SUPPORTING INFORMATION
Figure S1. First appearances of carbonate-mineralizing taxa in Nemakit-Daldynian
through Tommotian sequences. Note that not all taxa appear in all sections. Circles = taxa
with primary aragonite skeletons; squares = taxa with primary calcite skeletons. Unless
otherwise indicated, first appearance datum refers to all disputed subgroups of a taxon;
thus, ‘coeloscleritophorans’ include both chancelloriid and non-chancelloriid
representatives, and ‘molluscs’ include both molluscs, sensu stricto, and cap-shaped
fossils. Proposed boundaries between stages and/or systems may be based either on
biostratigraphy (indicated by ‘b’) or chemostratigraphy (indicated by ‘c’) and may differ
within a single section.
(A) Kotuikan River section, western Anabar region, northwestern Siberian platform.
Biostratigraphic and thickness data from Khomentovsky & Karlova (1993), Knoll et al.
(1995), and Kaufman et al. (1996). Archaeocyaths are not reported from the section
(Khomentovsky & Karlova, 1993; Kaufman et al., 1996), but are found in sections ~150
km away, where they co-occur with trilobites ~13 m above the top of the Medvezhya
Formation (Knoll et al., 1995). Three alternative placements of the NemakitDaldynian/Tommotian (ND/T) boundary are indicated by dashed lines (Knoll et al.,
1995; Kaufman et al., 1996).
(B) Composite of Dalir and Valiabad sections, Elburz Mountains, Iran.
Biostratigraphic and unit thickness data from Hamdi et al. (1989). Lower ND/T boundary
is based on the first appearance of the “Maikhanella fauna” (Hamdi et al., 1989). Upper
ND/T boundary is based on the presence of a major carbon-isotope excursion (~+4‰) in
the lower ~40 m the Upper Shale Member, which has been correlated with subTommotian peak I’ in the Kotuikan River section, northwestern Siberia (Brasier et al.,
1990; Knoll et al., 1995). Reports of Salterella in the Upper Dolomite Member and
trilobites in the Upper Shale Member are of questionable validity (Hamdi et al., 1989).
Trilobites and other calcitic taxa are known from overlying formations although their
specific stratigraphic level is not indicated here (Hamdi et al., 1989 and references
therein; Rozhnov, 2001). LDM = Lower Dolomite Member; MDM = Middle Dolomite
Member; UDM = Upper Dolomite Member.
(C) Krol Belt, Lesser Himalaya, India. Biostratigraphic and lithostratigraphic data
from summary diagram in Hughes et al. (2005: fig. 3). Stratigraphic terminology taken
from the Mussoorie syncline area (Shanker et al., 1993; cited in Hughes et al., 2005);
CPM = Chert Phosphate Member; CM = Calcareous Member; A&B = Member A and
Member B; C = Member C.
(D) Composite of Tsagaan Gol, Salaany Gol, and Bayan Gol sections, Zavkhan
Basin, western Mongolia. Biostratigraphic data from references cited in Brasier et al.
(1996). ‘Units’ refer to those of the Bayan Gol sections 3A and 3B (Brasier et al. 1996;
figs. 8-9). Sequence numbers and unit thicknesses from Lindsay et al. (1996). Alternative
placements of E/ND and ND/T boundaries from Brasier et al. (1996). Lower ND/T
candidate (just above the base of sequence 10) would imply the presence of a major
positive excursion in the Tommotian Stage; upper ND/T candidate (above sequence 12)
would imply the presence of a major hiatus in southern Siberian sections (Brasier et al.,
1996). Chemostratigraphic evidence from other sections favors the latter scenario (Knoll
et al., 1995; Kaufman et al., 1996; Kouchinsky et al., 2001, 2005, 2007).
(E) Composite section of Little Dantzic Cove and Fortune North sections, Avalon
Zone, southeastern Newfoundland. Unit thicknesses and biostratigraphic data from
Landing et al. (1989; figure 1). Radiometric date from volcanic ash collected from the
Somerset Street section, New Brunswick, and referable to the Watsonella crosbyi Zone
(Isachsen et al. 1994), which is equivalent to the upper part of Member 3 and all of
Member 4 of the Chapel Island Formation in the composite section shown here (Landing
et al., 1989). ND/T boundary placed somewhere above Watsonella crosbyi Zone (i.e. top
of Member 4) and below the middle of Member 3 of the Cuslett Formation, Bonavista
Group (Landing et al., 1989) based on biostratigraphic constraints. Branchian Series is
correlated with the Botomian Stage in Siberia (e.g., Landing, 1994).
(F) Meishucun section, Yunnan, South China. Biostratigraphic and bed thickness data
from Qian & Bengtson (1989) and references therein. Anabaritids, molluscs (cap-shaped
fossils), and hyoliths have been reported from the Xiaowaitoushan Member, but Qian &
Bengtson (1989) were unable to confirm their presence in beds below the Zhongyicun
Member. Sequence boundaries from Brasier et al. (1990). Archaeocyaths do not occur in
the Meishucun section; elsewhere in China they first occur in Qiongzhusian-aged rocks
(Jiang, 1992). Radiometric age from SHRIMP U-Pb analyses of zircons from tuff with
Bed 5, Zhongyicun Member, Meishucun section (Jenkins et al., 2002). Lower ND/T
boundary from Khomentovsky & Karlova (1993). Upper ND/T boundary based on
presence of a positive carbon isotope peak in the Dahai Member that has been correlated
with the sub-Tommotian positive excursion in the Dvorsty section, southeastern Siberia
(Magaritz et al., 1986; Brasier et al., 1990). D = Dahai Member; Shiyantou Member is
formerly known as the Badaowan Member; Xiaowaitoushan Member formerly included
in the Baiyanshao Member (Xing et al., 1991).
(G) Sukharikha River section, northwestern Siberian platform. Biostratigraphic data
from Rowland et al. (1998) and Kouchinsky et al. (2007); unit thicknesses from Rowland
et al. (1998). Alternative placements of the Ediacaran/Nemakit-Daldynian (E/ND)
boundary from Kouchinsky et al. (2007; lower boundary) and Rowland et al. (1998;
upper boundary). Alternative placements of the ND/T boundary from Rowland et al.
(1989; lower boundary, based on the appearance of diverse ‘Tommotian’ taxa) and
Kouchinsky et al. (2007; upper boundary, based on carbon-isotope correlation with the
stratotype section). Reports of archaeocyaths in the uppermost Sukharikha Formation
(Rozanov et al., 1969) are unconfirmed; Kouchinsky et al. (2007) place the first
archaeocyaths in the lowermost Krasnoporog Formation.
(H) Selinde River section, Uchur-Maya region, southeastern Siberian platform.
Biostratigraphic data from Khomentovsky & Karlova (1993). Lower ND/T boundary
from Khomentovsky & Karlova (1993); upper ND/T from Kouchinsky et al. (2005).
Fragments of archaeocyaths reported at ~2.7 m above the Ust-Yudoma/Pestrotsvet
contact (Khomentovsky & Karlova 2002, cited in Kouchinsky et al. 2005); several forms
have been reported at 5 m above the contact (Korshunov et al. 1969; also see
Khomentovsky & Karlova, 1993).
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