''Arandaspis prionotolepis'' is an
extinct
Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of
jawless fish
Agnatha (; ) or jawless fish is a paraphyletic infraphylum of animals in the subphylum Vertebrata of the phylum Chordata, characterized by the lack of jaws. The group consists of both extant taxon, living (Cyclostomi, cyclostomes such as hagfish ...
that lived in the
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...
period, about 480 to 470 million years ago. Its remains were found in the
Stairway Sandstone near
Alice Springs
Alice Springs () is a town in the Northern Territory, Australia; it is the third-largest settlement after Darwin, Northern Territory, Darwin and Palmerston, Northern Territory, Palmerston. The name Alice Springs was given by surveyor William ...
,
Australia
Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
in 1959, but it was not determined that they were the oldest known vertebrates until the late 1960s. ''Arandaspis'' is named after a local
Indigenous Australian
Indigenous Australians are people with familial heritage from, or recognised membership of, the various ethnic groups living within the territory of contemporary Australia prior to History of Australia (1788–1850), British colonisation. The ...
people, the Aranda (now currently called
Arrernte).
Description
''Arandaspis'' is estimated to reach around long, with a body covered in rows of knobbly armoured
scute
A scute () or scutum (Latin: ''scutum''; plural: ''scuta'' "Scutum (shield), shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of Bird anatomy#Scales, birds. The ter ...
s. The front of the body and the head were protected by hard plates with openings for the eyes, nostrils and
gill
A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...
s. It probably was a
filter-feeder
Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a specia ...
. The morphology of its trunk and tail is unknown.
According to comparisons with other early
ostracoderms, it would have lacked paired fins and the
caudal fin
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...
would be of a simple shape,
although another arandaspid ''
Sacabambaspis'' had a tail consisting of dorsal and ventral webs and an elongated notochordal lobe.
See also
* ''
Astraspis''
* ''
Sacabambaspis''
References
External links
*
Pteraspidomorphi genera
Ordovician jawless fish
Paleozoic fish of Australia
Early Ordovician genus first appearances
Early Ordovician genus extinctions
Fossil taxa described in 1977
{{Pteraspidomorphi-stub