What does the agnathans group include?

Answer 1

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.

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.

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Answer 2
Gabriella Anderson
The agnathans group includes jawless fish, such as lampreys and hagfish.
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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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