scholarly journals Allometric shell growth in infaunal burrowing bivalves: examples of the archiheterodonts Claibornicardia paleopatagonica (Ihering, 1903) and Crassatella kokeni Ihering, 1899

2018 ◽  
Author(s):  
Damián Eduardo Perez ◽  
María Belén Santelli
Keyword(s):  
Shell Growth ◽  
Late Oligocene ◽  
Allometric Growth ◽  
Ontogenetic Changes ◽  
Elliptic Fourier Analysis ◽  
Geometric Morphometric ◽  
Positive Allometry ◽  
Ontogenetic Trajectories ◽  
Early Paleocene ◽  
Ontogenetic Allometry

We present two cases of study of ontogenetic allometry in outlines of bivalves using longitudinal data, a rarity among fossils, based on the preserved post-larval record of shells. The examples are two infaunal burrowing bivalves of the southern South America, Claibornicardia paleopatagonica (Archiheterodonta: Carditidae) (early Paleocene) and Crassatella kokeni (Archiheterodonta: Crassatellidae) (late Oligocene–late Miocene). Outline analyses were conducted using a geometric morphometric approach (Elliptic Fourier Analysis), obtaining successive outlines from shells’ growth lines, which were used to reconstruct ontogenetic trajectories. In both taxa, ontogenetic changes are characterized by the presence of positive allometry in the extension of posterior end, resulting in elongated adult shells. This particular allometric growth is known in others infaunal burrowing bivalves (Claibornicardia alticostata and some Spissatella species) and the resulting adult morphology is present in representatives of several groups (e.g. Carditidae, Crassatellidae, Veneridae, Trigoniidae). Taxonomic, ecological and evolutionary implications of this allometric growth pattern are discussed.

scholarly journals Allometric shell growth in infaunal burrowing bivalves: examples of the archiheterodonts Claibornicardia paleopatagonica (Ihering, 1903) and Crassatella kokeni Ihering, 1899

2018 ◽  
Author(s):  
Damián Eduardo Perez ◽  
María Belén Santelli
Keyword(s):  
Shell Growth ◽  
Late Oligocene ◽  
Allometric Growth ◽  
Ontogenetic Changes ◽  
Elliptic Fourier Analysis ◽  
Geometric Morphometric ◽  
Positive Allometry ◽  
Ontogenetic Trajectories ◽  
Early Paleocene ◽  
Ontogenetic Allometry

We present two cases of study of ontogenetic allometry in outlines of bivalves using longitudinal data, a rarity among fossils, based on the preserved post-larval record of shells. The examples are two infaunal burrowing bivalves of the southern South America, Claibornicardia paleopatagonica (Archiheterodonta: Carditidae) (early Paleocene) and Crassatella kokeni (Archiheterodonta: Crassatellidae) (late Oligocene–late Miocene). Outline analyses were conducted using a geometric morphometric approach (Elliptic Fourier Analysis), obtaining successive outlines from shells’ growth lines, which were used to reconstruct ontogenetic trajectories. In both taxa, ontogenetic changes are characterized by the presence of positive allometry in the extension of posterior end, resulting in elongated adult shells. This particular allometric growth is known in others infaunal burrowing bivalves (Claibornicardia alticostata and some Spissatella species) and the resulting adult morphology is present in representatives of several groups (e.g. Carditidae, Crassatellidae, Veneridae, Trigoniidae). Taxonomic, ecological and evolutionary implications of this allometric growth pattern are discussed.

scholarly journals Allometric shell growth in infaunal burrowing bivalves: examples of the archiheterodontsClaibornicardia paleopatagonica(Ihering, 1903) andCrassatella kokeniIhering, 1899

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5051 ◽  
Author(s):  
Damián Eduardo Perez ◽  
María Belén Santelli
Keyword(s):  
Shell Growth ◽  
Late Oligocene ◽  
Allometric Growth ◽  
Ontogenetic Changes ◽  
Elliptic Fourier Analysis ◽  
Geometric Morphometric ◽  
Positive Allometry ◽  
Ontogenetic Trajectories ◽  
Early Paleocene ◽  
Ontogenetic Allometry

We present two cases of study of ontogenetic allometry in outlines of bivalves using longitudinal data, a rarity among fossils, based on the preserved post-larval record of shells. The examples are two infaunal burrowing bivalves of the southern South America,Claibornicardia paleopatagonica(Archiheterodonta: Carditidae) (early Paleocene) andCrassatella kokeni(Archiheterodonta: Crassatellidae) (late Oligocene–late Miocene). Outline analyses were conducted using a geometric morphometric approach (Elliptic Fourier Analysis), obtaining successive outlines from shells’ growth lines, which were used to reconstruct ontogenetic trajectories. In both taxa, ontogenetic changes are characterized by the presence of positive allometry in the extension of posterior end, resulting in elongated adult shells. This particular allometric growth is known in others infaunal burrowing bivalves (Claibornicardia alticostataand someSpissatellaspecies) and the resulting adult morphology is present in representatives of several groups (e.g., Carditidae, Crassatellidae, Veneridae, Trigoniidae). Taxonomic, ecological and evolutionary implications of this allometric growth pattern are discussed.

scholarly journals Ontogenetic allometry in the foot size of Oligoryzomys flavescens (Waterhouse, 1837) (Rodentia, Sigmodontinae)

2015 ◽  
Vol 75 (2) ◽  
pp. 435-441 ◽  
Author(s):  
R. Maestri ◽  
R. Fornel ◽  
TRO. Freitas ◽  
JR. Marinho
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Sexual Dimorphism ◽  
Encounter Rate ◽  
Allometric Growth ◽  
Positive Allometry ◽  
Rate Of Growth ◽  
Ontogenetic Allometry ◽  
Males And Females ◽  
Oligoryzomys Flavescens

Ontogenetic allometry is the study of how the size or shape of certain structures changes over the course of an animal’s development. In this study, using Huxley's formula of allometric growth (1932), we assessed the changes in the rate of growth of the feet size of the sigmodontine rodent Oligoryzomys flavescens during its ontogeny and compared differences between males and females. We find evidence of a change of polarity during the ontogenetic development of the species, with the presence of positive allometry during pregnancy and negative allometry in adulthood. Moreover, we note the presence of sexual dimorphism in the size of the feet, in which males of the species have a higher rate of growth than females. This growth pattern is positively related to escape from predators in childhood in both sexes and, in adulthood, provides a higher encounter rate of females by males, due to the larger displacement of the latter. We suggest that both the forces of natural selection and sexual selection have acted to shape the evolution of foot size in this species.

To grow or to reproduce? Sexual dimorphism and ontogenetic allometry in two Sesarmidae species (Crustacea: Brachyura)

2018 ◽  
Vol 99 (2) ◽  
pp. 473-486 ◽  
Author(s):  
Murilo Zanetti Marochi ◽  
Marcelo Costa ◽  
Renata Daldin Leite ◽  
Isis Danniele Cury Da Cruz ◽  
Setuko Masunari
Keyword(s):  
Sexual Dimorphism ◽  
Frontal Region ◽  
Shape Variation ◽  
Spatial Partitioning ◽  
Geometric Morphometric ◽  
Size Dependent ◽  
Ontogenetic Trajectories ◽  
Ontogenetic Trajectory ◽  
Ontogenetic Allometry ◽  
Aratus Pisonii

Differences between sexes may arise either during development or at the adult stage only. In both cases growth rate during development and level of allometry may influence sexual dimorphism and ontogenetic trajectories. To analyse the period in which sexual dimorphism appears during ontogeny and assess allometric ontogeny in Sesarmidae crabs, we evaluated: (1) sexual dimorphism in shape and size of the carapace and cheliped propodus of juveniles and adultAratus pisoniiandArmases rubripes, and (2) their ontogenetic trajectory, using geometric morphometric (GM) techniques. We tested the hypothesis that sexual dimorphism in sesarmid crab shape takes place before the puberty moult. InAratus pisoniithere was sexual dimorphism in the shape of the carapace in juveniles (before puberty moult) and variation between juveniles and adults was size-dependent, especially in the frontal region of the carapace. ForArmases rubripesthis shape sexual dimorphism was detected only after the puberty moult (adult phase). For males, carapace variation between juveniles and adults was also size-dependent, especially in the carapace frontal region, but for females, there was a change in shape with different trajectories. Our results also indicated that shape variation is a common pattern during growth for Sesarmidae species. This ontogenetic shape variation may be associated with spatial partitioning between juveniles and adults.

Ontogeny in the steinmanellines (Bivalvia: Trigoniida): an intra- and interspecific appraisal using the Early Cretaceous faunas from the Neuquén Basin as a case study

Paleobiology ◽  
2021 ◽  
pp. 1-23
Author(s):  
Pablo S. Milla Carmona ◽  
Dario G. Lazo ◽  
Ignacio M. Soto
Keyword(s):  
Trajectory Analysis ◽  
Sedentary Lifestyle ◽  
Shape Change ◽  
Shell Shape ◽  
Shape Variation ◽  
Ontogenetic Changes ◽  
Ontogenetic Trajectories ◽  
Higher Genus ◽  
Gradual Decay

Abstract Despite the paleontological relevance and paleobiological interest of trigoniid bivalves, our knowledge of their ontogeny—an aspect of crucial evolutionary importance—remains limited. Here, we assess the intra- and interspecific ontogenetic variations exhibited by the genus Steinmanella Crickmay (Myophorellidae: Steinmanellinae) during the early Valanginian–late Hauterivian of Argentina and explore some of their implications. The (ontogenetic) allometric trajectories of seven species recognized for this interval were estimated from longitudinal data using 3D geometric morphometrics, segmented regressions, and model selection tools, and then compared using trajectory analysis and allometric spaces. Our results show that within-species shell shape variation describes biphasic ontogenetic trajectories, decoupled from ontogenetic changes shown by sculpture, with a gradual decay in magnitude as ontogeny progresses. The modes of change characterizing each phase (crescentic growth and anteroposterior elongation, respectively) are conserved across species, thus representing a feature of Steinmanella ontogeny; its evolutionary origin is inferred to be a consequence of the rate modification and allometric repatterning of the ancestral ontogeny. Among species, trajectories are more variable during early ontogenetic stages, becoming increasingly conservative at later stages. Trajectories’ general orientation allows recognition of two stratigraphically consecutive groups of species, hinting at a potentially higher genus-level diversity in the studied interval. In terms of functional morphology, juveniles had a morphology more suited for active burrowing than adults, whose features are associated with a sedentary lifestyle. The characteristic disparity of trigoniids could be related to the existence of an ontogenetic period of greater shell malleability betrayed by the presence of crescentic shape change.

Morphological maturity and allometric growth in the squat lobster Munida rugosa

2009 ◽  
Vol 89 (6) ◽  
pp. 1189-1194 ◽  
Author(s):  
Thomas Claverie ◽  
I. Philip Smith
Keyword(s):  
Measurement Error ◽  
Sexual Maturity ◽  
Carapace Length ◽  
Size Range ◽  
Size At Maturity ◽  
Allometric Growth ◽  
Positive Allometry ◽  
Squat Lobster

Size at the onset of sexual maturity was determined in Munida rugosa based on allometric growth of chelipeds and abdomen, and on the proportion of ovigerous females. The variability of three different measurements of carapace length (CL) used previously for M. rugosa was also evaluated to minimize measurement error. Both sexes had symmetrical cheliped length and allometric cheliped growth over the size-range investigated, but males showed increased allometry beyond 22 mm CL. Females had greater positive allometry in abdomen width than males, but their size at maturity could not be precisely determined because sampled females were too large.

On the morphospace of eurypterine sea scorpions

2021 ◽  
pp. 1-6
Author(s):  
Russell D. C. BICKNELL ◽  
Lisa AMATI
Keyword(s):  
New Taxa ◽  
Compound Eye ◽  
Developmental Changes ◽  
Apex Predators ◽  
Geometric Morphometric ◽  
Eye Morphology ◽  
Morphometric Analyses ◽  
Ontogenetic Trajectories ◽  
Landmark Analyses ◽  
Shape Data

ABSTRACT Eurypterids (sea scorpions) are a group of extinct, marine euchelicerates that have an extensive Palaeozoic record. Despite lacking a biomineralised exoskeleton, eurypterids are abundantly preserved within select deposits. These collections make statistical analyses comparing the morphology of different genera possible. However, eurypterid shape has not yet been documented with modern geometric morphometric tools. Here, we summarise the previous statistical assessments of eurypterid morphology and expand this research by presenting landmark and semi-landmark analyses of 115 eurypterid specimens within the suborder Eurypterina. We illustrate that lateral compound eye morphology and position drives specimen placement in morphospace and separates proposed apex predators from more generalist forms. Additionally, evidence for size clusters in Eurypterus that may reflect ontogeny is uncovered. We highlight the use of geometric morphometric analyses in supporting the naming of new taxa and demonstrate that these shape data represent a novel means of understanding inter-generic ontogenetic trajectories and uncovering developmental changes within the diverse euarthropod group.

Cranial morphology and ontogeny of the Permo-Carboniferous temnospondyl Archegosaurus decheni Goldfuss, 1847 from the Saar–Nahe Basin, Germany

2005 ◽  
Vol 96 (2) ◽  
pp. 131-162 ◽  
Author(s):  
Florian Witzmann
Keyword(s):  
Prey Capture ◽  
Three Dimensional ◽  
Nasolacrimal Duct ◽  
Larval Period ◽  
Cranial Morphology ◽  
Growth Stages ◽  
Ontogenetic Changes ◽  
Positive Allometry ◽  
Lateral Process ◽  
Different Growth Stages

ABSTRACTMorphology and ontogenetic changes in the skull and hyobranchium of the Permo-Carboniferous temnospondyl Archegosaurus decheni from the Saar–Nahe Basin (SW Germany) are described in detail, based on 181 skulls ranging from 18 to 279 mm in length. Three-dimensional skull reconstructions including the palate of different growth stages are provided. The extremely elongate choanae and up to four median symphyseal teeth are unique to A. decheni. Among neurocranial elements, the exoccipital is well ossified and forms the paroccipital process as in stereospondyls. The shaft of the stapes which projects into the squamosal embayment grows with positive allometry and possesses a distinct lateral process. The basibranchial is well ossified in adults and exhibits a complex, spoon-like morphology. Small larvae were euryphagous and used non-directed suction and jaw prehension during prey capture. Larger larvae and adults were mainly ichthyophagous, as is indicated by the increasingly elongated snout, differentiation of marginal teeth, and nutrition remains. After a prolonged larval period, juvenile and adult A. decheni remained in the aquatic habitat, as suggested by the presence of lateral line sulci, the ‘aquatic type’ of septomaxilla and choana, and the absence of a nasolacrimal duct.

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