Skin of the Cretaceous mosasaur
            <i>Plotosaurus</i>
            : implications for aquatic adaptations in giant marine reptiles

Alwmark, C.; Fiorillo, Anthony R.

doi:10.1098/rsbl.2009.0097

Cited by 24 publications

(34 citation statements)

References 12 publications

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“…Moreover, judging from the preserved squamation in LACM 128319, the primitively-limbed mosasauroid Vallecillosaurus [4], and highly piscine mosasaurine Plotosaurus [5], there was a gradual reduction in both relative and absolute body scale size with increased marine specializations in mosasaurs, to suggest an adaptation for improved hydrodynamic efficiency by minimizing friction drag when water flowed past the body [29].…”

Section: Discussionmentioning

confidence: 99%

Convergent Evolution in Aquatic Tetrapods: Insights from an Exceptional Fossil Mosasaur

et al. 2010

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Mosasaurs (family Mosasauridae) are a diverse group of secondarily aquatic lizards that radiated into marine environments during the Late Cretaceous (98–65 million years ago). For the most part, they have been considered to be simple anguilliform swimmers – i.e., their propulsive force was generated by means of lateral undulations incorporating the greater part of the body – with unremarkable, dorsoventrally narrow tails and long, lizard-like bodies. Convergence with the specialized fusiform body shape and inferred carangiform locomotory style (in which only a portion of the posterior body participates in the thrust-producing flexure) of ichthyosaurs and metriorhynchid crocodyliform reptiles, along with cetaceans, has so far only been recognized in Plotosaurus, the most highly derived member of the Mosasauridae. Here we report on an exceptionally complete specimen (LACM 128319) of the moderately derived genus Platecarpus that preserves soft tissues and anatomical details (e.g., large portions of integument, a partial body outline, putative skin color markings, a downturned tail, branching bronchial tubes, and probable visceral traces) to an extent that has never been seen previously in any mosasaur. Our study demonstrates that a streamlined body plan and crescent-shaped caudal fin were already well established in Platecarpus, a taxon that preceded Plotosaurus by 20 million years. These new data expand our understanding of convergent evolution among marine reptiles, and provide insights into their evolution's tempo and mode.

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Section: Discussionmentioning

confidence: 99%

Convergent Evolution in Aquatic Tetrapods: Insights from an Exceptional Fossil Mosasaur

et al. 2010

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“…[9]), thereby reducing frictional drag when trying to overtake smaller, more streamlined prey. Surface deformation (and thereby frictional drag), may have been further reduced by the cross-woven helical fiber bundles in the subjacent dermis.…”

Section: Discussionmentioning

confidence: 99%

Three-Dimensionally Preserved Integument Reveals Hydrodynamic Adaptations in the Extinct Marine Lizard Ectenosaurus (Reptilia, Mosasauridae)

Everhart

2011

PLoS ONE

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The physical properties of water and the environment it presents to its inhabitants provide stringent constraints and selection pressures affecting aquatic adaptation and evolution. Mosasaurs (a group of secondarily aquatic reptiles that occupied a broad array of predatory niches in the Cretaceous marine ecosystems about 98–65 million years ago) have traditionally been considered as anguilliform locomotors capable only of generating short bursts of speed during brief ambush pursuits. Here we report on an exceptionally preserved, long-snouted mosasaur (Ectenosaurus clidastoides) from the Santonian (Upper Cretaceous) part of the Smoky Hill Chalk Member of the Niobrara Formation in western Kansas, USA, that contains phosphatized remains of the integument displaying both depth and structure. The small, ovoid neck and/or anterior trunk scales exhibit a longitudinal central keel, and are obliquely arrayed into an alternating pattern where neighboring scales overlap one another. Supportive sculpturing in the form of two parallel, longitudinal ridges on the inner scale surface and a complex system of multiple, superimposed layers of straight, cross-woven helical fiber bundles in the underlying dermis, may have served to minimize surface deformation and frictional drag during locomotion. Additional parallel fiber bundles oriented at acute angles to the long axis of the animal presumably provided stiffness in the lateral plane. These features suggest that the anterior torso of Ectenosaurus was held somewhat rigid during swimming, thereby limiting propulsive movements to the posterior body and tail.

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“…Indeed, published data show that keratin is robust, and its molecular fingerprints can persist into the geological record . In addition to feathers, the presence of many keratin‐derived structures in the rock record, including skin , beak , hair , and claw sheaths (and references therein), as well as ongoing experiments, support this conclusion. If the matrix depicted in association with “melanosomes” can be unambiguously assigned to keratin, and if animal melanin or its degradation products can be localized to the bodies, then any further arguments about their identity would be moot.…”

Section: Chemical Characterization Of the Matrix In Which Presumed Mementioning

confidence: 84%

Melanosomes and ancient coloration re‐examined: A response to Vinther 2015 (DOI 10.1002/bies.201500018)

Schweitzer¹,

Moyer²

2015

BioEssays

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Round to elongate microbodies associated with fossil vertebrate soft tissues were interpreted as microbial traces until 2008, when they were re-described as remnant melanosomes -intracellular, pigment-containing eukaryotic organelles. Since then, multiple claims for melanosome preservation and inferences of organismal color, behavior, and physiology have been advanced, based upon the shape and size of these microstructures. Here, we re-examine evidence for ancient melanosomes in light of information reviewed in Vinther (2015), and literature regarding the preservation potential of microorganisms and their exopolymeric secretions. We: (i) address statements in Vinther's recent (2015) review that are incorrect or which misrepresent published data; (ii) discuss the need for caution in interpreting ''voids'' and microbodies associated with degraded fossil soft tissues; (iii) present evidence that microorganisms are in many cases an equally parsimonious source for these ''voids'' as are remnant melanosomes; and (iv) suggest methods/criteria for differentiating melanosomes from microbial traces in the fossil record.

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Skin of the Cretaceous mosasaur Plotosaurus : implications for aquatic adaptations in giant marine reptiles

Cited by 24 publications

References 12 publications

Convergent Evolution in Aquatic Tetrapods: Insights from an Exceptional Fossil Mosasaur

Convergent Evolution in Aquatic Tetrapods: Insights from an Exceptional Fossil Mosasaur

Three-Dimensionally Preserved Integument Reveals Hydrodynamic Adaptations in the Extinct Marine Lizard Ectenosaurus (Reptilia, Mosasauridae)

Melanosomes and ancient coloration re‐examined: A response to Vinther 2015 (DOI 10.1002/bies.201500018)

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