Australia: The Land Where Time Began

A biography of the Australian continent 

Riversleigh Ringtail Possums

Those living ringtail possums (Pseudocherids) whose diet is known all eat the leaves of trees. Unlike other possums they don't eat insects that are on the leaves. Based on those whose diet is known, they would appear to be exclusively herbivorous. The Pygmy Possum (Pseudocheris mayeri) from New Guinea may be an exception. But this has only been seen in one captive individual, that refused leaves but drank sugar water.

The living ringtails come from 3 groups. The common ringtail, all species of Pseudocheris, the pseudochirops ringtails, all species of Pseudochirops. The third group is composed of the Greater Glider (Peraurides volans) and the Lemuroid Possum (P. hemibelideus). The earliest Petauriodes-like fossils are Early Pliocene forms from the Hamilton Local Fauna, Victoria, but none have been found in the Riversleigh deposits.

It is believed the lineage leading to the living forms may have originated in the rainforests, as the present-day Lemuroid Possum still lives in rainforest. It is thought the Greater Glider lineage probably originated in open woodland similar to the kind of woodland they live in now. In the Riversleigh deposits at least 3 Pseudochirops species have been found, but no common ringtails. All the known extant species are found in the rainforests of northeast Australia. These are the Green Ringtail Possum, that eats the leaves of the Stinging Nettle Tree, as well as others, and in New Guinea-the Coppery, Plush-coated and the D'Albertus Ringtails.

Most of the Riversleigh ringtails from the Oligocene-Miocene are bizarre, some of which are very primitive types that don't seem to be related to any extant groups. Among these, 3 genera were also represented in the central Australian deposits from the Oligocene-Miocene. Some appear to be endemic to the Riversleigh rainforests.

At present, the highest diversity of sympatric ringtails is found in the mountain rainforests of New Guinea. In the Dwornamor Local Fauna of the Riversleigh rainforests there were 9 sympatric species during the Oligocene-Miocene. They also had a wide biogeographic spread at this time, species of 3 genera, Pildra, Paljara and Marlu also being found in the central Australian Kutjamarpu Local Fauna.

Pseudokoala erlita was a comparatively large, folivorous (leaf-eating) species of ringtail that was apparently a rare occupant of the Hamilton rainforest in the Early Pliocene. Some think it may have been a species that evolved to fill the vacated niche left in the rainforest when the early koalas followed their favourite eucalypt as it flourished and spread outside the rainforest in the Late Tertiary and Quaternary.

New Australian Oligocene to Miocene Ringtail Possums (Pseudocheridae) and Revision of the Genus Marlu    Palaeontology Vol.52 Issue 2, Pages 441-456 12 March 2009

There are 4 genera of ringtail possums that have been found in deposits from the Oligocene-Miocene. The genus Marlu was known from 2 species, M. kutjamarpensis from the Miocene in the Kutjamarpu Local Fauna (Leaf Locality) and from the Late Oligocene, M praecursor from the Wadikali Local Fauna. Both sites are in northern South Australia. In what is now the Tirari Desert. Later finds at Kutjamarpu Local Fauna (Leaf Locality) and at Riversleigh, included Marlu Karya from Middle Miocene deposits containing Local Faunas at Riversleigh, and from the Kutjamarpu Local Fauna (Leaf Locality), Marlu sykes sp. nov. and M. ampelos sp. nov., as well as from the Early to Middle Miocene Riversleigh Local Faunas.

http://www3.interscience.wiley.com/journal/122260268/abstract?CRETRY=1&SRETRY=0

Sources & Further reading

  • Michael Archer, Suzanne J. Hand & Henk Godthelp, Australia's Lost World: Riversleigh, world heritage Site, Reed New Holland
Author: M. H. Monroe
Email:  admin@austhrutime.com
Last Updated 27/03/2011

 

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                                                                                           Author: M.H.Monroe  Email: admin@austhrutime.com     Sources & Further reading