Chancelloria sp. B

Clausen, Sébastien & Álvaro, J. Javier, 2006, Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain, Acta Palaeontologica Polonica 51 (2), pp. 223-238 : 228

Chancelloria sp. B

Fig. 4C–E .

Material.—More than 50 specimens preserved as phosphatic steinkerns in the Middle Cambrian “Beleño” facies, sections Cr 2 to Cr 4.

Description.—Radially symmetrical sclerites with central vertical ray (up to 300 µm long), and 5 to 7 lateral rays lying on the same plane, which can be approximately of equal (ca. 300 µm) or variable (200 to 400 µm) length (though most distal parts of the rays probably eroded off). A broken specimen ( Fig. 4E ) shows circular transverse sections of rays.

Remarks.—The Cantabrian species is relatively similar to other previously described sclerites, such as those from the Early Cambrian of Southern Spain (Ossa−Morena Zone; Fernández−Remolar 2001: fig. 4a, b) and Antarctica ( Wrona 2004: fig. 6j); and from the Middle Cambrian of Australia ( Mehl 1998: pl. 7: 3); however, the lateral rays of the Cantabrian specimens lie on the same plane whereas they are clearly bent in the others. The sclerites referred to as Chancelloria sp. A above differ from Chancelloria sp. B . in the significantly larger central ray and prominently recurved lateral rays.

Figures

Fig. 4. Scanning electron micrographs of skeletonized microfossils from the Lower–Middle Cambrian transition of the Esla Nappe, Cantabrian Mountains, Spain. A, B. Chancelloria sp. A; chancelloriid sclerites; section Cr4, “Beleño” facies, upper member of the Láncara Formation, early Leonian. A. DGO 21129, longitudinal section. B. DGO 21130, lateral view. C–E. Chancelloria sp. B; chancelloriid sclerites; section Cr4, “Beleño” facies, upper member of the Láncara Formation, early Leonian. C. (1+6) sclerite, DGO 21131, lateral views. D. (1+5) sclerite, DGO 21132, upper view. E. Incomplete (1+7) sclerite, DGO 21133, upper view. F. Parazhijnites cf. guizhouensis Qian and Yin, 1984; cambroclavid sclerite; section Cr4, “Beleño” facies, upper member of the Láncara Formation, early Leonian; DGO 21134, oblique (F1) and lateral (F2) views. G–J. Torellella sp.; hyolithelminth tubes; section Cr4, ooid/bioclastic limestone, lower member of the Láncara Formation, latest Early Cambrian. G. DGO 21135, lateral view. H. 21136, lateral view. I. DGO 21137, lateral view showing elliptic perforation (I1) and detail of the faint growth lines (squared area on I1; tilt adjust). J. DGO 21138, lateral (J1) and distal (J2) views. K. Phosphatic undefined tube; section Cr4, ooid/bioclastic limestone, lower member of the Láncara Formation, latest Early Cambrian; DGO 21139, lateral view (K1) and detail of broken termination (K2). Scale bars 250 µm, except I2 and K2 for which are 50 µm.