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.

scholarly journals Ontogenetic shift in diet of a large elapid snake is facilitated by allometric change in skull morphology

2021 ◽  
Author(s):  
Matthew Brenton Patterson ◽  
Ashleigh K Wolfe ◽  
Patricia A Fleming ◽  
Philip W Bateman ◽  
Meg Martin ◽  
...  
Keyword(s):  
Body Size ◽  
Morphological Changes ◽  
Full Range ◽  
Stomach Contents ◽  
Prey Type ◽  
Postnatal Ontogeny ◽  
Shape Variation ◽  
Ontogenetic Changes ◽  
Skull Morphology ◽  
Skull Shape

Abstract As snakes are limbless, gape-limited predators, their skull is the main feeding structure involved in prey handling, manipulation and feeding. Ontogenetic changes in prey type and size are likely to be associated with distinct morphological changes in the skull during growth. We investigated ontogenetic variation in diet from stomach contents of n = 161 dugite specimens (Pseudonaja affinis, Elapidae) representing the full range of body size for the species, and skull morphology of 46 specimens (range 0.25–1.64 m snout-vent-length; SVL). We hypothesised that changes in prey type throughout postnatal ontogeny would coincide with distinct changes in skull shape. Dugites demonstrate a distinct size-related shift in diet: the smallest individuals ate autotomised reptile tails, medium-sized individuals predominantly ate small reptiles (as snakes grew larger there was an increased likelihood of feeding on reptiles head-first), and the largest individuals (> 0.8 m SVL) ate mammals and large reptiles. Morphometric analysis revealed that ~ 40% of the variation in skull shape was associated with body size (SVL). Through ontogeny, skulls changed from a smooth, bulbous cranium with relatively small trophic bones (upper and lower jaws and their attachments), to more rugous bones (as an adaption for muscle attachment) and relatively longer trophic bones that would extend gape. Individual shape variation in trophic bone dimensions was greater in larger adults and this likely reflects natural plasticity of individuals feeding on different prey sizes/types. Rather than a distinct morphological shift with diet, the ontogenetic changes were consistent, but positive allometry of individual trophic bones resulted in disproportionate growth of the skull, reflected in increased gape size and mobility of jaw bones in adults to aid the ingestion of larger prey and improve manipulation and processing ability. These results indicate that allometric scaling is an important mechanism by which snakes can change their dietary niche.

scholarly journals Skull shape abnormalities in ischemic cerebrovascular and mental diseases in adults

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Masaya Nagaishi ◽  
Yoshiko Fujii ◽  
Yoshiki Sugiura ◽  
Kensuke Suzuki
Keyword(s):  
Carotid Artery ◽  
Internal Carotid Artery ◽  
Moyamoya Disease ◽  
Internal Carotid ◽  
Morphological Changes ◽  
Head Injuries ◽  
Internal Carotid Artery Stenosis ◽  
Skull Shape ◽  
Mental Diseases ◽  
Cervical Internal Carotid Artery

AbstractMorphological changes in the child skull due to mechanical and metabolic stimulation and synostosis of the suture are well known. On the other hand, few studies have focused on clinical conditions relevant for adult skull deformity. We retrospectively reviewed computed tomography (CT) findings obtained from 365 cases that were treated for head injuries, moyamoya disease, cervical internal carotid artery stenosis, and mental diseases, and investigated the morphological changes in the skull associated with these diseases. The findings from head injuries were used not only for control subjects, but also for the analysis of generational changes in skull shape based on birth year. Head shape had a brachiocephalic tendency with occipital flattening in people born from the 1950s onwards. Cases of moyamoya disease, cervical internal carotid artery stenosis, and mental diseases showed significantly thicker frontal and occipital bone than those of control subjects. The skull thickening was especially noticeable in the frontal bone in moyamoya disease. Plagiocephaly was significantly frequent in moyamoya disease. These uncommon skull shapes are useful CT findings in screening subjects for early evidence of mental diseases and intracranial ischemic diseases with arterial stenosis.

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 The first tetrapod from the mid-Miocene Clarkia lagerstätte (Idaho, USA)

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4880
Author(s):  
Jonathan J. M. Calede ◽  
John D. Orcutt ◽  
Winifred A. Kehl ◽  
Bill D. Richards
Keyword(s):  
Fossil Record ◽  
New Taxon ◽  
Ecological Diversity ◽  
Anoxic Zone ◽  
Large Specimen ◽  
Skeletal Morphology ◽  
Lower Incisor ◽  
Plant Fossils ◽  
First Occurrence ◽  
Preservation Conditions

The Clarkia lagerstätte (Latah Formation) of Idaho is well known for its beautifully preserved plant fossils as well as a fauna of insects and fish. Here we present the first known tetrapod fossil from these deposits. This specimen, recovered from the lower anoxic zone of the beds, is preserved as a carbonaceous film of a partial skeleton associated with a partial lower incisor and some tooth fragments. The morphology of the teeth indicates that the first tetrapod reported from Clarkia is a rodent. Its skeletal morphology as well as its bunodont and brachydont dentition suggests that it is a member of the squirrel family (Sciuridae). It is a large specimen that cannot be assigned to a known genus. Instead, it appears to represent the first occurrence of a new taxon with particularly gracile postcranial morphology likely indicative of an arboreal ecology. This new specimen is a rare glimpse into the poorly known arboreal mammal fossil record of the Neogene. It supports a greater taxonomic and ecological diversity of Miocene Sciuridae than previously recognized and offers new lines of inquiry in the paleoecological research enabled by the unique preservation conditions of the Clarkia biota.

scholarly journals Beyond the carapace: skull shape variation and morphological systematics of long-nosed armadillos (genus Dasypus)

2017 ◽  
Author(s):  
Lionel Hautier ◽  
Guillaume Billet ◽  
Benoit De Thoisy ◽  
Frédéric Delsuc
Keyword(s):  
Morphological Variation ◽  
Distinct Species ◽  
Morphological Characters ◽  
Molecular Data ◽  
Guiana Shield ◽  
Shape Variation ◽  
Skull Morphology ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Shape And Size

Background. The systematics of long-nosed armadillos (genus Dasypus) has been mainly based on a handful of external morphological characters and classical measurements. Here, we studied the pattern of morphological variation in the skull of long-nosed armadillos species, with a focus on the systematics of the widely distributed nine-banded armadillo (D. novemcinctus). Methods. We present the first exhaustive 3D comparison of the skull morphology within the genus Dasypus, based on µCT-scans. We used geometric morphometric approaches to explore the patterns of the intra- and interspecific morphological variation of the skull with regard to several factors such as taxonomy, geography, allometry, and sexual dimorphism. Results. We show that the shape and size of the skull vary greatly between Dasypus species, with D. pilosus representing a clear outlier compared to other long-nosed armadillos. The study of the cranial intraspecific variation in D. novemcinctus evidences clear links to the geographic distribution and argue in favour of a revision of past taxonomic delimitations. Our detailed morphometric comparisons detected previously overlooked morphotypes of nine-banded armadillo, especially a very distinctive unit circumscribed to the Guiana Shield. Discussion. As our results are congruent with recent molecular data and analyses of the structure of paranasal sinuses, we propose that D. novemcinctus should be regarded either as a polytypic species (with three to four subspecies) or as a complex of several distinct species.

scholarly journals Cranial shape diversification in horses: variation and covariation patterns under the impact of artificial selection

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Pauline Hanot ◽  
Jamsranjav Bayarsaikhan ◽  
Claude Guintard ◽  
Ashleigh Haruda ◽  
Enkhbayar Mijiddorj ◽  
...  
Keyword(s):  
Artificial Selection ◽  
Large Scale ◽  
Phenotypic Diversity ◽  
Morphological Changes ◽  
Rapid Evolution ◽  
Time Interval ◽  
Short Time Interval ◽  
Skull Morphology ◽  
Domestic Species ◽  
The Impact

AbstractThe potential of artificial selection to dramatically impact phenotypic diversity is well known. Large-scale morphological changes in domestic species, emerging over short timescales, offer an accelerated perspective on evolutionary processes. The domestic horse (Equus caballus) provides a striking example of rapid evolution, with major changes in morphology and size likely stemming from artificial selection. However, the microevolutionary mechanisms allowing to generate this variation in a short time interval remain little known. Here, we use 3D geometric morphometrics to quantify skull morphological diversity in the horse, and investigate modularity and integration patterns to understand how morphological associations contribute to cranial evolvability in this taxon. We find that changes in the magnitude of cranial integration contribute to the diversification of the skull morphology in horse breeds. Our results demonstrate that a conserved pattern of modularity does not constrain large-scale morphological variations in horses and that artificial selection has impacted mechanisms underlying phenotypic diversity to facilitate rapid shape changes. More broadly, this study demonstrates that studying microevolutionary processes in domestic species produces important insights into extant phenotypic diversity.

scholarly journals Geographic variation in the skull morphology of the lesser grison (Galictis cuja: Carnivora, Mustelidae) from two Brazilian ecoregions

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9388
Author(s):  
Raissa Prior Migliorini ◽  
Rodrigo Fornel ◽  
Carlos Benhur Kasper
Keyword(s):  
Atlantic Forest ◽  
Size Variation ◽  
Neotropical Region ◽  
Shape Variation ◽  
Skull Morphology ◽  
Geometric Morphometric ◽  
Morphological Variations ◽  
Skull Shape ◽  
Temperature And Precipitation ◽  
Forest Region

Background The lesser grison (Galictis cuja) is one of the least known carnivores in the Neotropical region. Its wide geographical occurrence and range of habitats could lead to morphological variations along its distribution. So, this study aimed to investigate the variation in skull shape and size of this species, by testing the existence of ecotypes adapted to their respective environments (Uruguayan savanna and Atlantic Forest), as well as its relationship with selected abiotic variables. Methods The skulls of 52 museum specimens were photographed in the ventral, dorsal, and lateral views, and were analyzed using geometric morphometric techniques. Results We found sexual size dimorphism, with males being larger than females. The shape variation between sexes, as well as between ecoregions, is mostly explained by the effect of allometry. The specimens from Uruguayan savanna are larger than the ones from the Atlantic Forest. Size variation was also significantly correlated to latitude, temperature and precipitation patterns. No correlation between skull shape with geographical distance was detected. Discussion Morphometric measurements and diet data of lesser grison in regions from higher latitudes than our sampling show a tendency to heavier individuals, and the consumption of bigger prey compared to Uruguayan savanna. The results indicated the smaller specimens associated to low variability in annual temperature, congruent to Atlantic Forest region. An explanation for observed variation may be related to the “resource rule” but, due the minimal natural history information regards this species, we can just speculate about this.

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.

To grow or to reproduce? Sexual dimorphism and ontogenetic allometry in two Sesarmidae species (Crustacea: Brachyura)

2018 ◽  
Vol 99 (2) ◽  
pp. 473-486 ◽  
Author(s):  
Murilo Zanetti Marochi ◽  
Marcelo Costa ◽  
Renata Daldin Leite ◽  
Isis Danniele Cury Da Cruz ◽  
Setuko Masunari
Keyword(s):  
Sexual Dimorphism ◽  
Frontal Region ◽  
Shape Variation ◽  
Spatial Partitioning ◽  
Geometric Morphometric ◽  
Size Dependent ◽  
Ontogenetic Trajectories ◽  
Ontogenetic Trajectory ◽  
Ontogenetic Allometry ◽  
Aratus Pisonii

Differences between sexes may arise either during development or at the adult stage only. In both cases growth rate during development and level of allometry may influence sexual dimorphism and ontogenetic trajectories. To analyse the period in which sexual dimorphism appears during ontogeny and assess allometric ontogeny in Sesarmidae crabs, we evaluated: (1) sexual dimorphism in shape and size of the carapace and cheliped propodus of juveniles and adultAratus pisoniiandArmases rubripes, and (2) their ontogenetic trajectory, using geometric morphometric (GM) techniques. We tested the hypothesis that sexual dimorphism in sesarmid crab shape takes place before the puberty moult. InAratus pisoniithere was sexual dimorphism in the shape of the carapace in juveniles (before puberty moult) and variation between juveniles and adults was size-dependent, especially in the frontal region of the carapace. ForArmases rubripesthis shape sexual dimorphism was detected only after the puberty moult (adult phase). For males, carapace variation between juveniles and adults was also size-dependent, especially in the carapace frontal region, but for females, there was a change in shape with different trajectories. Our results also indicated that shape variation is a common pattern during growth for Sesarmidae species. This ontogenetic shape variation may be associated with spatial partitioning between juveniles and adults.

scholarly journals Geometric morphometric analysis of skull morphology reveals loss of phylogenetic signal at the generic level in extant lagomorphs (Mammalia: Lagomorpha)

2015 ◽  
Vol 84 (4) ◽  
pp. 267-284 ◽  
Author(s):  
Deyan Ge ◽  
Lu Yao ◽  
Lin Xia ◽  
Zhaoqun Zhang ◽  
Qisen Yang
Keyword(s):  
Dna Sequences ◽  
Shape Change ◽  
Morphological Evolution ◽  
Phylogenetic Signal ◽  
Lateral View ◽  
Skull Morphology ◽  
Generic Level ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Long Time

The intergeneric phylogeny of Lagomorpha had been controversial for a long time before a robust phylogeny was reconstructed based on seven nuclear and mitochondrial DNA sequences. However, skull morphology of several endemic genera remained poorly understood. The morphology of supraorbital processes in Lagomorpha is normally used as a diagnostic characteristic in taxonomy, but whether shape change of this structure parallels its genetic divergence has not been investigated. In this study, we conducted a comparative analysis of the skull morphology of all 12 extant genera using geometric morphometrics. These results indicated that no significant phylogenetic signal is observed in the shape change of the dorsal and ventral views of the cranium as well as in the lateral view of the mandible. The supraorbital processes also show insignificant phylogenetic signal in shape change. Similarly, mapping the centroid size (averaged by genus) of these datasets onto the phylogeny also showed insignificant phylogenetic signal. Aside from homoplasy caused by convergent evolution of skull shape, the massive extinction of lagomorphs after the late Miocene is proposed as one of the main causes for diluting phylogenetic signals in their morphological evolution. Acknowledging the loss of phylogenetic signals in skull shape and supraorbital processes of extant genera sheds new light on the long-standing difficulties for understanding higher-level systematics in Lagomorpha.

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