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Timeline of fish evolution. The evolution of fishes took place over a timeline which spans the Cambrian to the Cenozoic, including during that time in particular the Devonian, which has been dubbed the "age of fishes" for the many changes during that period. The Late Devonian extinctions played a crucial role in shaping the evolution of fish ...
The first known footprints on land date to 530 Ma. [74] 520 Ma Earliest graptolites. [75] 511 Ma Earliest crustaceans. [76] 505 Ma Fossilization of the Burgess Shale: 500 Ma Jellyfish have existed since at least this time. 485 Ma First vertebrates with true bones (jawless fishes). 450 Ma First complete conodonts and echinoids appear. 440 Ma
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.
Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term taphonomy (from Greek táphos, τάφος 'burial' and nomos, νόμος 'law') was introduced to paleontology in 1940 [1] by Soviet scientist Ivan Efremov to describe the study of the transition of remains, parts, or products of organisms from the biosphere to the lithosphere.
In many lobe-finned fish, including living coelacanths and the Australian lungfish, the fin skeleton is based around a straight string of midline bones, making up the metapterygial axis. The component bones of the axis are known as axials or mesomeres. The axis is flanked by one or two series of rod-like bones known as radials.
The history of paleontology traces the history of the effort to understand the history of life on Earth by studying the fossil record left behind by living organisms. Since it is concerned with understanding living organisms of the past, paleontology can be considered to be a field of biology, but its historical development has been closely tied to geology and the effort to understand the ...
Thelenota ananas, a giant sea cucumber from the Indo-Pacific tropics. Sea cucumbers are echinoderms from the class Holothuroidea ( / ˌhɒləˌθjʊəˈrɔɪdiə, ˌhoʊ -/ HOL-ə-thure-OY-dee-ə, HOHL- ). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. They are found on the sea floor ...
The apparatus is made up of a set of bones known as Weberian ossicles, a chain of small bones that connect the auditory system to the swim bladder of fishes. [51] The ossicles connect the gas bladder wall with Y-shaped lymph sinus that is next to the lymph -filled transverse canal joining the saccules of the right and left ears.