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article imageVenomous prehistoric raptor discovered- Sinornithosaurus

By Paul Wallis     Dec 31, 2009 in Science
The ancient world had something ours doesn’t: Venomous bird lizards. Sinornithosaurus would have been a deadly part of any ecology, past or modern. Scientists have discovered indications of a snake-like venom delivery system.
A new study published by University of Kansas scientists in Proceedings of the National Academy of Sciences during the week of Dec. 21 is likely to shake a few current tail feathers. Sinornithosaurus ("Chinese bird lizard") lived 128 million years ago, in the early Cretaceous. It had front legs, claws, feathers, and a very long tail, indicating high agility. It’s quite Archaeopteryx like, but its flight capacity doesn’t get much of a mention in professional texts. This class of dinosaur is so similar to birds in structure that they're considered strong evidence of the direct link between the two. Feathers and even downy fur have also been reported on dinosaurs which were definitely not fliers.
This creature was originally considered a primitive dromeosaur, (aka raptor) when discovered in 1999 but the discovery of venomous capabilities puts it into a different bracket. This discovery is doing more of the constant major rewriting of dino ecology we've been seeing in recent years. It's a major discovery. Venomous dromeosaurs weren't even on the cards, previously. It’s a good evolutionary move for a small predator to have venom delivery systems. It reduces risk when attacking larger prey, and a highly agile animal can simply track its victim after delivery.
Science Daily reports that poison glands running to the curved, grooved teeth of Sinornithosaurus are similar to those of rear fanged snakes. The “Chinese bird lizard” lived in a diversified ecology, and is believed to have hunted small dinosaurs and birds.
Sinornithosaurus is very well stocked with curved teeth. A bite may have been able to deliver a lot of poison in a hurry. The current theory is that the victim would have gone into shock very quickly, reducing risk to Sinornithosaurus from attacks by its prey.
The long teeth are believed to have allowed Sinornithosaurus to penetrate layers of feathers. The curved teeth may have been a version of a very well known design of venomous fangs. Snake fangs are also curved, if not blade-like. This type of dentition produces a bite which delivers a highly penetrant puncture wound, able to enter the bloodstream easily. The blade shape would also open up a lot of tissue for the poison to enter.
Sinornithosaurus had some famous later relatives, including Deinonychus and Utahraptor, much bigger hunters with large sickle toes, which were true carnivores. It also had at least one related subspecies of its own, and perhaps another. The dromeosaurs were the wolves of the Cretaceous in their heyday, top predators. Their very diverse lineage is likely to be getting a much closer look, on the basis of this extraordinary find.
Meanwhile, we can consider ourselves lucky modern birds went with beaks instead.
More about Sinornithosaurus, Dinosaurs, Raptors dromeosaurs
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