Dataset Information

Remora cranial vein morphology and its functional implications for attachment.

ABSTRACT: Remora fishes adhere to, and maintain long-term, reversible attachment with, surfaces of varying roughness and compliance under wetted high-shear conditions using an adhesive disc that evolved from the dorsal fin spines typical of other fishes. Evolution of this complex hierarchical structure required extensive reorganization of the skull and fin spines, but the functional role of the soft tissues of the disc are poorly understood. Here I show that remora cranial veins are highly-modified in comparison to those of other vertebrates; they are transposed anteriorly and enlarged, and lie directly ventral to the disc on the dorsum of the cranium. Ancestrally, these veins lie inside the neurocranium, in the dura ventral to the brain, and return blood from the eyes, nares, and brain to the heart. Repositioning of these vessels to lie in contact with the ventral surface of the disc lamellae implies functional importance associated with the adhesive mechanism. The position of the anterior cardinal sinus suggests that it may aid in pressurization equilibrium during attachment by acting as a hydraulic differential.

SUBMITTER: Flammang BE

PROVIDER: S-EPMC5517627 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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Remora cranial vein morphology and its functional implications for attachment.

Flammang Brooke E BE Kenaley Christopher P CP

Scientific reports 20170719 1

Remora fishes adhere to, and maintain long-term, reversible attachment with, surfaces of varying roughness and compliance under wetted high-shear conditions using an adhesive disc that evolved from the dorsal fin spines typical of other fishes. Evolution of this complex hierarchical structure required extensive reorganization of the skull and fin spines, but the functional role of the soft tissues of the disc are poorly understood. Here I show that remora cranial veins are highly-modified in com ...[more]

PMID: 28725032

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Project description:BackgroundCaptive facilities such as zoos are uniquely instrumental in conservation efforts. To fulfill their potential as bastions for conservation, zoos must preserve captive populations as appropriate proxies for their wild conspecifics; doing so will help to promote successful reintroduction efforts. Morphological changes within captive populations may be detrimental to the fitness of individual animals because these changes can influence functionality; thus, it is imperative to understand the breadth and depth of morphological changes occurring in captive populations. Here, we conduct a meta-analysis of scientific literature reporting comparisons of cranial measures between captive and wild populations of mammals. We investigate the pervasiveness of cranial differences and whether cranial morphological changes are associated with ecological covariates specific to individual species, such as trophic level, dietary breadth, and home range size.ResultsCranial measures of skull length, skull width, and the ratio of skull length-to-width differed significantly between many captive and wild populations of mammals reported in the literature. Roughly half of captive populations differed from wild populations in at least one cranial measure, although the degree of changes varied. Carnivorous species with a limited dietary breadth displayed the most consistent changes associated with skull widening. Species with a more generalized diet displayed less morphological changes in captivity.ConclusionsWild and captive populations of mammals differed in cranial morphology, but the nature and magnitude of their cranial differences varied considerably across taxa. Although changes in cranial morphology occur in captivity, specific changes cannot be generalized for all captive mammal populations. The nature of cranial changes in captivity may be specific to particular taxonomic groups; thus, it may be possible to establish expectations across smaller taxonomic units, or even disparate groups that utilize their cranial morphology in a similar way. Given that morphological changes occurring in captive environments like zoos have the potential to limit reintroduction success, our results call for a critical evaluation of current captive husbandry practices to prevent unnecessary morphological changes.

Project description:BackgroundHeterodontosaurids are an important but enigmatic and poorly understood early radiation of ornithischian dinosaurs. The late-surviving heterodontosaurid Fruitadens haagarorum from the Late Jurassic (early Tithonian) Morrison Formation of the western USA is represented by remains of several small (<1 metre total body length, <1 kg body mass) individuals that include well-preserved but incomplete cranial and postcranial material. Fruitadens is hypothesized to represent one of the smallest known ornithischian dinosaurs.Methodology/principal findingsWe describe the cranial and postcranial anatomy of Fruitadens in detail, providing comparisons to all other known heterodontosaurid taxa. High resolution micro-CT data provides new insights into tooth replacement and the internal anatomy of the tooth-bearing bones. Moreover, we provide a preliminary functional analysis of the skull of late-surviving heterodontosaurids, discuss the implications of Fruitadens for current understanding of heterodontosaurid monophyly, and briefly review the evolution and biogeography of heterodontosaurids.Conclusions/significanceThe validity of Fruitadens is supported by multiple unique characters of the dentition and hindlimb as well as a distinct character combination. Fruitadens shares highly distinctive appendicular characters with other heterodontosaurids, strengthening monophyly of the clade on the basis of the postcranium. Mandibular morphology and muscle moment arms suggest that the jaws of late-surviving heterodontosaurids, including Fruitadens, were adapted for rapid biting at large gape angles, contrasting with the jaws of the stratigraphically older Heterodontosaurus, which were better suited for strong jaw adduction at small gapes. The lack of wear facets and plesiomorphic dentition suggest that Fruitadens used orthal jaw movements and employed simple puncture-crushing to process food. In combination with its small body size, these results suggest that Fruitadens was an ecological generalist, consuming select plant material and possibly insects or other invertebrates.

Dataset Information

Remora cranial vein morphology and its functional implications for attachment.

Publications

Remora cranial vein morphology and its functional implications for attachment.

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