Tuesday, August 31, 2010

Bună ziua, Balaur bondoc


Balaur bondoc, by Mick Ellison. From the PNAS paper.

I love the smell of lifted embargos in the morning. Yesterday, the web exploded to life with news of a new dromaeosaur from the Haţeg Basin in Romania, newly described in the Proceedings of the National Academy of Sciences. Remember the fuss Dr. Grant made over the Velociraptor's single sickle-claw at the beginning of Jurassic Park? Well, Balaur bondoc (the "stocky dragon") had two of them. Suck on those, Telmatosaurus and Magyarosaurus.

This is a significant discovery, helping paleontologists flesh out the menagerie of strange island dinosaurs from the European archipelago during the late Cretaceous. Balaur is the first good fossil of a predatory dinosaur from the time, and provides additional insight into the unique ways animals evolve on islands, where they are isolated from their mainland brethren and have to compete for food in different ways.

Because of limits on space, and therefore food, islands often cause populations of large herbivores to reduce in size over time. About a century ago, Franz Baron Nopsca believed this to be the explanation for the herbivorous dinosaurs discovered in Transylvania, an hypothesis that took a while to gain traction, but which is now widely accepted (I wrote about the Baron and his island dwarf ideas last spring). What was eating those smaller sauropods and dantier ornithopods? One of their harrassers would have been Balaur, a scaled-up relative of Velociraptor.

One part of the island rule holds that as herbivores reduce in size to better manage scarce food sources, predators grow to take advantage of the easier prey. Balaur is only a bit larger than Velociraptor (which in reality was a fraction of the size othe JP version, leading Dan Telfer to joke that he'd punt one out of the way if it tried anything with him). But it's a lot more robust than the lithe Mongolian dromaeosaur.

Its unique features don't end with its stockiness: Balaur possessed the above-mentioned twin sickle-claws, four functional toes on its feet as opposed to the typical three for theropods, and a two-fingered hand. This was clearly a predator adapted for a unique lifestyle. Those two claws on its feet have been proposed as its main weapons - as coauthor Steven Brussatte says, "Compared to Velociraptor, Balaur was probably more of a kickboxer than a sprinter, and it might have been able to take down larger animals than itself, as many carnivores do today." The skull of Balaur has yet to be found. I'd love to see if it had additional unique features which may have been of use in taking down prey.

The authors, led by Zoltán Csiki of Bucharest University, write that Balaur's close kinship to the Mongolian Velociraptor suggests that there must have been some connection between the islands and the mainland, an idea that has been hard to state firmly until now. Those herbivorous dwarf dinosaurs of Haţeg are more primitive than their late Cretaceous relatives, suggesting that they had been isolated from their mainland families since the Jurassic. Not so with Balaur. This is an animal descended from advanced dromaeosaurs of the late Cretaceous, so it must have arrived later.

This leads to my big, possibly stupid question, which I'll nonetheless pose here. What if Balaur isn't an example of the island rule after all? Dromaeosaurs are (for the most part) small, nimble predators who may have been able to travel between the island and the mainland more easily than the herbivores. Its unique features may have been of use on the mainland, and it may have been able to access the islands by swimming. Hoping for more skeletons of an interesting new dinosaur like Balaur is a lot to ask, but I'll be interested to see where else they might turn up. Preferably with a nice, complete skull. Csiki promises functional analyses to come in this interview, which will help shed light on how this two-finger, four-toed, robustly built dude hunted.

This is the kind of new species that's easy to get excited about. It represents new and interesting variations on the classic dromaeosaur body plan. It's in a geographically interesting place. Its relation to other dromaeosaurs is significant. And it's got one heck of a cool sounding name, conjuring a positively Tolkienian mood. Balaur bondoc sounds like some dark memory from the depths of elvenlore. Anytime you're compelled to say both the genus and species name, you know you've got a keeper.

More coverage of Balaur bondoc:

Not Exactly Rocket Science
Discovery
More From Discovery: Jennifer Viegas interviews Zoltán Csiki
Nat Geo
Science Daily
DinoGoss
Dinosaur Tracking
Wired (including very cool illo of Velociraptor)
HuffPo
BBC
The Dragon's Tales
Everything Dinosaur

PS. Bună ziua = "Good day" in Romanian.

3 comments:

  1. Swimming? So these guys were seabirds? I doubt derived dromaeosaurids could reach islands any better (or worse) than today's flightless birds. Nonetheless, a very cool find.

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  2. Yeah, I'm not sure about the swimming thing, but I figured I'd float it out there (pardon the pun). I just figured okay: you've got a chain of islands, not a single one. If there is a temporary land bridge, it's probably not going to provide access to every island in the chain. So maybe they could make it across short distances of water between other islands by swimming. More something to ponder than a serious suggestion!

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  3. Good discussion on Theropoda, inspired by a Facebook conversation, about Balaur possibly using all four toes for walking, and that it was a graviportal therizinosaur mimic.

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