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Arandaspis prionotolepis
Arandaspis #1
Arandaspis is a primitive vertebrate, lived in the Ordovician period 2), 4), 5), around 480 millions years ago 3). Arandaspida as well as Sacabambaspis are classified to the class Pteraspidomorphi (a group of extinct early jawless fish) 2).
Arandaspis #2
They are about 15cm in length 1), 3), 4), and have two‭ dermal bone sheilds which provide support for the body as well as protection 4).
There are a gap between two shields, where eyes and external gills open 2), 4).
Arandaspis #3
Since Arandaspis had no jaw, it might have swum with opened mouth and might have filtrated organic matters or smaller organisms 4). They may have lived behind scattered pebbles.
Arandaspis #4
The posterior half of the body is missing from the fossil, so the structure of the fins is unknown 1).
It seems that Arandaspis was not a good swimmer, propelled itself with undulating tail (and head) movement 4).
created in in January - April 2019.
References :
  1. Australia : The land where time began
  2. Janvier P (1997) Arandaspida. Version 01 January 1997 (under construction). in The Tree of Life Web Project
  3. Long J (2014) The oldest fish in the world lived 500 million years ago. The Conversation, June 12,2014(AEST) (accessed 2019.05.11)
  4. Prehistoric Wildlife(accessed 2019.05.11)
  5. Ritchie A. Gilbert-Tomlinson J. (1977) First Ordovician vertebrates from the Southern hemisphere. [abstract] Alcheringa 1(4), p351-368.(DOI:10.1080/03115517708527770)