Question

Which one is the first vertebrate to have evolved?
(a) Jawless fish
(b) Monkey
(c) Frog
(d) Horse

Answer 1

Hint: The first vertebrate to have evolved belongs to the class Agnatha. They include lampreys and hagfish. These first vertebrates do not have scales. They also lack jaws, fins, and stomach. They have a notochord and paired pouches.

Complete answer
The first vertebrate to have evolved is the jawless fish. Under kingdom Animalia, comes the phylum Chordata. Among the subphylums included under phylum Chordata, comes subphylum Vertebrata. Vertebrata includes all the known large animals and some rare and unusual animals as well. The seven living classes of vertebrates are distinguished majorly on the basis of the skeletal system, general environmental adaptation, and reproductive system. These seven classes are Agnatha, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammalia. Three among the vertebrate classes are fish. The most primitive of these is Agnatha. The class Agnatha consists of jawless fish.
Additional information:
- The term monkey is descriptively applied to groups of primates which include families of New World monkeys and Old World monkeys.
- Frogs constitute the order Anura which in ancient Greek literally means without a tail.
So, the correct answer is, ‘Jawless fish.’

Note:
- Monkey is a common name that may refer to a number of species of mammals. They belong to simians of infraorder Simiiformes.
- Frogs are members of a diverse and largely carnivorous group of tail- less, short- bodied amphibians.
- Horses (Equus ferus caballus) are one of the two extant subspecies of Equus ferus. They belong to the class Mammalia under phylum Chordata.