fish appeared in the Silurian reached their greatest diversity in the Devonian a time known as the Age of Fishes and became extinct at the end of the Devonian They had no true teeth although the jaws had sharp tusklike projections and no preservable internal skeleton The only structure made of bone was the external armor Denver Museum of Nature Science Dunkleosteus an extinct Devonian marine placoderm fish found in Ohio The skull is more than 1 m high and 1 m wide Use these references to answer the questions below American Museum of Natural History Hall of Vertebrate Origins http www amnh org exhibitions permanent exhibitions fossil halls hall of vertebrate origins American Museum of Natural History Dunkleosteus http www amnh org exhibitions permanent exhibitions fossil halls hall of vertebrate origins dunkleosteus Anderson P S L Westneat M W 2007 Feeding mechanics and bite force modeling of the skull of Dunkleosteus terrelli an ancient apex predator Biology Letters 3 76 79 http rsbl royalsocietypublishing org content 3 1 77 full Cleveland Museum of Natural History Dunkleosteus terrelli http www cmnh org site AtThe Museum OnExhibit PermanentExhibits Dunk aspx University of California Museum of Paleontology 2000 Introduction to the Placodermi Extinct Armored Fishes with Jaws http www ucmp berkeley edu vertebrates basalfish placodermi html 39 In what formation were the Dunkleosteus fossils found 40 How long was Dunkleosteus 41 How much did Dunkleosteus weigh 42 Was Dunkleosteus a predator or a scavenger 43 What is suction feeding and how did it work feet tons 44 Dunkleosteus did not have teeth so how did it bite Describe the jaw and how it stayed sharp 45 How did its bite compare to other animals including fish mammals alligators and dinosaurs 46 What did Dunkleosteus eat Look at the skull of the Dunkleosteus in the photo Examine the eye Notice the sclerotic ring the bony structure in the eye socket for the protection of the eye All birds have this sclerotic ring It protects their eyes against rapid air pressure changes during flights It is also used to help the eye focus on distant objects Read more about the sclerotic ring here