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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.
Cartilaginous fish, class Chondrichthyes, consisting of sharks, rays and chimaeras, appeared by about 395 million years ago, in the middle Devonian. During the Late Devonian the first forests were taking shape on land. The first tetrapods appeared in the fossil record over a period, the beginning and end of which are marked with extinction events.
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 ...
A newfound fossil of a jawless fish is the oldest known vertebrate cranium preserved in 3D. The 455 million-year-old find could illuminate how vertebrate heads evolved.
They are the earliest known vertebrates, and include the first and extinct fish that lived through the Cambrian to the Quaternary. 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 ...
Evolution and extinction of placoderms. The diagram is based on Michael Benton, 2005. [17] Dunkleosteus, among the first of the vertebrate apex predators, was a giant armoured placoderm predator. Amazichthys, a pelagic arthrodire from the Middle Famennian of the Late Devonian. Fin spine of Eczematolepis, from the Middle Devonian of Wisconsin
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.
Agnatha (/ ˈ æ ɡ n ə θ ə, æ ɡ ˈ n eɪ θ ə /; [3] from Ancient Greek ἀ-(a-) 'without' and γνάθος (gnáthos) 'jaws') is a paraphyletic infraphylum [4] of non-gnathostome vertebrates, or jawless fish, in the phylum Chordata, subphylum Vertebrata, consisting of both living (cyclostomes) and extinct (conodonts, anaspids, and ...