NOUN
- fish-like vertebrate with bony plates on head and upper body; dominant in seas and rivers during the Devonian; considered the earliest vertebrate with jaws
How To Use placoderm In A Sentence
- In addition, there are archaic elements, such as the antiarch and arthrodire placoderms as well as acanthodians.
- With their armored head shield and trunk shield composed of overlapping bony plates, the placoderms appear at first glance extremely similar to the ostracoderms (armoured jawless fish).
- The placoderms and chondrichthyans both show at least some capsular protuberance of the braincase, but the braincase is a single, undivided mass, whether or not ossified.
- The extinct armored fishes known as placoderms make up what is considered to be the earliest branch of the gnathostome family tree - the earliest branch of the jawed fishes.
- With their armored head shield and trunk shield composed of overlapping bony plates, the placoderms appear at first glance extremely similar to the ostracoderms (armoured jawless fish).
- In this capacity, it came to bear a very wide variety of cutting surfaces, from the inferognathals of arthrodire placoderms to the bizarre spiral symphysial tooth whorls of Helicoprion.
- Plourdosteus canadensis (Woodward 1892), un arthrodire du Frasnien inférieur du Canada: Contribution à l'étude morphologique et phylogénétique des Plourdosteidae (Vertebrata, Placodermi) du Dévonien moyen et supérieur. Miguasha Provincial Park, Canada
- Such giant cephalopods play or played a similar ecological role of top predator to that of Devonian arthrodire placoderms, Mesozoic pliosaurs and Cenozoic toothed whales.
- It was also covered in bony overlapping plates, like all placoderms, but had weak jaws and a peculiar high-crested bone, somewhat like a dorsal fin, straddled its back.
- They found that the primitive state for all chondrichthyans (and quite likely placoderms as well) is autodiastyly.
