Delgadella

Delgadella is a diminutive trilobite that lived during the late Lower Cambrian (Atdabanian to Botomian) and has been found in Russia (Siberian Platform, Altay Mountains), Mongolia, Spain, Italy (Sardinia), Portugal, Morocco and Canada (Newfoundland). It can be recognized by its strongly effaced headshield and tailshield, with narrow but distinct furrows and borders along its margins, and three thorax segments.[1]

Delgadella
Temporal range: Late Atdabanian to Botomian
↓
a drawing of Delgadella lenaicus, Lena River, Yakutia
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Trilobita
Order:
Agnostida
Family:
Hebediscidae
Genus:
Delgadella

Walcott, 1908
species
  • D. lusitanica (Delgado, 1904) (type species) = Lingulepis lusitanica
  • D. caudatus (Delgado, 1904) = Delgadodiscus caudatus, Microdiscus caudatus
  • D. lenaicus (Toll, 1899) = Microdiscus lenaicus
Synonyms

Alemtejoia, Delgadodiscus, Delgadoia, Pagetiellus, Pentagonalia

Description

The headshield (or cephalon) is convex, and axial furrow that surrounds the central area (or glabella) almost obsolete, particularly on the external surface. The glabella has no transvers furrows. The border furrow is distinct and wide anteriorly, and the border distinct and narrow. The eye lobe (or palpebral lobe) is poorly defined. The free cheeks (or librigenae) are long. The thorax has three segments. The tailshield (or pygidium) has a long axis of 10 almost indiscernible rings. The furrow that defines the axis in the pygidium (or rhachis) is almost obsolete. The area outside the rhachis (or pleural zone) is usually smooth, and like on the cephalon, the border and border furrow are very narrow but distinct.[1]

Distribution
  • Delgadella occurs in the Lower Cambrian of the Russian Federation (Atdabanian, Judomia trilobite-zone, Tyuser Formation, Chekurovka village, Biskeebit River mouth near Lena River 71.0° N, 127.5° E,[2] Erkeket Formation, Mattaiya Creek, 71.5° N, 124.6° E,[3] Bergeroniellus gurarii trilobite-zone, Sinsk Formation, Algal Lens Yakutia, 61.1° N, 126.6°;[4] Botomian, Lapworthella bella small shelly-zone, Krasnoporog Formation, Sukharikha River, Krasnoyarskiy Kray, 67.2° N, 87.0° E),[5] and Spain (Atdabanian, upper part of the La Hoya member, Alconera Formation).[6]
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References
  1. Whittington, H. B.; et al., eds. (1997). Part O, Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. Treatise on Invertebrate Paleontology.
  2. A.Y. Rozanov; V.V. Missarzhevsky; N.A. Volkova; L.G. Voronova; I.N. Krylov; B.M. Keller; I.K. Korolyuk; K. Lendzion; R. Mikhnyar; N.G. Pykhova; A.D. Sidorov (1969). "Tommotskiu jarus i problema nizhney granisty kembriya". Trudy Geoligske Institut Leningrad. 206: 1–379. cited in Paleobiological Database http://museumu03.museumwww.naturkundemuseum-berlin.de/cgi-bin/bridge.pl?action=basicCollectionSearch&collection_no=56855. Missing or empty |title= (help)
  3. I.V. Korovnikov (2007). "Trilobites of the Suborder Eodiscina from the Lower Cambrian of the Northeastern Siberian Platform (Khorbosuonka River Section)". Paleontological Journal. 41 (6): 614–620. doi:10.1134/s0031030107060044. cited in Paleobiolobical Database http://museumu03.museumwww.naturkundemuseum-berlin.de/cgi-bin/bridge.pl?action=basicCollectionSearch&collection_no=96839. Missing or empty |title= (help)
  4. E.Y. Ivantsov; A. Y. Zhuravlev; A. V. Leguta; V. A. Krassilov; L. M. Melnikova; G. T. Ushatinskaya (2005). "Palaeoecology of the Early Cambrian Sinsk biota from the Siberian Platform". Palaeogeography, Palaeoclimatology, Palaeoecology. 220 (1–2): 69–88. doi:10.1016/j.palaeo.2004.01.022. cited in Ivantsov, Andrey Yu.; Zhuravlev, Andrey Yu.; Leguta, Anton V.; Krassilov, Valentin A.; Melnikova, Lyudmila M.; Ushatinskaya, Galina T. (2005). "Palaeoecology of the Early Cambrian Sinsk biota from the Siberian Platform". Palaeogeography, Palaeoclimatology, Palaeoecology. 220 (1–2): 69–88. doi:10.1016/j.palaeo.2004.01.022.
  5. S. M. Rowland; V. A. Luchinina; I. V. Korovnikov; D. P. Sipin; A. I. Tarletskov; A. V. Fedoseev (1998). "Biostratigraphy of the Vendian-Cambrian Sukharikha River section, northwestern Siberian Platform". Canadian Journal of Earth Sciences. 35 (4): 339–352. Bibcode:1998CaJES..35..339R. doi:10.1139/cjes-35-4-339. cited in Paleobiological Database http://museumu03.museumwww.naturkundemuseum-berlin.de/cgi-bin/bridge.pl?action=basicCollectionSearch&collection_no=80843. Missing or empty |title= (help)
  6. Eladio Liñán (Ed.). The Cambrian system in Iberia. Guadernos del Museo Minero. Instituto Geologico y Minero d’ Espagna. pp. 1–65.CS1 maint: extra text: authors list (link)


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