Dasyuromorphiadasyuroid marsupials and marsupial carnivores

Diversity

The order Dasyuromorphia includes 23 genera and 71 species of carnivorous marsupials in three families: Dasyuridae (dasyurids), Myrmecobiidae (numbats), and Thylacinidae (thylacinids). Both Myrmecobiidae and Thylacinidae contain a single recent species, while Dasyuridae contains many species. The single species within Thylacinidae (Tasmanian wolf) is likely extinct. Dasyurids and thylacinids are more related to each other than they are to numbats.

In Australia, the oldest known members of the order Dasyuromorphia originated from south Queensland at least 55 million years ago. However, little is known about their evolution between the late Paleocene (55 mya) and the late Oligocene (about 24 mya). Fossil records are abundant from the early Miocene (23 to 16 mya), as the warm and wet greenhouse period resulted in high levels of diversity in rainforest communities. As rainfall decreased around 15 mya and Australia became cooler and drier, there was a steady and rapid increase in diversity of dasyuromorphs. Thereafter, with the arrival of humans and increased aridity, family-level diversity declined to the present level. (Flannery, 1995; Nowak, 1999; Strahan, 1995; Armati, et al., 2006; Flannery, 1995; Jones, et al., 2003; Nowak, 1999; Strahan, 1995; Wilson and Reeder, 2005)

Geographic Range

The order Dasyuromorphia is restricted to Australia, New Guinea, Tasmania, and some small nearby islands. During the Pleistocene era, land bridges connected the Australian mainland to New Guinea and Tasmania, allowing the exchange of faunas between these land masses. Modern distributions and genetic relationships of particular species serve as evidence of the interchange of fauna during this era. Because the Pleistocene was characterized by cooler temperatures, savanna and woodland species primarily migrated across the land bridges. (Archer, 1982; Flannery, 1995; Jones, et al., 2003; Nowak, 1999; Strahan, 1995)

Habitat

Physical Description

  • Sexual Dimorphism
  • sexes alike
  • male larger

Reproduction

Both male and female dasyuromorphs practice promiscuous mating during a relatively short but intense breeding season. Larger males are more successful at attracting females and fighting off competing males. During courtship, males display antagonistic behavior in which they chase the female. During copulation, the male grips the female’s neck with his teeth and clasps her body with his forepaws to facilitate mounting. This continues throughout copulation, which lasts several hours. While copulating, males in the genus Antechinus can turn their bodies 180 degrees to ward off other males. After mating, males may guard a female for up to 12 hours to prevent other males from mating with her. Male Tasmanian devils are particularly aggressive during mate guarding and do not allow the female to leave her den for food or water for days. Occasionally females are able to escape these aggressive males but usually not without injury.

Females release pheromones to signal their receptivity to mate. They solicit males they find attractive and ward off other males. Females have long periods of behavioral estrous which allow them to mate with several males unless particularly aggressive males prohibit their ability to do so. Thus, multiple paternity as a result of sperm competition is often observed. For example, it is not uncommon for a litter of four Tasmanian devils to have four different fathers. Dasyurids (Dasyuridae) exhibit a unique form of sperm competition, and, other than bats, they are the only mammals in which females can store competing sperm within their reproductive tracts prior to ovulation. (Archer, et al., 2002; Archer, 1982; Flannery, 1995; Glen, et al., 2009; Jones, et al., 2003; Lee and Cockburn, 1985; Naylor, et al., 2008; Nowak, 1999; Strahan, 1995; Tyndale-Biscoe, 1973; Tyndale-Biscoe, 1987)

Dasyuromorphs are either semelparous or iteroparous. Semelparity is very rare in mammals, having arisen only in dasyurids and didelphids. Semelparous dasyuromorphs, such as antechinuses, generally live in environments with predictable seasonal patterns of food abundance. It is thus advantageous to align reproductive patterns with seasonal variation in resource abundance. The mating season occurs in the winter when resources are scarce, and consequently young are born when resources are most abundant. Because seasonal patterns are so predictable, it not risky to dedicate all of their reproductive efforts into one brief mating season.

Males devote most of their energy to one big reproductive effort, and as a result have high concentrations of stress hormones in their blood. This inhibits inflammatory and immune responses and eventually kills the exhausted males. Females may survive for a second breeding season but almost never survive for a third. Semelparous dasyuromorphs are characterized by prolonged copulation, large testes size, male sexual dimorphism, mate guarding, long behavioral estrous of females, sperm storage in female reproductive tracts, high population densities, and sperm competition.

Iteroparous dasyuromorphs, on the other hand, reside in less restricted, less predictable environments. Therefore, it is risky to invest all of their energy into one reproductive effort when resource levels are so unpredictable. During the breeding season, Northern quolls exhibit normal levels of stress hormones and have larger body sizes and tail fat stores that help them survive to the next breeding season. Iteroparous dasyuromorphs do not display any of the identifying characteristics of semelparous dasyuromorphs. Additional reasons for semelparity in some species and iteroparity in others are not well understood. (Flannery, 1995; Strahan, 1995; Flannery, 1995; Strahan, 1995; Archer, 1982; Flannery, 1995; Jones, et al., 2003; Strahan, 1995)

After the brief mating season, male dasyuromorphs leave females with all parental responsibilities. In semelparous species, such as antechinuses, males die before their offspring are born.

Gestation time varies greatly with body size, as does time spent in the mother's pouch. After leaving the pouch permanently, young are carried into well-hidden dens. Dens are lined with vegetation for protection and warmth and are located in underground burrows, caves or hollow logs. As young near weaning, mothers take more frequent trips outside of the den. When mothers begin to sleep away from their young, male offspring disperse from the den. Males move away from their mother's home range while females remain in their mother’s home range for life.

During lactation, many dasyuromorph mothers are biased towards their male offspring and provide them with more nutrient-rich milk. Because larger males are more successful in attracting mates and reproducing, it is advantageous for mothers produce larger males that have a better chances of passing on her genes. (Archer, 1982; Flannery, 1995; Jones, et al., 2003; Strahan, 1995)

  • Parental Investment
  • altricial
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female
  • post-independence association with parents
  • inherits maternal/paternal territory

Lifespan/Longevity

The lifespan of dasyuromorphs varies greatly among the three families. Male numbats live up to 5 or 6 years in captivity, while females generally live longer. Little is known about Tasmanian wolves in the wild, and no information about their lifespan was recorded while they were still abundant. In captivity, however, they lived up to 12 years.

The lifespan of dasyurids is related to the amount of energy invested in early reproduction. Semelparous species, such as those in the genera Antechinus and Sminthopsis, invest heavily in one reproductive event and usually only live 1 to 2 years. Iteroparous species of dasyurids do not invest as much in early reproduction and live longer lives. For example, Tasmanian devils (iteroparous dasyurids) live an average of 8 years in the wild. (Archer, 1982; Flannery, 1995; Jones, et al., 2003; McAllan, 2006; Nowak, 1999; Strahan, 1995)

Although small dasyurids appear short lived, they actually have long lifespans compared to similarly sized eutherians. Whereas small dasyurids live 1 to 2 years, mice live only 4 to 6 months. The reasons behind these differences are still unknown but appear to be related to differences in metatherian and eutherian physiology. (McAllan, 2006)

Behavior

Dasyuromorphs are nocturnal or crepuscular but occasionally forage or bask during the daytime. They exhibit long-range movements and often shift home ranges. Most species of dasyuromorphs are solitary and typically only form small groups while mating or rearing young. They build burrows and nests, which they add to during pregnancy and as young develop. Some species groom themselves, especially after feeding, which involves washing the face, snout, nape of the neck, throat and chin with licked forepaws.Dasyurids (Dasyuridae) use their forepaws not only to catch and eat prey but also in tactile social interactions where they grasp and pull one another.

To cope with unpredictably fluctuating food supplies, dasyuromorphs utilize a variety of strategies to conserve body heat and reduce energy expenditures. One strategy involves lowering metabolic rates when resources are particularly scarce. Because dasyuromorphs cannot sweat, they lick and pant to keep cool. Because of the diverse habitats in which they live, strategies to conserve body heat and reduce energy loss vary greatly. Strategies include having a spherical body shape to maximize heat conservation, increasing fur thickness in the winter, living in protected hollows during the day to avoid the heat, lining nests with leaves, and huddling in groups. (Archer, 1982; Flannery, 1995; Jones, et al., 2003; Nowak, 1999; Strahan, 1995; Tyndale-Biscoe, 1973)

Communication and Perception

Due to their nocturnal habits, dasyuromorphs have reduced their dependence on sight for communication and perception and have adapted olfactory and auditory mechanisms to compensate. Dasyuromorphs utilize chemical signals such as scent markers as a primary mode of communication. Commonly used chemical signals include urine dribble, cloacal drag, chin rub, and sternal rub. These are used to mark territory or as a status signal during breeding. Other social behaviors, such as mouth sniffing, naso-nasal sniffing, touching, and cloacal sniffing have been observed. Cloacal sniffing is especially important in male-female interactions.

Auditory communication is also common in dasyuromorphs. Vocalizations are mostly associated with defensive situations, such as nest defense, food defense, and threats but are also used in parent-offspring interactions as well as courtship and mating. Dasyuromorphs emit a chatter, tail rattle, foot tap, huff, or bark as an alarm mechanism when they feel threatened or in danger. Defensive vocalizations include hisses, huffs, grunts, growls and screams. When separated from their mother, young dasyuromorphs produce vocalizations that trigger mother retrieval behavior.

Dasyuromorphs also possess vibrissae that orient their attacks during predation. Males use tactile communication during mounting and copulation by grasping the neck and abdomen of the female. (Archer, 1982; Flannery, 1995; Jones, et al., 2003; Nowak, 1999; Strahan, 1995; Tyndale-Biscoe, 1973)

Food Habits

Dasyuomorphs are generalized predators that eat a wide range of invertebrate and vertebrate prey. Numbats are insectivorous, and one individual can consume 10,000 to 20,000 termites each day. Other families within Dasyuromorphia are carnivorous. They catch and eat both terrestrial and arboreal insects, including moths, beetles, and mosquitoes. Large species are also known to eat juvenile mice.

Vision and olfaction play key roles in hunting. Most dasyuromorph species possess vibrissae that help orient their attack toward prey; however, visual and tactile methods are also employed. Carnivorous marsupials bite or pin their prey with their forepaws. Bites are directed toward the anterior part of the body (head or neck) in order to assure capture. They are also known to shake and toss prey if they show resistance. (Archer, et al., 2002; Archer, 1982; Flannery, 1995; Jones, et al., 2003; Nowak, 1999; Strahan, 1995)

Predation

Dasyuromorph are vulnerable to reptilian, avian, and mammalian predators. They do not have any physical adaptations to deter predators and thus tend to minimize predation by foraging at night and under protective covering. Small dasyuromorphs are particularly vulnerable to introduced European red foxes. Domestic dogs, dingos, and domestic cats also prey upon dasyuromorphs. (Archer, et al., 2002; Flannery, 1995; Nowak, 1999; Strahan, 1995; Archer, et al., 2002; Flannery, 1995; Nowak, 1999; Strahan, 1995; Archer, et al., 2002; Flannery, 1995; Nowak, 1999; Strahan, 1995; Archer, et al., 2002; Archer, 1982; Flannery, 1995; Jones, et al., 2003; Nowak, 1999; Strahan, 1995)

Ecosystem Roles

Before placental carnivores were introduced to Australia, New Guinea, and Tasmania, dasyuromorphs were the most prominent large predators. They still remain key predators, consuming a wide range of vertebrate and invertebrate prey. Numbats maintain stable termite populations by consuming an average of 10,000 to 20,000 individuals a day.

Dasyuromorphs coexist with other species in the order by partitioning resources in the structurally complex arid and forest environments. In the desert, dasyuromorphs forage above ground on clay soils, sand dunes, rocks, and grasslands. In the temperate and tropical forests, dasyuromorphs may be arboreal as well as terrestrial, searching for prey in the trees. Terrestrial dasyuromorphs search for food a few feet above the ground in shrubs and hollow trees. Larger dasyuromorphs, such as eastern quolls and Tasmanian devils, avoid competitors by foraging primarily in the trees.

Because dasyuromorphs include such a diverse array of species, they take on numerous ecosystem roles. Their most influential role, however, is predatory. (Archer, 1982; Flannery, 1995; Haythornthwaite and Dickman, 2006; Hume, 1999; Nowak, 1999; Stonehouse and Gilmore, 1977; Strahan, 1995; Tyndale-Biscoe, 1973)

Economic Importance for Humans: Positive

Dasyuromorphs, like other marsupials, are held in great regard by the native Australian Aborigines. Cultural practices such as dreaming stories, myths, rituals and totems were devoted to dasyuromorphs, especially the larger species. Australian Aborigines have hunted many species of dasyuromorphs as a source of food for thousands of years. On their arrival, European settlers also hunted dasyuromorphs for food.

Some species of dasyuromorphs are beneficial because they deter agricultural and forest pests, insects, and rodents. Eastern quolls often live on farmland and aid farmers by consuming pasture grubs, mice, and insects that invade human crops. (Jones, et al., 2003; Kennedy, 1992; Nowak, 1999; Tyndale-Biscoe, 1973)

Economic Importance for Humans: Negative

Large dasyuromorphs have a reputation for killing livestock, such as sheep, but they rarely kill prey this large. However, domestic eastern quolls, Tasmanian devils, and phascolages often prey on domestic poultry. Because of this, farmers view these large dasyuromorphs as pests. Tasmanian wolves were large enough to successfully prey on sheep, and retaliation from angry farmers may have contributed to their extinction. (Archer, 1982; Jones, et al., 2003; Kennedy, 1992; Nowak, 1999; Tyndale-Biscoe, 1973)

Conservation Status

Dasyuromorphs did not cope well with the arrival of Europeans to Australia more than a century ago. On the IUCN red list, six species are listed as endangered, one species, Sminthopsis aitkeni, as critically endangered and one species, Tasmanian wolves, as extinct. Currently, the most prominent threat to dasyuromorphs is the rapidly expanding human population. Clearing land for agriculture, draining and salination of wetlands, and grazing by livestock both destroys and fragments habitat. Introduced placental carnivores like red foxes have decimated populations by preying on smaller dasyuromorphs and competing with larger ones. Additionally, climate change has resulted in drought and uncontrollable fire regimes that alter their habitat. Because they rely on a large number of omnivorous and herbivorous prey to survive, dasyuromorphs are vulnerable to small changes in their habitat.

If habitat destruction and fragmentation continues, other dasyuromorph species may face the same fate as Tasmanian wolves, the only large carnivores to go extinct in recent times. The last confirmed sighting of a Tasmanian wolf in the wild was in 1930, and in 1936 the last captive animal died. There are claims of recent sightings and tracks of Tasmanian wolves, but proof of their continued existence is lacking.

Today, efforts are being made to remove rabbit populations from known dasyuromorph habitats. Rabbits not only damage the habitat of dasyuromorphs but also attract predators like dingos and red foxes. In the 1800s, a government bounty led to the death of over 2,000 Tasmanian wolves because of their predation on sheep and other livestock. Today, nearly all dasyuromorphs are protected from hunting and over-harvesting under the laws of the states and territories of Australia. (Archer, 1982; IUCN, 2008; Jones, et al., 2003; Kennedy, 1992; Lee and Cockburn, 1985; Nowak, 1999; Stonehouse and Gilmore, 1977; Tyndale-Biscoe, 1973)

  • IUCN Red List [Link]
    Not Evaluated

Contributors

Nicole Armbruster Chad Nihranz and Elizabeth Colvin (author), University of Michigan-Ann Arbor, Gail McCormick (editor), Animal Diversity Web Staff.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

delayed fertilization

a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scavenger

an animal that mainly eats dead animals

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

semelparous

offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

sperm-storing

mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

2008. "Carnivorous marsupials" (On-line). Parks and Wildlife Service: Tasmania. Accessed March 04, 2009 at http://www.parks.tas.gov.au/index.aspx?base=4803.

Aitkin, L. 1998. Hearing - the Brain and Auditory Communication in Marsupials. Berlin: Springer.

Aplin, K., M. Archer. 1987. Recent advances in marsupial systematics with a new syncretic classification. Pp. xv-lxxii in M Archer, ed. Possums and Opossums: Studies in Evolution, Vol. I. Chipping Norton: Surrey Beatty and Sons PTY Limited.

Archer, M., T. Flannery, S. Hand, J. Long. 2002. Prehistoric Mammals of Australia and New Guinea: One Hundred Million Years of Evolution. Sydney: UNSW Press.

Archer, M. 1982. Carnivorous Marsupials. Chipping Norton, Australia: Surrey Beatty & Sons Pty. Limited.

Armati, P., C. Dickman, I. Hume. 2006. Marsupials. Cambridge, United Kingdom: Cambridge University Press.

Collins, L. 1973. Monotremes and Marcupials. Washington DC, USA: Smithsonian Institution Press.

Feldhamer, G., L. Drickamer, S. Vessey, J. Merritt. 1999. Mammalogy. Adaptation, Diversity, and Ecology. Boston: WCB McGraw-Hill.

Firestone, K., B. Houlden, W. Sherwin, E. Geffen. 2000. Variability and differentiation of microsatellites in the genus Dasyurus and conservation implications for the large Australian carnivorous marsupials. Conservation Genetics, 1: 115-133.

Flannery, T. 1995. Mammals of New Guinea. Sydney: Reed Books.

Glen, A., M. Cardoso, C. Dickman, K. Firestone. 2009. Who's your daddy? Paternity testing reveals promiscuity and multiple paternity in the carnivorous marsupial Dasyurus maculatus (Marsupialia: Dasyuridae). Biological Journal of the Linnean Society, 96: 1-7.

Haythornthwaite, A., C. Dickman. 2006. Distribution, abundance, and individual strategies: a multi-scale analysis of dasyurid marsupials in arid central Australia. Ecography, 29: 285-300.

Hume, I. 1999. Marsupial Nutrition. United Kingdom: Cambridge University Press.

IUCN, 2008. "IUCN Red List of Threatened Species Version 2008.2" (On-line). Accessed March 10, 2009 at http://iucnredlist.org/.

Jones, M., A. Cockburn, R. Hamede, C. Hawkins, H. Hesterman, S. Lachish, D. Mann, H. McCallum, D. Pemberton. 2008. Life-history change in disease-ravaged Tasmanian devil populations. PNAS, 105: 10023-100127.

Jones, M., C. Dickman, M. Archer. 2003. Predators with Pouches: The Biology of Carnivorous Marsupials. Collingwood, Australia: CSIRO Publishing.

Kennedy, M. 1992. Australian Marsupials and Monotremes: An Action Plan for their Conservation. Gland, Switzerland: IUCN.

Lee, A., A. Cockburn. 1985. Evolutionary Ecology of Maruspials. Great Britain: Cambridge University Press.

McAllan, B. 2006. Dasyurid marsupials as models for the physiology of ageing in humans. Australian Journal of Zoology, 54: 159-172.

Naylor, R., S. Richardson, B. McAllan. 2008. Boom and bust: a review of the physiology of the marsupial genus Antechinus. Journal of Comparative Physiology B, 178(5): 545-562.

Nowak, R. 1999. Walker's Mammals of the World - Sixth Edition. Baltimore, Maryland: The John Hopkins University Press. Accessed March 10, 2009 at http://books.google.com/books?id=T37sFCl43E8C&pg=PA41&lpg=PA41&dq=didactylous+%2Bdasyuromorphia&source=bl&ots=rkxh_-VTNW&sig=6_BhPT7PKq7WTTzz6zJDFB0iHJs&hl=en&ei=c7O3SYmPJ53uNK76oOkK&sa=X&oi=book_result&resnum=1&ct=result#PPP1,M1.

Soderquist, T. 1995. Ontogeny of Sexual Dimorphism in Size among Polytocous Mammals: Tests of Two Carnivorous Marsupials. Journal of Mammalogy, 76(2): 376-390. Accessed April 10, 2009 at http://www.jstor.org/stable/1382349.

Stonehouse, B., D. Gilmore. 1977. The Biology of Marsupials. Baltimore, Maryland: University Park Press.

Strahan, R. 1995. The Mammals of Australia. Sydney: Reed Books.

Szalay, F. 1994. Evolutionary History of the Marsupials and an Analysis of Osteological Characters. Cambridge, UK: Press Syndicate of the University of Cambridge.

Taggart, D., W. Foster. 2008. Gender and parental influences on the growth of a sexually dimorphic carnivorous marsupial. Jouranl of Zoology, 275: 221-228.

Taylor, J. 1984. The Oxford Guide to Mammals of Australia. New York: Oxford University Press.

Thomas, O. 1888. Catalogue of the Marsupialia and Monotremata. London, England: Taylor and Francis.

Tyndale-Biscoe, H. 1973. Life of Marsupials. New York, New York: American Elsevier Publishing Company, Incoporated.

Tyndale-Biscoe, H. 1987. Reproductive Physiology of Marsupials. Great Britain: Cambridge University Press.

Vaughan, T., J. Ryan, N. Czaplewski. 2000. Mammalogy. Fourth Edition. Philadelphia: Saunders College Publishing.

Wilson, D., D. Reeder. 1993. Mammal Species of the World, A Taxonomic and Geographic Reference. 2nd edition. Washington: Smithsonian Institution Press.

Wilson, D., D. Reeder. 2005. Mammal Species of the World. New York: JHU Press.