Part G, Bryozoa (Revised), vol. 1, ch. 4, p. 358-488

Utgaard, John; Blake, Daniel B.

doi:10.17161/dt.v0i0.5182

Cited by 6 publications

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“…Landing et al (2010) noted that a calcareous, granular or granular-prismatic microstructure is primary in some bryozoans. It is widespread in the Cystoporata Astrova, 1964 (Utgaard, 1983, p. 358), and occurs locally in the generally laminated Cryptostomata Vine, 1884 (Blake, 1983b, p. 550). The interpretation of a phosphate-replaced, originally calcareous composition in Pywackia (Landing et al, 2010) comports with the phosphatization of the limestones that yield its zooaria, and with the phosphatized sclerites of associated calcareous taxa (Table 1).…”

Section: Histology Of Pywackia Zooariamentioning

confidence: 99%

Distinguishing Earth’s oldest known bryozoan (Pywackia, late Cambrian) from pennatulacean octocorals (Mesozoic–Recent)

Landing¹,

Antcliffe²,

Brasier

et al. 2015

J. Paleontol.

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Bryozoans and all biomineralized metazoan phyla extend back into the Cambrian.PywackiaLanding, 2010 is confirmed as a secondarily phosphatized, late Cambrian stenolaemate bryozoan with colonial habit; mineralized zooarium (originally calcareous); granular/rarely granular-prismatic histology of its trilamellar walls; and polymorphism shown by deep autozooecia with diaphragms and hemiphragms, axial zooecia with diaphragms, and probable nanozooecia. The irregular form ofPywackiareflects growth as a 14-hedron that could not branch and a lack of structures such as thickened walls or styles that maintain regular autozooecial spacing in later stenolaemates.Pywackiais a stem group stenolaemate with a stolon modified into a budding axial zooid and autozooid budding. It is morphologically simpler than the highly evolved late Tremadocian bryozoans of South China with features such as styles, cystiphragms, thickened zooecial walls, and massive or branching colonies. As with some bryozoans,Pywackialacks holdfasts but has lineated living chambers and variably sized autozooecia. The late Cambrian origin of bryozoans, euconodonts, polyplacophorans, and cephalopods set the stage for the Ordovician Radiation’s complex communities.Pywackiais not a pennatulacean octocoral. It lacks both a pennatulacean axial rod histology and a budding zooid that remains confluent with daughter autozooids. Indeed,Pywackiawalled off its axial zooid. Similarity of the 6- and 12-sidedPywackiazooarium with circular to 4-sided pennatulacean axes only includes calcareous composition and the general shapes ofPywackiazooaria and someLituariaaxial rods. The pennatulacean record does not extend from the Mesozoic into the Cambrian, and early cnidarians were not phosphatic. The diagnosis ofPywackiais modified.

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Section: Histology Of Pywackia Zooariamentioning

confidence: 99%

Distinguishing Earth’s oldest known bryozoan (Pywackia, late Cambrian) from pennatulacean octocorals (Mesozoic–Recent)

Landing¹,

Antcliffe²,

Brasier

et al. 2015

J. Paleontol.

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Stenolaemate bryozoans from the upper triassic (Norian-Rhaetian) Nayband Formation, Central Iran

Schäfer

Senowbari‐Daryan

Hamedani

2003

Facies

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Bryozoans from the Murfreesboro and Pierce Limestones (Early Black Riveran, Middle Ordovician), Stones River Group, of Central Tennessee

Karklins

1985

J. Paleontol.

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The Murfreesboro Limestone and the succeeding Pierce Limestone (Black Riveran, Middle Ordovician) of the Stones River Group, the oldest rocks exposed in central Tennessee, contain a fossil invertebrate fauna including bryozoans. Bryozoans are relatively scarce in the Murfreesboro Limestone but are abundant in the overlying Pierce Limestone. The bryozoan fauna includes the cryptostomes, Escharopora, Graptodictya, Pachydictya, Phylloporina, Stictopora, Stictoporella, Trigonodictya, Ulrichostylus; the trepostomes Amplexopora, Batostoma, Hemiphragma, Nicholsonella, Parvohallopora; and the cystoporates Ceramophylla and Constellaria. These bryozoans are the oldest known in Tennessee and are the only early Black Riveran assemblage in North America described at the species level. Species of Nicholsonella, Pachydictya, and Stictopora in the Murfreesboro and species of Constellaria and Phylloporina? in the Pierce are closely related to those found in rocks of Chazyan age in New York and Vermont. Species of Ceramophylla, Escharopora, and Trigonodictya in the Pierce Limestone of central Tennessee are decidedly similar to species found in Black Riveran strata of New York. The stratigraphic ranges, geographic distribution, and taxonomy of previously described species from Tennessee are updated.

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Part G, Bryozoa (Revised), vol. 1, ch. 4, p. 358-488

Cited by 6 publications

References 0 publications

Distinguishing Earth’s oldest known bryozoan (Pywackia, late Cambrian) from pennatulacean octocorals (Mesozoic–Recent)

Distinguishing Earth’s oldest known bryozoan (Pywackia, late Cambrian) from pennatulacean octocorals (Mesozoic–Recent)

Stenolaemate bryozoans from the upper triassic (Norian-Rhaetian) Nayband Formation, Central Iran

Bryozoans from the Murfreesboro and Pierce Limestones (Early Black Riveran, Middle Ordovician), Stones River Group, of Central Tennessee

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