Marsupials vs. Placental Mammals

According to the paleontologists, both the Marsupial and Placental mammals originated almost 125 million years ago. At that time, the earth had two super continents i.e., the Laurasia and the Gondwana. Laurasia had the Eurasia and North American continents and the fossils indicate that it was Eurasia from where both the Marsupials and Placental mammals originated.

Even though both the Marsupials and the Placental mammals originated from the Eurasian region, they have striking differences and variations from one another.

Despite the fact that both of these mammals have originated from the same area yet still they can still be differentiated from one another on the basis of their physical attributes. The current write up tries to differentiate the key differences in between the Marsupials and the Placental mammals.

Marsupials & Placental Mammals
Time of Origin
125 Million Years Place of Origin
Eurasia Marsupial vs. Placental Mammals
Key Differences

The most obvious differentiation in between the Marsupial mammals vs. the Placental mammals is the presence of the pouch within the female Marsupials. Almost all the female Marsupial mammals have pouch on their belly and within them their young ones grow. In fact; the Marsupial mammals are also termed as the pouched mammals as well.

The most obvious difference between a Marsupial and the Placental mammals is the presence of the pouch within the female Marsuipals mammals which is absent in the others.

On the other hand; not a single placental mammal either a male or a female has any pouch on its belly. This differentiation seems to be a good one as far as the females are concerned but what about the males? Pouches are absent within the male Marsupials, therefore; the Marsupial males can't be differentiated with the Placental mammals on the basis of the pouch.

Female Marsupials
Pouch Female Placental Mammals
No Pouch Male Marsupials
No Pouch

Scientifically; the paleontologists and biologists categorize the mammals in a very unique way. They analyze the skull or mouth of the mammals and specifically look into the teeth arrangement (premolars and molars) and categorize the mammals accordingly. The Marsupial mammals have three pre-molars and four molars while on the other hand, the Placental mammals have four pre-molars and three molars.

Marsupial mammals have 3 pre-molars and 4 molars while the Placental mammals have 4 pre-molars and 3 molars.

Furthermore; the first 2 of the 3 pre-molars within the Marsupials are non-replacing (not the milk molars). This is one of the best and professional method to differentiate a Marsupial mammal from a Placental mammal.

Marsupial Mammals
3 Premolars & 4 Molars Placental Mammals
4 Premolars & 3 Molars

Similarly; within the skull there lies another key differentiation in between the Marsupial and the Placental mammals and that is the cranial volume or the size of the brain. The cranial volume within the Marsupial mammals is much smaller than the cranial volume within the Placental mammals.

The Marsupial mammals have a smaller cranial volume as compared to the Placental mammals. Koalas have one of the smallest brains amongst all the Marsupials.

Having a much smaller cranial volume also means a smaller brain and consequently; the brain of the Marsupial mammals is even smaller than the brain of the Placental mammals. This brain size is always measured in proportion to the body size as well. Koalas have one of the smallest brains amongst the Marsupial mammals as its brain is much smaller in proportion to its body size.

Marsupial Mammals
Smaller Brain Placental Mammals
Bigger Brain Koalas
Smallest Brain

Marsupial mammals can also be differentiated from the Placental mammals on the basis of their reproductive system as well. Surprisingly; the Marsupial males have 2 penises and the Marsupial females have 3 vaginas. Two vaginas serve as the entry of the sperms while the third one serves as a travel passage for the neonate (newborn) at the time of the birth.

Marsupial mammals are different from the Placental mammals on the basis of their reproductive systems. They also have a very small gestation period (few weeks).

Furthermore; the female Marsupials also have twin oviducts and uteri as well. On the other hand; the placental mammals have a single penis (males) and single vagina (females). Another key difference also lies within the gestation period of the Marsupial mammals which is very brief i.e., 12 to 35 days while majority of the Placental mammals have a gestation period in months.

Marsupial Mammals
2 Penises (Males) & 3 Vaginas (Females) Placental Mammals
1 Penis (Males) & 1 Vagina (Females) Marsupial Mammals
Small Gestation Period

One of the obvious physical features within the Marsupial mammals is the presence of the claws and the absence of the hooves or fins etc. Not even a single Marsupial mammal has hooves while the Placental mammals can also be categorized on the basis of their hands, hooves, claws and even fins etc.

All the Marsupial mammals have claws while the Placental mammals are also categorized on the basis of their hands, hooves, claws and even fins etc.

No such categories exists within the Marsupial mammals because the pattern of their claws is almost the same. Furthermore; claws are required by all the baby marsupials at the time of their birth as they have to make a journey from the uterus straight to the pouch. Therefore; they can't afford to have hooves or fins etc.

Marsupial Mammals
Only Claws Placental Mammals
Either have Claws or Hooves or Fins or Paws etc.

Marsupial mammals can also be differentiated with the Placental mammals on the basis of their babies' sizes and their body development. The sizes of even bigger Marsupial mammal babies such as the kangaroos and the koalas at the time of birth are not even more than the size of a jelly bean. Furthermore; the Marsupial babies are born prematurely and their bodies are not fully developed.

The Marsupial mammal babies are very small and under-developed at the time of birth while the Placental mammal babies are relatively bigger and have all the basic body development.

On the other hand; the babies of the Placental mammals have all the basic physical development at the time of their birth and their sizes are relatively larger. Furthermore; the growth rate of the Placental mammals' babies is also faster than the growth rate of the Marsupial mammal babies who only have to rely for mother's milk for even their basic body development.

Marsupial Mammals
Small & Under-Developed Babies Placental Mammals
Fully Developed Babies

Both Marsupial mammals and the Placental mammals have specific names for their newborn and young babies. In the case of the Marsupials, only one name is used to state their babies i.e., the joeys. For example a koala joey and a kangaroo joey etc.

All baby marsupial mammals are called joeys while the baby placental mammals are categorized as cubs, pups, kittens, fawns, foals and calves etc.

On the other hand; the babies of the Placental mammals have great variety of names depending upon the classification of the animal i.e., cubs, pups, kittens, fawns, foals and calves etc. Therefore; both Marsupial and Placental mammals can be differentiated on the basis of their names.

Most of the Marsupial mammals are only found in Australia, South American and North America. On the other hand; the Placental mammals can be found in Asia, Europe, Africa, South America and North America. Today the Placental mammals have more classifications as compared to the Marsupial mammals.

Today out of 5500 classified mammals, about 95 percent of them are classified as Placental mammals while less than 5 percent of them are the Marsupial mammals.

It is estimated that out of 5500 discovered mammals less than 5 percent are classified as the Marsupial mammals while 95% of them are the Placental mammals. Therefore; the placental mammals are most dominant mammals on earth as compared to the Marsupial mammals.

Marsupial Mammals
Australia, South America & North America Placental Mammals
Asia, Africa, South America, Europe and North America

Lastly; the Marsupial mammals are also considered as the inferior and less competitive mammals as compared to the Placental mammals. Furthermore; the Marsupials are also not as much cunning as the Placental mammals. It is speculated that the Marsupial mammals in any competition with the Placental mammals may not be able to thrive in a given territory.

Marsupial mammals are considered inferior and less competitive when compared to the Placental mammals.

The examples from North and South American continents are the key in this regard, where; only a handful of Marsupial mammals are left and their existence is overtaken by the Placental mammals. Similarly; it is also believed that in Australia the intervention of the rabbits, sheep and rats etc. have dented the thriving lifestyle of the Marsupials as well.

Marsupial Mammals
Inferior & Less Competitive Placental Mammals
Intelligent & Competitive