Does Acanthostega have a wrist?
Fish-like features: No true elbows, knees, wrists or ankles (ie not weight-bearing) Long fin rays around the tail.
What are the characteristics of Acanthostega?
The 60 cm (24 in) Acanthostega had eight digits on each hand (the number of digits on the feet is unclear) linked by webbing, it lacked wrists, and was generally poorly adapted for walking on land. It also had a remarkably fish-like shoulder and forelimb.
Do Acanthostega have gills?
Acanthostega seems to have retained fish-like internal gills and an open opercular chamber for use in aquatic respiration, implying that the earliest tetrapods were not fully terrestrial.
What was the significance of the fossil Acanthostega What did this fossil suggest about the evolution of tetrapods?
Both extinct species, known as Ichthyostega and Acanthostega, lived an estimated 360-370 million years ago in what is now Greenland. Acanthostega was thought to have been the most primitive tetrapod, that is, the first vertebrate animal to possess limbs with digits rather than fish fins.
What does two lives mean for an amphibian?
The term Amphibian comes from the Greek word amphibious. Amphi means “both” and bios means “life”. Those names refer to the two lives that many amphibians live – one in water during their larval stage and the other on land during their adult stage. The life cycle of Amphibians begins with an egg.
Acanthostega also had a deep tail which sported a large bony fin. In short, it had a tail suited for swimming, a fish’s spine and paddle-like limbs. A primarily, if not exclusively, aquatic lifestyle for Acanthostega is further indicated by the presence of internal, fish-like gills.
What is the evolutionary history of Acanthostega?
Acanthostega is seen as part of widespread evolutionary radiation in the late Devonian period, starting with purely aquatic finned tetrapodomorphs, with their successors showing increased air-breathing capability and related adaptions to the jaws and gills, as well as more muscular neck allowing freer movement of the head than fish have, and use…
Why did Acanthostega have Nares instead of fins?
Acanthostega’s small, fish-like nares (nostrils) were probably used only for smelling under water; air may have been brought to the lungs by gulping. Although Acanthostega had many fish-like characteristics it did have legs and feet rather than fins. These feet, however, also affected our thinking on the evolution of tetrapod limbs.
Did Acanthostega live in shallow swamps?
It has been inferred that Acanthostega probably lived in shallow, weed-choked swamps, its legs apparently being adapted for these specific ecosystems (the animal was not adapted in any way for walking on land).