In this article, we’ll be discussing about the taxonomical classification of kangaroos of the modern world. You’ll also be learning about the three distinctive clades that all living mammals are classified into.
Are kangaroos rodents?
Kangaroos may look like the upgraded versions of rodents, but these two aren’t directly related to one another whatsoever.
Both kangaroos and the various species of rodents are broadly classified under the animal group ‘Mammalia’, but they each represent a different clade within this broad group.
Kangaroos belong to the marsupial clade whereas rodents belong to the placental clade. Keep reading to find out the differences between these two groups.
The three extant clades of mammals
Earlier on, we made mention of placental and marsupials as the active members of the Mammalian class, but there’s a third addition to this tally known as monotremes. These set of animals are more distantly related to the other two members than the two members are to themselves.
The monotreme mammals form the only members of the much broader group called prototheria, whereas theria is the general group used to classify placentals and marsupials. Note that you may not find the Prototheria and Eutheria system of classification used in some literatures or textbooks because it’s validity is still debated by many scientists.
Expounding a bit further, placental mammals are themselves alternatively called eutherians, whereas marsupials are referred to as metatherians. The former translates into the greek language as “other beasts” whereas the latter translates as “true beasts”
The breakdown of mammals into these three distinctive clades (or sub-class) is recognized popularly on the basis of reproductive anatomy and pattern, but other distinct peculiarities also exist to differentiate members of one clade from the other.
By the way, just think clade as group of animals that share one common ancestor. The characteristic feature they all inherit from this common ancestor is the basis for grouping them under one clade.
Generally, mammals are members of the mammalia class characterized by having these peculiar traits among a few prominent others:
- a pair of specialized sweat glands called mammary glands that function to produce milk (in females and rarely in males) for nursing their offspring,
- a neocortex region of the brain responsible for perception and cognition (among many other functions),
- Body hairs at any lifecycle stage,
- and three bones in their middle ears.
Placental mammals on the other hand are a sub class of mammals that give birth to a fully developed young after a relatively long period of gestation (about 9 months to 2 years, depending on the species).
Placental mammals have well-developed placenta that attaches to the embryo growing in their womb and nourishes it throughout the period of gestation. The placenta also performs protection and immunity functions for the embryo.
Examples of animals that belong to this group include: Rodents, humans, bats, elephants, felids etc.
Marsupials are mammals that give birth to their young ones at a very immature state (resembling the larval state) after a relatively short period of gestation (around 8 to 43 days depending on the species).
The young are born super tiny, weighing only less than one percent of the entire body weight of their mothers, and their internal organs and external morphological features have only barely begun forming.
The near exception to this is usually their forelimbs and facial strictures which have become fairly-well developed within this timeframe because they are required for locomotion from the mothers reproductive canal unto a pouch located on her body for further development.
This age of such neonate is equivalent to that of a 5 week old human baby, who at that stage of development are extremely immature and helpless to survive being birthed let alone be able to crawl their way out of their mothers reproductive canal to the external environment.
The altricial young when born, emerge from their mothers reproductive canal and crawl through her thick body all the way into her pouch or pouch-like structure located on her abdomen or underside.
Once in the pouch, the young fasten onto one of the teats (or nipples) located therein and begin suckling until they grow and develop into precocial individuals and are able to survive outside the pouch. This takes any where from 8 moths to about a year.
Example of marsupial mammals include: Kangaroos, opossums, wombats, Tasmanian devil etc.
Unlike placental and marsupial mammals, monotermes do not give birth to their young ones alive. They lay eggs, which is outside nor for most mammal, and the young ones hatch with the aid of their embryonic milk tooth around ten days or so.
When they emerge from their shells, they suckle milk from their mother’s teats for up to six months or until they fully develop. Suckling dosent seem like the appropirate word since the milk squirst for the mothers teats and the yougg try as much as possible to catch the falling droplets.
Some species protect their young in a temporary pouch on the mothers body, while others nurture their young at their hatching sites.
The eggs that monotermes lay are soft shelled and short lived, spanning about 13 -15 mm in diameter, and are usually placed in the mothers pouch. Eggs are incubated outside of the mothers body, just like it happens in reptiles and birds.
Examples of monotreme mammals (or better still, the only two extant families include: Echidnas and platypus
The Rodent Group
The group Rodetia is an order under the class mammalia that consist of mammals having pairs of continuously growing incisors on each of their upper an lower jaws.
The name of the group is also a reflection (to some extent) of this characteristcs, with rodentia meaning “to gnaw” and the mammals are popular for their abilities to gnaw and loosen tough materials like wood and concrete using their pair of incisors.
NB: If you don’t have first hand knowledge about taxonomical classification, and thus aren’t familier with the terms ‘class’, ‘order’ or even ‘species’, you can read our simple and easy to understand guide below to get a general overview.
Now back to the main discussion. Members of the Rodentia order form nearly half of the mammalian population and are found widespread across all landmasses with the exception of Antarctica.
They are also the most diverse mammalian order, (meaning they have different individual species), and are found in almost any type of habitat from terrestrial, including human made environments, arboreal, fossorial (burrows), to semi-aquatic environments.
Rodents as they are scientifically called have the following characteristics:
- Are small (measurement lies in the gram for most mammals).
- Are robust.
- Have long tails.
- Have short limbs.
- Are social.
- Give birth to many babies per litter and have a relatively short gestation compared to most other placentals.
- Are notable for being pests.
Example of rodents include: mice, rat, squirrel, chipmunk, beaver, hamster, guinea pig and porcupine.
Taxonomical classification showing the difference between kangaroos and rodents
|Group||Kangaroo (animal)||Rodents (group)|
More interesting kangaroo articles:
- Inside of a kangaroo pouch: What does a kangaroo pouch look like?
- Kangaroo Predators: What eats kangaroos?
- Baby Kangaroo: Everything you should know
Cite this Article ” (APA Format)
Bunu. M. (2020, April 26). Are kangaroos rodents?. Retrieved from http://emborawild.com/are-kangaroos-rodents/