Ichthyostega


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Ichthyostega

[‚ik·thē·ə′steg·ə]
(paleontology)
Four-legged vertebrates that evolved from their lobe-finned fish ancestors during the later Devonian Period (400-350 million years ago).

Ichthyostega

 

the most ancient and primitive genus of extinct amphibians. Ichthyostega measured approximately 1 m long. The structure of its skull as a whole was that of most labyrinthodonts, but there were characteristics typical of cross-opterygians (short snout with a rostral element, vestiges of bones of the gill cover, lateral organs enclosed in bony canals). The extremities and girdles were constructed like those of terrestrial animals, but the tail bore a fin with bony rays. Apparently Ichthyostega lived in water and never abandoned it for long. It is an important connecting link between terrestrial vertebrates and fish, and proves the origin of amphibians from crossopterygians. Remains of Ichthyostega and closely related forms have been discovered in Upper Devonian deposits of Greenland.

REFERENCE

Shmal’gauzen, I. I. Proiskhozhdenie nazemnykh pozvonochnykh. Mos-cow, 1964. Chapter 8.
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References in periodicals archive ?
She and her colleagues have proposed that an early land invader called Ichthyostega moved right and left forelimbs forward together, similar to the way a person on crutches sweeps the supports forward in unison.
One of the studied animals was a fierce-looking, toothy beast known as Ichthyostega.
She recognized a previously unexpected diversity of taxa, including a possible reptiliomorph, a possible colosteid stem tetrapod, and a form resembling the famous stem tetrapod Ichthyostega from Late Devonian (Famennian) strata of East Greenland.
Both extinct species, identified as Ichthyostega and Acanthostega, lived an estimated 370,000,000 years ago in what now is Greenland.
Tiktaalik lived a little over 380 million years ago, and its structure fills ill a gap between that of the fully aquatic fish and the first known tetrapod, Ichthyostega.
Cladoselache, Tristychius, Ctenacanthus, Paleospinax, Spathobatis, Protospinax, Acanthodians, Cheirolepis, Mimia, Canobius, Aeduella, Parasemionotus, Oreochima, Leptolepis, Osteolepis, Eusthenopteron, Sterropterygion, Panderichthys, Elpistostege, Hynerpeton, Acanthostega, Ichthyostega, Pholidogaster, Pteroplax, Dendrerpeton acadianum, Archegosaurus decheni, Eryops megacephalus, Trematops, Amphibamus lyelli, Doleserpeton annectens, Triadobatrachus, Vieraella, Karaurus, Proterogyrinus, Limnoscelis, Tseajaia, Solenodonsaurus, Hylonomus, Paleothyris, Captorhinus, Scutosaurus, Deltavjatia vjatkensis, Proganochelys, Hylonomus, Paleothyris, Petrol- acosaurus, Araeoscelis, Apsisaurus, Claudiosaurus, Planocephalosaurus, Protorosaurus, Prolacerta, Proterosuchus, Hyperodapedon, Trilopho- saurus.
Como una forma de Ichthyostega, la criatura primitiva que evoluciono depescado a animal mamifero saliendo del agua.
Two of the first such creatures were called Ichthyostega and Acanthostega.
The study, published in this week's issue of Nature, found that that the fishy four-limbed animal Ichthyostega used its front limbs like crutches, pushing its body up and forward onto land while its legs and tail trailed behind.
The best known of these early land-dwelling tetrapods are Ichthyostega and Acanthostega, both of which lived about 365 million years ago in what is now Greenland.
As a sort of Ichthyostega, the primordial creature that evolved from fish to land-going animal by vacating the waters).
Scientists believe this is the case because fossils like Ichthyostega, which has legs that couldn't bear its weight and a large, finned tail, are clearly aquatic.