Several months ago, a team of paleontologists led by Enpu Gong published a study of the small theropod Sinornithosaurus in which they put forth the idea that it may have been venomous. It was a bold conjecture begging to be examined by other paleontologists. The trio of Federico A. Gianechini, Federico L. Agnolín and Martín D. Ezcurra have done just that.
Sinornithosaurus by funkmonk, via Wikimedia Commons
Their conclusion, published in the German journal Paläontologische Zeitschrift, is that there is scant evidence that Sinornithosaurus was venomous, and the original evidence presented was mistaken. What Gong et al. believed to be an elongated teeth, they say, was a result of the tooth being pulled out of its socket postmortem. They say that the grooves along the jaw that were posited as being a venom delivery system are common in theropods, and that there is no evidence that the skull housed a venom gland. They don't believe that the skull of Sinornithosaurus is particularly out of line with its dromaeosaur kin at all.
These findings echo the initial opinion of University of Maryland paleontologist Thomas Holtz, Jr. after the Gong paper came out.
In the same issue of Paläontologische Zeitschrift, Gong and his coauthors write a strongly worded defense of their research, refuting Gianechini et al. point by point. It's unfortunately not available in abstract. On the first page jpg provided by SpringerLink database they write that they wonder "if the authors have ever examined the actual material."
I have a feeling that Sinornithosaurus is going to be a bit of a paleontological hot potato. That is, if enough paleontologists find this field of inquiry compelling. We'll probably never know for sure. Unless, of course, one is captured on a mist-enshrouded, uncharted island somewhere in the Pacific and bites some poor so and so.