The hydrostatics of Paleozoic ectocochleate cephalopods (Nautiloidea and Endoceratoidea) with implications for modes of life and early colonization of the pelagic zone

Peterman, David J.; Barton, Christopher C.; Yacobucci, Margaret M.

doi:10.26879/884

Cited by 21 publications

(43 citation statements)

References 35 publications

(109 reference statements)

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“…Hydrostatic stability is significantly large enough for living Nipponites to assume static, syn vivo orientations throughout its entire ontogeny (excluding some short time after hatching when Reynolds numbers are significantly low). While the hydrostatic stability index slightly decreases throughout ontogeny, the computed values are all larger than the extant Nautilus (~0.05 [40]), suggesting that living Nipponites probably was not able to significantly modify its own apertural orientation (in terms of its vertical orientation). The highest stability in ectocochleates seem to occur for the orthocones, especially those without cameral deposits [36,40].…”

Section: Discussionmentioning

confidence: 99%

“…While the hydrostatic stability index slightly decreases throughout ontogeny, the computed values are all larger than the extant Nautilus (~0.05 [40]), suggesting that living Nipponites probably was not able to significantly modify its own apertural orientation (in terms of its vertical orientation). The highest stability in ectocochleates seem to occur for the orthocones, especially those without cameral deposits [36,40]. Lower stability values should occur for morphotypes with larger body chambers that wrap around the phragmocone (e.g., serpenticones [6,47,49]).…”

Section: Discussionmentioning

confidence: 99%

“…However, two portions had to be virtually reconstructed; the crushed ~5 cm section of the adoral-most body chamber, and 2) the earliest crioconic whorls that are partially embedded in a remnant of the original concretion. These two portions of the shell were reconstructed (Fig 2B) with array algorithms [37–40], which replicate a whorl section and simultaneously translate, rotate, and scale it to build the shell from the adoral direction to adapical direction (Table 1). Such arrays are similar to the morphospace parameters of Raup [61].…”

Section: Methodsmentioning

confidence: 99%

“…This depends upon the body chamber to phragmocone ratio. If the phragmocone (the chambered portion of the shell) is too small, the living cephalopod would not be able to compensate for its organismal weight and it would become negatively buoyant [34,36,40]. This condition also depends upon shell thickness and the densities assigned to each component of the living animal, which have been somewhat variable in previous research [39,41].…”

Section: Introductionmentioning

confidence: 99%

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The balancing act ofNipponites mirabilis(Nostoceratidae, Ammonoidea): managing hydrostatics during a complex ontogenetic trajectory

Peterman

Mikami

Inoué

2020

Preprint

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Nipponites is a heteromorph ammonoid with a complex and unique morphology that obscures its mode of life and ethology. The seemingly aberrant shell of this Late Cretaceous nostoceratid seems deleterious. However, hydrostatic simulations suggest that this morphology confers several advantages for exploiting a quasi-planktic mode of life. Virtual, 3D models of Nipponites mirabilis were used to compute various hydrostatic properties through 14 ontogenetic stages. At each stage, Nipponites had the capacity for neutral buoyancy and was not restricted to the seafloor. Throughout ontogeny, horizontally facing to upwardly facing soft body orientations were preferred. These orientations were aided by the obliquity of the shell’s ribs, which were parallel to former positions of the aperture during life. Static orientations were somewhat fixed, inferred by stability values that are slightly higher than extant Nautilus. The initial open-whorled, planispiral phase is well suited to horizontal backwards movement with little rocking. Nipponites then deviates from this coiling pattern with a series of alternating U-shaped bends in the shell. This modification allows for proficient rotation about the vertical axis, while possibly maintaining the option for horizontal backwards movement by redirecting its hyponome. These particular hydrostatic properties likely result in a tradeoff between hydrodynamic streamlining, suggesting that Nipponites assumed a low energy lifestyle of slowly pirouetting in search for planktic prey. Each computed hydrostatic property influences the others in some way, suggesting that Nipponites maintained a delicate hydrostatic balancing act throughout its ontogeny in order to facilitate this mode of life.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The balancing act ofNipponites mirabilis(Nostoceratidae, Ammonoidea): managing hydrostatics during a complex ontogenetic trajectory

Peterman

Mikami

Inoué

2020

Preprint

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“…For a cephalopod shell to experience postmortem drift, it must first become positively buoyant after the death of the animal. Numerous workers have investigated the buoyancy of cephalopod shells, both during life and after death, via physical experiments and mathematical models ( Trueman, 1941 ; Denton & Gilpin-Brown, 1966 ; Westermann, 1971 ; Chamberlain Jr & Weaver, 1978 ; Ward & Martin, 1978 ; Ward & Greenwald, 1982 ; Greenwald & Ward, 1987 ; Jacobs & Chamberlain Jr, 1996 ; Kröger, 2002 ; Hammer & Bucher, 2006 ; Naglik, Rikhtegar & Klug, 2014 ; Tajika et al, 2014 ; Hoffmann et al, 2015 ; Naglik et al, 2015 ), with new imaging and computational techniques ( Hoffmann & Zachow, 2011 ; Hoffmann et al, 2015 ; Lemanis et al, 2015 ; Peterman, Barton & Yacobucci, 2018 ) enabling ever more sophisticated analyses. Workers have established that, in life, modern nautilids are generally neutral to slightly negatively buoyant ( Ward & Martin, 1978 ; Greenwald & Ward, 1987 ).…”

Section: Introductionmentioning

confidence: 99%

Postmortem transport in fossil and modern shelled cephalopods

Yacobucci

2018

PeerJ

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The chambered shells of cephalopod mollusks, such as modern Nautilus and fossil ammonoids, have the potential to float after death, which could result in significant postmortem transport of shells away from living habitats. Such transport would call into question these clades’ documented biogeographic distributions and therefore the many (paleo)biological interpretations based on them. It is therefore imperative to better constrain the likelihood and extent of postmortem transport in modern and fossil cephalopods. Here, I combine the results of classic experiments on postmortem buoyancy with datasets on cephalopod shell form to determine that only those shells with relatively high inflation are likely to float for a significant interval after death and therefore potentially experience postmortem transport. Most ammonoid cephalopods have shell forms making postmortem transport unlikely. Data on shell forms and geographic ranges of early Late Cretaceous cephalopod genera demonstrate that even genera with shell forms conducive to postmortem buoyancy do not, in fact, show artificially inflated biogeographic ranges relative to genera with non-buoyant morphologies. Finally, georeferenced locality data for living nautilid specimens and dead drift shells indicate that most species have relatively small geographic ranges and experience limited drift. Nautilus pompilius is the exception, with a broad Indo-Pacific range and drift shells found far from known living populations. Given the similarity of N. pompilius to other nautilids in its morphology and ecology, it seems unlikely that this species would have a significantly different postmortem fate than its close relatives. Rather, it is suggested that drift shells along the east African coast may indicate the existence of modern (or recently extirpated) living populations of nautilus in the western Indian Ocean, which has implications for the conservation of these cephalopods.

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Effects of annulation on low Reynolds number flows over an orthocone

Thakor

Seh

Gladson

et al. 2023

Theor. Comput. Fluid Dyn.

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This study examines the influences of transverse annulation around a cone surface on the characteristics of a flow over the orthocone. This work is inspired by Spyroceras, a fossilized genus of the nautiloid family during the Paleozoic era, whose method of locomotion is understudied. As a baseline case, a flow over a smooth orthoconic model with a blunt cone end is investigated numerically at Reynolds numbers from 500 to 1500. As Reynolds increases, two different shedding mechanisms -hairpin-vortex wake and spiral-vortex wake -are captured. We notice that an introduction of annulation over the cone surface changes the critical Reynolds number for the transition of the shedding mechanism. The dominant shedding frequency increases with the Reynolds number for the smooth and annulated cone flows. Moreover, the annulation reduces the dominant frequency for the same Reynolds number and increases the time-averaged drag coefficient. Modal decompositions -Proper Orthogonal Decomposition (POD) and Spectral Proper Orthogonal Decomposition (SPOD) -are used to capture the coherent structures and their oscillating frequencies. We have captured modes corresponding to the hairpin-vortex wake and spiral-vortex wake shedding mechanisms. Effects of Annulation on Flows over an OrthoconeComparing the leading POD modes for the smooth and the annulated cone flows, we find that the annulation can reduce the twisting effects of the coherent structures in the wake. Additionally, we find that the SPOD analysis can identify modes presenting both hairpin-vortex wake and spiral-vortex wake in one flow condition as leading modes, while the POD leading modes only reveal one shedding mechanism in each flow.

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The hydrostatics of Paleozoic ectocochleate cephalopods (Nautiloidea and Endoceratoidea) with implications for modes of life and early colonization of the pelagic zone

Cited by 21 publications

References 35 publications

The balancing act ofNipponites mirabilis(Nostoceratidae, Ammonoidea): managing hydrostatics during a complex ontogenetic trajectory

The balancing act ofNipponites mirabilis(Nostoceratidae, Ammonoidea): managing hydrostatics during a complex ontogenetic trajectory

Postmortem transport in fossil and modern shelled cephalopods

Effects of annulation on low Reynolds number flows over an orthocone

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