Paralenorthis

Paralenorthis; Temporal range: Ordovician PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Brachiopoda
Class:	Rhynchonellata
Order:	†Orthida
Family:	†Orthidae
Genus:	†Paralenorthis; Havlíček & Branisa, 1980
Type species
	†Paralenorthis immitatrix; Havlíček & Branisa, 1980
Species
	P. immitatrix (type); P. orbicularis; P. costata; P. buttsi; P. marshalli; P. semnanensis; P. carlottoi; P. suriensis; P. riojanus; P. alata; P. estenaensis; P. luritjaorum; P. lolae; P. rgaitensis;

Paralenorthis is an extinct genus of orthid brachiopods, found in Ordovician strata all around the world. Many species of Paralenorthis were previously classified as other orthid genera, such as Orthambonites.

Taxonomic history

The genus Paralenorthis was erected by Havliček and Branisa as a name replacing the defunct name Lenorthis Andreeva and Nikiforova, 1955. The type species, P. immitatrix, was found in Middle Ordovician strata of Bolivia. Species previously assigned to Lenorthis were transferred into this genus, including P. alata and P. orbicularis.

A later study revising the taxonomy of multiple species previously assigned to Orthambonites would reassign many previously described species into this genus. Many more records of Paralenorthis would be described since, hailing from all parts of the world such as Iran, Tibet, Australia, Kazakhstan, Peru, and Morocco.

Morphological description

Paralenorthis is a small brachiopod, with length not exceeding 20 milimeters. Its surface is covered with large unbranching radial ribbings (costae) and small radial lineations (capillae). The ventral valve is more convex than the dorsal valve, and a fold-sulcus structure can be found.

The shape of the ventral vascula media distinguishes this genus from similar genera, like Orthambonites and Orthis. In Paralenorthis, the vascula media is proximally divergent, unlike in Orthambonites and Orthis where it is proximally adjacent.

References

1 2 3 4 Jaanusson, Valdar; Bassett, Michael G. (1993). "Orthambonites and related Ordovician brachiopod genera". Palaeontology. 36 (1): 21–63.
1 2 Havlíček, Vladimir; Branisa, Leonardo (1980). "Ordovician brachiopods of Bolivia". Rozpravy Ceskoslovenske Akademie Ved, Praha. 90: 1–54.
↑ Popov, Leonid E.; Ghobadi Pour, Mansoureh; Bassett, Michael G.; Kebria-Ee, Mohammad (2009). "Billengsellide and Orthide Brachiopods: New Insights into Earliest Ordovician Evolution and Biogeography from Northern Iran". Palaeontology. 52 (1): 35–52. doi:10.1111/j.1475-4983.2008.00833.x. ISSN 1475-4983.
↑ Zhan, Renbin; Harper, David A. T.; Jin, Jisuo; Liang, Yan; Liu, Jianbo; Stemmerik, Lars; Stouge, Svend (2014). Alvarez, Fernando (ed.). "Middle O rdovician A porthophyla brachiopod fauna from the roof of the W orld, southern T ibet". Palaeontology. 57 (1): 141–170. doi:10.1111/pala.12058. ISSN 0031-0239.
↑ Jakobsen, Kristian G.; Brock, Glenn A.; Nielsen, Arne T.; Topper, Timothy P.; Harper, David A.T. (2013-11-21). "Middle Ordovician brachiopods from the Stairway Sandstone, Amadeus Basin, central Australia". Alcheringa: An Australasian Journal of Palaeontology. 38 (2): 190–208. doi:10.1080/03115518.2013.858204. ISSN 0311-5518.
↑ Nikitina, O.; Popov, Leonid; Neuman, Robert; Bassett, Michael; Holmer, Lars (2006-01-01). "Mid Ordovician (Darriwilian) brachiopods of South Kazakhstan". National Museum of Wales Geological Series. 25: 145–222.
↑ "Brachiopods from the uppermost Lower Ordovician of Peru and their palaeogeographical significance - Acta Palaeontologica Polonica". www.app.pan.pl. Retrieved 2026-11-04.
↑ Candela, Yves; Harper, David A. T.; Mergl, Michal (2024). "The brachiopod faunas from the Fezouata Shale (Lower Ordovician; Tremadocian–Floian) of the Zagora area, Anti‐Atlas, Morocco: evidence for a biodiversity hub in Gondwana". Papers in Palaeontology. 10 (5). doi:10.1002/spp2.1592. ISSN 2056-2799.

[JaanussonBassett1993-1-1] 1 2 3 4 Jaanusson, Valdar; Bassett, Michael G. (1993). "Orthambonites and related Ordovician brachiopod genera". Palaeontology. 36 (1): 21–63.

[HavlíčekBranisa1980-1-2] 1 2 Havlíček, Vladimir; Branisa, Leonardo (1980). "Ordovician brachiopods of Bolivia". Rozpravy Ceskoslovenske Akademie Ved, Praha. 90: 1–54.

[3] Popov, Leonid E.; Ghobadi Pour, Mansoureh; Bassett, Michael G.; Kebria-Ee, Mohammad (2009). "Billengsellide and Orthide Brachiopods: New Insights into Earliest Ordovician Evolution and Biogeography from Northern Iran". Palaeontology. 52 (1): 35–52. doi:10.1111/j.1475-4983.2008.00833.x. ISSN 1475-4983.

[4] Zhan, Renbin; Harper, David A. T.; Jin, Jisuo; Liang, Yan; Liu, Jianbo; Stemmerik, Lars; Stouge, Svend (2014). Alvarez, Fernando (ed.). "Middle O rdovician A porthophyla brachiopod fauna from the roof of the W orld, southern T ibet". Palaeontology. 57 (1): 141–170. doi:10.1111/pala.12058. ISSN 0031-0239.

[5] Jakobsen, Kristian G.; Brock, Glenn A.; Nielsen, Arne T.; Topper, Timothy P.; Harper, David A.T. (2013-11-21). "Middle Ordovician brachiopods from the Stairway Sandstone, Amadeus Basin, central Australia". Alcheringa: An Australasian Journal of Palaeontology. 38 (2): 190–208. doi:10.1080/03115518.2013.858204. ISSN 0311-5518.

[6] Nikitina, O.; Popov, Leonid; Neuman, Robert; Bassett, Michael; Holmer, Lars (2006-01-01). "Mid Ordovician (Darriwilian) brachiopods of South Kazakhstan". National Museum of Wales Geological Series. 25: 145–222.

[7] "Brachiopods from the uppermost Lower Ordovician of Peru and their palaeogeographical significance - Acta Palaeontologica Polonica". www.app.pan.pl. Retrieved 2026-11-04.

[8] Candela, Yves; Harper, David A. T.; Mergl, Michal (2024). "The brachiopod faunas from the Fezouata Shale (Lower Ordovician; Tremadocian–Floian) of the Zagora area, Anti‐Atlas, Morocco: evidence for a biodiversity hub in Gondwana". Papers in Palaeontology. 10 (5). doi:10.1002/spp2.1592. ISSN 2056-2799.