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Balaur

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Everyone's talking about and doing pictures of this new maniraptor, so I may as well join. (Blah, Haplocheirus sollers is more significant!*)

Either way, Balaur bondoc is a newly described dromaeosaurid (robust "raptor") from Romania, which was part of an island archipelago in the Cretaceous. Interesting things happen to creatures that happen to reach islands, and Balaur bondoc is no exception. Its first toe was very large and reached the ground, whereas in typical theropods ("meat-eating" dinosaurs) the first toe is small and high on the foot. Most deinonychosaurs ("raptors") have a retractable second toe, and the describers of Balaur bondoc interpret the first toe as a second retractable digit. Its legs and pelvis were very stoutly built, suggesting it was a rather thickset animal. If it was a predator, it certainly would've fulfilled the popular image of dromaeosaurids as powerful hunters that grappled with larger prey. This was one dromaeosaurid that could've conceivably attacked the hadrosaurs and sauropods in its habitat. (To be fair, these herbivores were smaller than their mainland counterparts, but they were still the size of horses, quite a bit larger than Balaur bondoc.)

However, paleontologist Andrea Cau of the Theropoda blog has come up with an alternative hypothesis, known as the dodo raptor hypothesis. The big first toe of Balaur bondoc may have been used for supporting its weight instead of a weapon. (We don't actually know if the first toe really is retractable. Although the fossilized foot preserves it that way, a dead animal can bend in ways a live animal can't. Dead Microraptor zhaoianus can sprawl their hind legs and dead Archaeopteryx lithographica can reverse their first toes, for example.) The strong pelvis and hind limbs may have been to hold longer intestines for digesting vegetation. Also interesting is that Balaur bondoc has only two claws on each wing, unlike other deinonychosaurs, which have three, suggesting a reduced function in predation. It may also have had a shorter tail than other deinonychosaurs. In other words, Balaur bondoc may have been an omnivorous or herbivorous dromaeosaurid, similar in form to therizinosaurs (ground sloth dinosaurs) and flightless columbiforms! (If so, this would make it almost as important as Haplocheirus sollers. Almost. Not quite.)

Since there is no skull material for Balaur bondoc so far, we can't be sure if either of these hypotheses are correct, but it makes for good discussion.

*There are only about five Haplocheirus sollers on DeviantArt. It's unfair!
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Comments19
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No consensus as of yet...

What I think we can be sure is that this thing is one of the very few theropods that really would be ridiculously slow in its own element (hell Utahraptor seems like a much faster runner than this thing is)
SpongeBobFossilPants's avatar
It appears that Dyke et al. will suggest at SVP that Balaur was an omnivore. ALL HAIL THE PROPHET! XD

Is it as important as Haplocheirus now that it's (likely) an avialan? ;)
Albertonykus's avatar
Re importance: It doesn't tell us about the evolution of an enigmatic radiation the way Haplocheirus did. But being a unique and unexpected offshoot (which it already was as a dromaeosaurid, but perhaps even more so as a basal avialan) certainly makes it interesting.
SpongeBobFossilPants's avatar
Not to mention the ghost lineage implied by a Late Cretaceous long-tailed bird…
Albertonykus's avatar
That's right. I still hope we get a skull someday that will allow us to be certain one way or another.
SpongeBobFossilPants's avatar
Yeah, hopefully TetZoo and Theropoda will divulge more info when that time comes around (Darren and Andrea are coauthors).
Dennonyx's avatar
If you want I can make an accurate Haplocheirus drawing ^_^
Albertonykus's avatar
ClockwerkMao's avatar
I propose a third mode of life for Balaur: termite-eater. It's got big leg bones with big muscle attachments, and it's got two claws to tear open logs with, and it's got dinky arms for display and whatever else. It's like a Giant Anteater with more exciting coloring.
"Dead Microraptor zhaoianus can sprawl their hind legs and dead Archaeopteryx lithographica can reverse their first toes,"

To be fair, the 1st toes of Archaeopteryx ARE reversed ("Weakly reversed", yes, but reversed nonetheless: [link] ).
Albertonykus's avatar
I didn't know that. Still, I assume that they're not reversed to the degree shown in the fossils.
You assume right. See "How To Get Your T.rex to Perch on Your Finger" in this link for more info on that: [link]
Albertonykus's avatar
It does. (Thanks for the mass faves!)
Tomozaurus's avatar
I like this hypothesis, and at the moment it seems quite plausible.

Would it make you happy if I drew a Haplocheirus? lol
Albertonykus's avatar
Yes, do Haplocheirus. We need alvarezsauroids to take over the world! XD
Tomozaurus's avatar
Hahaha. I'll see what I can do.
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