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Anostraca
Lineage (NCBI):
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» Anostraca
| node name Anostraca Look for this name in NCBI Wikipedia Animal Diversity Web | ||
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recommended citations Wolfe et al. 2016a |
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node minimum age 125.71 Ma The type locality of P. rasnitsyni, briefly described by Trussova (1971), is the left bank of Daya River, upstream from Shiviya Falls, in eastern Transbaikal, Russia. This locality, within the Unda-Daya Basin,has been assigned to the Glushkovo Formation (Sinitshenkova, 2005).The age of the Glushkovo Formation is poorly constrained, suggested as Late Jurassic (Sinitsa and Starukhina, 1986), Early Cretaceous (Sinitshenkova, 2005; Zherikhin et al., 1998), or perhaps at the Jurassic/Cretaceous boundary (Rasnitsyn and Quicke, 2002). However,P. rasnitsyni itself (along with palaeopteran insects such as Proameletus caudatus and Equisetum undense) correlates the Glushkovo Formation to the Baigul locality, also in Transbaikalia (Ignatov et al., 2011). The Baigul locality preserves fossil Bryokhutuliinia jurassica, one of only five known genera of Jurassic mosses (Ignatov et al., 2011). Thus Baigul can be correlated to the Ulugey Formation of Mongolia, which also preserves Bryokhutuliinia fossils (Ignatov, 1992). The Ulugey Formation, in turn, is correlated to the La Cabrúa (Sierra del Montsec, Pyrenees, Spain) locality based on the shared presence of the coleopteran genus Gobicar (Gratshev and Zherikhin, 2000; Legalov, 2010; Soriano et al., 2006). Fossil charophyte algae (Atopochara trivolvis triquetra) indicate an age oflate Hauterivian-early Barremian for the freshwater deposits of LaCabrúa (Gomez et al., 2002;Martín-Closas and López-Morón, 1995). Althoughit has been proposed that a minimum age of the Montsec limestone may be as young as the end Maastrichtian (O'Reilly et al., 2015),recent biostratigraphic work proposes the last appearance of A. trivolvis triquetra is correlated to the Deshayesites weissi ammonite Zone at its youngest (Martín-Closas et al., 2009). Revision of Tethyan ammonite dates indicates the D. weissi Zone, now the Deshayesites forbesi Zone, had an upper boundary of 125.71 Ma (Ogg et al., 2012a).This age is early Aptian, and provides a minimum for the correlated Glushkovo Formation. | ||
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node maximum age 521 Ma A soft maximum age is obtained from the oldest mandibulate, Y. dianensis, which was recovered from the Yu'anshan Formation at Xiaotan section, Yongshan, Yunnan Province, attributed to the Eoredlichia–Wutingaspis Biozone (Zhang et al., 2007). Chinese Cambrian stratigraphy has been revised substantially and the Eoredlichia –Wutingaspis Biozone is no longer recognized (Peng, 2003, 2009). However, Eoredlichia is known to co-occur with Hupeidiscus, which is diagnostic of the Hupeidiscus-Sinodiscus Biozone, which is formally recognized as the second biozone of the Nangaoan Stage of the Qiandongian Series of the Cambrian of China (Peng and Babcock,2008). The Nangaoan is the proposed third stage of the Cambrian System for the International Geologic Timescale (Peng et al., 2012a).Thus, a soft maximum constraint can be established on the age of the lower boundary of the Nangaoan, which has been dated to 521 Ma (Peng et al., 2012a; Peng and Babcock, 2008). | ||
| primary fossil used to date this node | ||
TsGM 7a/10303 | ||
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phylogenetic justification
P. rasnitsyni (formerly Chirocephalus rasnitsyni Trussova, 1971) has not been included in a phylogenetic analysis. Taxonomic placement of its family, Palaeochirocephalidae, implicitly relates them to the extant family Chirocephalidae, though this family is considered incertae sedis by Rogers (2013). Morphological characters (shared with Chirocephalidae) supporting this relationship include 11 thoracic appendages bearing two pre-epipodites, the nine-segmented abdomen, and the basally separated two-segmented antennae in males (Trussova, 1971). A possible position on the stem lineage of Chirocephalidae would therefore place P. rasnitsyni within the crown group of Anostraca. |
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phylogenetic reference(s)
Trussova, E.K., 1971. On the first finding of the Mesozoic species of order Anostraca (Crustacea). Paleontol. Zh. 4, 68–73.
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| tree image (click image for full size) | ||
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Figure 15 from Wolfe et al. (2016)
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