...Figure 3 —Uncoated conulariids from the heterolithic facies, St. Lawrence Formation, northern Mississippi Valley photographed in an environmental chambered scanning electron microscope (Model ISI ABT55). 1, Baccaconularia meyeri n. sp., adapertural portion of tuberculate exoskeleton showing from...

... basin and shelf slope facies represented by dark shales and lime mudstones. In certain Ordovician and later rock units, Sphenothallus occurs in association with conulariids (e.g., Van Iten et al., 1996 ), a group whose oldest known representative, Baccaconularia , occurs in dolomitic claystones...

... symmetry occurs only as the intraspecific variations (e.g., Metaconularia anomala (Barrande, 1867 ); Sendino et al., 2012 ). From tetraradial Baccaconularia , the new taxon differs in expression of the median-aligned isolated structures. They appear as invaginations on Baccaconularia (Hughes et al...

... , 23.3), unlike other genera of conulariids (e.g., Glyptoconularia and Baccaconularia ) in which columns are more distinctive than rows. However, given that the differences in the means are small compared to the regional differences within individuals documented above, we do not use these differences...

... and microstructure of Baccaconularia Hughes, Gunderson et Weedon, 2000, a Cambrian (Furongian) conulariid from the north-central USA : Palaeoworld , v. 15 , p. 294 – 306 , doi:10.1016/j.palwor.2006.10.006 . Vermeij G.J. , 1989 , The origin of skeletons : Palaios , v. 4 , p. 585 – 589 , doi...

..., the corners are sulcate, and in some genera (e.g., Archaeoconularia Bouček, 1939 and Pseudoconularia Bouček, 1939 ) the longitudinal center line, or midline, of the faces also is sulcate or is marked by a straight or zigzagged ridge. In the oldest known conulariid, Baccaconularia Hughes, Gunderson...

... differentiation of soft part structures such as gonads, septa, and the vascular system. Finally, the apertural lobes of hexangulaconulariids are not triangular as in carinachitids and olivooids. Carinachitids share detailed similarities with Paleozoic conulariids (except for Cambrian Baccaconularia...

.... , Leme , J.M. , and Simões , M.G. , 2006b , Additional observations on the gross morphology and microstructure of Baccaconularia Hughes, Gunderson et Weedon, 2000, a Cambrian (Furongian) conulariid from the north-central USA : Palaeoworld , v...

... and Palaeontology, Nanjing, China (NIGP). We detected microscopic circular pores in 16 of the 21 species sampled ( Table 1 , Figs. 1 , 2.1–2.3 ). The five species in which pores were not detected are Archaeoconularia mirifica ( Reed, 1933 ), A . sp., Baccaconularia robinsoni Hughes, Gunderson, and Weedon...

... gracilis is a member of a subclade of conulariids that also includes the type species of Archaeoconularia , Exoconularia Sinclair, 1952 , Baccaconularia Hughes, Gunderson, and Weedon, 2000 , and Anaconularia . Now, however, Glyptoconularia consists of two known species, making it (presumably...

... : Journal of Paleontology , v. 79 , p. 400 – 407 . Van Iten , H. , Leme , J.M. , and Simões , M.G. , 2006 a, Additional observations on the gross morphology and microstructure of Baccaconularia Hughes, Gunderson et Weedon, 2000, a Cambrian (Furongian) conulariid from the north...