Eldonia
Encyclopedia
Eldonia is a soft-bodied animal of unknown affinity, best known from the Fossil Ridge outcrops of the Burgess Shale
, particularly in the 'Great Eldonia layer' in the Walcott Quarry
. In addition to the 550 collected by Walcott, Species also occur in the Chengjiang biota, and in Upper Ordovician
strata of Morocco
.
Walcott's original interpretation as a holothurian was rapidly disputed. Alternative affinities to be suggested, which did not stand the test of time, included the siphonophores and a coelentrate medusa.
It takes the form of a round, medusoid disk (which originally led to suggestions of a jellyfish affinity) with a C-shaped gut trace. The gut is recalcitrant and can be extracted using HF acid. The organism is frequently found in association with the lobopod Microdictyon
, which is presumed to have fed on Eldonia.
The eldoniids form a clade that also includes Paropsonema
, Rotadiscus
, and Stellostomites
.
Burgess Shale
The Burgess Shale Formation, located in the Canadian Rockies of British Columbia, is one of the world's most celebrated fossil fields, and the best of its kind. It is famous for the exceptional preservation of the soft parts of its fossils...
, particularly in the 'Great Eldonia layer' in the Walcott Quarry
Walcott Quarry
The Walcott Quarry is the most famous quarry of the Burgess Shale, bearing the Phyllopod beds. This lies at the base of the Walcott Quarry member, and three other quarries – the Raymond, UE and EZ – lie above it...
. In addition to the 550 collected by Walcott, Species also occur in the Chengjiang biota, and in Upper Ordovician
Ordovician
The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...
strata of Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
.
Walcott's original interpretation as a holothurian was rapidly disputed. Alternative affinities to be suggested, which did not stand the test of time, included the siphonophores and a coelentrate medusa.
It takes the form of a round, medusoid disk (which originally led to suggestions of a jellyfish affinity) with a C-shaped gut trace. The gut is recalcitrant and can be extracted using HF acid. The organism is frequently found in association with the lobopod Microdictyon
Microdictyon
Microdictyon is an extinct "armored worm" coated with dot-likescleritic scales, known from the Early CambrianMaotianshan shale of Yunnan China. Microdictyon is sometimes included...
, which is presumed to have fed on Eldonia.
The eldoniids form a clade that also includes Paropsonema
Paropsonema
Paropsonema is a discoidal animal known from the Cambrian Chengjiang biota and classified with the eldoniids....
, Rotadiscus
Rotadiscus
Rotadiscus is a genus of discoidal animal known from the Cambrian Chengjiang biota and classified with the eldoniids.As with other eldoniids, it was originally thought to have been pelagic, but is now thought to be benthic....
, and Stellostomites
Stellostomites
Stellostomites is a discoidal animal known from the Cambrian Chengjiang biota and classified with the eldoniids....
.