(of a fish's tail) approximately symmetrical and with the vertebral column continuing to the tip, as in lampreys.‘The symmetrical, diphycercal tail, not perfected by gnathostomes until the Cretaceous, was standard equipment on heterostracans in the Silurian.’
- ‘In Strepsodus the tail was diamond shaped and diphycercal; in Gooloogongia loomesi it was nearly so.’
- ‘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.’
- ‘Bodies are long and slender, somewhat like salamanders, with a diphycercal tail.’
- ‘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.
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