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.