Nigersaurus: just when you thought you'd seen everything...

Today is an exciting day in the world of palaeontology. This morning Paul Sereno went public with a PLoS paper on one of the most amazing dinosaur finds to date: Nigersaurus taqueti. This possibly the one of the most interesting fossils ever discovered, in my opinion. I really urge you to check out the Project Exploration website devoted to it. The dinosaur itself is obviously the main attraction, but the announcement is significant for another reason as well. Sereno is making a significant statement by choosing to publish this ground-breaking data in PLoS ONE, which is an open-access journal with many innovative features that allow readers to participate in commentary and discussions about articles. Open-access is a major issue in the world of science publishing right now (just yesterday a bill including open access legislation was vetoed), and this support from Sereno will bring more attention to PLoS and the services it offers.

Now on to the dinosaur itself! The title of the paper is "Structural Extremes in a Cretaceous Dinosaur," and Sereno does not exaggerate. This African sauropod's cranial anatomy is truly astonishing. Its jaws are actually wider than the rest of its skull, creating a very distinctive face shape (see the above portrait by Todd Marshall). There are over 500 tiny teeth arranged along the front of the jaw (see the photo, taken by M. Hettwer). It seems that the animal had a foraging strategy similar to that of a lawn-mower, reaching its long neck down to crop plants from the ground. This is interesting, because it belongs to the diplodocoid radiation of sauropods, which are generally thought to have fed upon treetop vegetation, reaching up instead of down to the ground.

Like many sauropods, these were animals of immense size, measuring about 30 feet long and 8 feet high at the hip. What makes them unique, however, is that their bones are surprisingly delicate: they are hollow. The image at right shows how thin the bones are, light can penetrate through them, definitely not what you would expect from a lumbering creature the size of a school bus. Partly due to the pneumatization of the bones, it is estimated that Nigersaurus only weighed around 4 tons, about the same as a modern elephant. This hollowing of bones is very similar to that found in modern birds, which have air sacs extending throughout much of their skeleton to reduce weight for flight. Keep in mind, however, that although birds do descend from dinosaurs, they are derived from the theropods, not the sauropods. This shows that extensive pneumatic skeletons have evolved independently multiple times, and possibly for different purposes (reducing weight due to sheer size versus reducing weight for flight and other physiological functions). It has been known for a while that sauropods had some hollow bones to minimize weight, but the degree seen in this specimen is truly amazing.

This specimen is going to be on display at the National Geographic Museum in Washington, D.C. until March 15, I am not sure where it is scheduled to go after that. I highly encourage everyone to go download the paper from PLoS ONE (no subscription required!) and to check out all the photos and special features on the Project Exploration website.

(All images credits go to the Project Exploration website, and there are plenty more there, go check it out!)

UPDATE:
National Geographic has also put up a photo gallery with many shots of this specimen, including a close up of that amazing battery of teeth, head over there now!