scholarly journals The cranial morphology of Tanystropheus hydroides (Tanystropheidae, Archosauromorpha) as revealed by synchrotron microtomography

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10299
Author(s):  
Stephan N.F. Spiekman ◽  
James M. Neenan ◽  
Nicholas C. Fraser ◽  
Vincent Fernandez ◽  
Olivier Rieppel ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
Lateral Wall ◽  
Cranial Morphology ◽  
Ecological Diversity ◽  
Skull Morphology ◽  
Postcranial Morphology ◽  
Horizontal Orientation ◽  
Synchrotron Microtomography

The postcranial morphology of the extremely long-necked Tanystropheus hydroides is well-known, but observations of skull morphology were previously limited due to compression of the known specimens. Here we provide a detailed description of the skull of PIMUZ T 2790, including a partial endocast and endosseous labyrinth, based on synchrotron microtomographic data, and compare its morphology to that of other early Archosauromorpha. In many features, such as the wide and flattened snout and the configuration of the temporal and palatal regions, Tanystropheus hydroides differs strongly from other early archosauromorphs. The braincase possesses a combination of derived archosaur traits, such as the presence of a laterosphenoid and the ossification of the lateral wall of the braincase, but also differs from archosauriforms in the morphology of the ventral ramus of the opisthotic, the horizontal orientation of the parabasisphenoid, and the absence of a clearly defined crista prootica. Tanystropheus hydroides was a ram-feeder that likely caught its prey through a laterally directed snapping bite. Although the cranial morphology of other archosauromorph lineages is relatively well-represented, the skulls of most tanystropheid taxa remain poorly understood due to compressed and often fragmentary specimens. The recent descriptions of the skulls of Macrocnemus bassanii and now Tanystropheus hydroides reveal a large cranial disparity in the clade, reflecting wide ecological diversity, and highlighting the importance of non-archosauriform Archosauromorpha to both terrestrial and aquatic ecosystems during the Triassic.

scholarly journals New specimen of <i>Cacops woehri</i> indicates differences in the ontogenetic trajectories among cacopine dissorophids

Fossil Record ◽  
2015 ◽  
Vol 18 (1) ◽  
pp. 73-80 ◽  
Author(s):  
N. B. Fröbisch ◽  
A. Brar ◽  
R. R. Reisz
Keyword(s):  
Morphological Changes ◽  
Lower Permian ◽  
Ecological Diversity ◽  
Large Specimen ◽  
Skull Morphology ◽  
Skull Shape ◽  
Ontogenetic Trajectories ◽  
Ontogenetic Trajectory ◽  
Taxic Diversity

Abstract. The Lower Permian Dolese locality has produced numerous exquisitely preserved tetrapod fossils representing members of a lower Permian upland fauna. Therein, at least nine taxa of the clade Dissorophoidea, ranging in size from the large predaceous trematopid Acheloma to the miniaturized amphibamid Doleserpeton, highlight the great taxic and ecological diversity of this anamniote clade. Here we describe a large specimen of the dissorophid Cacops woehri, which was previously only known from the juvenile or subadult holotype skull. Another member of the genus Cacops present at the Dolese locality, Cacops morrisi, is also represented by specimens spanning juvenile, subadult, and adult stages, allowing for a comparison of morphological changes taking place in the late phases of the ontogenetic trajectory of cacopine dissorophids. The new find shows that, in contrast to C. morrisi and C. aspidephorus, C. woehri only undergoes relatively subtle changes in skull morphology in late ontogeny and retains the overall more gracile morphology into adult stages. This includes retention of the rather shallow skull shape as well as a pattern of sculpturing consisting of elongate ridges and grooves and a large occipital flange. This suggests somewhat different functional demands in C. woehri than in other known species of Cacops, possibly associated with a different ecology paralleling the great taxic diversity of dissorophoids at the Dolese locality.

Constraint and adaptation in the evolution of carnivoran skull shape

Paleobiology ◽  
2011 ◽  
Vol 37 (3) ◽  
pp. 490-518 ◽  
Author(s):  
Borja Figueirido ◽  
Norman MacLeod ◽  
Jonathan Krieger ◽  
Miquel De Renzi ◽  
Juan Antonio Pérez-Claros ◽  
...  
Keyword(s):  
Morphological Plasticity ◽  
Shape Space ◽  
Cranial Morphology ◽  
Skull Morphology ◽  
Skull Shape ◽  
Olfactory Sense ◽  
History Of ◽  
Proximate Source ◽  
Brain Processing ◽  
Iterative Evolution

The evolutionary history of the Order Carnivora is marked by episodes of iterative evolution. Although this pattern is widely reported in different carnivoran families, the mechanisms driving the evolution of carnivoran skull morphology remain largely unexplored. In this study we use coordinate-point extended eigenshape analysis (CP-EES) to summarize aspects of skull shape in large fissiped carnivores. Results of these comparisons enable the evaluation of the role of different factors constraining the evolution of carnivoran skull design. Empirical morphospaces derived from mandible anatomy show that all hypercarnivores (i.e., those species with a diet that consists almost entirely of vertebrate flesh) share a set of traits involved in a functional compromise between bite force and gape angle, which is reflected in a strong pattern of morphological convergence. Although the paths followed by different taxa to reach this “hypercarnivore shape-space” differ because of phylogenetic constraints, the morphological signature of hypercarnivory in the mandible is remarkably narrow and well constrained. In contrast, CP-EES of cranial morphology does not reveal a similar pattern of shape convergence among hypercarnivores. This suggests a lesser degree of morphological plasticity in the cranium compared to the mandible, which probably results from a compromise between different functional demands in the cranium (e.g., feeding, vision, olfactory sense, and brain processing) whereas the mandible is only involved in food acquisition and processing. Combined analysis of theoretical and empirical morphospaces for these skull data also show the lower anatomical disparity of felids and hyaenids compared to canids and ursids. This indicates that increasing specialization within the hypercarnivorous niche may constrain subsequent morphological and ecological flexibility. During the Cenozoic, similar skull traits appeared in different carnivoran lineages, generated by similar selection pressures (e.g., toward hypercarnivory) and shared developmental pathways. These pathways were likely the proximate source of constraints on the degree of variation associated with carnivoran skull evolution and on its direction.

scholarly journals Ecological correlates to cranial morphology in Leporids (Mammalia, Lagomorpha)

2014 ◽  
Author(s):  
Brian P Kraatz ◽  
Nicholas Bumacod ◽  
Emma Sherratt ◽  
Mathew J Wedel
Keyword(s):  
Cranial Morphology ◽  
Form And Function ◽  
Postcranial Morphology ◽  
Ecological Correlates ◽  
The Subject ◽  
And Function ◽  
The Relationship ◽  
Cranial Shape

The mammalian order Lagomorpha has been the subject of many morphometric studies aimed at understanding the relationship between form and function as it relates to locomotion, primarily in postcranial morphology. The leporid cranial skeleton, however, may also reveal information about their ecology, particularly locomotion and vision. Here we investigate the relationship between cranial shape and the degree of facial tilt with locomotion (cursoriality, saltation, and burrowing) within crown leporids. Our results suggest that facial tilt is more pronounced in cursors and saltators compared to generalists. However cranial shape does not differ significantly among these locomotor groups, nor does it differ significantly between species that burrow and those that do not.

scholarly journals Craniofacial development illuminates the evolution of nightbirds (Strisores)

2021 ◽  
Vol 288 (1948) ◽  
Author(s):  
Guillermo Navalón ◽  
Sergio M. Nebreda ◽  
Jen A. Bright ◽  
Matteo Fabbri ◽  
Roger B. J. Benson ◽  
...  
Keyword(s):  
Shape Change ◽  
Phenotypic Variability ◽  
Cranial Morphology ◽  
Skull Morphology ◽  
Bird Evolution ◽  
Ontogenetic Trajectory ◽  
Evolutionary Variation ◽  
Evo Devo ◽  
Shape Changes

Evolutionary variation in ontogeny played a central role in the origin of the avian skull. However, its influence in subsequent bird evolution is largely unexplored. We assess the links between ontogenetic and evolutionary variation of skull morphology in Strisores (nightbirds). Nightbirds span an exceptional range of ecologies, sizes, life-history traits and craniofacial morphologies constituting an ideal test for evo-devo hypotheses of avian craniofacial evolution. These morphologies include superficially ‘juvenile-like’ broad, flat skulls with short rostra and large orbits in swifts, nightjars and allied lineages, and the elongate, narrow rostra and globular skulls of hummingbirds. Here, we show that nightbird skulls undergo large ontogenetic shape changes that differ strongly from widespread avian patterns. While the superficially juvenile-like skull morphology of many adult nightbirds results from convergent evolution, rather than paedomorphosis, the divergent cranial morphology of hummingbirds originates from an evolutionary reversal to a more typical avian ontogenetic trajectory combined with accelerated ontogenetic shape change. Our findings underscore the evolutionary lability of cranial growth and development in birds, and the underappreciated role of this aspect of phenotypic variability in the macroevolutionary diversification of the amniote skull.

scholarly journals Size, microhabitat, and loss of larval feeding drive cranial diversification in frogs

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Carla Bardua ◽  
Anne-Claire Fabre ◽  
Julien Clavel ◽  
Margot Bon ◽  
Kalpana Das ◽  
...  
Keyword(s):  
Larval Stage ◽  
Morphological Evolution ◽  
Ecological Factors ◽  
Evolutionary Rates ◽  
Cranial Morphology ◽  
Larval Feeding ◽  
Skull Morphology ◽  
Life History Stages ◽  
Evolutionary Allometry ◽  
Developmental Phases

AbstractHabitat is one of the most important factors shaping organismal morphology, but it may vary across life history stages. Ontogenetic shifts in ecology may introduce antagonistic selection that constrains adult phenotype, particularly with ecologically distinct developmental phases such as the free-living, feeding larval stage of many frogs (Lissamphibia: Anura). We test the relative influences of developmental and ecological factors on the diversification of adult skull morphology with a detailed analysis of 15 individual cranial regions across 173 anuran species, representing every extant family. Skull size, adult microhabitat, larval feeding, and ossification timing are all significant factors shaping aspects of cranial evolution in frogs, with late-ossifying elements showing the greatest disparity and fastest evolutionary rates. Size and microhabitat show the strongest effects on cranial shape, and we identify a “large size-wide skull” pattern of anuran, and possibly amphibian, evolutionary allometry. Fossorial and aquatic microhabitats occupy distinct regions of morphospace and display fast evolution and high disparity. Taxa with and without feeding larvae do not notably differ in cranial morphology. However, loss of an actively feeding larval stage is associated with higher evolutionary rates and disparity, suggesting that functional pressures experienced earlier in ontogeny significantly impact adult morphological evolution.

Evolution of skull shape in carnivores. 3. The origin and early radiation of the modern carnivore families

Paleobiology ◽  
1982 ◽  
Vol 8 (3) ◽  
pp. 177-195 ◽  
Author(s):  
Leonard B. Radinsky
Keyword(s):  
Alternative Hypothesis ◽  
Late Eocene ◽  
Cranial Morphology ◽  
Morphological Transformation ◽  
Skull Morphology ◽  
The Family ◽  
Prey Resources ◽  
Early Radiation ◽  
Families First

Functionally significant aspects of skull morphology were examined in Eocene miacids and in early members of the modern carnivore families to see if functional craniology might shed light on factors involved in the origin and early evolution of the modern carnivores. No key innovations are apparent at the beginning of the modern carnivore radiation, and an alternative hypothesis to account for that radiation is proposed: the radiation represents the filling of niches vacated by the extinction of several groups of archaic carnivores in the late Eocene. Differences that distinguish modern viverrids, canids, felids, and mustelids from each other today were less pronounced in the Oligocene, when these families first appeared, and provide no insights into possible ecological differences at the family level. However, body size differences among the early members of the modern carnivore families suggest that partitioning of prey resources by size may have been a factor in their initial radiation. Comparison of cranial morphology in Eocene miacids, early members of the modern carnivore families, and living carnivores allows reconstruction of the primitive conditions of carnivore skull morphology and determination of the pathways of morphological transformation that resulted in the diversity of skull morphology seen in modern carnivores.

scholarly journals Cranial morphology of the tanystropheid Macrocnemus bassanii unveiled using synchrotron microtomography

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Feiko Miedema ◽  
Stephan N. F. Spiekman ◽  
Vincent Fernandez ◽  
Jelle W. F. Reumer ◽  
Torsten M. Scheyer
Keyword(s):  
Cranial Morphology ◽  
Synchrotron Microtomography

scholarly journals Ecological correlates to cranial morphology in Leporids (Mammalia, Lagomorpha)

2014 ◽  
Author(s):  
Brian P Kraatz ◽  
Nicholas Bumacod ◽  
Emma Sherratt ◽  
Mathew J Wedel
Keyword(s):  
Cranial Morphology ◽  
Form And Function ◽  
Postcranial Morphology ◽  
Ecological Correlates ◽  
The Subject ◽  
And Function ◽  
The Relationship ◽  
Cranial Shape

The mammalian order Lagomorpha has been the subject of many morphometric studies aimed at understanding the relationship between form and function as it relates to locomotion, primarily in postcranial morphology. The leporid cranial skeleton, however, may also reveal information about their ecology, particularly locomotion and vision. Here we investigate the relationship between cranial shape and the degree of facial tilt with locomotion (cursoriality, saltation, and burrowing) within crown leporids. Our results suggest that facial tilt is more pronounced in cursors and saltators compared to generalists. However cranial shape does not differ significantly among these locomotor groups, nor does it differ significantly between species that burrow and those that do not.

scholarly journals Systematic revision of the pocket gopher genus Orthogeomys

2016 ◽  
Vol 97 (2) ◽  
pp. 405-423 ◽  
Author(s):  
Theresa A. Spradling ◽  
James W. Demastes ◽  
David J. Hafner ◽  
Paige L. Milbach ◽  
Fernando A. Cervantes ◽  
...  
Keyword(s):  
Nuclear Gene ◽  
Taxonomic Revision ◽  
Single Species ◽  
Cranial Morphology ◽  
Ecological Diversity ◽  
Pocket Gopher ◽  
Base Pairs ◽  
Systematic Revision ◽  
Pocket Gophers ◽  
The Family

Abstract Pocket gophers of the genus Orthogeomys show unusually high morphological and ecological diversity compared to other genera in the family Geomyidae. Whereas this diverse group once was divided into 3 genera ( Merriam 1895 ), a revision by Russell (1968) recognized only Orthogeomys , with Merriam’s original genera relegated to subgeneric status as Heterogeomys , Macrogeomys , and Orthogeomys . Recent studies have called into question the monophyly of Orthogeomys , as well as the validity of 4 currently recognized Orthogeomys species. To date, the taxonomic validity of only 1 of these species has been verified ( Hafner et al. 2014 ). In this analysis, the first to include all 11 recognized species of the genus, we examine 3 mitochondrial and 2 nuclear gene sequences (4,352 base pairs) and analyze cranial morphology to explore relationships within the genus. Our data support a taxonomic revision that restricts the genus Orthogeomys to a single species ( O. grandis ) and combines the subgenera Heterogeomys and Macrogeomys into the resurrected genus, Heterogeomys (7 species). In addition, 3 currently recognized species of Orthogeomys are synonymized as follows: O. cuniculus with O. grandis ; H. thaeleri with H. dariensis ; and H. matagalpae with H. cherriei . A synonymy and a key to the species of the genera Orthogeomys and Heterogeomys are provided. Las tuzas del género Orthogeomys muestran una diversidad morfológica y ecológica inusual en comparación con otros géneros de la familia Geomyidae. Aunque este diverso grupo fue alguna vez dividido en 3 géneros ( Merriam 1895 ), la revisión de Russell (1968) reconoció solo a Orthogeomys , mientras que los géneros originales de Merriam fueron relegados a estatus subgenérico como Heterogeomys , Macrogeomys y Orthogeomys . Estudios recientes han cuestionado la monofilia de Orthogeomys , así como la validez de 4 de las especies actualmente reconocidas. A la fecha, la validez taxonómica de sólo una de estas especies ha sido verificada. En este análisis, el primero en incluir las 11 especies reconocidas en el género, examinamos secuencias de 3 genes mitocondriales y 2 nucleares y analizamos la morfología craneal para explorar las relaciones dentro del género. Nuestras 4,352 pares de bases de secuencias de ADN apoyan una revisión taxonómica que retiene al género Orthogeomys (incluyendo sólo a O. grandis ) y combina los subgéneros Heterogeomys y Macrogeomys en un género recuperado, Heterogeomys (7 especies). Además, 3 especies de Orthogeomys actualmente reconocidas son sinonimizadas de la siguiente forma: O. cuniculus con O. grandis ; H. thaeleri con H. dariensis ; y H. matagalpae con H. cherriei . Se incluye sinonimia y una clave para las especies de los géneros Orthogeomys y Heterogeomys .

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