Extreme abundance of ammonoids in mass accumulations from the Late Devonian of the Moroccan Anti-Atlas
The eastern Anti-Atlas is renowned for its highly fossiliferous outcrops of Devonian rocks. Ammonoids occur in rock-forming numbers at many localities in the Tafilalt and Maïder. This study addresses the questions of how many ammonoids are preserved within a standardized area as well as over the w...
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| Format: | Article |
| Language: | English |
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Institute of Paleobiology PAS
2022-09-01
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| Series: | Acta Palaeontologica Polonica |
| Subjects: | |
| Online Access: | https://www.app.pan.pl/archive/published/app67/app009352021.pdf |
| _version_ | 1797995329655668736 |
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| author | MERLE GREIF JAMES H. NEBELSICK CHRISTIAN KLUG |
| author_facet | MERLE GREIF JAMES H. NEBELSICK CHRISTIAN KLUG |
| author_sort | MERLE GREIF |
| collection | DOAJ |
| description | The eastern Anti-Atlas is renowned for its highly fossiliferous outcrops of Devonian rocks. Ammonoids occur in
rock-forming numbers at many localities in the Tafilalt and Maïder. This study addresses the questions of how many
ammonoids are preserved within a standardized area as well as over the whole Tafilalt and Maïder basins, and how
these mass occurrences formed. Five samples from the Tafilalt and Maïder were analysed. The ammonoids contained
therein were prepared, measured and counted as a base for estimates of the orders of magnitude of the total number of
preserved ammonoids and their biomass within the respective Famennian strata in the eastern Anti-Atlas. Two samples
were stratigraphically assigned to the lower Famennian, two samples to the middle Famennian and one sample to the
upper Famennian. For these samples, estimates for a standardized area of 1 km2 and a layer thickness of 100 mm lie
between 19.9×109 and 1.25×1010 ammonoids. The estimated numbers for the whole study area with a retrodeformed
size of 15 512.5 km2 and a sediment thickness of 100 mm, ranges from 30.9×1013 to 19.4×1014 ammonoids and a annual
accumulation of 15.4×109 to 97.1×109 ammonoid conchs. This corresponds to a annual total palaeo-biomass that ranges
from 25 954 t to 47 058 t within the whole study area and from 1.67 t to 3.03 t within an area of 1 km2. Based on these
results and size-distribution in the samples, the ecological role of the small and highly abundant, subspherical ammonoids
from the early and middle Famennian is discussed and reproductive rates are estimated. With ca. 230 eggs produced
by an adult female, cheiloceratids and small maeneceratids from the early Famennian deposits are at the lower end of
ammonoid reproductive rates. |
| first_indexed | 2024-04-11T09:59:55Z |
| format | Article |
| id | doaj.art-ca4a3ea002ae4b1fbda92b9ac9237022 |
| institution | Directory Open Access Journal |
| issn | 0567-7920 1732-2421 |
| language | English |
| last_indexed | 2024-04-11T09:59:55Z |
| publishDate | 2022-09-01 |
| publisher | Institute of Paleobiology PAS |
| record_format | Article |
| series | Acta Palaeontologica Polonica |
| spelling | doaj.art-ca4a3ea002ae4b1fbda92b9ac92370222022-12-22T04:30:27ZengInstitute of Paleobiology PASActa Palaeontologica Polonica0567-79201732-24212022-09-0167366768410.4202/app.00935.2021Extreme abundance of ammonoids in mass accumulations from the Late Devonian of the Moroccan Anti-AtlasMERLE GREIF0JAMES H. NEBELSICK1CHRISTIAN KLUG2Palaeontological Institute and Museum, University Zurich, Karl-Schmid-Strasse 4, 8006, Zurich, Switzerland.Department of Geoscience, Schnarrenbergstraße 94-96, 72076 Tübingen, Germany.Palaeontological Institute and Museum, University Zurich, Karl-Schmid-Strasse 4, 8006, Zurich, Switzerland.The eastern Anti-Atlas is renowned for its highly fossiliferous outcrops of Devonian rocks. Ammonoids occur in rock-forming numbers at many localities in the Tafilalt and Maïder. This study addresses the questions of how many ammonoids are preserved within a standardized area as well as over the whole Tafilalt and Maïder basins, and how these mass occurrences formed. Five samples from the Tafilalt and Maïder were analysed. The ammonoids contained therein were prepared, measured and counted as a base for estimates of the orders of magnitude of the total number of preserved ammonoids and their biomass within the respective Famennian strata in the eastern Anti-Atlas. Two samples were stratigraphically assigned to the lower Famennian, two samples to the middle Famennian and one sample to the upper Famennian. For these samples, estimates for a standardized area of 1 km2 and a layer thickness of 100 mm lie between 19.9×109 and 1.25×1010 ammonoids. The estimated numbers for the whole study area with a retrodeformed size of 15 512.5 km2 and a sediment thickness of 100 mm, ranges from 30.9×1013 to 19.4×1014 ammonoids and a annual accumulation of 15.4×109 to 97.1×109 ammonoid conchs. This corresponds to a annual total palaeo-biomass that ranges from 25 954 t to 47 058 t within the whole study area and from 1.67 t to 3.03 t within an area of 1 km2. Based on these results and size-distribution in the samples, the ecological role of the small and highly abundant, subspherical ammonoids from the early and middle Famennian is discussed and reproductive rates are estimated. With ca. 230 eggs produced by an adult female, cheiloceratids and small maeneceratids from the early Famennian deposits are at the lower end of ammonoid reproductive rates.https://www.app.pan.pl/archive/published/app67/app009352021.pdfcephalopodaammonoideapalaeoecologybiomassfecundityfamenniananti-atlas |
| spellingShingle | MERLE GREIF JAMES H. NEBELSICK CHRISTIAN KLUG Extreme abundance of ammonoids in mass accumulations from the Late Devonian of the Moroccan Anti-Atlas Acta Palaeontologica Polonica cephalopoda ammonoidea palaeoecology biomass fecundity famennian anti-atlas |
| title | Extreme abundance of ammonoids in mass accumulations from the Late Devonian of the Moroccan Anti-Atlas |
| title_full | Extreme abundance of ammonoids in mass accumulations from the Late Devonian of the Moroccan Anti-Atlas |
| title_fullStr | Extreme abundance of ammonoids in mass accumulations from the Late Devonian of the Moroccan Anti-Atlas |
| title_full_unstemmed | Extreme abundance of ammonoids in mass accumulations from the Late Devonian of the Moroccan Anti-Atlas |
| title_short | Extreme abundance of ammonoids in mass accumulations from the Late Devonian of the Moroccan Anti-Atlas |
| title_sort | extreme abundance of ammonoids in mass accumulations from the late devonian of the moroccan anti atlas |
| topic | cephalopoda ammonoidea palaeoecology biomass fecundity famennian anti-atlas |
| url | https://www.app.pan.pl/archive/published/app67/app009352021.pdf |
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