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 Actinistia, or coelacanths, unlike the Rhipidistia, have exhibited exceptional evolutionary stability. They evolved in the Middle Devonian (397–385 million years ago) and rapidly became specialized so that they looked very much like the modern coelacanths.

Coelacanth is any sarcopterygian fish of the subclass Coelacanthimorpha (Actinistia) and order Coelacanthiformes, characterized by a three-lobed, diphycercal caudal fin, external nostrils, and an anterior dorsal fin in front of the center of the body (Nelson 2004).

At one time coelacanths were a large group comprising about 90 valid species that were distributed worldwide in both marine and freshwaters. Today, there are two known living species. Numerous characteristics are unique to the coelacanth among living fishes.

2021年12月18日 · Scientists have long known that coelacanths once swam Earth’s seas. Fossilized remains helped experts date the supposedly extinct fish species back 66 million years, to the Late Cretaceous period. But on a dewy morning in December 1938, a South African museum curator shockingly rediscovered them — alive.

2024年9月12日 · The living coelacanth Latimeria (Sarcopterygii: Actinistia) is an iconic, so-called ‘living fossil’ within one of the most apparently morphologically conservative vertebrate groups. We...

The Actinistia, or coelacanths, unlike the Rhipidistia, have exhibited exceptional evolutionary stability. They evolved in the Middle Devonian (397–385 million years ago) and rapidly became specialized so that they looked very much like the modern coelacanths.

Morphological and molecular sequence data clearly demonstrate that the living coelacanth Latimeria (Actinistia) is the closest relative of lungfishes and tetrapods (Cloutier & Ahlberg 1997; Brinkmann et al. 2004).

2024年9月12日 · The living coelacanth Latimeria (Sarcopterygii: Actinistia) is an iconic, so-called 'living fossil' within one of the most apparently morphologically conservative vertebrate groups. We describe a new, 3-D preserved coelacanth from the Late Devonian Gogo Formation in Western Australia.

We tackle evolutionary traits of the coelacanth lineage by comparing stratigraphical genus duration within the ray-finned fish clade (Actinopterygii) and coelacanth clade (Actinistia) in the Devonian–Palaeogene time interval.