North America’s newest dinosaur had the makings of a monster: razor-sharp claws, a runner’s body, and similarities with the Velociraptor of Jurassic Park infamy. If only it’d been bigger than a chicken [National Geographic News]. The four-pound Hesperonychus elizabethae has claimed the title of the smallest carnivorous dinosaur to have tromped on North American soil. Study coauthor Nick Longrich says that while Hesperonychus was a fierce hunter, only small creatures learned to fear it. “My guess is that it was a small-game hunter, taking down mammals and birds and baby dinosaurs” [Reuters], he says.
The identification of the new genus and species wasn’t based on a new fossil find. The tiny bones—originally assumed to come from a youngster—had languished in a collection at the University of Alberta in Edmonton for 25 years before Longrich and a fellow researcher decided to take another look at them. On closer examination, they noticed that the pelvis was fused, an indication that the 75-million-year-old dino that it came from had reached maturity and stopped growing [Scientific American].
Few fossils of small, carnivorous dinosaurs have been discovered in North America, but Longrich says that the new discovery proves that dinosuars did fill that niche. “Small carnivorous dinosaurs seemed to be completely absent from the environment, which seemed bizarre because today the small carnivores outnumber the big ones. It turns out that they were here and they played a more important role in the ecosystem than we realised” [Telegraph], he says. Their smaller bones are more likely to have been destroyed over the millennia, but Longrich says that Hesperonychus should motivate other researchers to search for still smaller dinosaur predators.
The study, published in the Proceedings of the National Academy of Sciences, also suggests that Hesperonychus had some bird-like traits. Based on the size of the hips, and because one of the hip bones was bent – the pubis, a small bone that sits between the legs – “we know this dinosaur was a tree-climber”, [study coauthor Philip] Currie explained. “It likely used the long feathers on its limbs to glide or parachute from tree to tree” [BBC News].
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Image: Nick Longrich/University of Calgary
March 17th, 2009 at 12:31 pm
It’s a tokage!
http://www.usagiyojimbo.com/characters/spot/spot.gif
March 18th, 2009 at 10:37 am
““It likely used the long feathers on its limbs to glide or parachute from tree to tree””
It had feathers? Where did that information come from? Dr. Currie isn’t exactly known for his impartiality and rigorous scientific examination of evidence that he thinks may confirm his own beliefs. E.g. the infamous dino-bird that 6 months later was found to be two fossils put together…although at least two researchers within weeks publicly announced it was most likely two fossils, they were ignored. Scientific American (and Dr. Currie) ended up with egg on their face for their over-the-top proclamations, and SA later had an article on why they failed to detect the fraud (human biases and wanting something to be true, failure to think critically).
Looking things up I see they’re saying this small dinosaur is fully feathered and was probably warm-blooded.?! I’m just having difficulty believing this because if it was fully-feathered or had “long feathers” then shouldn’t this have been noticed in the fossil? Instead, it was stored away for 25 years…not something you’d do with a fossil showing evidence of feathers. Since there were many fossils found, did any of them show evidence of feathers?
This seems like wholesale conjecture on their part, and now I’m wondering how much of the other information is just wish-fulfilment thinking (e.g. fused pelvis, climbed trees, was carnivorous). I think that before we promote this find as a feathered dinosaur, we should wait till others have examined it carefully so we don’t repeat the same mistake we did a decade ago. Let’s see what an impartial study will reveal. Dr. Currie may not have learned his lesson, but one would hope the rest of us did.
I hope Discover has a follow up on this story either confirming the conjecture (that’d be fantastic and exciting!!) or demonstrating that too much was read into the fossils (disappointing but at least honest…and honesty is what science is about).
March 18th, 2009 at 1:42 pm
Thanks for the background info, Daniel. I didn’t know the story of the A. liaoningensis fossil.
As far as I can tell, the BBC was the only publication to report Currie’s suppositions about this latest dino’s possibly arboreal lifestyle. But I haven’t seen other paleontologists questioning those hypotheses, or questioning the finding in general. If you have, I hope you’ll let us know.