion, as early paleontologists assumed dinosaurs would be more like lizards (the young were simply tiny versions of adults). Tyrannosaurus juveniles had much longer legs compared to adults, and Triceratops had distinct horn and frill shapes for each part of its life. In many of these cases, each growth stage was given its own genus and species. Three distinct morph of dome-headed dinosaurs, or Pachycephalosaurs, lived in the same environment at the end of the cretaceous: named Dracorex, Stygimoloch, and Pachycephalosaurus. There is now general concensus among paleontologists that these three were all Pachycephalsaurus, respectively representing juvenile, subadult, and adult growth stages. Pachycephalosaurus was the largest of the dome-headed dinosaurs. It was an herbivore which thrived at the very end of the age of dinosaurs.

Media: colored pencil. 8 by 8 inches.

Part 3 of 3: total project 19-22 hours (3 for research, 4 for skull measurements and reconstruction, and 4-5 hours for each of the three drawings)

Subadult Pachycephalosaurus wyomingensis (or Stygimoloch spinifer)

For many dinosaurs, each growth stage came with striking characteristics. This has led to a great deal of taxonomic confusion, as early paleontologists assumed dinosaurs would be more like lizards (the young were simply tiny versions of adults). Tyrannosaurus juveniles had much longer legs compared to adults, and Triceratops had distinct horn and frill shapes for each part of its life. In many of these cases, each growth stage was given its own genus and species. Three distinct morph of dome-headed dinosaurs, or Pachycephalosaurs, lived in the same environment at the end of the cretaceous: named Dracorex, Stygimoloch, and Pachycephalosaurus. There is now general concensus among paleontologists that these three were all Pachycephalsaurus, respectively representing juvenile, subadult, and adult growth stages. Pachycephalosaurus was the largest of the dome-headed dinosaurs. It was an herbivore which thrived at the very end of the age of dinosaurs.

Media: colored pencil. 8 by 8 inches.

Part 2 of 3: total project 19-22 hours (3 for research, 4 for skull measurements and reconstruction, and 4-5 hours for each of the three drawings)

Juvenile Pachycephalosaurus wyomingensis (or Dracorex hogwartsia)

For many dinosaurs, each growth stage came with striking characteristics. This has led to a great deal of taxonomic confusion, as early paleontologists assumed dinosaurs would be more like lizards (the young were simply tiny versions of adults). Tyrannosaurus juveniles had much longer legs compared to adults, and Triceratops had distinct horn and frill shapes for each part of its life. In many of these cases, each growth stage was given its own genus and species. Three distinct morph of dome-headed dinosaurs, or Pachycephalosaurs, lived in the same environment at the end of the cretaceous: named Dracorex, Stygymolach, and Pachycephalosaurus. There is now general concensus among paleontologists that these three were all Pachycephalsaurus, respectively representing juvenile, subadult, and adult growth stages. Pachycephalosaurus was the largest of the dome-headed dinosaurs. It was an herbivore which thrived at the very end of the age of dinosaurs.

Media: colored pencil. 8 by 8 inches.

Part 1 of 3: total project 19-22 hours (3 for research, 4 for skull measurements and reconstruction, and 4-5 hours for each of the three drawings)

Quetzalcoatlus northropi and young Tyrannosaurus rex

One of my gallery pieces for the Pacific Science Center. To this day, the diet and lifestyle of giant azhdarchid pterosaurs like Quetzalcoatlus is poorly understood. Some paleontologists suggest these giants were waders feeding on crustaceans and fish, others believe they ambled about hunting lizards and young dinosaurs, while others think they soared the cretaceous skies looking for corpses like a giant vulture. It is possible that, despite a wingspan of nearly forty feet, they couldn't fly. What is known is that they were massive. Some of the largest species stood over twenty feet tall when on all fours. Whatever these mysterious creatures were, they would certainly have been impressive to behold!

Media: colored Pencil. 6 by 11 inches.

12 hours (3 for research, 2 on skeletal drawings and muscular studies, 7 for the final illustrations)

Triceratops prorsus

A commission from the Pacific Science Center for their paleoart gallery. The diet of Triceratops consisted mostly of the ferns shown at its feet, although its sharp beat and strong jaws could handle almost anything it could reach. Like modern large herbivores, such as water buffalo and hippos, Triceratops males were likely aggressive animals. Considering the variety of large predators in its environment (Tyrannosaurus and Dakotaraptor), this behavior served as a deterrent, making predators think twice about attacking young Triceratops for fear that an adult male might be nearby.

Media: colored Pencil. 7 by 9 inches.

10 hours (2 for research, 2 on skeletal drawings and muscular studies, 6 for the final illustration)

Pteranodon longiceps

Part of a gallery collection I'm working on for the Pacific Science Center. Pteranodon was a piscivorous (fish eating) pterosaur that thrived in the shallow sea that ran through what are now the central United States during the late Cretaceous period. It's name means 'toothless wing', yet is often depicted with a toothed beak in modern media. With a wingspan of 18-20 in the males (females were much smaller), they were the largest pterosaurs known until the discovery of the azhdarchid pterosaurs- animals like Quetzalcoatlus with a wingspan of nearly 40 feet.

Media: colored pencil. 5 by 10 inches.

12 hours (3 for research, 1 for preliminary sketches and skeletal reconstructions, and 8 total for the final illustrations)

Dimetrodon borealis

Numerous recent findings have reshaped how this classic animal is reconstructed. Skin impressions from related animals suggest it had smooth, porous skin. Hair has not been found directly associated with Dimetrodon, but as a relative of mammals, it is a possibility. What was once assumed to be a full sail is now known to have protrusions at least part of the way up, as shown by the tips of the sail being broken and healed in a way that couldn't happen if the sail membrane continued to the top.

Media: colored pencil. 8 by 8 inches.

6 hours (2 for research, 1 for preliminary sketches and skeletal reconstructions, and 3 for the final illustration)

Thylacoleo carnifex

Thylacoleo carnifex, done for my upcoming short story, Lessons.

Media: colored pencil

Time: 5 hours (1 for research and measurements, 4 for drawing)

Tyrannosaurus rex (1910's style)

When it was first discovered, Tyrannosaurus was depicted like most dinosaurs of the late 19th century and early 20th: cold blooded and sluggish. The coloration was believed to be dull greens and browns. The typical references used by illustrators were lizards like iguanas.