Quokka Evolution and Ancestry

Embryology

Can control the composition of their milk to control growth within the pouch.

Marsupials have dual reproductive glands in order to have dual pregnancies.

• One embryo remains in a dormant state while another grows after a certain amount of development.
• After the first is "born" and fully developed, a gestation period of 30 days continues with the second embryo.
• This results from early Eutherian mammals evolving and splitting their reproductive organs to create the current marsupial.
• Quokkas have three "vaginas", one being a birth canal, the other two leading to the dual ovaries.

QUOKKA

Pronounced: "Kwo-ka" or "Kwah-ka"

*Eutherian mammals are basic placental mammals, such as humans and their ancestors.

The Quokka

Phylogenic Order

Kingdom Animalia

Phylum Chordata

Class Mammalia

Infraclass Marsupialia

Order Diprotodontia

Family Macropodidae

Subfamily Macropodinae

Genus Setonix

Species Brachyurus

Population ranging from 8,000 to 12,000

Citations

Web citations by Citation Machine

"Quokka Videos, Photos and Facts." - Setonix Brachyurus. Web. 25 May 2015.

"Quokka." (Setonix Brachyurus). Web. 25 May 2015.

By Jennifer S. Holland, National Geographic PUBLISHED March 06, 2015. "Quokka Selfies: What's the Deal With That Cute Australian Critter?" National Geographic. National Geographic Society. Web. 25 May 2015.

"Quokka Facts | Quokkas | Australian Marsupials." Animal Fact Guide. Web. 25 May 2015.

Comparative Anatomy and DNA

Marsupials are characterized by their teeth; they have a total of 50, as opposed to the placental mammal total of 46.

Other similar traits include:

• Lack of an ear bulla
• Cheek bones meet the jaw joint
• General tooth formula
• Lacrimal visible from the side
• Wide nasal bones
• Holes in palatal bones

Metatherian Fossil (ancestor of marsupials) vs Teeth of Kangaroo

Compared to placentals, marcupials are born underdeveloped and not yet capable of independant life.

Evolution

Metatherian animals were very early ancestors of marsupials. Early Metatherian fossils were found in China suggesting they lived there about 125 million years ago. Pangaea then split which started isolated evolutions. Since, their descendants migrated to Australia. These findings support that marsupials diverged from placental mammals about 90 million years ago.

The quokka was first discovered in Australia in 1697 when it was mistaken for a cat-sized rat.

A Day In The Life

Quokka's specifically live in Rottnest Island near Perth, which is right off the coat of Australia.

The quokka prefers dense vegetation, yet they survive in large numbers in the arid conditions of Rottnest Island.

Quokka's have adapted claws to protect themselves from larger animals.

The quokka control the amount of vegetation, and are a food source for predators.

The Quokka population is clumped and restricted to Southwest Australia.

Biotic and Abiotic Factors of Rottnest Island

• The abundance of shrubs protect the quokka from heat and a variety of different animals.
• The salinity of the water determines how much the quokka can stock up on water, because fresh water is only available on the island for a few months out of the year.
• The light intensity determines the variety of plants that the quokka eats and drinks from.
• The presence of predators determines how safe the quokka is.

Quokkas eat grass, and dingos or foxes eat the quokka. Lions then eat the quokka's predators.