comment on this calibration
Mollusca
Lineage (NCBI):
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» Protostomia
» Lophotrochozoa
» Mollusca
| node name Mollusca 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 532 Ma Aldanella yanjiahensis has been found to be associated with Watsonella crosbyi and Oelandiella korobkovi in the Dahai member in the middle Meishucunian of China (Steiner et al., 2007). It has been suggested that this assemblage serves as a biozone. Chemostratigraphic correlations place this unit in the Nemakit Daldynian within the interval 534-532 Ma (Maloof et al., 2010). | ||
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node maximum age 549 Ma We established a soft maximum constraint on the approximate maximum age of the Nama Group (549 Ma; Narbonne et al., 2012; Grotzinger et al., 1995) which preserves an open marine community including the earliest animal skeletal remains, viz. Cloudina, Namacalathus and Namapoika (Wood, 2011), but does not preserve the skeletal remains of molluscs, nor does any of the very widespread strata that preserve Cloudina. Since a biomineralized skeleton with distinctly molluscan microstructure (e.g., crossed lamellar tissue is a synapomorphy of crown molluscs), the absence of such remains in a suite of deposits ecologically compatible with molluscs and capable of preserving their remains, suggests their absence in the prior interval of Earth history. | ||
| primary fossil used to date this node | ||
TU YXII02-02 | ||
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phylogenetic justification
Aldanella is a dextrally coiled mollusc assigned to the Pelagiellida. The distinct assymetries and the preservation of muscle scars (Runnegar, 1981) suggest that it is a partially coiled stem-group gastropod. |
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phylogenetic reference(s)
Runnegar, B. 1981. Muscle scars, shell form and torsion in Cambrian and Ordovician univalved molluscs. Lethaia 14:311-322.
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| tree image (click image for full size) | ||
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Figure 1 from Benton et al. (2014).
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