Sprigginidae

Last updated

Sprigginidae
Temporal range: Ediacaran 560  Ma
Ꞓ
O
S
D
C
P
T
J
K
Pg
N
↓
Spriggina floundersi - MUSE.jpg
A reconstruction of the type species, Spriggina floundersi
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum:† Proarticulata
Class:† Cephalozoa
Family:† Sprigginidae
Glaessner, 1958 [1]
Type species
† Spriggina floundersi
Glaessner, 1958
Genera

See text

Sprigginidae is an extinct family of the class Cephalozoa, characterized by having a greater number of isomers than its sister taxon, Yorgiidae. They lived approximately 635 million years ago, in the Ediacaran period.

Contents

Description

Like most members of Proarticulata, their body plan consists of isomers arranged in a glide symmetry, meaning they do not have true bilateral symmetry, although what sets them out from other proarticulates is their greater number of isomers, numbering up to around 40, sometimes more, overall. They also have a distinct 'horseshoe' shaped 'head'. [1]

When the first member of the family, Spriggina , was discovered, it was considered to be a polychaete annelid, [1] and petalonamid frond, and even an arthropod, with probable relations to trilobites. [2] Although most recent studies now agree that Spriggina, and the family its apart of, are apart of the phylum Proarticulata. [3]

Distribution

Most genera are restricted to sediments within the Flinders Ranges of South Australia, [1] although some can be found within the Ust' Pinega Formation of Russia. [3]

Taxonomy

Sprigginidae includes the following genera:

Due to the rather small size of known Praecambridium specimens, and the large grain size of the matrix they are commonly found in, the placement of Praecambridium within the Sprigginidae family is tentative, as its hard to discern certain details in such small specimens, but are placed within Sprigginidae based on a recent study that suggested they may be juvenile forms, if not of Spriggina itself, which has been found within the same beds of Praecambridium. [4] Although other studies have noted that most reconstructions show similarities with juvenile forms of Yorgia , with it possibly being a larval stage of Yorgia itself. [5]

Metaspriggina was previously tentatively assigned to Sprigginidae, even deriving its generic name from Spriggina, [6] although a more recent study redescribing the genus saw it re-assigned within the phylym Chordata. [7]

See also

References

  1. 1 2 3 4 Glaessner, Martin F. (1958). "New Fossils from the Base of the Cambrian in South Australia" (PDF). Transactions of the Royal Society of South Australia. 81: 185–188. BHL page 41001421. Archived from the original (PDF) on 29 September 2007.
  2. ↑ Sokolov, B; Iwanowski, A (1985). The Vendian System. Springer Berlin.
  3. 1 2 Ivantsov, A.Yu (2004). "New Proarticulata from the Vendian of the Arkhangel'sk region" (PDF). Paleontological Journal. 38 (3): 247–253. Archived from the original (PDF) on 2007-09-27. Retrieved 2007-09-27.
  4. ↑ Ivantsov, A. Yu. (April 2007). "Small Vendian transversely Articulated fossils". Paleontological Journal. 41 (2): 113–122. Bibcode:2007PalJ...41..113I. doi:10.1134/S0031030107020013.
  5. ↑ Ivantsov, A.Y. (2001). "Vendia and Other Precambrian "Arthropods"". Paleontological Journal. 35 (4): 335–343.
  6. ↑ Simonetta, Alberto M.; Insom, Emilio (January 1993). "New animals from the Burgess Shale (Middle Cambrian) and their possible significance for the understanding of the Bilateria". Bolletino di Zoologia. 60 (1): 97–107. doi:10.1080/11250009309355797.
  7. ↑ Morris, Simon Conway (March 2008). "A redescription of a rare chordate, Metaspriggina Walcotti Simonetta and Insom, from the Burgess Shale (Middle Cambrian), British Columbia, Canada". Journal of Paleontology. 82 (2): 424–430. Bibcode:2008JPal...82..424M. doi:10.1666/06-130.1.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.