Falcarius, Clarified

I'm not even going to try to make excuses. This paper has been sitting on my desktop since January because I forgot about it. I found it this morning when I executed a sorely needed declutterization operation. So, six months after it was published by the Linnaean Society, I'm going to write about paleontologist Lindsay Zanno's detailed description of the therizinosaur Falcarius. Like Jell-O desserts, there's always room for therizinosaurs.


Falcarius, by Michael Skrepnick. From the University of Utah via NatGeo.

I've written about the therizinosaurs before, because they're some of my favorite dinosaurs: fiercely clawed feathered theropods who've gone vegetarian, some of whom grew to huge sizes. They're primarily known from Asia; North America joined the club in the early 2000's with the discovery of late Cretaceous Nothronychus in New Mexico. Soon afterwards, Falcarius was discovered in Utah, and was found to be contemporaneous with the then-earliest known therizinosaur, China's early Cretaceous Beipiaosaurus. As Zanno notes in her analysis, Falcarius differs from Beipiaosaurus in lacking many of its more derived features - those that would be further refined and emphasized by their ancestors. It's an evolutionary puzzle: why is Falcarius so primitive compared to its Chinese contemporary? Zanno puts forward three hypotheses that will require new discoveries or research to clear up:

1. Better dating of the sediments in which the two therizinosaurs were found could reveal that Falcarius is actually a bit older.
   
2. Environmental factors in Asia may have favored therizinosaurs there to evolve at a faster rate than their North American relatives.
3. Falcarius shared North America with other therizinosaurs more similar to Beipiaosaurus, which haven't been found yet.

One of Falcarius' distinguishing features is its teeth. Like primitive relatives of the oviraptorosaurs, which also evolved toothless beaks, Falcarius had relatively large teeth in the front of its jaws. It's likely due to the therizinosaurs' shift from carnivory to omnivory and then herbivory (that last step isn't necessarily where the oviraptorosaurs settled). What's interesting is that a herbivorous diet required the suite of anatomical adjustments that make the later therizinosaurs so unique - large guts to breakdown nutrient-stingy plant material, wider pelvises, stouter legs. Falcarius shows some initial steps toward those features, probably necessary to compete in North American ecosystems with the dromaeosaurs and tyrannosaurs who dominated predatory niches. As Zanno says in her conclusion, we're going to need some serious functional studies of the skeletons of derived therizinosaurs to really determine how they lived and moved, and this in-depth look at Falcarius provides a "baseline" for that work.

Of course, maybe an apparently advanced therizinosaur from the Jurassic will be discovered in Australia and turn the world upside down. That could happen, too.

Therizinosaur Party 2k10

Every couple of months, the paleoart blog Art Evolved assembles new galleries dedicated to specific groups of dinosaurs. The latest deals with the therizinosaurs, one of the hippest groups of late. Really, very hot right now, though I could see the alvarezsaurs usurping their spot, becoming the Hannah Montana to their Lizzie McGuire. I'm not saying it's inevitable. The stature of dinosaur clans in the popular imagination is governed by a complex set of factors. Therizinosaurs certainly have the size advantage. But the alvarezsaurs have weirdness on their side. I'm not saying that alvarezsaurs are, in fact, weirder than therizinosaurs; it's just that weirdness fades over time and therizinosaurs have been better known for longer. And if some animated entertainment decides to create a cuddly Shuvuuia... all bets are off.

Anyway, you ought to skip on over to the ol' Art Evolved. Brett Booth does a cool profile of Therizinosaurus, and Rachael Revelle does a very cool linoprint. And here is a teaser from the Hoosier state's own Matt Tames.



Matt has done work for the Children's Museum of Indianapolis, which is without a doubt the coolest children's museum around. Proof? You want proof? Check this out.


Photo by Bob Wollpert, via Flickr

Therizinosaurs Through the Years

Here's a cool drawing of the changing perceptions of those odd therizinosaurs by Tricia Arnold, a cartoonist with a heavy paleo-influence. Tricia seems to share my interest in the way artistic conceptions of extinct critters evolve as new fossils come to light. Evolve, get it? Science joke.



Here, she looks at three views of therizinosaurs that have been put forth as paleontologists tried to fit the existing fossil evidence into the dinosaur family tree. First, the "predatory prosauropod," that rather docile looking, almost sloth-like fellow in green and tan. Next, Tricia uses an idea inspired by the Dino Crisis video game - a nasty, blood-thirsty carnivore. Finally, she presents our modern idea - a largely herbivorous, pot bellied, bird-like oddball. Check out more of her artwork at flickr.

Jurassic Park 4

I'm going to go ahead and ask that you bop on over to the super dino blog Dinosaur Tracking, written by the knowledgable and charming Brian Switek, and vote on today's poll: which dinosaur (from his own list) would you like to see in the long-rumored but stalled Jurassic Park 4?

From his list, I'd definitely want to see a therizinosaur or two. My list:

1. Oviraptor: The first time I saw Oviraptor, it blowed my brain up real proper. Such a strange head, and now that we know it bore feathers, it's time to give it some bigger exposure. One of the great dinosaurs, for sure. Let's see what ILM could do with it.

2. Amargasaurus: Switek's sauropod wish is Nigersaurus. Can't fault that, but I think people would go bonkers for fin-backed Amargasaurus.

Amargasaurus, via Alex 95 @ flickr

3. Styracosaurus: One of the wildest ceratopsians. Heck of a head.

4. Troodon: Always one of my favorites. Maybe not much of a threat to the protagonists, but I'd love to see those big eyes come to life.

5. A clever plot and well-written characters: Perhaps more improbable than genetically engineered dinosaurs.

Who knows if JP4 will ever happen. There have been many rumors over the years. Perhaps the most entertaining was reported at Ain't It Cool News five years ago. Quoth AICN's Moriarty: "There’s the eight-year-old-boy side of me that thinks that a DIRTY DOZEN-style mercenary team of hyper-smart dinosaurs in body armor killing drug dealers and rescuing kidnapped children will be impossible to resist." Read the rest here. I know you want to...

A Therizinosaur's Lesson

Therizinosaurs, which until earlier this decade were not known to have lived in the land of the free and the home of the brave, are a delightfully strange clan of dinosaurs. Their hands sported some of the largest claws in all of dinosauria, but we know from their small, beaked heads and massive guts that they were largely herbivorous. Here's a nice side view of Beipiaosaurus inexpectatus, that illustrates just how odd the therizinosaurs looked:

B. inexpectatus via Dinosaur World

Therizinosaurs, including the recently named species Nothronychus graffami from Utah, were maniraptors, a group of theropods which also includes the dromaeosaurs, or raptors. A study led by The Field Museum's Lindsay Zanno has found that among their maniraptoran kin, the therizinosaurs were the earliest branch, pointing to the possibility that they and the dromaeosaurs may have shared an omnivorous or herbivorous ancestor, and hypercarnivory (or the exclusive eating of meat) was not necessarily the norm. It's always nice to have more detailed shading of the frequently cartoonified dinosaurs, which are usually depicted strictly as belonging to two teams: meat-eaters and veggiesauruses. Dinosaurs dominated terrestrial ecosystems for hundreds of millions of years, so it makes sense that their diverse forms evolved to fill niches in all kinds of neat ways. The therizinosaurs are striking in the way they subvert pop culture's roster of standby dinos.

Nothronychus by Victor Leshyk for the Museum of Northern Arizona

Adding a bit of maritime intrigue to the N. grafammi specimen: it was discovered in sediment that would have been 60 to 100 miles from shore, among the remains of ammonites (which with their spiral shells superficially resemble the nautilus but are closer kin to squids). I love when a fossil gives such vivid fuel to the imagination.

Demerit to the Salt Lake City Tribune for this little gaffe:

The discovery adds to science's understanding of therizinosaur, a dinosaur belonging to the therapod (sic) family, whose members include Tyrannosaurus rex and Velociraptor. The study suggests these famous predators may have evolved from plant-eating ancestors.

T. rex and the other tyrannosauroids are distant cousins to the maniraptors. The study only deals with maniraptors and doesn't suggest that T. rex had a vegetarian ancestor. This seems to be a pretty common mistake: reporters throwing out the names of one of the classic dinosaurs as a sort of shorthand.

A traveling exhibit on recent discoveries of therizinosaurs in the United States, THERIZINOSAUR—Mystery of the Sickle-Claw Dinosaur, will be at the Museum of Northern Arizona until August 30, 2009.

More N. grafammi: Live Science, Dinosaur Tracking, and nice personal observations at Chinleana.