Definition of diphycercal in US English:



  • (of a fish's tail) approximately symmetrical and with the vertebral column continuing to the tip, as in lampreys.

    Contrasted with heterocercal, homocercal
    • ‘Sharks, and similar chondrichthyes, have heterocercal tails; the diphycercal tails are found in lungfish and their relatives; and the homocercal tail is characteristic of bony fish.’
    • ‘In Strepsodus the tail was diamond shaped and diphycercal; in Gooloogongia loomesi it was nearly so.’
    • ‘Bodies are long and slender, somewhat like salamanders, with a diphycercal tail.’
    • ‘The symmetrical, diphycercal tail, not perfected by gnathostomes until the Cretaceous, was standard equipment on heterostracans in the Silurian.’
    • ‘The Heterostracan head is covered with several armoured plates, the body with large scales and the tail is most often diphycercal.’


Mid 19th century: from Greek diphu- ‘of double form’ + kerkos ‘tail’ + -al.