Bottom-dwelling placoderms, such as the antiarchs, had small, ventrally placed mouths and presumably fed on bottom detritus and small invertebrates.Click to see full answer. Likewise, people ask, why did Placoderms become extinct?It was thought for a time that placoderms became extinct due to competition from the first bony fish and early sharks, given a combination of the supposed inherent superiority of bony fish and the presumed sluggishness of placoderms.One may also ask, do Placoderms have teeth? Unlike all other jawed vertebrates, placoderms never had teeth, and did not descend from toothed ancestors. Instead, bony plates associated with the jaws performed the function of teeth, sometimes forming razor-like, literally self-sharpening edges (as can be seen in Dunkleosteus on the left). Simply so, what did Placoderms look like? Placoderms lacked teeth but biting or grinding structures are often found in the dermal bones lining their mouths. They had one dorsal fin, a pair of pectoral fins and a pair of pelvic fins with shark-like shape and internal structure, many species also had a single anal fin.What did dunkleosteus eat?This fish was anything but picky with its food. It ate fish, sharks and even its own kind. And it seems that Dunkleosteus suffered from indigestion as a result: its fossils are often associated with regurgitated, semi-digested remains of fish.