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Journal of Paleontology 89(5):695–729
Occurrence.—Lower Cambrian: Kyrshabakta Formation (Berkuta Member), South Kazakhstan.
Remarks.—The distinctive features of Berkutaphycus elongatus, such as the breakage of its filaments into elongate segments and the presence of isolated akinete-like cylindrical and spherical bodies, suggest affinity to hormogonian cyano- bacteria (or, perhaps, to eukaryotic green or chrysophyte algae). The anthraxolite-like contents of the Berkuta filaments are not uncommon in metamorphosed Proterozoic deposits but are relatively rare in Cambrian and younger strata. Though this new taxon is somewhat similar to Cyanonema majus described from the Lower Cambrian of Tarim Platform of China (Dong et al., 2009), in the absence of a comparative study of the Chinese population it would be premature to propose a formal synonymy.
Genus Botominella Reitlinger, 1959 Type species.—Botominella lineata Reitlinger, 1959.
Botominella lineata Reitlinger, 1959 Figure 13.1–13.5
Botominella lineata Reitlinger, 1959, p. 25, pl. 10, figs. 1–7.
(non) Botominella lineata Reitlinger, 1959. Sergeev, 1989, pl. 1, figs. 11.
Description.—Solitary, unbranched, unsheathed, nontapering filaments up to 130 μmlong (complete specimen) that consist of separated short-discoidal opaque cell-like bodies that range from 2 to 5 µm in width and 20 to 60 μm in length that are separated by 1.5- to 3.5-μm gaps.
Material examined.—Three well-preserved specimens.
Occurrence.—Widely distributed in Lower Cambrian formations.
Remarks.—Botominella lineata, first described by Reitlinger (1959) from the Lower Cambrian Pestrocvetnaya Formation of Siberia, is known from numerous Lower Cambrian carbonate units. Similar structures, initially referred to Botominella lineata and reported from the Chulaktau-underlying Neoproterozoic Chichkan Formation (Sergeev, 1989), have been interpreted to
be inorganic and of nonbiological origin (Sergeev, 1992, pl. 23, figs. 1–3). However, the Chulaktau specimens described here differ morphologically from these earlier reported pseudofossils and their biological origin is confirmed by Raman spectroscopy
that shows them to be composed of apatite-permineralized kerogen. The morphology of the Chulaktau specimens suggests them to be either relatively broad cyanobacterial oscillator- iacean filaments or, less likely, eukaryotic (chlorophycean?) algae.
Genus Chlorogloeaopsis Maithy, 1975, emend. Hofmann and Jackson, 1994
Type species.—Chlorogloeaopsis zairensis Maithy, 1975.
Chlorogloeaopsis contexta Hermann, 1976 (in Timofeev, Hermann and Mikhailova, 1976), comb. Hofmann and Jackson, 1994 Figure 11.10
Polysphaeroides contextus Hermann, 1976 in Timofeev, Hermann and Mikhailova, 1976, p. 42 and 43, pl. 14, figs. 3, 4; Yankauskas, 1989, p. 119, pl. 27, figs. 10a, 10б; Hermann, 1990, pl. 7, fig. 8; Schopf, 1992c, pl. 24, figs. B1,B2; Sergeev,
2001, p. 443, fig. 9.1–9.3; Sergeev, 2006, p. 230 and 231, pl. 18, figs. 1–3.
Chlorogloeaopsis contexta Hofmann and Jackson, 1994, p. 19, figs. 12.13–12.15; Prasad, Uniyal and Asher, 2005, pl. 7, fig. 9, pl. 11, fig. 14; Sergeev, Sharma and Shukla, 2012, pl. 14, figs. 7–9 (see Hofmann and Jackson, 1994, p. 19 for additional synonymy).
Description.—Solitary unbranched non-ensheathed nontaper- ing filaments composed of irregularly oriented spheroidal
compressed cells. Cell walls are single-layered, translucent, fine-grained, and <0.5 μmthick. Cell diameters vary from 3.5 to 4.5 μm; filament diameters range from 7.5 to 12.5 μm, having a maximum length of 50 μm.
Material examined.—Three specimens, none well preserved.
Occurrence.—Mesoproterozoic: Bylot Supergroup, Baffin Island, Canada. Neoproterozoic: Burovaya and Miroedikha formations, Turukhansk Uplift; Nelkan, Kumakhtinskaya, Kandykskaya and Ust’-Kirba formations, Uchur-Maya Region; Daskinskaya Formation, Yenisey Ridge, Siberia. Lower Cambrian, Chulaktau Formation, South Kazakhstan.
or, less likely, of stigonematalean cyanobacterial filaments or filamentous green algae.
Remarks.—The Chulaktau C. contexta specimens are probably compessed remnants of chroococcalean cyanobacterial colonies
Figure 13. Optical photomicrographs (1, 5, 6, 9–11, 13), confocal laser scanning micrographs (2, 7, 12, 14, 16), two-dimensional Raman images showing the spatial distribution of kerogen (3; blue, acquired at its ~1605cm−1 major band) and apatite (4; red, acquired at its major band at ~965cm−1), and optical images superimposed by kerogen 2-D Raman images (8, 15; blue) of quartz- and apatite-permineralized organic-walled microfossils from the Chulaktau Formation (1–5, 9, 10) and chert-permineralized specimens from the Berkuta Member of the Kyrshabakta Formation (6–8, 11–16). A part of the specimen in (1), indicated by the arrow, is shown in the Raman images in (3) and (4), whereas the part of a specimen denoted by the arrow in (13) is shown in the combined optical-Raman kerogen image in (15). (1–5) Botominella lineata Reitlinger, 1959: (1–4), 4681-365 (102), specimen location point (p.) 1, England Finder Slide (EFS) P47[3], GINPC 1282; 5, 4681-371 (117), p. 1, EFS F42[0], GINPC 1283. (6–8, 11–16) Berkutaphycus elongatus new genus and new species: (6–8) 4681-372 (115a), p. 25, EFS Q40[3], GINPC 1284; (11, 12) 4681-372 (115a), p. 1, EFS H38[0], GINPC 192; (13–15) 4681-372 (115a), p. 24, EFS H38[0], GINPC 1285; (16) 4681-382 (115a), p. 3, EFS Q42[0], GINPC 1286. (9) Leosphaeridia tenuissima Eisenack, 1958, 4681-371 (117), p. 7, EFS G39[2], GINPC 1287. (10) Leiosphaeridia minutissima (Naumova, 1949), 4681-364 (102), p. 4, J48[1], GINPC 1288.
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