The placenta is primarily found in the class Mammalia, which includes all mammals. This organ facilitates the exchange of nutrients and waste between the mother and developing fetus during gestation. While some other vertebrates, like certain reptiles and fish, have structures that perform similar functions, true placentation is characteristic of mammals.
Humans belong to the class mammalia of vertebrate.
The axolotl is in the vertebrate classification of amphibians.
The frog is a vertebrate considering it is in the class Amphibia.
a sparrow is a vertebrate it is under the classification of class aves
mammal
Aves
amphibians
mammal class
Osteichthyes, the bony fish class, has over 30,000 species.
The cockatoo is a bird, so it is in the vertebrate class Aves.
Fish are the largest group or class of vertebrate
Aves (birds)