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The '''Riversleigh rainforest koala''' ('''''Nimiokoala greystanesi''''') is an [[extinct]] [[marsupial]], closely related to the [[Neontology|extant]] [[koala]], that inhabited northwestern [[Queensland]] in the early-middle [[Miocene]] (23–16&nbsp;million years ago).<ref name=":0">{{Cite journal|last=K.|first=Black|last2=J.|first2=Price, Gilbert|last3=Michael|first3=Archer,|last4=J.|first4=Hand, Suzanne|title=Bearing up well? Understanding the past, present and future of Australia&#39;s koalas|url=http://www.academia.edu/5610674/Bearing_up_well_Understanding_the_past_present_and_future_of_Australias_koalas._Black_K.H._Price_G.J._Archer_M._Hand_S.J._2014|journal=Gondwana Research|language=en|volume=25|issn=1342-937X}}</ref> Along with [[species]] of [[Sister group|sister]] [[genus]] ''[[Litokoala]]'', the Riversleigh rainforest koala is the smallest representative of [[Family (biology)|family]] ''[[Phascolarctidae|Phascolarctide]]''.<ref name=":0" /> Based on [[Cladistics|cladistic]] analysis, ''Nimiokoala'' is one of the more [[Basal (phylogenetics)|basal]] genera of ''Phascolarctide''. It died out due to [[climate change]] rendering the environment more arid.<ref name=":0" /> It probably had a more generalized diet than that of the modern species, but its exact food preferences are unknown.<ref name="Australian Museum">''Musser, A.'' [https://australianmuseum.net.au/nimiokoala-greystanesi Riversleigh Rainforest koala]. Australian Museum (July 15, 2009). Verified September 8, 2016.</ref>
The '''Riversleigh rainforest koala''' ('''''Nimiokoala greystanesi''''') is an [[extinct]] [[marsupial]], closely related to the [[Neontology|extant]] [[koala]], that inhabited northwestern [[Queensland]] in the early-middle [[Miocene]] (23–16&nbsp;million years ago).<ref name=":0">{{Cite journal|last=Black|first=K.|last2=Price|first2=G.|last3=Archer|first3=M.|last4=Hand|first4=S.|date=April 2014|title=Bearing up well? Understanding the past, present and future of Australia&#39;s koalas|url=http://www.academia.edu/5610674/Bearing_up_well_Understanding_the_past_present_and_future_of_Australias_koalas._Black_K.H._Price_G.J._Archer_M._Hand_S.J._2014|journal=Gondwana Research|language=en|volume=25|issue=3|pages=1193-1194|doi=10.1016/j.gr.2013.12.008|issn=1342-937X}}</ref> Along with [[species]] of [[Sister group|sister]] [[genus]] ''[[Litokoala]]'', the Riversleigh rainforest koala is the smallest representative of [[Family (biology)|family]] ''[[Phascolarctidae|Phascolarctide]]''.<ref>Black, K. (2014) 1192</ref> Based on [[Cladistics|cladistic]] analysis, ''Nimiokoala'' is one of the more [[Basal (phylogenetics)|basal]] genera of ''Phascolarctide''. It died out due to [[climate change]] rendering the environment more arid.<ref>Black, K. (2014) 1195</ref> It probably had a more generalized diet than that of the modern species, but its exact food preferences are unknown.<ref>{{Cite web|url=https://australianmuseum.net.au/nimiokoala-greystanesi|title=Nimiokoala greystanesi - Australian Museum|last=Musser|first=A.|date=July 15, 2009|website=australianmuseum.net.au|language=en|archive-url=|archive-date=|dead-url=|access-date=2017-05-14}}</ref>


== Etymology ==
== Etymology ==
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== History of Research ==
== History of Research ==
As of 2013, the fossil record of extinct koalas consists of 163 specimens across 58 deposits in [[Riversleigh]]; 55 specimens are attributed to the Riversleigh rainforest koala.<ref name=":0" /> To date, a partial [[skull]] has been found along with several [[Mandible|lower jaws]] and isolated teeth. On the basis of these fossils, the dental apparatus of the animal has been completely restored. The species was named in 1997. Specimen QMF30482 was assigned as a [[holotype]]; it's bones are stored in the [[Queensland Museum]].<ref name="Australian Museum" />
As of 2013, the fossil record of extinct koalas consists of 163 specimens across 58 deposits in [[Riversleigh]]; 55 specimens are attributed to the Riversleigh rainforest koala.<ref name=":0" /> To date, a partial [[skull]] has been found along with several [[Mandible|lower jaws]] and isolated teeth. On the basis of these fossils, the dental apparatus of the animal has been completely restored. The species was named in 1997. Specimen QMF30482 was assigned as a [[holotype]]; it's bones are stored in the [[Queensland Museum]].<ref name="Australian Museum">''Musser, A.'' [https://australianmuseum.net.au/nimiokoala-greystanesi Riversleigh Rainforest koala]. Australian Museum (July 15, 2009). Verified September 8, 2016.</ref>


== Description ==
== Description ==

Revision as of 03:10, 14 May 2017

Content in this edit is translated from the existing Russian Wikipedia article; see its history for attribution.

Riversleigh rainforest koala
Temporal range: early-middle Miocene
Scientific classification
Kingdom:
Phylum:
Class:
Infraclass:
Order:
Family:
Genus:
Nimiokoala
Species:
N. greystanesi
Binomial name
Nimiokoala greystanesi
Black and Archer, 1997[1]

The Riversleigh rainforest koala (Nimiokoala greystanesi) is an extinct marsupial, closely related to the extant koala, that inhabited northwestern Queensland in the early-middle Miocene (23–16 million years ago).[2] Along with species of sister genus Litokoala, the Riversleigh rainforest koala is the smallest representative of family Phascolarctide.[3] Based on cladistic analysis, Nimiokoala is one of the more basal genera of Phascolarctide. It died out due to climate change rendering the environment more arid.[4] It probably had a more generalized diet than that of the modern species, but its exact food preferences are unknown.[5]

Etymology

The generic name, Nimiokoala, is derived from the Latin word Nimio "excessive" referring to its complex molar morphology relative to other koala species. The specific name, greystanesi, honors Greystanes High School.[6]

History of Research

As of 2013, the fossil record of extinct koalas consists of 163 specimens across 58 deposits in Riversleigh; 55 specimens are attributed to the Riversleigh rainforest koala.[2] To date, a partial skull has been found along with several lower jaws and isolated teeth. On the basis of these fossils, the dental apparatus of the animal has been completely restored. The species was named in 1997. Specimen QMF30482 was assigned as a holotype; it's bones are stored in the Queensland Museum.[7]

Description

In the absence of postcranial fossils, the dimensions of the Riversleigh rainforest koala were calculated from measurements of its surviving teeth. It is estimated to have body length of about 25–30 cm (9.8-11.8 in), and a weight of about 3.5 kg (7.7 lb), one third the size of modern koalas and more than 10 times smaller than the largest known representative of Phascolarctide (Phascolarctos yorkensis). Its muzzle was more prominent than that of modern koalas,[7] resembling the possum snout.[8] The teeth of the Riversleigh rainforest koala are selenodontal (crescent-shaped), with a numerous cusps and accessory shearing blades.[2] The fossilized skull contains large orbits and very large auditory bulliae relative to its size.[2]

Ecology and Behavior

In the early-middle Miocene, Riversleigh was covered with tropical forests. More open areas, with karst soil, occurred at forest edges or freshwater streams and lakes.[7] As the climate became more arid, with a more pronounced change of seasons, small species of koalas died out, including the Riversleigh rainforest koala.

The small size of Nimiokoala, which requires a proportionately more intensive diet, and large eye sockets, which indicate good night vision, suggest that this animal was much more mobile than the modern koala.[2] The structure of the ear of Nimikoala corresponds to that which can be observed in modern koalas; in conjuction with the large auditory bulliae, it can be concluded that the Riversleigh rainforest koala was sensitive to and used low-frequency sounds for communication, including to attract mates.[9]

References

  1. ^ Black, K.; Archer, M. "Nimiokoala gen. nov. (Marsupialia, Phascolarctidae) from Riversleigh, northwestern Queensland, with a revision of Litokoala". Memoirs of the Queensland Museum. 41: 209–228. ISSN 0079-8835.
  2. ^ a b c d e Black, K.; Price, G.; Archer, M.; Hand, S. (April 2014). "Bearing up well? Understanding the past, present and future of Australia's koalas". Gondwana Research. 25 (3): 1193–1194. doi:10.1016/j.gr.2013.12.008. ISSN 1342-937X.
  3. ^ Black, K. (2014) 1192
  4. ^ Black, K. (2014) 1195
  5. ^ Musser, A. (July 15, 2009). "Nimiokoala greystanesi - Australian Museum". australianmuseum.net.au. Retrieved 2017-05-14. {{cite web}}: Cite has empty unknown parameter: |dead-url= (help)
  6. ^ Hamlyn-Harris, Ronald (June 30, 1997). Memoirs of the Queensland Museum. South Brisbane : Queensland Museum. pp. 209–228.
  7. ^ a b c Musser, A. Riversleigh Rainforest koala. Australian Museum (July 15, 2009). Verified September 8, 2016.
  8. ^ "Discovery: 20 million year old extinct koala species - UNSW Science for society". www.science.unsw.edu.au. Retrieved 2017-04-09.
  9. ^ "Loud and lazy but didn't chew gum: Ancient koalas - UNSW Science for society". www.science.unsw.edu.au. Retrieved 2017-04-09.