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The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fish lineages belong to the Agnatha, or jawless fish. Early examples include Haikouichthys.
They evolved from lobe-finned fish of the clade Sarcopterygii, appearing in coastal water in the middle Devonian, and giving rise to the first amphibians. [ 59 ] The group of lobe-finned fishes that were the ancestors of the tetrapod are grouped together as the Rhipidistia , [ 60 ] and the first tetrapods evolved from these fish over the ...
First vertebrates with true bones (jawless fishes). 450 Ma First complete conodonts and echinoids appear. 440 Ma First agnathan fishes: Heterostraci, Galeaspida, and Pituriaspida. 420 Ma Earliest ray-finned fishes, trigonotarbid arachnids, and land scorpions. [77] 410 Ma First signs of teeth in fish. Earliest Nautilida, lycophytes, and ...
Haikouichthys, from about in China, may be the earliest known fish. [1] [additional citation(s) needed] Prehistoric fish are early fish that are known only from fossil records. They are the earliest known vertebrates, and include the first and extinct fish that lived through the Cambrian to the Quaternary.
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. [1] Tetrapods (under the apomorphy-based definition used on this page) are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals.
Placoderms were among the first jawed fish (their jaws likely evolved from the first pair of gill arches), as well as the first vertebrates to have true teeth. They were also the first fish clade to develop pelvic fins, the second set of paired fins and the homologous precursor to hindlimbs in tetrapods.
Coelacanths (/ ˈ s iː l ə k æ n θ / ⓘ SEE-lə-kanth) (order Coelacanthiformes) are an ancient group of lobe-finned fish (Sarcopterygii) in the class Actinistia. [2] [3] As sarcopterygians, they are more closely related to lungfish and tetrapods (which includes amphibians, reptiles, birds and mammals) than to ray-finned fish.
The earliest fish appeared during the Cambrian as small filter feeders; they continued to evolve through the Paleozoic, diversifying into many forms. The earliest fish with dedicated respiratory gills and paired fins, the ostracoderms, had heavy bony plates that served as protective exoskeletons against invertebrate predators.