What does the agnathans group include?
1 Answer
Apr 17, 2017
AGNATHANs are 'jaw less' vertebrates: gnathos in Greek means jaw. They were the first vertebrate to evolve in early Palaeozoic, more than 500 million years ago.
Explanation:
Superclass Agnatha is included under phylum Chordata, subphylum Vertebrata.
Very few living agnathans are present today, all are aquatic.
There is a single living class Cyclostomata, that includes all living agnathans.
Class Cyclostomata includes two members:
Hag fish/ Myxine
and
Lamprey/ Petromyzon.
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Most of extinct Agnathans are referred to as Ostracoderm : a group of fish like organisms whose head was protected by a bony shield.
Most agnathans were extinct by the end of Paleozoic.