Weejasperaspididae ("Shields of
Wee Jasper
Wee Jasper is a hamlet in the Goodradigbee River, Goodradigbee valley at the western foot of the Brindabella Ranges, near Burrinjuck Dam in New South Wales, Australia in Yass Valley Council, Yass Valley Shire. It is located about 90 km nort ...
") is a
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
of three
extinct acanthothoracid placoderms indigenous to the Early
Devonian of
Victoria
Victoria most commonly refers to:
* Victoria (Australia), a state of the Commonwealth of Australia
* Victoria, British Columbia, provincial capital of British Columbia, Canada
* Victoria (mythology), Roman goddess of Victory
* Victoria, Seychelle ...
and
New South Wales
)
, nickname =
, image_map = New South Wales in Australia.svg
, map_caption = Location of New South Wales in AustraliaCoordinates:
, subdivision_type = Country
, subdivision_name = Australia
, established_title = Before federation
, es ...
,
Australia.
Description
The Weejasperaspids are known from median dorsal plates with distinctive, blade-like crests in the median-posterior portion, and ossified eye capsules.
Evolutionary relationships
The main reasons why the weejasperaspids are not considered to be closely related to other non-acanthothoracid placoderms, as opposed to the
palaeacanthaspids, are that their
skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...
anatomies and plate histologies are generalized, and do not bear any similarities to any specific non-acanthothoracid group, and that the patterns of ornamentation on their dermal plates are unique to this family.
The placoderm ''
Brindabellaspis stensioi'' was once regarded as a weejasperaspid because of the similarities between its dermal plates to the other weejasperaspids. Even before it was split off into its own order, it stood out from the others because of its long, pointed snout. French paleontologist Phillipe Janvier placed ''B. stensioi'' in its own order, Brindabellaspida, because of how the internal anatomy of the braincase resembled more like those of
osteostracans or
galeaspids than those of other placoderms.
External links
Mikko's Phylogeny Archiv
References
* Janvier, Philippe. ''Early Vertebrates'' Oxford, New York: Oxford University Press, 1998.
* Long, John A. ''The Rise of Fishes: 500 Million Years of Evolution'' Baltimore: The Johns Hopkins University Press, 1996.
{{Taxonbar, from=Q7979382
Acanthothoracids
Placoderms of Australia
Placoderm families
Early Devonian first appearances
Early Devonian extinctions