Colour Patterns in Early Devonian Cephalopods from the Barrandian Area: Taphonomy and taxonomy

Turek, Vojtěch

doi:10.4202/app.2007.0064

Cited by 12 publications

(20 citation statements)

References 29 publications

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“…A specimen of Dawsonoceras annulatum (Sowerby, 1816) shows the same characteristic. A recently discovered colour pattern in two earlier Devonian (Lochkovian) straight-shelled cephalopods from Central Bohemia (Turek 2009) also shows its development around the entire circumference of the shell. Both specimens, belonging perhaps to separate species, are fragments flattened in shale, so their internal morphology, which could indicate their living position, is unknown.…”

Section: Colour Pattern and Its Significance For The Determination Ofmentioning

confidence: 88%

“…The development of colour stripes only on the dorsal half of the shell has been documented in a few Early Palaeozoic orthocerids and pseudoorthocerids (Ruedemann 1921, Teichert 1964, Turek 2009, Manda & Turek 2009) and one Ordovician endocerid (Balashov 1964). Some authors (Ruedemann 1921, Flower 1955 andothers) have assumed that it is a characteristic of the majority of orthocerids, indicating horizontal life position of the shell.…”

Section: Colour Pattern and Its Significance For The Determination Ofmentioning

confidence: 99%

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"An endocochleate experiment" in the Silurian straight-shelled cephalopod Sphooceras

Turek¹,

Manda²

2012

Bull. Geosci.

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Sphooceras truncatum (Barrande, 1860), a Silurian straight-shelled cephalopod with a short finger-shaped shell, is one of a few cephalopods in which natural truncation of the apical part of the phragmocone from the rest of the conch is confirmed. Periodic natural removal of the apical part of the shell (4 to 5 phragmocone chambers) preceded formation of a terminal callus and a calcareous plug closing the septal foramen. The apical callus probably originated by fusion of the truncation septum with episeptal deposits. These structures temporarily formed the new apex on which two additional calcareous layers had been secreted. A unique specimen preserves a colour pattern in the convex apical region, which proves that the shell in Sphooceras was temporarily completely surrounded by mantle extending from the body chamber, i.e. the cephalopod was at least temporarily endocochleate. The co-occurrence of different growth stages of S. truncatum together with one type of short juvenile orthoceracone shell, with a maximum of eight phragmocone chambers and a very small subglobular initial chamber indicates that these embryonic shells may belong to Sphooceras. Two other genera are discussed, both previously included in the family Sphooceratidae: Disjunctoceras Gnoli in Kiselev, 1992 and Andigenoceras Gnoli in Kiselev, 1992. The newly discovered thickening of the apex in "Disjunctoceras" disjunctum, the type species of Disjunctoceras, indicates that this species does not differ substantially from Sphooceras and should be reassigned to this genus. Similarly, representatives of Andigenoceras also possess characteristic features of Sphooceras. Sphooceras has many features characteristic for modern cephalopods: short, thin-walled, semi-internal shell; phragmocone reduced to only a few chambers; uncalcified connecting rings; apical callus (a structure analogous to the belemnite rostrum); retractor muscle scars situated dorsally; very small protoconch without cicatrix. In some exceptionally well-preserved cephalopods with orthoceracone shell radula with seven rows of teeth were observed. All these features support the thesis that some straight-shelled cephalopods are evolutionarily closer to coleoids than nautiloids and their separation from nautiloids is legitimate. Vascular imprints on the surface of the cameral deposits provide further support for their primary origin and the existence of a cameral mantle. The character of cameral deposits in Sphooceras demonstrates that the systematic value of these structures in other straight-shelled cephalopods, a subject of controversy, has limited value. The morphology of Sphooceras also demonstrates that the boundary between endocochleate and ectocochleate cephalopods is not sharp, i.e. internalisation of the shell in cephalopods occurred repeatedly.•

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Section: Colour Pattern and Its Significance For The Determination Ofmentioning

confidence: 88%

Section: Colour Pattern and Its Significance For The Determination Ofmentioning

confidence: 99%

"An endocochleate experiment" in the Silurian straight-shelled cephalopod Sphooceras

Turek¹,

Manda²

2012

Bull. Geosci.

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“…Colour pattern is known only in a small number of Early Palaeozoic nautiloid genera (Kobuk & Mapes 1989, Turek 2009 and further references herein). Colour patterning was described in the Ordovician tarphycerid Trocholites Conrad, 1838 from Germany (Schuh 1920), in the Silurian oncocerids Octameroceras Hyatt, 1900from Gotland (Stritsberg 1985 and Rizosceras Hyatt, 1900 from Canada (Foerste & Savage 1927).…”

Section: Colour Pattern In Nautiloidsmentioning

confidence: 99%

“…Turek (2009) assumed that low oxygen level on and below the sea-floor, combined with rapid burial and cementation provided suitable conditions for the preservation of colour markings. However, although such 756 Figure 1.…”

Section: Colour Pattern In Nautiloidsmentioning

confidence: 99%

“…Hyatt (1883Hyatt ( , 1994Hyatt ( , 1900 and later Flower & Kummel (1950) adopted new systematic approaches emphasising the importance of the morphology of the siphonal tube. Subsequent studies of muscle scars (e.g., Mutvei 1964, Evans 2005, Kröger & Mutvei 2005, embryonic development (e.g., Manda 2008), and shell colouration (e.g., Kobluk & Mapes 1989, Turek 2009) provided important additional data with significant implications in relation to the taxonomy and palaeoecology of nautiloids. Some of this data is not yet fully incorporated into concepts of classification and remain a matter of debate; for example, the significance of variation in the number of multiple paired muscle scars in oncocerids and discosorids.…”

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A Silurian oncocerid with preserved colour pattern and muscle scars (Nautiloidea)

Manda¹,

Turek²

2009

Bull. Geosci.

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A new genus Euryrizocerina (Nautiloidea, Oncocerida, Oonoceratidae) from the late Silurian strata of Bohemia (Prague Basin) is established. Two species are included within the genus: the type species E. normata (Barrande, 1877) and E. pulchra sp. nov. The genus is striking for two features -the preservation of shell colouration and muscle attachment scars in the type species. These features are reliable for taxonomic and palaeoecological analysis of nautiloids, but due to their only occasional preservation in fossils, the evolutionary trends of these characters remain poorly understood. The colour pattern of Euryrizocerina consists of irregular pulsed transverse bands that clearly differ from the colour patterns known in other oncocerids where rather regular wave-like or zig-zag bands have been observed. It is questionable whether the new type of colouration represents a taxonomic or morphotypic feature, as Euryrizocerina is the first oncocerid to be recognised with a highly curved shell that retains colouration. Oncocerids exhibit multiple paired muscle scars and there is uncertainty whether these represent an original metamery, inherited from a cephalopod ancestor, or a derived feature. Euryrizocerina possesses four pairs of retractor muscle scars, but its ancestor "Oonoceras" fraternum and allied forms, possess multiple pairs of muscle scars around the base of the body-chamber, as do the majority of oncocerids. A similar reduction in the number of muscle scar pairs has been documented in Devonian rutoceratoids. The high evolutionary plasticity of muscle attachments patterns, as indicated by these examples, suggests that the muscle complex and its attachment to the shell was under adaptive control and is more likely to reflect the form of the shell and the mode of life of the organism. It seems likely that shell colouration and the pattern of attachment of the retractor muscles have a much more complex evolutionary history (including several convergences) than was previously supposed. •

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Late Emsian Rutoceratoidea (Nautiloidea) from the Prague Basin, Czech Republic: morphology, diversity and palaeoecology

Manda

Turek

2011

Palaeontology

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Nautiloids of the superfamily Rutoceratoidea from the late Emsian (late Early Devonian) of the Prague Basin (Czech Republic) are commented upon. Species recognized include the hercoceratids Hercoceras mirum, H.? transiens, Ptenoceras proximum, P. nudum, P. minusculum and Anomaloceras anomalum, as well as the rutoceratids Adelphoceras bohemicum, Homoadelphoceras devonicans, Pseudorutoceras bolli and Goldringia? devonicans. In addition, four new species are described: Parauloceras regulare sp. nov., Roussanoffoceras chlupaci sp. nov., Otomaroceras sp. nov. and Goldringia sp. nov. Morphology and distribution patterns of Pragian and late Emsian rutoceratoid faunas from the Prague Basin are compared. They show that an increased diversity was accompanied by a higher level of specialization of rutoceratoids, which manifested itself in low abundance, increased facies dependence and greater variation in shell size during the Early Devonian. The evolution of sculpture and a contracted aperture, both regarded as protective adaptive features, was also examined, but no adaptive trend towards more pronounced sculpture and constriction of the aperture was found to have occurred in the Early Devonian. A more distinctive sculpture was, however, observed in shallow-water assemblages of P. proximum in comparison with deeper-water faunules, and two additional cephalopod species were examined in order to obtain comparative data. The presence of distinct sculpture patterns in coeval shallowand deeper-water assemblages suggests limited migration between them and consequently reflects some degree of territoriality in Devonian nautiloids. New data on early shell development in P. proximum are presented. During the Choteč Event, rutoceratoid generic diversity dropped dramatically, one family became extinct and the Early Devonian diversification of the group came to an end. The recovery of nautiloid faunas was slower than that of other cephalopods and associated, unrelated invertebrates. The absence of change in abundance patterns between Pragian and late Emsian rutoceratoid faunas, i.e. prior to and subsequent to ammonoid radiation, suggests that the appearance and radiation of the latter group in the early Emsian did not affect the structure of nautiloid assemblages, i.e. these two clades did not occupy the same niches.

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Colour Patterns in Early Devonian Cephalopods from the Barrandian Area: Taphonomy and taxonomy

Abstract: Five cephalopod specimens from the Lower Devonian of Bohemia (Czech Republic)

Cited by 12 publications

References 29 publications

"An endocochleate experiment" in the Silurian straight-shelled cephalopod Sphooceras

"An endocochleate experiment" in the Silurian straight-shelled cephalopod Sphooceras

A Silurian oncocerid with preserved colour pattern and muscle scars (Nautiloidea)

Late Emsian Rutoceratoidea (Nautiloidea) from the Prague Basin, Czech Republic: morphology, diversity and palaeoecology

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