Tuarangia

Tuarangia; Temporal range: early Middle Cambrian PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Bivalvia
Informal group:	† Euprotobranchia
Order:	† Tuarangiida ; MacKinnon, 1982
Family:	† Tuarangiidae ; MacKinnon, 1982
Genus:	† Tuarangia ; MacKinnon, 1982
Species
	T. gravgaerdensis; T. paparua;

Last updated November 19, 2024

Tuarangia is a Cambrian shelly fossil interpreted as an early bivalve,^[1] though alternative classifications have been proposed and its systematic position remains controversial.^[2] It is the only genus in the extinct family Tuarangiidae^[3] and order Tuarangiida.^[1] The genus is known solely from Middle to Late Cambrian fossils found in Europe and New Zealand.^[3] The genus currently contains two accepted species, Tuarangia gravgaerdensis and the type species Tuarangia paparua.^[3]

Description

Tuarangia is a minute bivalve which was first described in 1982 by David I. MacKinnon of the University of Canterbury in Christchurch, New Zealand. Generally the shells of Tuarangia are subquadrate to trapezoidal and elongate in shape. The long hinge is straight with an indistinct umbone positioned close to the lateral midline of the hinge. The subparallel bar-like teeth of Tuarangia are taxodontic, and with a grouped into two rows with a ridge in between. An erect, narrow ligament is placed on the separating ridge. The shell structure of Tuarangia is noted for being composed of platy calcite sections in a zig-zag patterning. This is different from the shells of other Cambrian bivalves, which have a prismatic calcite shell and layers of carbonate nacre which similar to the laminar aragonite layer found in extant monoplacophora.^[4] The genus name is taken from the Maori word tuarangi, which means "ancient or of ancient date".^[5]

Tuarangia paparua is based on the holotype specimen, UCM 923, and the paratype specimens, UCM 924-UCM 931, all of which are housed in the University of Canterbury Geology Department. The fossils were found in sediments of the late middle Cambrian aged Tasman Formation which outcrops 1 kilometre (1,000 m) west of Cobb Reservoir in the Tasman Region, South Island, New Zealand. The specific epithet is from the Maori words papa, which translates as "shell", and rua, which means "two". The species would have lived along the coast of the paleocontinent Eastern Gondwana.^[3]

The second species of Tuarangia to be described, Tuarangia gravgaerdensis, is from sediments of the middle Cambrian aged Ardrarum Limestone Formation which outcrops on the island of Bornholm in the Baltic Sea.^[6] During the Cambrian Bornholm was a segment of ocean floor off the coast of the paleocontinet Baltica.^[3] The species was proposed by Berg-Madsen in 1987.^[3]

The family Tuarangiidae and the order Tuarangiida were first proposed by MacKinnon in his 1982 paper on the genus. Since that description, the superfamily Tuarangiacea, which MacKinnon also proposed has been dropped from use. Tuarangiidae is now placed directly into the order Tuarangiida and the order is placed into the bivalve evolutionary grade Euprotobranchia. This puts Tuarangiida as a sister taxon to the order Fordillida.^[1] Euprotobranchia includes the earliest confirmed crown group bivalves to have been described, with Tuarangia being one of only four accepted bivalve genera to have been described from the Cambrian, the other three being Fordilla , Pojetaia , and Camya .^[3]

Related Research Articles

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Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1987.

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Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1986.

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Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1980.

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Anabarella is a species of bilaterally-flattened monoplacophoran mollusc, with a morphological similarity to the rostroconchs. Its shell preserves evidence of three mineralogical textures on its outer surface: it is polygonal near the crest of the shell, subsequently changing to both spiny and stepwise. Its internal microstructure is calcitic and semi-nacreous. Its name reflects its provenance from Anabar, Siberia. It has been interpreted as ancestral to the rostroconchs, and has been aligned to the Helcionellidae.

<i>Fordilla</i> Extinct genus of bivalves

Fordilla is an extinct genus of early bivalves, one of two genera in the extinct family Fordillidae. The genus is known solely from Early Cambrian fossils found in North America, Greenland, Europe, the Middle East, and Asia. The genus currently contains three described species, Fordilla germanica, Fordilla sibirica, and the type species Fordilla troyensis.

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Pojetaia is an extinct genus of early bivalves, one of two genera in the extinct family Fordillidae. The genus is known solely from Early to Middle Cambrian fossils found in North America, Greenland, Europe, North Africa, Asia, and Australia. The genus currently contains two accepted species, Pojetaia runnegari, the type species, and Pojetaia sarhroensis, though up to seven species have been proposed. The genera Buluniella, Jellia, and Oryzoconcha are all considered synonyms of Pojetaia.

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<span class="mw-page-title-main">Fordillidae</span> Extinct family of bivalves

Fordillidae is an extinct family of early bivalves and one of two families in the extinct superfamily Fordilloidea. The family is known from fossils of early to middle Cambrian age found in North America, Greenland, Europe, the Middle East, Asia, and Australia. The family currently contains two genera, Fordilla and Pojetaia, each with up to three described species. Due to the size and age of the fossil specimens, Fordillidae species are included as part of the Turkish Small shelly fauna.

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<span class="mw-page-title-main">Fordilloidea</span> Extinct superfamily of bivalves

Fordilloidea is an extinct superfamily of early bivalves containing two described families, Fordillidae and Camyidae and the only superfamily in the order Fordillida. The superfamily is known from fossils of early to middle Cambrian age found in North America, Greenland, Europe, the Middle East, Asia, and Australia. Fordillidae currently contains two genera, Fordilla and Pojetaia each with up to three described species while Camyidae only contains a single genus Camya with one described species, Camya asy. Due to the size and age of the fossil specimens, Fordillidae species are included as part of the Turkish Small shelly fauna.

References

1 2 3 Carter, J.G.; et al. (2011). "A Synoptical Classification of the Bivalvia (Mollusca)" (PDF). Paleontological Contributions. 4: 1–47.
↑ Elicki, O., & Gürsu, S. (2009). First record of ~Pojetaia runnegari~ Jell, 1980 and ~Fordilla~ Barrande, 1881 from the Middle East (Taurus Mountains, Turkey) and critical review of Cambrian bivalves. Paläontologische Zeitschrift, 83(2), 267–291. doi:10.1007/s12542-009-0021-9
1 2 3 4 5 6 7 Elicki, O.; Gürsu, S. (2009). "First record of Pojetaia runnegari Jell, 1980 and Fordilla Barrande, 1881 from the Middle East (Taurus Mountains, Turkey) and critical review of Cambrian bivalves" (PDF). Paläontologische Zeitschrift. 83 (2): 267–291. doi:10.1007/s12542-009-0021-9. S2CID 49380913.
↑ Vendrasco, M.J.; Checa, A.G.; Kouchinsky, A.V. (2011). "Shell microstructure of the early bivalve Pojetaia and the independent origin of nacre within the Mollusca". Palaeontology. 54 (4): 825–850. doi: 10.1111/j.1475-4983.2011.01056.x .
↑ MacKinnon, D.I. (1982). "Tuarangia paparua n. gen. and n. sp. A late Middle Cambrian bivalve from New Zealand". Journal of Paleontology. 56 (3): 589–598. JSTOR 1304393.
↑ The Paleobiology database "At Olea" entry accessed 9 January 2012

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[Carter2011-1] 1 2 3 Carter, J.G.; et al. (2011). "A Synoptical Classification of the Bivalvia (Mollusca)" (PDF). Paleontological Contributions. 4: 1–47.

[2] Elicki, O., & Gürsu, S. (2009). First record of ~Pojetaia runnegari~ Jell, 1980 and ~Fordilla~ Barrande, 1881 from the Middle East (Taurus Mountains, Turkey) and critical review of Cambrian bivalves. Paläontologische Zeitschrift, 83(2), 267–291. doi:10.1007/s12542-009-0021-9

[Elicki2009-3] 1 2 3 4 5 6 7 Elicki, O.; Gürsu, S. (2009). "First record of Pojetaia runnegari Jell, 1980 and Fordilla Barrande, 1881 from the Middle East (Taurus Mountains, Turkey) and critical review of Cambrian bivalves" (PDF). Paläontologische Zeitschrift. 83 (2): 267–291. doi:10.1007/s12542-009-0021-9. S2CID 49380913.

[Vendrasco2011-4] Vendrasco, M.J.; Checa, A.G.; Kouchinsky, A.V. (2011). "Shell microstructure of the early bivalve Pojetaia and the independent origin of nacre within the Mollusca". Palaeontology. 54 (4): 825–850. doi: 10.1111/j.1475-4983.2011.01056.x .

[MacKinnon1982-5] MacKinnon, D.I. (1982). "Tuarangia paparua n. gen. and n. sp. A late Middle Cambrian bivalve from New Zealand". Journal of Paleontology. 56 (3): 589–598. JSTOR 1304393.

[TPBDB-6] The Paleobiology database "At Olea" entry accessed 9 January 2012

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