Salt glands in the fossil crocodile<i>Metriorhynchus</i>

Gandola, Robert; Buffetaut, Éric; Monaghan, Nigel T.; Dyke, Gareth J.

doi:10.1671/0272-4634(2006)26[1009:sgitfc]2.0.co;2

Cited by 33 publications

(36 citation statements)

References 6 publications

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“…In addition to anatomical characteristics, histological and physiological data support the separation of habitat space between these two thalattosuchian families (Hua & Buffrenil, 1996; Fernández & Gasparini, 2000, 2008; Gandola et al. 2006).…”

Section: Introductionmentioning

confidence: 75%

“…Conversely, metriorhynchids have a modified bone histology that includes extensive osteoporotic lightening of the skull, ribs, and limbs providing increased buoyancy within the water column (Hua & Buffrenil, 1996). In addition, metriorhynchids likely possessed a hypertrophied nasal salt excretion gland to maintain constant plasma osmolality even when seawater or osmoconforming prey were ingested (Fernández & Gasparini, 2000, 2008; Gandola et al. 2006).…”

Section: Introductionmentioning

confidence: 99%

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Shape and mechanics in thalattosuchian (Crocodylomorpha) skulls: implications for feeding behaviour and niche partitioning

2009

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Variation in modern crocodilian and extinct thalattosuchian crocodylomorph skull morphology is only weakly correlated with phylogeny, implying that factors other than evolutionary proximity play important roles in determining crocodile skull shape. To further explore factors potentially influencing morphological differentiation within the Thalattosuchia, we examine teleosaurid and metriorhynchid skull shape variation within a mechanical and dietary context using a combination of finite element modelling and multivariate statistics. Patterns of stress distribution through the skull were found to be very similar in teleosaurid and metriorhynchid species, with stress peaking at the posterior constriction of the snout and around the enlarged supratemporal fenestrae. However, the magnitudes of stresses differ, with metriorhynchids having generally stronger skulls. As with modern crocodilians, a strong linear relationship between skull length and skull strength exists, with short-snouted morphotypes experiencing less stress through the skull than long-snouted morphotypes under equivalent loads. Selection on snout shape related to dietary preference was found to work in orthogonal directions in the two families: diet is associated with snout length in teleosaurids and with snout width in metriorhynchids, suggesting that teleosaurid skulls were adapted for speed of attack and metriorhynchid skulls for force production. Evidence also indicates that morphological and functional differentiation of the skull occurred as a result of dietary preference, allowing closely related sympatric species to exploit a limited environment. Comparisons of the mechanical performance of the thalattosuchian skull with extant crocodilians show that teleosaurids and long-snouted metriorhynchids exhibit stress magnitudes similar to or greater than those of long-snouted modern forms, whereas short-snouted metriorhynchids display stress magnitudes converging on those found in short-snouted modern species. As a result, teleosaurids and long-snouted metriorhynchids were probably restricted to lateral attacks of the head and neck, but short-snouted metriorhynchids may have been able to employ the grasp and shake and ⁄ or 'death roll' feeding and foraging behaviours.

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Section: Introductionmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Shape and mechanics in thalattosuchian (Crocodylomorpha) skulls: implications for feeding behaviour and niche partitioning

2009

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“…The openings classically referred as the “antorbital fenestrae” in this clade is in fact neomorphic preorbital openings for the excretion of salt. These openings are connected via ducts to a chamber that housed large salt-glands (see [12], [13], [77], [78]). Both preorbital fenestrae are bound by an elongate, narrow and obliquely orientated fossa, which in turn are bound by the jugal, the lachrymal, the nasal and the maxilla.…”

Section: Resultsmentioning

confidence: 99%

The First Metriorhynchid Crocodylomorph from the Middle Jurassic of Spain, with Implications for Evolution of the Subclade Rhacheosaurini

et al. 2013

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BackgroundMarine deposits from the Callovian of Europe have yielded numerous species of metriorhynchid crocodylomorphs. While common in English and French Formations, metriorhynchids are poorly known from the Iberian Peninsula. Twenty years ago an incomplete, but beautifully preserved, skull was discovered from the Middle Callovian of Spain. It is currently the oldest and best preserved metriorhynchid specimen from the Iberian Peninsula. Until now it has never been properly described and its taxonomic affinities remained obscure.Methodology/Principal FindingsHere we present a comprehensive description for this specimen and in doing so we refer it to a new genus and species: Maledictosuchus riclaensis. This species is diagnosed by numerous autapomorphies, including: heterodont dentition; tightly interlocking occlusion; lachrymal anterior process excludes the jugal from the preorbital fenestra; orbits longer than supratemporal fenestrae; palatine has two non-midline and one midline anterior processes. Our phylogenetic analysis finds Maledictosuchus riclaensis to be the basal-most known member of Rhacheosaurini (the subclade of increasingly mesopelagic piscivores that includes Cricosaurus and Rhacheosaurus).Conclusions/SignificanceOur description of Maledictosuchus riclaensis shows that the craniodental morphologies that underpinned the success of Rhacheosaurini in the Late Jurassic and Early Cretaceous, as a result of increasing marine specialization to adaptations for feeding on fast small-bodied prey (i.e. divided and retracted external nares; reorientation of the lateral processes of the frontal; elongate, tubular rostrum; procumbent and non-carinated dentition; high overall tooth count; and dorsolaterally inclined paroccipital processes), first appeared during the Middle Jurassic. Rhacheosaurins were curiously rare in the Middle Jurassic, as only one specimen of Maledictosuchus riclaensis is known (with no representatives discovered from the well-sampled Oxford Clay Formation of England). As such, the feeding/marine adaptations of Rhacheosaurini did not confer an immediate selective advantage upon the group, and it took until the Late Jurassic for this subclade to dominate in Western Europe.

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“…This clade evolved extensive osteological and soft tissue adaptations to a marine existence, including hydrofoil-like forelimbs, a hypocercal caudal vertebral column, loss of osteoderms and enlarged salt glands with a neomorphic opening for excess salt excretion (Fraas, 1902;Andrews, 1913;Gasparini, 2000, 2008;Gandola et al, 2006;Fern andez and Herrera, 2009;Young et al, 2010;Leardi et al, 2012). During the Jurassic and Lower Cretaceous, metriorhynchids were exceptionally diverse in lagoonal, coastal and open-shelf ecosystems (e.g.…”

Section: Introductionmentioning

confidence: 99%

The youngest record of metriorhynchid crocodylomorphs, with implications for the extinction of Thalattosuchia

Chiarenza

Foffa

Young

et al. 2015

Cretaceous Research

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Salt glands in the fossil crocodileMetriorhynchus

Cited by 33 publications

References 6 publications

Shape and mechanics in thalattosuchian (Crocodylomorpha) skulls: implications for feeding behaviour and niche partitioning

Shape and mechanics in thalattosuchian (Crocodylomorpha) skulls: implications for feeding behaviour and niche partitioning

The First Metriorhynchid Crocodylomorph from the Middle Jurassic of Spain, with Implications for Evolution of the Subclade Rhacheosaurini

The youngest record of metriorhynchid crocodylomorphs, with implications for the extinction of Thalattosuchia

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