Porpitids (Cnidaria: Hydrozoa) from the early Cambrian (Series 2: Stage 4) of Nevada, U.S.A.
- Published
- Accepted
- Subject Areas
- Paleontology, Taxonomy, Zoology
- Keywords
- Porpitid, Hydrozoa, Cnidaria, Cambrian, Burgess Shale type fossil, Elemental mapping
- Copyright
- © 2017 Lieberman et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2017. Porpitids (Cnidaria: Hydrozoa) from the early Cambrian (Series 2: Stage 4) of Nevada, U.S.A. PeerJ Preprints 5:e2706v1 https://doi.org/10.7287/peerj.preprints.2706v1
Abstract
The morphology and affinities of newly discovered soft-bodied fossils from the early Cambrian (Series 2: Stage 4, Dyeran) Carrara Formation that resemble modern and fossil porpitids are discussed. These specimens show substantial similarity to the Ordovician porpitid Discophyllum peltatum Hall, 1847. The status of various Proterozoic and Phanerozoic taxa previously referred to porpitids is also briefly considered. To verify that the specimens were not dubio- or pseudofossils, elemental mapping using energy dispersive X-ray spectroscopy (EDS) was conducted. This indicated that the fossils were not hematite, iron sulfide, pyrolusite, or other abiologic mineral precipitates. Instead, their status as biologic structures and thus actual fossils is supported. Enrichment in the element carbon, and also possibly to some extent the elements magnesium and iron, seems to be playing some role in the preservation process.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
SEM image and spectra of KUMIP 389538
An SEM image and the spectra and weight percentages of elements for the portion of the D. cf. peltatum fossil, KUMIP specimen 389538, subjected to elemental mapping; maps shown in Fig. 1.
SEM image and spectra of another part of KUMIP 389538
An SEM image and the spectra and weight percentages of elements for a different portion of the D. cf. peltatum fossil, KUMIP specimen 389538, that was also subjected to elemental mapping; maps shown in supplemental file “ElementalmapsKUMIP389538a2.pdf”.
SEM image and element maps of another part of D. cf. peltatum, KUMIP specimen 389538, and surrounding rock matrix
The margin of the fossil is demarcated by the illuminated line that runs from approximately the middle part of the left-hand side of each panel to approximately the middle part of the bottom side of each panel in the C, P, and Ca maps. The surrounding matrix thus occupies the lower left hand quadrant of each panel, while the fossil occupies the rest of each panel. Scale bars are 1mm. Images generated using Oxford Instruments AZtecEnergy EDS software.