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In the 1920s, the biologists Johan Kiær and Erik Stensiö first recognized the Cephalaspidomorphi as including the osteostracans, anaspids, and lampreys, because all three groups share a single dorsal "nostril", now known as a nasohypophysial opening. [5] Since then, opinions on the relations among jawless vertebrates have varied.
Cephalaspidomorphi or cephalaspids ('head-shields'), like most contemporary fishes, were very well armoured. Particularly the head shield was well developed, protecting the head, gills and the anterior section of innards. The body were in most forms well armoured too.
Cephalaspidomorphi were, like most contemporary fish, very well armoured. Particularly, the head shield was well developed, protecting the head, gills and the anterior section of the innards. The body was in most forms well armoured as well. The head shield had a series of grooves over the whole surface forming an extensive lateral line organ ...
Fish account for more than half of vertebrate species. As of 2016, there are over 32,000 described species of bony fish, over 1,100 species of cartilaginous fish, and over 100 hagfish and lampreys. A third of these fall within the nine largest families; from largest to smallest, these are Cyprinidae , Gobiidae , Cichlidae , Characidae ...
The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, the osteostracans, especially the Devonian species, were among the most advanced of all known ...
Because its mouth was situated directly beneath its head, Cephalaspis was thought of as being a bottom-feeder, akin to a heavily armoured catfish or sturgeon.It moved its plow-like head from side to side, Cephalaspis easily stirring sand and dust into the water, along with revealing the hiding places of its prey, digging up worms or crustaceans hidden in the mud and algae, as well as sifting ...
Osteichthyes (/ ˌ ɒ s t iː ˈ ɪ k θ iː z / ost-ee-IK-theez), [2] also known as osteichthyans or commonly referred to as the bony fish, is a diverse superclass of vertebrate animals that have endoskeletons primarily composed of bone tissue.
The study of prehistoric fish is called paleoichthyology. A few living forms, such as the coelacanth are also referred to as prehistoric fish, or even living fossils, due to their current rarity and similarity to extinct forms. Fish which have become recently extinct are not usually referred to as prehistoric fish. They were very different from ...