The discovery of excellent specimens of this Devonian tetrapod has revitalised study of the so-called 'fish-tetrapod' transition, and has changed many perceptions about this major evolutionary event. For example, rather than envisaging a 'fish' crawling out of the water, to evolve feet to walk on land, we now think that animals with feet - 'tetrapods' - evolved their feet for uses in water, and only later became land-going. Rather than gaining all their distinctive features early on in their history, tetrapods seem to have evolved fully terrestrial adaptations only gradually over the 30 million years between the end of the Devonian and the middle of the succeeding Carboniferous period.

Features such as a terrestrially adapted ear, an occiput with a mobile joint (a condyle), a sacral joint for attachment of the pelvic girdle, loss of gill-breathing and acquisition of the structures associated with air-breathing using ribs for aspiration all seemed to have been acquired bit by bit after the end of the Devonian. Acanthostega is in many ways the most primitive tetrapod described so far, in that it retained internal gills for breathing, a tail-fin with fin rays above and below the vertebral column, a braincase into which the notochord passed as it did in the tetrapods' fish relatives, and a radius that was longer and more substantial than the ulna. Although it had limbs with digits, its ankle, knee, wrist and elbow joints were not developed into weight-bearing joints with the characteristic degrees of movement found in terrestrial tetrapods.

Acanthostega and its influence on our understanding of the fish-tetrapod transition has been covered in a variety of books and papers. As well as the formal publications listed in my publications list and on the web page for Acanthostega in the University of Arizona Tree of Life site site, there have been many more popular publications in books and journals, and the origin of tetrapods has been covered in several television programmes.