Image Flea fossil

P 26202 | Museum Victoria image number MN 4863

This is a colour photograph of an ancient flea ('Tarwinia australis') fossilised in mudstone. This specimen is from the Koonwarra fossil bed in South Gippsland, Victoria. The rounded body, long legs that are wider at the top, and the relatively long antennae of this flea specimen are clearly visible.



Educational details

Educational value
  • This fossil of the flea 'Tarwinia australis' is from the Koonwarra fossil bed, which formed 118-115 million years ago during the Cretaceous Period. The Koonwarra fossil bed contains fossils as diverse as plants, fish, insects, crustaceans, spiders, worms, bird feathers, a horseshoe crab and a mussel. The range of insects found here includes wasps, ants, flies, mayflies, water beetles and fleas.
  • This flea fossil specimen is an adult with a rounded body 7 mm in length, and a head that is about as long as it is wide and not particularly compressed. It has long thin legs that are wide at the top and covered with fine bristles, and long antennae with 18 or 19 short segments. It belongs to a group of parasitic insects called the siphonapterans, which contain more than 2,500 existing species of modern fleas.
  • Fossils are the remains, moulds or traces of dead plants or animals preserved in rock, mostly sedimentary rock such as sandstones, siltstones, shales and limestones. Fossils are an important source of information about the Earth's past. As well as shedding light on previous climatic and environmental conditions, they provide clues about the evolution of plants and animals, the age and formation of rocks, and the former positions of the continents.
  • The Koonwarra fossil bed is composed of fine-grained mudstone and is believed to have formed in the shallow part of a large freshwater lake. The numerous fish fossils found here are well preserved and show no signs of rotting, which suggests the lake probably froze over in winter, trapping and killing many animals. The insect fossils are also well preserved, supporting the theory that the freezing lake rapidly preserved the plants and animals.
  • The Koonwarra fossils provide invaluable information about the climate of the ancient environment. Some of the fossilised insects such as the mayflies and a beetle are similar to modern forms found only in cool alpine and subalpine regions, indicating that the climate at the time was cool. This is consistent with the geographic position of Australia at the time, which was much further south and attached to Antarctica, with southern Victoria in the polar regions.
  • The flea fossilised in the Koonwarra fossil bed probably fell from its host into the lake water where it was frozen and preserved through time. The host may have been a terrestrial mammal or bird that lived near the lake.
  • This particular flea specimen is the 'holotype', or type specimen of the species 'Tarwinia australis'. A holotype is the individual used to name and classify a new species. The holotype is usually kept in a special museum collection, and although it may not be the most typical or well-preserved specimen, it is never replaced.
Year level

4; 5; 6; 7; 8; 9; 10; 11; 12

Learning area
  • science
Strand
  • Science/Science understanding

    Other details

    Contributors
    • Content provider
    • Copyright holder
    • Organisation: Museum of Victoria
    • Address: Carlton VIC 3053 Australia
    • Remarks: Reproduced courtesy of Museum Victoria
    • Publisher
    • Date of contribution: 05 Sep 2013
    • Organisation: Education Services Australia
    • Address: Melbourne VIC 3000 Australia
    • URL: http://www.esa.edu.au/
    • Author
    • Name: John Broomfield
    • Remarks: photographer
    Access profile
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    Learning resource type
    • Image
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    • © Education Services Australia Ltd and Museum Victoria, 2016, except where indicated under Acknowledgments