Frontier Ceratopsians

For most of the time that we've known about them, large ceratopsians seemed to be limited to North America. Smaller species were more widespread, inhabiting both North America and Asia, but were scarce elswhere. Overall the past five years, however, ceratopsian fossils have come in new shapes as well as from new places:

1. Ajkaceratops - 2010 - Hungary, 86-84 million B.C.E

2. Turanoceratops - 1989 - Uzbekistan, 90 million B.C.E.

3. Sinoceratops - 2010 - China, 72-66 million B.C.E.

4. Pachyrhinosaurus (perotorum) - 2012 - Alaska, 70-69 million B.C.E. (northmost ceratopsian and latest Pachyrhinosaurus species)

5. Koreaceratops - 2011 - South Korea, 103 million B.C.E.

6. Coahuilaceratops - 2010 - Mexico, 72.5-71 million B.C.E. (southmost large ceratopsian) 

The range ceratopsians inhabited may have gone even further: Two possible ceratopsians called Notoceratops and Serendipaceratops were identified from fragmentary bones in Argentina and Australia, respectively.

The Doom of Giants

Many of the largest mammals alive today are also among the most vulnerable. For the past three centuries, wildlife populations of African elephants, blue whales, giant pandas, and all species of tigers, rhinos, and gorillas have been hobbled both by habitat loss and human hunting (both for sport and resources of dubious real value like ivory). 

This phenomenon isn't limited to human times. Bus-sized nautiloids, 20-foot armored fish, gorgonopsids, sauropods, and basilosaurid cetaceans were all the biggest animals of their world and all were obliterated forever in mass extinctions at the end of the Ordovician, Devonian, Permian, Cretaceous, and Eocene, respectively.

While my output for endangered mammal drawings have slowed down of late, I did manage to draw two threatened giants in October that I've yet to post here:

Javan rhinoceros (Rhinoceros sondaicus)
Current Range: Ujung Kulon National Park, westernmost Java, Indonesia
Conservation Status: Critically endangered (58-61 as of March 2015)

Northern right whale (Eubalaena glacialis)
Current Range: From the east coast of Florida to the North Sea
Conservation Status: Endangered

Incidentally, pick up A Dynasty of Dinosaurs! It's an amazing dinosaur coloring book for more mature artists by paleontologists Jason Poole and Jason Schein. Here's a set of pages I've been coloring in lately:

While I'm not of the identity of each sauropod here, I know that number 2 (if we follow their heads left to right) is Amargasaurus, and I'm pretty sure that numbers 1, 5, 7, and 9 are Nigersaurus, Saltasaurus, Plateosaurus, and Lessemsaurus, respectively. Numbers 4 and 8 are almost certainly super-sized titanosaurs (possibly Dreadnoughtus and/or Paralititan?), while 3 and 6 are likely diplodocoids (Rebbachisaurus and Suuwassea, perhaps?).

In any case, great job Jasons!

A Thanksgiving Therizinosaur

I have to admit that I'm not enamored with many feathered theropods. While I recognize that dinosaur feathers underlines their connection to birds and so makes dinosaurs as a whole more relevant, these animals lose a bit of their mystique when you learn that they're not as alien as you might imagine.

There's an exception to every rule, however, and I can't help but be amazing by therizinosaurs. Known for decades only from a giant set of hands (belong to the type genus Therizinosaurus), these enigmas turned out to be the dinosaur precursor to the giant ground sloths -- herbivores that stood tall as they fed from the trees, pulling down the higher branches with an impressive set of claws.

Nothronychus is one of the earliest and mostly completely known therizinosaurs, as well as the first identified from North America. It has all the qualities that make these theropods so alien -- the giant claws, the long neck, the fat turkey body...In fact, the only thing remotely familiar about this dinosaur is the furcula, or wishbone, betraying its link, however distant, to modern dinosaurs.

Hope you all had a wonderful Thanksgiving!

Antiquarian Amphibians

For a few months of my sophomore year of college (Fall 2008-Spring 2009), I endeavored to fill a blank, hardcover drawing book with animals predating the dinosaurs. I had already completed similar projects with Mesozoic and Cenozoic fauna, but this one was to be more ambitious: Not only would I draw and color over a hundred animals belonging to groups alien to me, but this time, I would depict each organism's habitat in full color as well. Unfortunately, my workload only mounted while my interest in the Paleozoic (and sadly, drawing environments) waned.

However, when my enthusiasm was high, I did manage to complete a set of drawings focusing on early amphibians, specifically the temnospondyls and the lepospondyls. Both of these groups arose and diversified during the Carboniferous period (roughly 360 to 300 million years ago) but eventually died out during the early Cretaceous period (around 120 million years ago).

TEMNOSPONDYLS:

 Greererpeton

5 ft long

West Virginia

 Dendrerpeton

3.3 ft long

Nova Scotia

 Cochleosaurus

4-5.2 ft long

Czech Republic

LEPOSPONDYLS:

(Clockwise from left)

Phlegethontia

 3.3 ft long

 Czech Republic, Illinois, and Ohio

Microbrachis

 6 in long

 Czech Republic

Keraterpeton

1 ft long

Czech Republic and Ohio

Karoo's Dragons, Dragon Hunters, and Their Children

After Plateosaurus, Massospondylus is the poster child early sauropodomorph (or, as they were called before their ties to sauropods were clearer, prosauropods). Not only are they known from complete adult skeletons in Early Jurassic sites across southern Africa, but they are also the earliest dinosaurs known from eggs and embryos. Baby Massospondylus were big-headed quadrupeds, in stark contrast to their small-headed bipedal parents. Because they were born without teeth, and since adult tracks (but no adult bones) have been found in close proximity to fossilized nests, it's possible that Massospondylus provided their offspring with basic parenting -- perhaps cutting up and regurgitating vegetation for their brood like modern birds.

The contemporary Dracovenator may well have been these dinosaurs' chief predator. While it's known from only a few skull fragments, these bones seem to have belonged to a dilophosaur. This classification is probably best demonstrated by the end of a juvenile Dracovenator's snout, filled with snaggle teeth and arching between the nostril and front teeth, as in adult dilophosaurs.

Buried at Sea

One of the most interesting Early Cretaceous marine beds is the Paja Formation in central Colombia, dating back between 125 and 113 million B.C.E. Among the notable finds described from here include South American species of Kronosaurus and Platypterygius -- both better known from fossils in Australia -- an elasmosaurine plesiosaur called Callawayasaurus, and Desmatochelys padillae, described only this year and currently the oldest known sea turtle. Another surprise from this site, though, were ten tail vertebrae belonging to a brachiosaur, later named Padillasaurus. These sauropods are the tallest known dinosaurs, and until this year were only known from North America, Europe, and Africa. Ironically, most sauropods were regarded as amphibious, with legs too weak to support their bulk on land and high nostrils to allow them to breath while submerged. Both of these ideas have since been rejected, so the Padillasaurus probably died on land and had its remains washed out to sea.

Padillasaurus is hardly the first dinosaur to be buried at sea. The type of Archaeopteryx, one of the most famous fossils of all time, was excavated from the Late Jurassic Solnhofen Limestone in Bavaria, alongside fossilized ichthyosaurs, fish, and brittle stars. The carcasses of the ankylosaur Aletopelta and the hadrosaur Lophorhothon were both carried to sea between 80 and 75 million B.C.E (to Pacific and the Caribbean, which then covered northern Alabama, respectively).

One of the more recent and complete dinosaurs found in marine beds is Tethyshadros, uncovered in northern Italy and named for the ocean that covered most of Europe during the Late Cretaceous. This species is one of a handful of hadrosaurs known from Europe, and may have been a dwarf genus, just like the contemporaneous dinosaurs from Hațeg Island, now in modern Romania.

Giganotosaurus v. Mapusaurus

Both had huge skulls and knife-like teeth. Both roamed Patagonia about 100 million years ago. Both may have been bigger than T. rex, and both may have hunted the biggest-known dinosaurs.

From documentary depictions of these two carcharodontosaurs alone, you could be forgiven for thinking they were the same animal: In the second episode of Chased by Dinosaurs, a 2003 spin-off of the influential BBC miniseries Walking with Dinosaurs, host Nigel Marven travels back to mid-Cretaceous Argentina and witnesses a gang of Giganotosaurus isolate and slowly tire and bleed a 90-plus ton Argentinosaurus to death. Eight years later, in the fifth episode of the all-CGI BBC series Planet Dinosaur, a less-coordinated band of Mapusaurus hunt the same sauropod species, though in this case, the predators only manage to tear a strip of flesh from the beast's back and one of them ends up being crushed by a defending adult. Only hours or even days later do these theropods get to feast on their prize, long after it has expired from its wound.

Despite differences in these portrayals, the fossil record doesn't support them. There is no evidence either for relentless, disciplined hunting from Giganotosaurus, nor proof of less organized, more patient predation by Mapusaurus. Yet differences are there: Giganotosaurus hails from the Candeleros Formation, dating to about 100 to 97 million years ago, while fossils of Mapusaurus, though found nearby, are found in the younger Huincul Formation, the same site as Argentinosaurus. The circumstances of each dinosaur's discovery also differed, with Giganotosaurus found as one, mostly complete specimen and Mapusaurus found from several, crudely preserved individuals of different ages and sizes (hence their constant portrayal as more social hunters).

Physically, I had little idea of what separated the two, other than the maximum Giganotosaurus size estimates tended to be larger than those for Mapusaurus. The former dinosaur was my first subject in my Mesozoic sketchbook (see above) and yesterday I decided to draw the latter, based on the two mounts that dominate Google searches of this dinosaur.

The biggest difference I found between these animals was in their nasal crests: While those of Giganotosaurus' clearly diverge before arching over the eye, Mapusaurus' seemed lower and closer together, if not fused together in real life.