The evolution of jaw mechanism and dental function in heterodont crocodyliforms

Ősi, Attila

doi:10.1080/08912963.2013.777533

Cited by 84 publications

(92 citation statements)

References 159 publications

(371 reference statements)

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“…longirostrine animals compensate the higher pressure from dragging with narrower snouts; McHenry et al ., 2006; Walmsley et al ., 2013). Similarly, other regions of the crocodylomorph skull that vary significantly also have important implications for biomechanics and feeding strategies, such as the changes in quadrate condyle width, which are presumably associated with the craniomandibular joint (Kley et al ., 2010; Stubbs et al ., 2013; Ősi, 2014), even though relatively less variation is observed in these regions when compared to the snout.…”

Section: Discussionmentioning

confidence: 92%

Crocodylomorph cranial shape evolution and its relationship with body size and ecology

Godoy

2019

Preprint

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Crocodylomorpha, which includes living crocodylians and their extinct relatives, has a rich fossil record, extending back for more than 200 million years. Unlike modern semi-aquatic crocodylians, extinct crocodylomorphs exhibited more varied lifestyles, ranging from marine to fully terrestrial forms. This ecological diversity was mirrored by a remarkable morphological disparity, particularly in terms of cranial morphology, which seems to be closely associated with ecological roles in the group. Here, I use geometric morphometrics to comprehensively investigate cranial shape variation and disparity in Crocodylomorpha. I quantitatively assess the relationship between cranial shape and ecology (i.e. terrestrial, aquatic, and semi-aquatic lifestyles), as well as possible allometric shape changes. I also characterise patterns of cranial shape evolution and identify regime shifts. I found a strong link between shape and size, and a significant influence of ecology on the observed shape variation. Terrestrial taxa, particularly notosuchians, have significantly higher disparity, and shifts to more longirostrine regimes are associated with large-bodied aquatic or semi-aquatic species. This demonstrates an intricate relationship between cranial shape, body size and lifestyle in crocodylomorph evolutionary history. Additionally, disparity-through-time analyses were highly sensitive to different phylogenetic hypotheses, suggesting the description of overall patterns among distinct trees. For crocodylomorphs, most results agree in an early peak during the Early Jurassic and another in the middle of the Cretaceous, followed by nearly continuous decline until today. Since only crown-group members survived through the Cenozoic, this decrease in disparity was likely the result of habitat loss, which narrowed down the range of crocodylomorph lifestyles.

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Section: Discussionmentioning

confidence: 92%

Crocodylomorph cranial shape evolution and its relationship with body size and ecology

Godoy

2019

Preprint

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“…Additionally, many crocodylians (e.g., Alligator mississippiensis , Caiman crocodilus , Crocodylus moreletii , Osteolaemus tetraspis , Paleosuchus trigonatus ) have mixed diets (McNease and Joanen, ; Delany and Abercrombie, ; Tucker et al, ; Pauwels et al, ; Pauwels et al, ; Saalfeld et al, ; Laverty and Dobson, ), and this may be reflected in their somewhat high complexity, 5.23–6.8 PPT at 25 RPT. That being said, crocodylian tooth morphology also is, in part, controlled by the ability to resist extremely high bite forces (Erickson et al, ; Ősi, ).…”

Section: Discussionmentioning

confidence: 99%

The relationship between diet and tooth complexity in living dentigerous saurians

Melstrom

2017

Journal of Morphology

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Living saurian reptiles exhibit a wide range of diets, from carnivores to strict herbivores. Previous research suggests that the tooth shape in some lizard clades correlates with diet, but this has not been tested using quantitative methods. I investigated the relationship between phenotypic tooth complexity and diet in living reptiles by examining the entire dentary tooth row in over 80 specimens comprising all major dentigerous saurian clades. I quantified dental complexity using orientation patch count rotated (OPCR), which discriminates diet in living and extinct mammals, where OPCR-values increase with the proportion of dietary plant matter. OPCR was calculated from high-resolution CT-scans, and I standardized OPCR-values by the total number of teeth to account for differences in tooth count across taxa. In contrast with extant mammals, there appears to be greater overlap in tooth complexity values across dietary groups because multicusped teeth characterize herbivores, omnivores, and insectivores, and because herbivorous skinks have relatively simple teeth. In particular, insectivorous lizards have dental complexities that are very similar to omnivores. Regardless, OPCR-values for animals that consume significant amounts of plant material are higher than those of carnivores, with herbivores having the highest average dental complexity. These results suggest reptilian tooth complexity is related to diet, similar to extinct and extant mammals, although phylogenetic history also plays a measurable role in dental complexity. This has implications for extinct amniotes that display a dramatic range of tooth morphologies, many with no modern analogs, which inhibits detailed dietary reconstructions. These data demonstrate that OPCR, when combined with additional morphological data, has the potential to be used to reconstruct the diet of extinct amniotes. J. Morphol. 278:500-522, 2017. © 2017 Wiley Periodicals, Inc.

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“…Alligators have relatively generalist diets among crocodylians (Brochu, ). Though there is some diversity in extant crocodylian feeding, the trophic diversity of extinct crocodyliforms is far greater (Case, ; Brochu, ; Turner & Sertich, ; Ősi, ). To begin to understand the relationship of enamel thickness and diet, we also measured enamel thickness in the caudal, relatively blunt molariforms of select extinct crocodyliforms with derived dental morphologies and presumed diets: an unnamed protosuchid (UCMP 97638), Iharkutosuchus (MTM VER 2018.837) and Allognathosuchus (YPM‐PU 16989).…”

Section: Introductionmentioning

confidence: 99%

“…UCMP 97638 is a protosuchian from the Jurassic of North America. Its bicuspid teeth had wear patterns that suggest active oral processing (Ősi, ). Ih arkutosuchus is a stem eusuchian from the Cretaceous of Europe (Ősi et al , ) and has complex, multi‐cusped teeth reminiscent of mammalian dentition (Ősi & Weishampel, ) that are thought to engage in oral processing of plant matter.…”

Section: Introductionmentioning

confidence: 99%

The significance of enamel thickness in the teeth of Alligator mississippiensis and its diversity among crocodyliforms

2019

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Enamel is the hardest tissue in the vertebrate body. Although variation in enamel microstructure is often linked with diet, the gross proportions of the tissues that compose vertebrate teeth remain relatively unexplored in reptiles. To investigate the patterns of enamel thickness in crocodyliforms, we used micro‐computed tomography scanning to evaluate enamel thickness in teeth of Alligator mississippiensis from rostral, intermediate and caudal locations in the tooth row from an ontogenetic range of animals. We also evaluated enamel thickness in the derived teeth of several extinct crocodyliforms with disparate craniodental morphologies. Our data show that enamel thickness scales isometrically with skull length. We also show that enamel is relatively thicker in caudal teeth than teeth in more rostral positions, concordant with the higher bite forces they experience during feeding. We compared our data with existing enamel thickness data reported from dinosaurs and mammalian taxa to find that archosaurs have markedly thinner enamel than most mammals. These findings serve as a basis for future investigations into the diversity and function of the proportions of dental tissues.

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The evolution of jaw mechanism and dental function in heterodont crocodyliforms

Cited by 84 publications

References 159 publications

Crocodylomorph cranial shape evolution and its relationship with body size and ecology

Crocodylomorph cranial shape evolution and its relationship with body size and ecology

The relationship between diet and tooth complexity in living dentigerous saurians

The significance of enamel thickness in the teeth of Alligator mississippiensis and its diversity among crocodyliforms

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