Spriggina
Encyclopedia
Fossils of Spriggina are known from the Ediacaran
period, around . The segmented organism reached about 3 cm in length and may have been predatory. Its bottom is covered with two rows of tough interlocking plates, while one row covered its top; its front few segments fused to form a head, which may have borne eyes and antennae.
Sprigginas affinity is currently unknown; it has been classified as an annelid
worm, a rangeomorph
-like frond, Proarticulata
, and an arthropod
, perhaps related to the trilobite
s. Lack of known segmented legs or limbs may make an arthropod classification premature.
The first two segments formed a "head". The front segment was 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 annulation
s.
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
n, but appears to be a glide 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 end members.
Fossils from the Vindyhan, 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.
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
, but its lack of chaeta
e, along with other lines of evidence, suggests that it cannot be placed in this phylum. It was also compared to the rangeomorph
s, frondose members of the Ediacara biota
that may represent a separate kingdom.
While its glide symmetry may suggest otherwise, Spriggina is currently considered to be an arthropod
; its resemblance to the trilobite
s may suggest a close relationship to this class
. Spriggina may have been predatory, and played a role in initiating the Cambrian transition
.
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
. Spriggina ovata has now been moved into its own genus, Marywadea
. Spriggia wadea is probably a junior synonym of Aspidella
preserved under specific conditions.
Ediacaran
The Ediacaran Period , named after the Ediacara Hills of South Australia, is the last geological period of the Neoproterozoic Era and of the Proterozoic Eon, immediately preceding the Cambrian Period, the first period of the Paleozoic Era and of the Phanerozoic Eon...
period, around . The segmented organism reached about 3 cm in length and may have been predatory. Its bottom is covered with two rows of tough interlocking plates, while one row covered its top; its front few segments fused to form a head, which may have borne eyes and antennae.
Sprigginas affinity is currently unknown; it has been classified as an annelid
Annelid
The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...
worm, a rangeomorph
Rangeomorph
The Rangeomorphs are a form taxon of frondose Ediacaran fossils that are united by a similarity to Rangea. Some workers, e.g. Pflug and Narbonne, suggest that a natural taxon Rangeomorpha may include all similar-looking fossils....
-like frond, Proarticulata
Proarticulata
Proarticulata is a proposed extinct phylum of very early bilateral animals known from fossils found in the Ediacaran fauna. Mikhail A. Fedonkin describes animals in Proarticulata as having a "shield-like" shape, an unmineralized, thin, flexible carapace and a thick, segmented body...
, and an arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
, perhaps related to the trilobite
Trilobite
Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...
s. Lack of known segmented legs or limbs may make an arthropod classification premature.
Morphology
Spriggina grew to around three centimetres 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, paired plates.The first two segments formed a "head". The front segment was 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 annulation
Annulus (zoology)
In zoology, an annulus is an external circular ring. Annuli are commonly found in segmented animals such as earthworms and leeches. The bodies of these annelids are externally marked by annuli that are arranged in series with each other....
s.
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
Bilateria
The bilateria are all animals having a bilateral symmetry, i.e. they have a front and a back end, as well as an upside and downside. Radially symmetrical animals like jellyfish have a topside and downside, but no front and back...
n, but appears to be a glide reflection
Glide reflection
In geometry, a glide reflection is a type of isometry of the Euclidean plane: the combination of a reflection in a line and a translation along that line. Reversing the order of combining gives the same result...
, 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 end members.
Fossil occurrences
Spriggina is known only from beds of Ediacaran age.Fossils from the Vindyhan, 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.
Affinity
Ediacara biota
The Ediacara biota consisted of enigmatic tubular and frond-shaped, mostly sessile organisms which lived during the Ediacaran Period . Trace fossils of these organisms have been found worldwide, and represent the earliest known complex multicellular organisms.Simple multicellular organisms such as...
, the relationship of Spriggina to other groups is unclear. It bears some similarity to the living polychaete worm Tomopteris
Tomopteris
Tomopteris is a genus of marine planktonic polychaete. If disturbed, some species are known to make a flurry of glowing sparks erupt from their parapodia. One species, Tomopteris nisseni, is one of the few marine creatures with yellow bioluminescence....
, but its lack of chaeta
Chaeta
A chaeta or cheta is a chitinous bristle or seta found on an insect, arthropod or annelid worms such as the earthworm, although the term is also frequently used to describe similar structures in other invertebrates. The plural form is chaetae or chetae.In the Polychaeta, they are located on the...
e, along with other lines of evidence, suggests that it cannot be placed in this phylum. It was also compared to the rangeomorph
Rangeomorph
The Rangeomorphs are a form taxon of frondose Ediacaran fossils that are united by a similarity to Rangea. Some workers, e.g. Pflug and Narbonne, suggest that a natural taxon Rangeomorpha may include all similar-looking fossils....
s, frondose members of the Ediacara biota
Ediacara biota
The Ediacara biota consisted of enigmatic tubular and frond-shaped, mostly sessile organisms which lived during the Ediacaran Period . Trace fossils of these organisms have been found worldwide, and represent the earliest known complex multicellular organisms.Simple multicellular organisms such as...
that may represent a separate kingdom.
While its glide symmetry may suggest otherwise, Spriggina is currently considered to be an arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
; its resemblance to the trilobite
Trilobite
Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...
s may suggest a close relationship to this class
Class (biology)
In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
. Spriggina may have been predatory, and played a role in initiating the Cambrian transition
Cambrian explosion
The Cambrian explosion or Cambrian radiation was the relatively rapid appearance, around , of most major phyla, as demonstrated in the fossil record, accompanied by major diversification of other organisms, including animals, phytoplankton, and calcimicrobes...
.
History
The genus was named after Reg SpriggReg Sprigg
Reginald Claude Sprigg, AO, HonDSc ANU, HonDSc Flinders, MSc Adelaide, FTSE was an Australian geologist and conservationist. At age 17 he became the youngest Fellow of the Royal Society of South Australia. In 1946, in the Ediacara Hills, South Australia he discovered the Ediacara biota, an...
who discovered the fossils of the
Ediacara biota
The Ediacara biota consisted of enigmatic tubular and frond-shaped, mostly sessile organisms which lived during the Ediacaran Period . Trace fossils of these organisms have been found worldwide, and represent the earliest known complex multicellular organisms.Simple multicellular organisms such as...
Ediacara Hills
Ediacara Hills
Ediacara Hills are a range of low hills in the northern part of the Flinders Ranges of South Australia, around 650 km north of Adelaide. The area has many old copper and silver mines from mining activity in the late 19th century...
—part of the Flinders Ranges
Flinders Ranges
Flinders Ranges is the largest mountain range in South Australia, which starts approximately north west of Adelaide. The discontinuous ranges stretch for over from Port Pirie to Lake Callabonna...
in South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
—and was a proponent of their recognition as multicellular organisms.
Spriggina floundersi is at present the only generally accepted species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in this genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
. Spriggina ovata has now been moved into its own genus, Marywadea
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. The fossil has an asymmetrical first chamber of the quilt. It has transverse ridges away from the central axis that may be gonads. The head is shaped as a...
. Spriggia wadea is probably a junior synonym of Aspidella
Aspidella
Aspidella is an Ediacaran disk-shaped fossil.- Morphology :Aspidella consists of disk-shaped fossils, with concentric rings and/or centripetal rays. The diameter of circular Aspidella varies from 1 to 180 mm. Most individuals are between 4 and 10 mm, however; smaller animals would...
preserved under specific conditions.
See also
- YorgiaYorgiaYorgia waggoneri is a member of the Ediacara biota, and resembles a cross between the organisms Dickinsonia and Spriggina. It has a low, segmented body consisting of a short wide "head", no appendages, and a long body region, reaching a maximum length of...
- DickinsoniaDickinsoniaDickinsonia is an iconic fossil of the Ediacaran biota. It resembles a bilaterally symmetrical ribbed oval. Its affinities are presently unknown; most interpretations consider it to be an animal, although others suggest it may be fungal, or a member of an "extinct kingdom".-Species variety:A...
- List of Ediacaran genera
External links
- Google Image Search: Spriggina