Ichthyostega And Acanthostega - Different Life Histories.
Ichthyostegalia is an order of extinct amphibians, representing the earliest landliving vertebrates. The group is thus an evolutionary grade rather than a clade.
Ichthyostega Ichthyostega, genus of extinct animals, closely related to tetrapods (four-legged land vertebrates) and found as fossils in rocks in eastern Greenland from the late Devonian Period (about 370 million years ago).
Fossil representation: Enough fossils have been found to give a good understanding of Ichthyostega’s build, however the forelimbs have never been found. Ichthyostega is considered to be one of the important transitional links between marine and fully terrestrial vertebrates.
Secondly, both sub-adult and adult humeri of Ichthyostega lacked several derived characters that were shared by Acanthostega and other, Carboniferous, early tetrapods. These findings argued against the general and widely accepted idea that Acanthostega was the more primitive of the two taxa.
Ichthyostega spp. The re-interpretation of existing fossil specimens is a recurring theme in the study of early tetrapods. Typically, this involved re-assigning a specimen —often a lower jaw— that once believed to be that of a lobe-fin to that of a tetrapod.
The researchers have identified several half-grown, as well as fully grown, upper arm bones from Ichthyostega and Acanthostega, allowing them to study how the shape of the bone changed during growth. It turns out that the two animals had different life histories.
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).
Erik Jarvik and Ichthyostega. Below is the usual compressed summary of the characteristics of Ichthyostega.In preparing this summary, we have done our usual incomplete survey of the descriptive literature; and, like a blackbird, we have probably picked up shiny facts more for their intrinsic attraction than for their significance.
Dr. Pierce used the 3-D model to measure the amount of mobility in the shoulder, elbow, hip and knee joints of Ichthyostega.She then compared it to mobility in five modern animals that can move both in water and on land: a salamander, a crocodile, a platypus, an otter, and a seal.
Ichthyostega - WikiMili, The Free Encyclopedia Ichthyostega (Greek: fish roof) is an early genus of tetrapodomorphs that lived at the end of the Late Devonian Period. It was one of the first four-limbed vertebrates in the fossil record. Ichthyostega possessed lungs and limbs that helped it navigate through shallow water in swamps.
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Acanthostega lad lungs as well as internal gills, and this lung back-up would have allowed it to exploit the oxygen in the air as well, something that predatory fish would not have been able to do. The legs while crude compared to the land animals to come, would have enabled it scramble over and around submerged obstacles and aquatic plants.
Fossilworks hosts query, analysis, and download functions used to access large paleontological data sets. It presents taxonomic, distributional, and ecological data about the entire fossil record.
