KANGAROOS, WALLABIES, AND TREE KANGAROOS

Their higher classification is:

Class Mammalia

Infraclass Marsupialia (the pouched mammals)

Order Diprotodontia

 Family Macropodidae (macropods = kangaroos, wallabies,  

        and tree kangaroos) 

                    

There are several genera and many species within the macropods.

[note: The word macropod literally “means bigfoot.”]

KANGAROOS:

The word “kangaroo” is usually reserved for larger members of macropods. Kangaroos are also called “roos,” and their post-birth young, that live in the mothers’ pouch, are called “Joey’s.” 

The ancestors of kangaroos were tree-dwelling opossum-like animals that lived during middle Miocene time. These earliest species had tiny size, primitive features (probably quadrapedal, probably a bounding gait, and lived in rainforests). By late Miocene time, kangaroos appeared. They increased greatly in diversity during the much drier times during the Pliocene and early Pleistocene, and they eventually developed the true bipedal hop. 

The largest known kangaroo, Procoptodon golidath appeared during the Pleistocene. As shown in the figure below, it was a bipedal grazer, with a short face and a single functioning hind toe.

Procoptodon golidath, up to 6.5 feet tall and as much as 530 pounds. Image modified from Savage and Long (1986: p. 189).

Modern kangaroos have large, powerful hind legs, a long tail for balance, and a relatively small head. Today there are four living species of kangaroos assigned to genus Macropus. They include M. rufus (the "red" kangaroo); M. giganteus (the “eastern gray" kangaroo), M. fuliginosus (the “western gray” kangaroo), and M. antilopinus (the antilopine kangaroo [also gray in color].” For images of each of these species, see <worldatlas.com/articles/how-many-species-of-kangaroos-are there.html> 

Kangaroos live mostly on dry plains, where they eat grasses. Australian kangaroos are strict vegetarians. The larger species are the Australian equivalents of large browsing and grazing animals like antelope, buffalo, deer) found on other continents. 

 

Kangaroos have no lower canine their teeth, and upper canines are usually also absent. As a result of their diet, kangaroos have specialized molars, which are unusually curved and high-crowned. Their molars grind down fast (because of the hard silica content of the grass) and are unusual, in that they actually move forward before falling out and replaced by new teeth growing in the back of the jaws. This process is called polyphyodonty, and only occurs in hyraxes, elephants, manatees, and kangaroos!

“Western-gray kangaroo,” Yanchep National Park, north of the city of Perth (see the Google Image near the end of this blog post), in Western Australia. Image kindly donated by Matt Ventimiglia, 2023. This park is a bushland and wetland that harbors kangaroos and rich birdlife.

WALLABIES:

A wallabie is a small to medium-sized (less than 45 pounds) kangaroo, ranging from rabbit size to less than about 3 feet tall). Also compared to larger-sized kangaroos (which can weight up to 200 pounds and up to 8 feet tall), wallabies have much shorter legs and greater color variation in their fur. Wallabies are fast runners and can jump quite high. Their teeth are flatter with lower crowns than those of larger kangararoos.

There are several genera, and they live in the wild in Australia and New Guinea. 

A 13-pound “Yellow-footed Rock Wallaby,” living at the Living Zoo in Palm Desert, Riverside County, southern California. This animal belongs to genus Petrogale. Image courtesy of C. and K., 2023.

In the wild. in Queensland of South Australia, wallabies are considered as “near threatened.” Thus, zoos throughout the world are sheltering these animals in order to help preserve them. 

“TREE KANGAROOS”:

Tree-dwelling (aboreal) small-sized (up to 30 inches long and up to 20 pounds) kangaroos belonging to genus Dendrolagus live only in a small area in extreme northeastern Australia and in relatively large areas on an island comprised of both the countries of Papua and New Guinea, immediately north of Australia.

Google Earth image (2004). 

The common name “tree kangaroos” is commonly used for at least eight living species of them. They are slow-moving animals but are great leapers. They live in trees, mostly in the montane tropical-rain forests. They have very thick coats of fur, which can have multi-colored)  areas. They also have a sponge-like grip on their paws and soles of their feet. Their front and hind limbs are muscular with curved, long, and very sharp claws for climbing trees. Also, their hind feet have rather long pads. It is interesting that tree kangaroos never back down trees head first, unlike what opossums do. However, tree-kangaroos do not eat grass, instead their diet consists of berries, roots, and insects and other invertebrates (Lawlor, 1979). Most of the “Golden-mantled tree kangaroos” are the most threatened of all marsupials because of habitat destruction and uncontrolled hunting (Wikipedia, 2023). Dendrolagus has a geologic time range of Pliocene to recent (Prideaux and Warburton, 2023).

An example of a tree kangaroo: the Goodfellow’s tree kangaroo (Dendrolagus goodfellowi) (this sketch by the author was based on a Wikipedia, 2023) image). 

Modern-day tree kangaroosThey are about 16 pounds in weight and up to three feet long. They live in rainforests, from sea level to 10,000 feet in elevation, only on the island of New Guinea, just north of Australia. They live up to 23 years in captivity (Animal Diversity Website, 2023).

References Consulted:

Animaldiversity.org/accounts/Dendrolagus_goodfellowi/2023

en.Wikipedia. 2023.

Prideaux and Warburton. 2023. A review of the late Cenozoic genus Bohra (Diprotodontia: Macropodidae) and the evolution of tree-kangaroos. Zootaxa, June, 2023:1–95 (pdf not free).

 

Savage, A.J.G. and M.R. Long (1986). Mammal evolution. British Museum (Natural History), 259 pp. 

worldatlas.com/articles/how-many-species-of-kangaroos-are-there.