Spriggina Floundensi 4.png
   HOME

TheInfoList



OR:

''Spriggina'' is a genus of early
bilateria The Bilateria or bilaterians are animals with bilateral symmetry as an embryo, i.e. having a left and a right side that are mirror images of each other. This also means they have a head and a tail (anterior-posterior axis) as well as a belly and ...
n animals whose relationship to living animals is unclear. Fossils of ''Spriggina'' are known from the late
Ediacaran The Ediacaran Period ( ) is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and th ...
period in what is now South Australia. ''Spriggina floundersi'' is the official fossil emblem of South Australia. It has been found nowhere else. The organism reached about in length and may have been predatory. Its bottom was covered with two rows of tough interlocking plates, while one row covered its top; its front few segments fused to form a "head." ''Spriggina'' affinity is currently unknown; it has been variously classified as an
annelid The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecol ...
worm, a
rangeomorph The rangeomorphs are a form taxon of frondose Ediacaran Ediacaran biota, fossils that are united by a similarity to ''Rangea''. Some researchers, such as Pflug and Narbonne, suggest that a natural taxon Rangeomorpha may include all similar-look ...
-like frond, a variant of ''
Charniodiscus ''Charniodiscus'' is an Ediacaran fossil that in life was probably a stationary filter feeder that lived anchored to a sandy sea bed. The organism had a holdfast, stalk and frond. The holdfast was bulbous shaped, and the stalk was flexible. The ...
'', a proarticulatan, or an arthropod perhaps related to the trilobites, or even an extinct
phylum In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature f ...
. Lack of known segmented legs or limbs, and
glide reflection In 2-dimensional geometry, a glide reflection (or transflection) is a symmetry operation that consists of a reflection over a line and then translation along that line, combined into a single operation. The intermediate step between reflection ...
instead of symmetric segments, suggest an arthropod classification is unlikely despite some superficial resemblance. The genus ''Spriggina'' may have originally contained 3 different species, although now it has been concluded that there is only one species within the genus. These species are ''Spriggina floundersi'', ''"Spriggina" ovata'' and ''"Spriggina" borealis''. Spriggina ovata is now a junior synonym of
Marywadea ''Marywadea'' is a genus of Ediacaran biota shaped like an oval with a central ridge. It is a bilaterian organism as evidenced by its symmetry, vaguely resembling a very primitive trilobite. The fossil has an asymmetrical first chamber of the qui ...
ovata. The latter of the organisms, ''S. borealis'', is still being debated upon whether or not it's part of the genus ''Spriggina'' as it differs from ''S. floundersi''.


Description

''Spriggina'' grew to in length, and was approximately oblong. The organism was segmented, with no fused segments, with the segments sometimes being curved. The upper surface of the organism was covered by one row of overlapping cuticular plates, the underside with paired plates. The first two segments formed a "head". The front segment had the shape of a horseshoe with a pair of depressions on its upper surface which may represent eyes. The second segment may have borne antennae. Subsequent segments bore annulations. Some fossils have what may be a circular mouth at the centre of the semicircular head – although interpretation is hampered by the small size of the creature relative to the large grains of sandstones in which it is preserved. Legs are not preserved. The symmetry observed is not exactly
bilateria The Bilateria or bilaterians are animals with bilateral symmetry as an embryo, i.e. having a left and a right side that are mirror images of each other. This also means they have a head and a tail (anterior-posterior axis) as well as a belly and ...
n, but appears to be a
glide reflection In 2-dimensional geometry, a glide reflection (or transflection) is a symmetry operation that consists of a reflection over a line and then translation along that line, combined into a single operation. The intermediate step between reflection ...
, where opposite segments are shifted by half an interval. In some specimens the body segments tilt backwards, making roughly chevron patterns; while in others they are more or less straight. There appear to be fairly complex variations between these two extremes.


Discovery and naming

The genus was named after Reg Sprigg who discovered the fossils of the Ediacara Hills—part of the Flinders Ranges in South Australia—and was a proponent of their recognition as multicellular organisms. ''Spriggina floundersi'' is at present the only generally accepted species in this genus. The
specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...
"''floundersi''" refers to amateur South Australian fossil hunter Ben Flounders. ''Spriggina ovata'' has now been moved into its own genus, ''
Marywadea ''Marywadea'' is a genus of Ediacaran biota shaped like an oval with a central ridge. It is a bilaterian organism as evidenced by its symmetry, vaguely resembling a very primitive trilobite. The fossil has an asymmetrical first chamber of the qui ...
''. ''Spriggina'' is known only from beds of Ediacaran age. Fossils from the Vindhyan basin, reliably dated to around , have been classified as ''Spriggina'', but in all likelihood represent microbial artifacts. ''Spriggina'' possessed a tough, though uncalcified body, evident from the fossils' preservation: always as a mould in the lower surface of the fossiliferous bed.


Classification

Like many of the Ediacara biota, the relationship of ''Spriggina'' to other groups is unclear. It bears some similarity to the living polychaete worm ''
Tomopteris The gossamer worm (''Tomopteris'', Neo-Latin from Greek meaning "a cut" + "wing" but taken to mean "fin") is a genus of marine planktonic polychaetes. All described species are known to be holoplanktic, meaning that they spend their entire lif ...
'' and
Amphinomidae Amphinomidae, also known as the bristle worms or sea mice, are a family of marine polychaetes, many species of which bear chaetae mineralized with carbonate. The best-known amphinomids are the fireworms, which can cause great pain if their toxin ...
, but its lack of chaetae, along with other lines of evidence, suggests that it cannot be placed in this phylum. It was also compared to the
rangeomorph The rangeomorphs are a form taxon of frondose Ediacaran Ediacaran biota, fossils that are united by a similarity to ''Rangea''. Some researchers, such as Pflug and Narbonne, suggest that a natural taxon Rangeomorpha may include all similar-look ...
s,
frondose Frondosity (from Latin ''frondōsus'' meaning 'leafy') is the property of an organism that normally flourishes with fronds or leaf-like structures. Many frondose organisms are thalloid and lack the organization of tissues into organs, with the ...
members of the Ediacara biota that may represent a separate kingdom. While its glide symmetry may suggest otherwise, ''Spriggina'' is considered by some other researchers to be an arthropod; its superficial resemblance to the trilobites may suggest a close relationship to this
class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...
. This similarity to trilobites could also be an example of convergent evolution. ''Spriggina'' may have been predatory, and may have played a role in initiating the Cambrian transition.


See also

* '' Yorgia'' * ''
Dickinsonia ''Dickinsonia'' is an extinct genus of basal animal that lived during the late Ediacaran period in what is now Australia, China, Russia and Ukraine. The individual ''Dickinsonia'' typically resembles a bilaterally symmetrical ribbed oval. Its a ...
'' * List of Ediacaran genera


References


External links


Google Image Search
''Spriggina'' {{Taxonbar, from=Q132927 Sprigginidae Prehistoric bilaterian genera †Spriggina Emblems of South Australia