Wikipedia

Macropodidae

Not to be confused withMacropodiaorMacropodinae.

Macropodidaeis afamilyofmarsupialsthat includeskangaroos,wallabies,tree-kangaroos,wallaroos,pademelons,quokkas,and several other groups. These genera are allied to the suborderMacropodiformes,containing other macropods, and are native to theAustralian continent(the mainland and Tasmania),New Guineaand nearby islands.[2]

Macropods[1]
Temporal range:28–0MaLateOligoceneto recent
A youngred-necked wallaby
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Marsupialia
Order: Diprotodontia
Suborder: Macropodiformes
Family: Macropodidae
Gray,1821
Type genus
Macropus
Shaw,1790
Genera

Description

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ABennett's wallabyskull

Althoughomnivorous kangarooslived in the past, these were not members of the family Macropodidae; modern macropods are generallyherbivorous.Some arebrowsers,but most aregrazersand are equipped with appropriately specialised teeth for cropping and grinding up fibrous plants, in particulargrassesandsedges.Modern omnivorous kangaroos generally belong to a different family (for example, theMusky rat-kangaroo). In general, macropods have a broad, straight row of cutting teeth at the front of the mouth, nocanineteeth, and a gap before themolars.The molars are large and, unusually, do not appear all at once but a pair at a time at the back of the mouth as the animal ages, eventually becoming worn down by the tough, abrasive grasses and falling out. Like manyMacropodiformes,early kangaroos hadplagiaulacoids,but these converted into normal molars in more derived species.[3]Most species have four molars and, when the last pair is too worn to be of use, the animals starve to death.[4]Thedental formulafor macropods is3.0–1.2.41.0.2.4.

Like theeutherianruminantsof the Northern Hemisphere (sheep, cattle, and so on), macropods have specialised digestive systems that use a high concentration ofbacteria,protozoans, and fungi in the first chamber of a complex stomach to digest plant material. The details of organisation are quite different, but the result is somewhat similar.

The particular structure-function relationship of the Macropodidae gut and the gutmicrobiotaallows the degradation oflignocellulosicmaterial with a relatively low emission ofmethanerelative to other ruminants. These low emissions are partly explained by the anatomical differences between the macropodid digestive system and that of ruminants, resulting in shorter retention times of particulate digesta within the foregut. This fact might prevent the establishment of methanogenicarchaea,which has been found in low levels in tammar wallabies (Notamacropus eugenii) and eastern grey kangaroo (M. giganteus). Metagenomic analysis revealed that the foregut of tammar wallabies mainly contains bacteria belonging to the phylaBacillota,Bacteroidota,andPseudomonadota.Among Pseudomonadota populations of theSuccinivibrionaceaefamily are overrepresented and may contribute to lowmethane emissions.[5]

Macropods vary in size considerably, but most have very large hind legs and long, powerfully muscled tails. The termmacropodcomes from theGreekfor "large foot" and is appropriate: most have very long, narrow hind feet with a distinctive arrangement of toes. The fourth toe is very large and strong, the fifth toe moderately so; the second and third are fused; and the first toe is usually missing. Their short front legs have five separate digits. Some macropods have sevencarpal bonesinstead of the usual eight in mammals.[6]All have relatively small heads and most have large ears, except fortree-kangaroos,which must move quickly between closely spaced branches. Theyoungare born very small and thepouchopens forward.

The unusual development of the hind legs is optimised for economical long-distance travel at fairly high speed. The greatly elongated feet provide enormous leverage for the strong legs, but the famous kangaroo hop has more: kangaroos and wallabies have a unique ability to store elastic strain energy in their tendons. In consequence, most of the energy required for each hop is provided "free" by the spring action of the tendons (rather than by muscular effort). The main limitation on a macropod's ability to leap is not the strength of the muscles in the hindquarters, it is the ability of the joints and tendons to withstand the strain of hopping.

A femalequokkawith a joey

Furthermore, the act of hopping in kangaroos and wallabies is associated with their breathing process. The movement of their feet off the ground helps to expel air from their lungs, while bringing their feet forward for landing replenishes their lungs with air, resulting in greater energy efficiency. Studies conducted on these animals have shown that hopping at faster speeds requires only a minimal increase in effort beyond the energy required to hop in general, which is significantly less than what would be required in other animals like horses, dogs, or humans. Additionally, it has been observed that carrying extra weight requires little additional energy, which is particularly important for female kangaroos and wallabies carrying heavy pouch young.[citation needed]

The ability of larger macropods to survive on poor-quality, low-energy feed, and to travel long distances at high speed without great energy expenditure (to reach fresh food supplies or waterholes, and to escape predators) has been crucial to their evolutionary success on a continent that, because of poor soil fertility and low, unpredictable average rainfall, offers only very limited primary plant productivity.

Most macropod species have apolygynousmating system[7]and produce amating plugaftercopulation.[8][9][10]Gestationin macropods lasts about a month, being slightly longer in the largest species. Typically, only a single young is born, weighing less than 1 g (0.035 oz) at birth. They soon attach themselves to one of four teats inside the mother's pouch. The young leave the pouch after five to 11 months, and are weaned after a further two to six months. Macropods reachsexual maturityat one to three years of age, depending on the species.[11]

Fossil record

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Main article:Evolution of Macropodidae
Procoptodon goliah
Simosthenurus occidentalis
Sthenurus strilingi

The evolutionary ancestors of marsupials split from placental mammals during the Jurassic period about 160 million years ago (Mya).[12]The earliest known fossil macropod dates back about 11.61 to 28.4 Mya, either in theMioceneorLate Oligocene,and was uncovered inSouth Australia.Unfortunately, the fossil could not be identified any further than the family. AQueenslandfossil of a species similar toHadronomashas been dated at around 5.33 to 11.61 Mya, falling in theLate MioceneorEarly Pliocene.The earliest completely identifiable fossils are from around 5.33 Mya.[13]

Classification

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See also:List of macropodiformes
Tree-kangarooshave smaller ears for easier maneuvering between tree branches, and a much longer tail.
A red kangaroo showing pentapedal locomotion while grazing: the forelimbs and tail take the animal's weight while the hind legs are brought forward.
Apademelonhas typical macropod legs, although they are obscured by fur in this image.
A pademelon eating a slice ofsweet potato:Although usually grazing directly from the ground with their mouth, macropods may also use their front paws to assist in grazing.
A "forester kangaroo"hopping over a puddle

The listing for extant species is based on The Third edition of Wilson & Reeder'sMammal Species of the World(2005), except where theMammal Diversity DatabaseandIUCNagree on a change. The two livingsubfamiliesin the family Macropodidae are the Lagostrophinae, represented by a single species, thebanded hare-wallaby,and the remainder, which make up the subfamily Macropodinae (67 species).

See also

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References

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  1. ^abGroves, C. P.(2005).Wilson, D. E.;Reeder, D. M. (eds.).Mammal Species of the World: A Taxonomic and Geographic Reference(3rd ed.). Baltimore: Johns Hopkins University Press. pp.58–70.ISBN0-801-88221-4.OCLC62265494.
  2. ^Clode, D (2006).Continent of Curiosities: A Journey Through Australian Natural History.Melbourne: Cambridge University Press. pp.25–8.ISBN978-0-521-86620-0.
  3. ^Gurovich, Y.; Beck, R. (2009). "The phylogenetic affinities of the Enigma tic mammalian clade Gondwanatheria".Journal of Mammalian Evolution.16(1):25–49.doi:10.1007/s10914-008-9097-3.S2CID42799370.
  4. ^Attenborough, D. 1979. Life on Earth. Boston, MA: Little, Brown and Company. 319 p.
  5. ^Pope, PB (2011)."Isolation of Succinivibrionaceae implicated in low ethane emissions from Tammar Wallabies".Science.333(6042):646–648.Bibcode:2011Sci...333..646P.doi:10.1126/science.1205760.PMID21719642.S2CID206534060.
  6. ^Swamp Wallaby (Wallabia bicolor) carpals
  7. ^Sigg, Dominique P., and Anne W. Goldizen."Male reproductive tactics and female choice in the solitary, promiscuous bridled nailtail wallaby (Onychogalea fraenata)."Journal of Mammalogy 87.3 (2006): 461-469.
  8. ^Vogelnest, Larry; Woods, Rupert (18 August 2008).Medicine of Australian Mammals.Csiro Publishing.ISBN978-0-643-09797-1.
  9. ^Staker, Lynda (30 June 2014).Macropod Husbandry, Healthcare and Medicinals--Volumes One and Two.Lynda Staker.ISBN978-0-9775751-2-1.
  10. ^Jackson, Stephen M. (2003).Australian Mammals: Biology and Captive Management.Csiro Publishing.ISBN978-0-643-06635-9.
  11. ^Poole, WE (1984). Macdonald, D (ed.).The Encyclopedia of Mammals.New York: Facts on File. pp.862–71.ISBN0-87196-871-1.
  12. ^Luo, Z. X.; Yuan, C. X.; Meng, Q. J.; Ji, Q. (25 August 2011). "A Jurassic eutherian mammal and divergence of marsupials and placentals".Nature.476(7361):442–445.Bibcode:2011Natur.476..442L.doi:10.1038/Nature10291.PMID21866158.S2CID205225806.
  13. ^The Paleobiology Database (2011)."Macropodidae (kangaroo)".The Paleobiology Database.Majura Park, ACT, Australia: Australian Research Council.Retrieved11 July2011.
  14. ^Haaramo, M (20 December 2004)."Macropodidae: kenguroos".Mikko's Phylogeny Archive.Archived fromthe originalon 31 March 2007.Retrieved15 March2007.
  15. ^Prideaux, GJ; Warburton, NM (2010)."An osteology-based appraisal of the phylogeny and evolution of kangaroos and wallabies (Macropodidae: Marsupialia)".Zoological Journal of the Linnean Society.159(4):954–87.doi:10.1111/j.1096-3642.2009.00607.x.
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