comment on this calibration
Xenarthra
Lineage (NCBI):
root
» Eukaryota
» Opisthokonta
» Metazoa
» Eumetazoa
» Bilateria
» Coelomata
» Deuterostomia
» Chordata
» Craniata <chordata>
» Vertebrata <Metazoa>
» Gnathostomata <vertebrate>
» Euteleostomi
» Sarcopterygii
» Tetrapoda
» Amniota
» Mammalia
» Theria <Mammalia>
» Eutheria
» Xenarthra
| node name Xenarthra Look for this name in NCBI Wikipedia Animal Diversity Web | ||
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recommended citations http://palaeo-electronica.org/content/fc-1 Benton et al. 2015 |
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node minimum age 47.6 Ma Until recently, Itaboraí was regarded as upper Paleocene in age, but Woodburne et al. (2014) suggest that it is early Eocene, which would lead to a paleontological minimum estimate for crown Xenarthra corresponding to the the top of the Ypresian marine stage, 47.8 Ma ± 0.2 Myr = 47.6 Ma (Gradstein et al., 2012). | ||
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node maximum age 164.6 Ma The soft maximum date is based on the divergence of Eutheria from other mammals in the late Jurassic, represented by Juramaia (Luo et al., 2011). This taxon is represented in the Daxigou site of the Tiaojishan Formation, Liaoning Province, Northeastern China, and has been constrained by radiometric dates to derive from deposits of just over 160 Ma in age (Luo et al., 2011). The equivalent marine stage is the Oxfordian (Gradstein et al., 2012), with a lower boundary of 163.5 Ma ± 1.1 Myr, and thus 164.6 Ma is a soft maximum. | ||
| primary fossil used to date this node | ||
MCN PV 1774 | ||
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phylogenetic justification
Riostegotherium belongs to crown Xenarthra based on the diagnostically cingulate osteoderms (e.g., the type mentioned above). Other skeletal elements (e.g., astragali) with a close resemblance to cingulates are also known from Itaboraí (Bergqvist et al., 2004). |
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phylogenetic reference(s)
Bergqvist, L. P., Abrantes, E. A. L. & Avilla, L. D. 2004. The Xenarthra (Mammalia) of Sao Jose de Itaborai Basin (upper Paleocene, Itaboraian), Rio de Janeiro, Brazil. Geodiversitas 26: 323-337.
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| tree image (click image for full size) | ||
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