Placentalia (胎盘)
Placentals are partly distinguished from other mammals in that the fetus is carried in the uterus of its mother to a relatively late stage of development.
features
- a sufficiently wide opening at the bottom of the pelvis to allow the birth of a large baby relative to the size of the mother.
- the rearmost bones of the foot fit into a socket formed by the ends of the tibia and fibula, forming a complete mortise and tenon upper ankle joint.
- the presence of a malleolus at the bottom of the fibula.
Marsupial (有袋)
Ossified patellae are absent in most modern marsupials (though a small number of exceptions are reported) and epipubic bones are present. Marsupials (and monotremes) also lack a gross communication (corpus callosum) between the right and left brain hemispheres.
Monotremata (单孔)
The only surviving examples of monotremes are all indigenous to Australia and New Guinea
Platypus
- It is one of the few species of venomous mammals
Echidna
- Their spines are actually hairs
- They have different coloured spines
- They form mating ‘trains’ during breeding season
- Male echidnas have a four-headed appendage
- They lay eggs
- Echidnas are actually toothless mammals
- They’re made for digging
Reptilia
Boa constrictor (红尾蚺)
Though all boids are constrictors, only this species is properly referred to as a “boa constrictor”—a rare instance of an animal having the same common English name and scientific binomial name.
Green anaconda (森蚺)
It is the heaviest and one of the longest known extant snake species. Like all boas, it is a non-venomous constrictor.
Reticulated python (网纹蟒)
Domestic
Sheep
- ruminant mammals
- An adult female is referred to as a ewe
- An intact male as a ram
- A castrated male as a wether
- A young sheep as a lamb
Goat
- Milk from goats is often turned into goat cheese.
- Female goats are referred to as does or nannies, intact males are called bucks or billies, and juvenile goats of both sexes are called kids. Castrated males are called wethers.
- Sheep and goats are closely related: both are in the subfamily Caprinae. However, they are separate species, so hybrids rarely occur and are always infertile.