66123
The very earliest tetrapods would have been animals similar to " Acanthostega " , with legs and lungs as well as gills , but still primarily aquatic and unsuited to life on land .
 Acanthostega
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Acanthostega