Africa's Jurassic Park

Though Spinosaurus has a superstar among dinosaurs (thanks, in part to Jurassic Park III and Paul Sereno's aquatic restoration of this animal proposed in 2014), few other dinosaurs from this continent receive half as much exposure. About a decade before Ernst Stromer described this bizarre theropod, however, other German paleontologists like Eberhard Fraas and Werner Janensch uncovered a host of amazing new dinosaurs from the Tendaguru Formation in Tanzania (then the colony of German East Africa). The largest of these was Giraffatitan, known as "Brachiosaurus brancai" until the 2000s. Its skeleton at the Museum fur Natürkunde in Berlin stands over 40 feet high and remains the most complete of any large brachiosaur.

Despite the sheer size of this sauropod, Kentrosaurus is easily the Tendaguru Formation's stand-out dinosaur. It was smaller but thornier cousin of Stegosaurus, and according to a 2011 study by Heinrich Mallison, a single swipe of the tail would have been more than enough to crack open a human skull. Like many other dinosaurs, Kentrosaurus is believed to have had a much thicker tail than previously thought (thanks to a 2010 paper by Phil Currie and W. Scott Parsons). In addition to the animal's rear anatomy as a whole, this drawing is intended to reflect that idea, as well as the discovery of small osteoderms in other stegosaurs.

One of Kentrosaurus' contemporaries was Dicraeosaurus, an oddity among Late Jurassic sauropods in that A) it was less than 50 feet long, B) it had an unusually short neck and C) an strangely high spine. To emphasize this latter feature, I gave my Dicraeosaurus bright markings along its back, drawing inspiration from the Malagasy rainbow frog (albeit without the blue). Since the skull of the Berlin mount is quite obviously a plastic cast based on Diplodocus, I chose to draw this copy rather than reconstruct the actual head.

Theropods are also known from the Tendaguru Formation, including the early spinosaur Ostafrikasaurus and the carcharodontosaur Veterupristisaurus. Since neither is known from a good skeleton yet, however, I chose to portray an equally mysterious theropod from the site.

Like Dicraeosaurus, Elaphrosaurus is also mounted at the Museum für Naturkunde as a half-bone, half-cast skeleton. Growing up, it was also portrayed as an early, carnivorous ancestor to the toothless ornithomimosaurs. In recent years, however, paleontologists have come to regard it as a ceratosaur -- possibly a large relative of the short-armed, ostrich-like Limusaurus. which was running around China about this time. My sketch of Elaphrosaurus is meant to wed this idea with the museum's current mount, implying that the animal was a long-legged herbivorous theropod rather than the dinosaur equivalent of the cheetah. 

Crazy Arms

When I was boy, one of the greatest mysteries about dinosaurs for me was "who owned the biggest arms of all time?". This question revolved around not one, but two theropod dinosaurs from Late Cretaceous Mongolia: Deinocheirus and Therizinosaurus. For decades, both were known from nothing but a pair of menacing arms, each measuring about eight feet long. Each seemed to belong to jumbo-sized killer theropod, dwarfing and capable of ripping a T. rex to pieces.

Then, in 2001, the Discovery Channel program When Dinosaurs Roamed America aired, and I (along with countless other paleofans, I'm sure) was introduced to a therizinosaur for the first time in the form of Nothronychus. It was a herbivore North American predecessor to its family's namesake that, in the words of narrator John Goodman, "[looked] like a half-plucked turkey and [walked] like a potbellied bear". While it mostly used its arms pull down high branches, Nothronychus at one point used them to smack down an attacking dromaeosaur. Though we have few Therizinosaurus fossils outside of its arms, the image of these dinosaurs as the archosaur version of ground sloths has been cemented by the discovery of other therizinosaurs (particularly the much earlier Beipiaosaurus and Alxasaurus), as well as the portrayal of these animals in subsequent paleo docudramas like Chasing by Dinosaurs: The Giant Claw (featuring Therizinosaurus meeting Nigel Marven) and Planet Dinosaur (featuring Nothronychus again).

And what about Deinocheirus? This contemporary of Therizinosaurus turned out to be stranger still: Paleontologists had long suspected that it was an overgrown ornithomimosaur, based on the similar arms and claws (which were too blunt to be instruments of death). Based on two headless specimens in storage at a Mongolian museum and a skull smuggled into Europe, Deinocheirus a bulky, hump-backed herbivore with a head more like a hadrosaur than an ornithomimosaur. Like Therizinosaurus, it too was a colossal plant-eating theropod that was probably covered in feathers.

While both probably confronted Tarbosaurus, a close cousin to T. rex known from the same bone bed as each, I do wonder if they ever competed for same leaves and branches with one another, indirectly as a species or directly (and perhaps violently) as individuals.

Tylosaurus' Troublesome Tummy

While non-avian dinosaurs were my gateway to science and remain my favorite prehistoric creatures, I've developed an appreciation for other extinct animal groups, including ichthyosaurs, mammoths, terror birds, and notosuchians. Lately, I've been fascinated by mosasaurs, and not just thanks to Jurassic World. While I grew up with images of green, ridge-backed leviathans that tussled with serpentine plesiosaurs and snatched pterosaurs from the sky, I'm much more intrigued with mosasaurs as depicted now, in light of recent discoveries about their tail anatomy (which now includes a sickle-shaped tail), skin color (which in some was black on top and white on bottom), and birthing methods (live underwater birth, like ichthyosaurs, plesiosaurs, and cetaceans).

With that in mind, I set out to depict the largest, most famous -- er, the most famous mosasaur after Mosasaurus, Tylosaurus.

While sketching the beasts' skull was no cakewalk, the thing that gave me the most trouble was capturing the underside of the mosasaur in the flesh. The skeletal mount I used looked fantastic, peering down on visitors like Smaug over Bilbo Baggins in the second Hobbit film; in retrospect, however, Tylosaurus may not have been flexible enough to assume this undulating pose. This made capturing the animal's tummy a nightmare, with constant erasures and redrawing of borders.

In the end, I settled with the boundaries established in the draft on the left, and tried to make the proximity of each body segment as clear as possible with different degrees of shading, but I still feel the drawing could have been much better if I had gotten the underside right.