Video transcript: Chewing not just for mammals
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Video shows footage of the tuatara
Dr Marc Jones, UCL Cell & Developmental Biology
The tuatara is a reptile found today in New Zealand. It is the only living relative of a group of reptiles that were successful during the time of the dinosaurs, when they were found all over the globe. They eat spiders, insects, snails and when they can they eat vertebrate animals such as lizards and frogs and sea birds.
Video shows diagram of a tuatara jaw opening and closing
The tuatara is special. Whereas we have one upper row of teeth the tuatara actually has two. It has a second large row of teeth on the inside of the palette. So when its jaws close the lower jaw actually closes between these two upper rows of teeth and after its closed it then slides forwards and blades on the teeth act to cut the food apart that is held in the mouth. What we found is that the lower jaws of the animal is separate so they move relative to one another and they do this in a very subtle way that this enhances the actual cutting action of the teeth. This is quite unique compared to other animals today there are not any other animals that slide their jaws forward after they have closed to cut food apart in this fashion.
Video shows Marc Jones biting into an apple and chewing
Most mammals chew their food very effectively and because they are warm blooded they generate their own body temperature and have a high resting metabolic rate. It makes a lot of sense to associate the two things. However, the tuatara also chews its food and yet doesn't have a high metabolism. So it shows us that the link between high metabolism and chewing food isn't as close as one might first expect.
Copyright University College London, University of Hull, The Hull York Medical School.