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Thursday, October 7, 2010

Dinosaurs were even bigger

We all know that many dinosaurs were enormous. Now it turns out that we may have been underestimating them by as much as ten percent. Casey Holliday from the University of Missouri, Ryan Ridgely and Lawrence Witmer from Ohio University and Jayc Sedlmayr of Louisiana State University based their new size determinations on a hitherto under-examined anatomical feature: cartilage.

Cartilage is the stiff yet flexible tissue found between bones in our joints. It also makes up the bulk of our ears and noses. We mammals have a thin layer of cartilage between the long bones of our upper and lower limbs. This cartilage adds little to our overall height. Dinosaurs, like their modern descendents, alligators and birds, have much larger cartilage pads. This has to do with the way the leg bones connect with each other. If you examine an ostrich’s leg bones with or without cartilage, the height estimate for that bird will vary by 4 to 10%. In other words, by not accounting for cartilage, paleontologists have been assigning too little height to many species of dinosaurs.

In addition to size discrepancies, the amount of cartilage can also affect things like overall speed and posture. Put together, the new data may mean that dinosaurs looked and moved somewhat differently than previously thought. The researchers plan to look more closely at how different types of vertebrates build their joints in an attempt to better predict dinosaur anatomy.