Batocara belongs to one of the most popular fossil groups to have appeared in the fossil record, trilobites. They are an extinct group of marine arthropods (same group as spiders, scorpions, crabs and horseshoe crabs) that first appeared in the Cambrian period (540 Million of years ago) and went extinct at the end of the Permian period (250 Million years ago). Trilobites form one of the earliest-known groups of arthropods. Since trilobites are found all over the world, limited to a particular geological time frame, are easily recognisable and preserve very well for a fossil, they are extremely useful for relatively dating the age of a rock.
The name trilobite comes from their three lobed exoskeleton, two lateral lobes and one axial lobe. There are over 20,000 species of described trilobites recorded, with more every year. Since trilobites occupied a wide array of different environments from tropical shallow and reef systems to ocean dwelling habits and beyond. It is believed that the huge diversity in form is related to these specific habitats and palaeontologists can use this information to infer the ecology of these long extinct arthropods.
Batocara mitchelli is the most common trilobite in ACT, however it is commonly found as fragments. Originally described as Encrinurus in the 1980s and collected by a researcher John Mitchell (who the species was named after) currently at the Museum of National History, London, it was later allocated to the new genus, Batocara. Excitingly, a near-complete specimen was found while drilling the foundations of the John Gorton Building in Canberra, which is very rare to find a fossil in a core sample. Specimens of the Batocara were also found while developing in Braddon and now there is a development named Batocara in their honour. An incredible feature about this particular trilobite is the head (cephalon) and tail (pygidium) are covered by small round knobs which is distinctive for the species. The function of these knobs are not well understood, but its distinctiveness and interesting appearance makes for excellent topic of debate by scientists.


  • Title: Batocara mitchelli
  • Location: Geoscience Australia, Canberra
  • Type: Fossil
  • Rights: Geoscience Australia / CC-BY 4.0
  • Photographer: Errol Fries
  • Museum ID: CPC18033

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