Question

Какая группа рыб является наиболее древней? какие признаки строения подтвержают это?"

Answer 1

Кистепертые рыбы- древнее время могли дышать кислородом

Answer 2

The Most Ancient Group of Fish

The most ancient group of fish is believed to be the agnathans, which are jawless fish. Agnathans include lampreys and hagfish. These fish lack true jaws and have a cartilaginous skeleton. They are considered to be the most primitive and ancient group of fish due to their simple body structure and lack of certain features found in more advanced fish groups.

Features Supporting the Ancient Status

Several features of the agnathans' body structure support their status as the most ancient group of fish:

1. Lack of Jaws: Agnathans, as jawless fish, lack true jaws. Instead, they have a circular mouth surrounded by a sucker-like structure. This primitive characteristic suggests that they represent an early stage in the evolution of fish.

2. Cartilaginous Skeleton: Agnathans have a skeleton made of cartilage rather than bone. This is a primitive characteristic shared with other ancient fish groups, such as sharks and rays.

3. Simple Body Structure: Agnathans have a relatively simple body structure compared to more advanced fish groups. They lack paired fins and have a cylindrical body shape. These features indicate a more primitive form of fish.

4. Lack of Scales: Agnathans do not possess true scales like many other fish. Instead, they have a smooth, slimy skin. This is another primitive characteristic that suggests their ancient status.

These features collectively support the notion that agnathans are the most ancient group of fish. Their simple body structure, lack of jaws, cartilaginous skeleton, and absence of scales indicate an early stage in the evolution of fish.

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