Silurian tarphycerid<i>Discoceras</i>(Cephalopoda, Nautiloidea): systematics, embryonic development and paleoecology

Manda, Štěpán; Turek, Vojtěch

doi:10.1017/jpa.2017.122

Cited by 4 publications

(5 citation statements)

References 59 publications

(90 reference statements)

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“…The palaeogeographic position of the Perunica microplate in the early Cambrian to Late Ordovician in the cold-water areas of the peri-Gondwanan shelf (see Ramsköld & Chatterton 1991, Frýda & Frýdová 2014, as a part of the Armorican terrane assemblage, drifted during the Silurian to a position closer to Baltica in the late Wenlock. This trajectory, favoured by Cocks & Torsvik (2002), Budil et al (2014), and Manda & Turek (2018), receives further support herein, based on the occurrence of the Exallaspis representatives outside the Laurussian region, in the distinct Homerian-age trilobite assemblages of the Motol Formation in the Prague Basin. Etymology: This species is named after its occurrence in the lower Silurian epicontinental sea of the microcontinent Perunica.…”

Section: Systematic Partsupporting

confidence: 71%

The Rare Trilobites Exallaspis (Odontopleuridae) and Kosovoproetus? (Tropidocoryphidae) in the Homerian (Silurian) Of The Prague Basin, Bohemian Massif

Hartl

Vokáč

Pavlovič³

et al. 2022

Folia Musei Rerum Naturalium Bohemiae Occidentalis. Geologica Et Paleobiologica

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The deep-water Aulacopleura koninckii Assemblage in the lower Homerian (T. testis Sub-Biozone) “Aulacopleura shales“ strata at the classical ‘Barrande’s pits’ locality on the Černidla hillside at Loděnice in the Prague Basin is supplemented by the addition of two new trilobite taxa, viz. Exallaspis? perunicana sp. n. and Kosovoproetus? aff. praecursor (Přibyl & Vaněk 1987). The palaeogeographic distribution of Exallapis Ramsköld & Chatterton, 1991 is extended by the occurrence of Exallaspis? perunicana sp. n. and the younger Exallaspis sp. in the upper Homerian (the P. parvus – G. nassa Biozone) of the Prague Basin, reflecting the faunal migration between the southern shelf of the Baltica palaeocontinent and the Perunica microcontinent accross the Rheic Ocean. The small dimensions of the K.? aff. praecursor exoskeletons compared to those of K.? praecursor in the bordering shallow-water Liolalax–Sphaerexochus– Cheirurus Assemblage represent another example of adaptive nanism in trilobites of the Aulacopleura-Raphiophorus Biofacies.

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Section: Systematic Partsupporting

confidence: 71%

The Rare Trilobites Exallaspis (Odontopleuridae) and Kosovoproetus? (Tropidocoryphidae) in the Homerian (Silurian) Of The Prague Basin, Bohemian Massif

Hartl

Vokáč

Pavlovič³

et al. 2022

Folia Musei Rerum Naturalium Bohemiae Occidentalis. Geologica Et Paleobiologica

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“…In the Silurian tarphyceratid Ophioceras simplex, the diameter of the initial portion of the conch ranges from 1.2 to 2.6 mm (N = 94) (Turek and Manda 2016). This diameter appears to have a similar range in Silurian species of Discoceras (Manda and Turek 2018) and suggests a decrease in the size of the protoconch in at least some tarphyceratid lineages.…”

Section: Early Development Of the Conchmentioning

confidence: 87%

High-level classification of the nautiloid cephalopods: a proposal for the revision of the Treatise Part K

King¹,

Evans

2019

Swiss J Palaeontol

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High-level classification of the nautiloid cephalopods has been largely neglected since the publication of the Russian and American treatises in the early 1960s. Although there is broad general agreement amongst specialists regarding the status of nautiloid orders, there is no real consensus or consistent approach regarding higher ranks and an array of superorders utilising various morphological features has been proposed. With work now commencing on the revision of the Treatise Part K, there is an urgent need for a methodical and standardised approach to the high-level classification of the nautiloids. The scheme proposed here utilizes the form of muscle attachment scars as a diagnostic feature at subclass level; other features (including siphuncular structures and cameral deposits) are employed at ordinal level. We recognise five subclasses of nautiloid cephalopods (Plectronoceratia, Multiceratia, Tarphyceratia nov., Orthoceratia, Nautilia) and 18 orders including the Order Rioceratida nov. which contains the new family Bactroceratidae. This scheme has the advantage of relative simplicity (it avoids the use of superorders) and presents a balanced approach which reflects the considerable morphological diversity and phylogenetic longevity of the nautiloids in comparison with the ammonoid and coleoid cephalopods. To avoid potential confusion arising in the higher levels of nautiloid classification employed in the revision of the Treatise Part K, we propose herein to replace the suffix '-oidea' at subclass level with the suffix '-ia'. Apart from removing ambiguity and clarifying the nomenclature, this approach also brings greater consistency and affinity with modern zoological classification schemes used for cephalopods. The original Treatise Part K adopted an 'abbreviated' form of name for nautiloid orders using the ending '-cerida' rather than '-ceratida' (e.g., Order Actinocerida rather than Actinoceratida). For the revision of Treatise Part K, we propose using the 'full' version of the ordinal names. This approach re-employs several order names in their original form, e.g., Ellesmeroceratida, Oncoceratida, and Tarphyceratida. For reasons of consistency, we also apply the same to ordinal names created since the original Treatise Part K; therefore, Order Bisonocerida becomes Bisonoceratida.

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“…Discinocaris and Peltocaris appeared to be overshadowed by Aptychopsis and almost disappeared from palaeontological literature in recent decades, only Page et al . (2008) mentioned them as structures whose affinities remain uncertain, and Manda & Turek (2018) briefly mentioned them as cephalopod opercula. Devonian genera of discinocarins such as Ellipsocaris and Spathiocaris are currently widely regarded as the lower jaws of ammonoids (Frye & Feldmann 1991; Goolaerts et al .…”

Section: Resultsmentioning

confidence: 99%

“…It should be noted, however, that the second hypothesis is now mostly consider outdated, the last article in which the Apthychopsis was considered as the part of jaw apparatus was published almost 40 years ago (Zakharov & Lominadze 1983). In more recent publications it is referred to exclusively as an operculum (Stridsberg 1984; Edgecombe & Chatterton 1987; Holland 1987a, 1987b; Frye & Feldmann 1991; Kiselev 1992; Holland 1996; Manda 2007; Manda & Turek 2018).…”

mentioning

confidence: 99%

Early Palaeozoic Discinocarina: a key to the appearance of cephalopod jaws

Mironenko

2021

LET

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Cephalopoda is the only class of molluscs in which virtually all its modern representatives have a pair of powerful jaws. There is little doubt that jaws have contributed to the evolutionary success of cephalopods, but their origin still remains a mystery. Though cephalopods appeared at the end of the Cambrian, the oldest unequivocal jaws have been reported to date from the Late Devonian, though they were initially interpreted as phyllopod crustaceans of the suborder Discinocarina. After their relation with ammonoids was proven, they were considered as opercula, and only later their mandibular nature was recognized and widely accepted. Finds of discinocarins from Silurian deposits are still considered as opercula of ammonoid ancestors ‐ nautiloids of the order Orthocerida. However, according to modern ideas, there is no place within their soft body for the location of such large opercula. Moreover, the repeated appearance of very similar structures in the same evolutionary line at least twice, but in different places of the body and for different purposes seems highly improbable. A new hypothesis is proposed herein, in which the Silurian fossils, earlier assigned to Discinocarina, are not specialized opercula, but protective shields, to defend orthocerids not from the predators, but from their own prey. The chitinous plates around the mouth likely appeared in the Silurian orthocerids for protection from such damage and later, during Silurian and Devonian, most likely gradually evolved into the jaws.

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Silurian tarphyceridDiscoceras(Cephalopoda, Nautiloidea): systematics, embryonic development and paleoecology

Cited by 4 publications

References 59 publications

The Rare Trilobites Exallaspis (Odontopleuridae) and Kosovoproetus? (Tropidocoryphidae) in the Homerian (Silurian) Of The Prague Basin, Bohemian Massif

The Rare Trilobites Exallaspis (Odontopleuridae) and Kosovoproetus? (Tropidocoryphidae) in the Homerian (Silurian) Of The Prague Basin, Bohemian Massif

High-level classification of the nautiloid cephalopods: a proposal for the revision of the Treatise Part K

Early Palaeozoic Discinocarina: a key to the appearance of cephalopod jaws

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