A Newly Hatched Coiled Nautiloid From the Permian of Italy

Mapes, Royal H.; Niko, Shuji; Frýda, Jiří; Nützel, Alexander

doi:10.1666/pleo05-144.1

Cited by 7 publications

(6 citation statements)

References 9 publications

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“…An exception to the trend toward smaller embryonic shells is the lineage leading to Agoniatites , which has the largest known initial chamber of all ammonoids (compare House 1985, 1996). By contrast, the main trend in nautiloid evolution might have been the increase in size of the embryonic shell (Dzik 1981, p. 162, 1984), possibly also in the lineage leading up to Recent Allonautilus and Nautilus (Mapes et al 2007).…”

Section: Resultsmentioning

confidence: 99%

Early Evolutionary Trends in Ammonoid Embryonic Development

et al. 2012

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A major macroecological event happened long after the Cambrian Explosion and the Great Ordovician Biodiversification Event, the Devonian Nekton Revolution . It signifies the rapid occupation of the free water column with nektonic animals, an important component of all post-Silurian and Recent marine ecosystems. This event coincides with an explosive diversification of gnathostomes (jawed fishes), the initial radiation of ammonoids (extinct, externally shelled cephalopods), and the intensification of the radiation of mollusks with planktotrophic larvae or hatchlings (ammonoids, bivalves, gastropods; see also Frýda et al. 2008;Manda and Frýda 2010).Many externally shelled mollusk groups (ammonoids, dacryoconarids, gastropods, nautiloids, etc.) show a progressive coiling in their embryonic and/or post-embryonic conch in the Devonian

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Section: Resultsmentioning

confidence: 99%

Early Evolutionary Trends in Ammonoid Embryonic Development

et al. 2012

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“…Nautiloid eggs and juveniles are rather large, whereas Ammonoidea and Bactritoidea have smaller early juvenile shells: ammonitellas and bactritellas (Mapes et al . ; Mapes and Nützel ). Scaphopoda have tube‐like bilateral symmetrical larval shells (Engeser and Riedel ).…”

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confidence: 99%

Larval ecology and morphology in fossil gastropods

Nützel

2014

Palaeontology

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The shell of marine gastropods conserves and reflects early ontogeny, including embryonic and larval stages, to a high degree when compared with other marine invertebrates. Planktotrophic larval development is indicated by a small embryonic shell (size is also related to systematic placement) with little yolk followed by a multiwhorled shell formed by a free‐swimming veliger larva. Basal gastropod clades (e.g. Vetigastropoda) lack planktotrophic larval development. The great majority of Late Palaeozoic and Mesozoic ‘derived’ marine gastropods (Neritimorpha, Caenogastropoda and Heterobranchia) with known protoconch had planktotrophic larval development. Dimensions of internal moulds of protoconchs suggest that planktotrophic larval development was largely absent in the Cambrian and evolved at the Cambrian–Ordovician transition, mainly due to increasing benthic predation. The evolution of planktotrophic larval development offered advantages and opportunities such as more effective dispersal, enhanced gene flow between populations and prevention of inbreeding. Early gastropod larval shells were openly coiled and weakly sculptured. During the Mid‐ and Late Palaeozoic, modern tightly coiled larval shells (commonly with strong sculpture) evolved due to increasing predation pressure in the plankton. The presence of numerous Late Palaeozoic and Triassic gastropod species with planktotrophic larval development suggests sufficient primary production although direct evidence for phytoplankton is scarce in this period. Contrary to previous suggestions, it seems unlikely that the end‐Permian mass extinction selected against species with planktotrophic larval development. The molluscan classes with highest species diversity (Gastropoda and Bivalvia) are those which may have planktotrophic larval development. Extremely high diversity in such groups as Caenogastropoda or eulamellibranch bivalves is the result of high phylogenetic activity and is associated with the presence of planktotrophic veliger larvae in many members of these groups, although causality has not been shown yet. A new gastropod species and genus, Anachronistella peterwagneri, is described from the Late Triassic Cassian Formation; it is the first known Triassic gastropod with an openly coiled larval shell.

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“…Growth lines or longitudinal lirae are present. The nepionic constriction, a break in shell curvature or a change in sculpture, is linked with hatching (Ruzhentsev and Shimansky 1954;Shimansky 1967;Mapes et al 2007). In the Triassic Tainoceratina, the embryonic shell of some taxa corresponds roughly to the first whorl (e.g.…”

Section: Early Ontogeny Of Lechritrochoceratids and Later Nautilids: mentioning

confidence: 99%

“…data). However, the fossil record of hatchlings of lechritrochocerids and tainoceratids is very limited (Miller and Thomas 1936;Ruzhentsev and Shimansky 1954;Mapes et al 2007). A possible benefit of the curved embryonic shell may be the egg-size; the curved shell needs less space than an almost straight shell of the same axis length.…”

Section: Early Ontogeny Of Lechritrochoceratids and Later Nautilids: mentioning

confidence: 99%

Embryonic and early juvenile development in the Silurian basal nautilid Peismoceras Hyatt, 1894

Manda

Turek

2019

Swiss J Palaeontol

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The family Lechritrochoceratidae Flower, 1950 includes the earliest cephalopods acquiring a lateral pair of retractor muscles-a diagnostic character of the Nautilida. The embryonic shell of Silurian lechritrochoceratids is minute, with a diameter of 2-4 mm, a length of 4.5-7.5 mm and consists of three growth stages: (1) elliptical, dorsoventrally elongated and flattened cicatrix with a central bar, (2) a short, rapidly expanding shell part and (3) a gradually expanding, very slightly curved shell. The sculpture consists of longitudinal lirae, and faintly distinct growth lines or ridges. A ventral lobe formed by ridges corresponds in its course to post-hatching ribs. This lobe indicates the early development of the hyponome in the egg capsule. The hatching is indicated by the appearance of ribs and sometimes also by a change in shell curvature. The juvenile stage is characterised by the prolongation of the body chamber, a change in the shape of the cross section, increasing expansion rate, and by a deepening of the hyponomic sinus. The juveniles were probably demersal with the aperture oriented more or less towards the sea floor. The dorsoventrally elongated cicatrix with a central bar and a depression corresponding to the caecum position and the appearance of longitudinal lirae near the cicatrix margin support systematic position of the lechritrochoceratids among the Nautilida. The hemispherical apex and the very slightly curved embryonic shell, ribbed juvenile shell and narrow annular elevation around the body chamber base, however, call for the definition of a new suborder Lechritrochoceratina.

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A Newly Hatched Coiled Nautiloid From the Permian of Italy

Cited by 7 publications

References 9 publications

Early Evolutionary Trends in Ammonoid Embryonic Development

Early Evolutionary Trends in Ammonoid Embryonic Development

Larval ecology and morphology in fossil gastropods

Embryonic and early juvenile development in the Silurian basal nautilid Peismoceras Hyatt, 1894

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