Emsian Ammonoidea and the age of the Hunsrück Slate (Rhenish Mountains, Western Germany)

Baets, Kenneth De; Klug, Christian; Korn, Dieter; Bartels, Christoph; Poschmann, Markus

doi:10.1127/pala/299/2013/1

Cited by 52 publications

(131 citation statements)

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“…The density distribution of the fossil sample is also flatter (more platykurtic) than is ever observed in a single time slice Fossil ammonoids can be deformed and distorted by abrasion, compaction, dissolution and tectonic deformation, these processes represent an important obstacle to research on their variability. Depending on the degree of deformation, specimens can be retrodeformed to their original shape in many cases, but not necessarily their original dimensions (Blake 1878;Tan 1973;Rocha and Dias 2005;De Baets et al 2013b;Yamaji and Maeda 2013). Studies of intraspecific variability have therefore preferentially used largely undeformed, three-dimensionally preserved specimens.…”

Section: Sources Of Variation Within and Between Fossil Populationsmentioning

confidence: 99%

“…The appearance of ornamentation and measurements of the same parameters might differ between differentially preserved specimens (internal moulds vs. shell preservation). Furthermore, fossils can be extremely compacted in some lithologies, particularly in shales, which might lead to the increase of the whorl height and diameter as well as a decrease of whorl thickness and umbilical width (e.g., Morard 2004;De Baets et al 2013b;Wani and Gupta 2015). These effects could even lead to the erection of endemic "species" restricted to certain lithologies (see De Baets et al 2013b for such a case in the early Emsian ammonoid Ivoites).…”

Section: Sources Of Variation Within and Between Fossil Populationsmentioning

confidence: 99%

“…Furthermore, fossils can be extremely compacted in some lithologies, particularly in shales, which might lead to the increase of the whorl height and diameter as well as a decrease of whorl thickness and umbilical width (e.g., Morard 2004;De Baets et al 2013b;Wani and Gupta 2015). These effects could even lead to the erection of endemic "species" restricted to certain lithologies (see De Baets et al 2013b for such a case in the early Emsian ammonoid Ivoites). In such cases, it probably makes sense to correct for taphonomic processes in the most conservative way to avoid artificially inflating diversity (De Baets et al 2013b).…”

Section: Sources Of Variation Within and Between Fossil Populationsmentioning

confidence: 99%

“…These effects could even lead to the erection of endemic "species" restricted to certain lithologies (see De Baets et al 2013b for such a case in the early Emsian ammonoid Ivoites). In such cases, it probably makes sense to correct for taphonomic processes in the most conservative way to avoid artificially inflating diversity (De Baets et al 2013b). Specimens from the same sample (with similar preservation) are generally deformed in the same way, so that the introduced systematic error might be less significant (Dzik 1985).…”

Section: Sources Of Variation Within and Between Fossil Populationsmentioning

confidence: 99%

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Ammonoid Intraspecific Variability

Baets

Bert

Hoffmann

et al. 2015

Topics in Geobiology

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Because ammonoids have never been observed swimming, there is no alternative to seeking indirect indications of the locomotory abilities of ammonoids. This approach is based on actualistic comparisons with the closest relatives of ammonoids, the Coleoidea and the Nautilida, and on the geometrical and physical properties of the shell. Anatomical comparison yields information on the locomotor muscular systems and organs as well as possible modes of propulsion while the shape and physics of ammonoid shells provide information on buoyancy, shell orientation, drag, added mass, cost of transportation and thus on limits of acceleration and swimming speed. On these grounds, we conclude that ammonoid swimming is comparable to that of Recent nautilids and sepiids in terms of speed and energy consumption, although some ammonoids might have been slower swimmers than nautilids.

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Section: Sources Of Variation Within and Between Fossil Populationsmentioning

confidence: 99%

Section: Sources Of Variation Within and Between Fossil Populationsmentioning

confidence: 99%

Section: Sources Of Variation Within and Between Fossil Populationsmentioning

confidence: 99%

Section: Sources Of Variation Within and Between Fossil Populationsmentioning

confidence: 99%

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Ammonoid Intraspecific Variability

Baets

Bert

Hoffmann

et al. 2015

Topics in Geobiology

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“…Broad outcrops of sediments of the Hunsrückschiefer type (here Zerf Formation) in this region have, thus far, not provided any faunal evidence for biostratigraphic correlation with the Hunsrückschiefer of the classical sites, which has recently been dated as early Emsian (Middle Kaub Formation) by ammonoids (De Baets et al 2013b). The recent discovery of palynomorph assemblages at Siesbach now holds promises for closer assessment of age relations among sediments of the Hunsrückschiefer type and in particular to those of the type area at Bundenbach and Gemünden.…”

Section: Discussionmentioning

confidence: 99%

Palynological data from sediments of the Hunsruckschiefer type, Lower Devonian of the SW Hunsruck, Germany

Brocke¹,

Kneidl²,

Wilde³

et al. 2017

Bull. Geosci.

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A three‐dimensional placoderm (stem‐group gnathostome) pharyngeal skeleton and its implications for primitive gnathostome pharyngeal architecture

Brazeau

Friedman

Jerve

et al. 2017

Journal of Morphology

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The pharyngeal skeleton is a key vertebrate anatomical system in debates on the origin of jaws and gnathostome (jawed vertebrate) feeding. Furthermore, it offers considerable potential as a source of phylogenetic data. Well‐preserved examples of pharyngeal skeletons from stem‐group gnathostomes remain poorly known. Here, we describe an articulated, nearly complete pharyngeal skeleton in an Early Devonian placoderm fish, Paraplesiobatis heinrichsi Broili, from Hunsrück Slate of Germany. Using synchrotron light tomography, we resolve and reconstruct the three‐dimensional gill arch architecture of Paraplesiobatis and compare it with other gnathostomes. The preserved pharyngeal skeleton comprises elements of the hyoid arch (probable ceratohyal) and a series of branchial arches. Limited resolution in the tomography scan causes some uncertainty in interpreting the exact number of arches preserved. However, at least four branchial arches are present. The final and penultimate arches are connected as in osteichthyans. A single median basihyal is present as in chondrichthyans. No dorsal (epibranchial or pharyngobranchial) elements are observed. The structure of the pharyngeal skeleton of Paraplesiobatis agrees well with Pseudopetalichthys from the same deposit, allowing an alternative interpretation of the latter taxon. The phylogenetic significance of Paraplesiobatis is considered. A median basihyal is likely an ancestral gnathostome character, probably with some connection to both the hyoid and the first branchial arch pair. Unpaired basibranchial bones may be independently derived in chondrichthyans and osteichthyans.

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Emsian Ammonoidea and the age of the Hunsrück Slate (Rhenish Mountains, Western Germany)

Cited by 52 publications

References 0 publications

Ammonoid Intraspecific Variability

Ammonoid Intraspecific Variability

Palynological data from sediments of the Hunsruckschiefer type, Lower Devonian of the SW Hunsruck, Germany

A three‐dimensional placoderm (stem‐group gnathostome) pharyngeal skeleton and its implications for primitive gnathostome pharyngeal architecture

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