Fig 1.
Palaeoposition of the Guryul Ravine Section in the northern peri-gondwanan region during the P-T transition (after Shen et al., 2006; base map after Ziegler et al., 1997 under a CC BY license (3606870471810); with permission from [Elsevier], original copyright year- 2006).
Fig 2.
Permian Triassic Boundary (PTB) study section at Guryul Ravine, Kashmir (after Kapoor 1996) Red Triangles pointing to the levels of reported occurrence of thecamoebians along with previously studied faunal elements.
Conodont biozones after Algeo et al., 2007. PTB- Permian-Triassic boundary; LPME- Late Permian Mass Extinction. Occurrence of thecamoebians.
Fig 3.
Thecamoebian fossil record of the families Arcellidae and Centropyxidae Thecamoebians preserved in sediments noted by a circle, whereas thecamoebians preserved in amber are noted by a triangle.
The basal part of the figure depicting ecology of the genera Centropyxis and Arcella through time has been modified in the light of this study and other published data. (a) Wolf, 1995; (b) Kumar et al., 2011; (c) Farooqui et al., 2014; (d) Wightmann et al., 1994; (e) Medioli et al., 1990a; (f) Schönborn et al., 1999; (g) Poinar et al., 1993; (h) Schmidt et al., 2004;(i) Waggoner, 1996b; (j) van Hengstum et al., 2007; (k) Porter and Knoll, 2000 and (*) denotes this study. The geological time axis is not to scale. The figure has been modified after van Hengstum et al. 2007 (with written permission from the original author van Hengstum).
Fig 4.
Location and geological map of the study area also depicting geological section of Guryul Ravine and the recovered thecamoebians (modified after Bhat and Bhat, 1997).
Fig 5.
Relative abundance of recovered thecamoebians showing high diversity within the genera Centropyxis.
Unit E2 displays maximum diversity. The scale represents number of forms present.
Table 1.
A list of examined thecamoebian forms and their morphological details.
The morphological features (hypostome shape and dimensions, number of visible spines) have been subjected to post-depositional compression and compaction and are thus incomparable to the recent forms. All the morphometric measurements are in μm.
Fig 6.
A,B. Centropyxis platystoma (Penard, 1890) Elongated shell, apertural view, 3- shows inner linning of the test, slide no. 14974. C. Cucurbitella tricuspis (Y53/4), slide no.14974. D. Centropyxis Stein, 1857, (Q40/3), test agglutinated and small in size, silde no.14881. E-G. Centropyxis aerophila-complex Foissner and Korganova, 2000 (E,F: S11/4; 7: E35/4), E,F- apertural and dorsal view, respectively, G- apertural view, slide nos. (E,F) 14976, (G) 14973. H,I. Cyclopyxis eurystoma (Deflandre, 1929) (R15/3) H-Ventral view and I-dorsal view, test is small in size, slide no. 14976. J. Arcella Ehrenberg, 1832 (T63/4), slide no.14971. K,L. Incertae sedis (U18/2), test shows two apertures, K-aperture one, L- aperture two, test small in size, slide no. 14976.
Fig 7.
(A, B) Centropyxis aculeata var. spinosa, (H20/2), A- apertural view (lobate aperture), B- Dorsal view showing spines on the folded dorsal surface, slide no. 14976. C, D. Centropyxis aculeata (R36/3), C- dorsal view showing broken spines at the margin, D- apertural view shows ventral margin of the aperture connected to the dorsal face by bridges (shown by arrows) slide no.14869. E-L, Centropyxis aculeata (E,F: Q22/3; G,H: P31/4; I,J: R41/2; K,L: N18/2) (E,G,I, K apertural views; F, H, J, L dorsal views showing spines), test covered with sand grains and BDOM from the vicinity, sand grains impart grey colour to the tests, slide nos.(E,F) 14975, (G,H) 14869, (I,J) 14975, (K,L) 14972. Scale bar: 20 μm.
Fig 8.
A. Centropyxis aculeata var. spinosa Ehrenberg, 1832 (Q31/4), apertural view, slide no. 14974. B. Centropyxis aculeata var. spinosa Ehrenberg, 1832 (E41/3), B-dorsal view showing spines, xenosomes on the test, C. ventral/apertural view, slide no. 14869. D. Centropyxis aculeata var. spinosa Ehrenberg, 1832 (T40/3), apertural view showing 9–10 spines at the margin, degraded brown organic matter and detrital grains on the agglutinated test, slide no. 14975. E. Centropyxis aculeata var. spinosa Ehrenberg, 1832 (U21/3), apertural view, dark coloured test with three spines, slide no. 14976. F. Centropyxis aculeata var. spinosa Ehrenberg, 1832 (N18/4), apertural view, test light coloured agglutinated formed by material from the surrounding, slide no. 14973. G, H. Centropyxis aculeata var. discoides Penard, 1902 (P29/2), test constituted of both autosomes and xenosomes, slide no. 14974. I. Centropyxis aculeata var. discoides Penard, 1902 (K34/1), slide no. 14976. J-L Centropyxis aculeata var. discoides Ehrenberg, 1832 (H30/4), apertural view, J, image is focussed on the margin of the test showing two broken spines, K- aperture focused, L- Margin focused showing a complete spine, slide no. 14976.