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Fish may have evolved from an animal similar to a coral-like sea squirt (a tunicate), whose larvae resemble early fish in important ways. The first ancestors of fish may have kept the larval form into adulthood, as some sea squirts do today, although this path cannot be proven. Vertebrates, in other words the first fish, originated about 530 ...
At long irregular intervals, Earth's biosphere suffers a catastrophic die-off, a mass extinction, [9] often comprising an accumulation of smaller extinction events over a relatively brief period. [10] The first known mass extinction was the Great Oxidation Event 2.4 billion years ago, which killed most of the planet's obligate anaerobes.
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.
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
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.
Marine invertebrates are animals that inhabit a marine environment apart from the vertebrate members of the chordate phylum; invertebrates lack a vertebral column. Some have evolved a shell or a hard exoskeleton. The earliest animal fossils may belong to the genus Dickinsonia, [183] 571 million to 541 million years ago. [184]
Tiktaalik (/ t ɪ k ˈ t ɑː l ɪ k /; Inuktitut ᑎᒃᑖᓕᒃ) is a monospecific genus of extinct sarcopterygian (lobe-finned fish) from the Late Devonian Period, about 375 Mya (million years ago), having many features akin to those of tetrapods (four-legged animals). [1]
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 ...