Cranial Morphology of Panperissodacyla (project)

10.7934/p4079 ◽  
2021 ◽  
Author(s):  
R MacPhee ◽  
S Pino ◽  
A Kramarz ◽  
A Forasiepi ◽  
M Bond ◽  
...  
Keyword(s):  
Cranial Morphology

Additional Dermal Ossifications in the Anuran Skull: Morphological Novelties or Archaic Elements?

2011 ◽  
Vol 4 (1) ◽  
pp. 17-27 ◽  
Author(s):  
Sergei V. Smirnov
Keyword(s):  
Common Ancestor ◽  
The State ◽  
Cranial Morphology ◽  
Anterior Portion ◽  
Bombina Orientalis ◽  
Common Event ◽  
Rostral Portion ◽  
Morphological Novelties ◽  
Dermal Bones

Examination of the cranial morphology in Bombina orientalis (Anura: Discoglossidae) revealed the occurrence of additional dermal bones lying: a) between the nasals and frontoparietals, b) between frontoparietals, and c) on the tectum synoticum behind the frontoparietals. The presence of similar bones as well as extra ossifications lying in the midline in the rostral portion of skull was shown to be a rather common event among anurans. Based on the occurrence of bones with similar topology in crossopterygians and different stegocephalians, it was concluded that extra ossifications sporadically appearing in anurans are more likely to be ancient cranial elements than neomorphs. Additional dermal bones found in the anterior portion of the anuran skull are homologous to the postrostrals of crossopterygians; extra ossifications lying between the frontoparietals correspond to the bones with similar topology sporadically appearing in crossopterygians and stegocephalians; and extra bones situated behind the frontoparietals are homologous to the lateral extrascapulars (postparietals of stegocephalians) and the median extrascapular of crossopterygians. These extra bones were proposed to be inherited from the presumed common ancestor of all Gnathostomes and retained in anurans in the state of latent capacities. The sporadic appearance of these bones in anurans results from the phenotypical realization of these latent capacities.

From Phenotype to Genotype And Back Again

2019 ◽  
Author(s):  
J. Richtsmeier ◽  
K.M. Lesciotto
Keyword(s):  
Human Evolution ◽  
Evolutionary Change ◽  
Cranial Morphology ◽  
Phenotypic Trait ◽  
Critical Feature ◽  
Developmental Mechanism ◽  
Experimental Approaches ◽  
Physical Forces ◽  
Collaborative Efforts ◽  
Current Emphasis

Traditionally, anthropologists study evolutionary change throughmorphological analysis of fossils and comparative primate data. For the analysis of the genotypephenotype continuum, the current emphasis on genes is misplaced because genes don’t make structure. Developmental processes make structure through the activity of cells that use instructions specified by genes. A critical mechanism underlying any phenotypic trait is the genetically guided change in developmental events that produce the trait. But even when a developmental mechanism is identified, the links between genetically guided instructions and phenotypic outcome are lengthy, complicated, flexible, and sensitive to physical forces of functioning organs. We use the study of craniofacial phenotypes of craniosynostosis (premature closure of sutures) to demonstrate how patterns produced by the covariation of cranial traits cannot always reveal mechanism. Next we turn to encephalization, a critical feature of human evolution that covaries with cranial phenotypes, and show how experimental approaches can be used to analyze mechanism underlying this well-documented pattern in human evolution. With the realization that no single line of evidence can explain the dramatic changes in cranial morphology that characterize human evolution come fundamental changes in the way we conduct anthropological inquiry - collaborative efforts from scientists with diverse expertise will continue to push the field forward.

scholarly journals Genome-Wide Association Studies Based on Equine Joint Angle Measurements Reveal New QTL Affecting the Conformation of Horses

Genes ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 370 ◽  
Author(s):  
Annik Imogen Gmel ◽  
Thomas Druml ◽  
Rudolf von Niederhäusern ◽  
Tosso Leeb ◽  
Markus Neuditschko
Keyword(s):  
Joint Angle ◽  
Association Studies ◽  
Genome Wide Association ◽  
Cranial Morphology ◽  
Genome Wide Association Studies ◽  
Joint Angles ◽  
Mineral Density ◽  
Mixed Effect ◽  
Stifle Joint ◽  
Genome Wide

The evaluation of conformation traits is an important part of selection for breeding stallions and mares. Some of these judged conformation traits involve joint angles that are associated with performance, health, and longevity. To improve our understanding of the genetic background of joint angles in horses, we have objectively measured the angles of the poll, elbow, carpal, fetlock (front and hind), hip, stifle, and hock joints based on one photograph of each of the 300 Franches-Montagnes (FM) and 224 Lipizzan (LIP) horses. After quality control, genome-wide association studies (GWASs) for these traits were performed on 495 horses, using 374,070 genome-wide single nucleotide polymorphisms (SNPs) in a mixed-effect model. We identified two significant quantitative trait loci (QTL) for the poll angle on ECA28 (p = 1.36 × 10−7), 50 kb downstream of the ALX1 gene, involved in cranial morphology, and for the elbow joint on ECA29 (p = 1.69 × 10−7), 49 kb downstream of the RSU1 gene, and 75 kb upstream of the PTER gene. Both genes are associated with bone mineral density in humans. Furthermore, we identified other suggestive QTL associated with the stifle joint on ECA8 (p = 3.10 × 10−7); the poll on ECA1 (p = 6.83 × 10−7); the fetlock joint of the hind limb on ECA27 (p = 5.42 × 10−7); and the carpal joint angle on ECA3 (p = 6.24 × 10−7), ECA4 (p = 6.07 × 10−7), and ECA7 (p = 8.83 × 10−7). The application of angular measurements in genetic studies may increase our understanding of the underlying genetic effects of important traits in equine breeding.

Sexual differences in human cranial morphology: is one sex more variable or one region more dimorphic?

2021 ◽  
Author(s):  
Marco Milella ◽  
Daniel Franklin ◽  
Maria Giovanna Belcastro ◽  
Andrea Cardini
Keyword(s):  
Sexual Differences ◽  
Cranial Morphology

Osteological description of the braincase of Rhabdodon (Dinosauria, Euornithopoda) and phylogenetic implications

2006 ◽  
Vol 177 (2) ◽  
pp. 97-104 ◽  
Author(s):  
Marie Pincemaille-Quillevere ◽  
Eric Buffetaut ◽  
Frédéric Quillevere
Keyword(s):  
Cranial Nerves ◽  
Sister Group ◽  
Suture Line ◽  
Foramen Magnum ◽  
Cranial Morphology ◽  
Common Element ◽  
Occipital Condyle ◽  
Adult Individual ◽  
Southern France ◽  
Phylogenetic Implications

Abstract Since the 19th century, the Campanian and Maastrichtian continental deposits of southern France have yielded numerous dinosaur remains [Le Loeuff, 1991; 1998; Buffetaut et al., 1997; Laurent et al., 1991; Allain and Suberbiola, 2003]. The ornithopod remains that have not been referred to the hadrosaurids have been systematically attributed to Rhabdodon [Buffetaut and Le Loeuff, 1991; Buffetaut et al., 1996; Garcia et al., 1999; Pincemaille-Quillévéré, 2002]. This genus, initially named by Matheron [1869] after its discovery in the lower Maastrichtian of La Nerthe (Bouches-du-Rhône), belongs to the Euornithopoda [sensu Sereno, 1999]. Rhabdodon represents the most common element of the dinosaur assemblages from the late Cretaceous of southern France [e.g. Allain and Suberbiola, 2003]. Nevertheless, since the localities have only provided some fragmentary material [Pincemaille-Quillévéré, 2002], the global morphology of this dinosaur and its phylogenetic placement within the euornithopods are still debated. The cranial morphology of Rhabdodon is particularly poorly understood due to the rarity of cranial remains preserved in the localities of southern France [Matheron, 1869; Garcia et al., 1999; Buffetaut et al., 1999; Pincemaille-Quillévéré, 2002]. Buffetaut et al. [1999] first mentioned the discovery of a braincase (M4) referred to Rhabdodon, at Massecaps, a locality close to the village of Cruzy (Hérault, France). More recently, a new braincase (MN25) has been discovered at Montplô Nord, another locality close to Cruzy (specimens M4 and MN25 are conserved in the Museum of Cruzy). Both these localities have revealed a diverse and abundant vertebrate fauna suggesting a late Campanian to early Maastrichtian age [Buffetaut et al., 1999]. These braincases are described here in an attempt to detect potential autapomorphic characters in Rhabdodon, and compared to a more complete braincase of Tenontosaurus, an euornithopod from the Lower Cretaceous of North America, considered as the sister group of Rhabdodon [Weishampel et al., 1998; 2003; Garcia et al., 1999; Pincemaille-Quillévéré, 2002], in order to determine the potential differences and synapomorphies between the occiputs of the two genera. Finally, the braincases from Cruzy are compared to those of the other euornithopods described in the literature. Specimen M4 (figs. 1–4) is incomplete but exceptionally well preserved. This braincase belongs to a juvenile individual, as shown by the numerous visible suture lines between the different cranial elements. Specimen MN25 (fig. 5) is badly deformed and attributable to an adult individual. Until now, all the ornithopods from the Upper Cretaceous of southern France have been referred either to hadrosaurs or to Rhabdodon. The Hadrosauridae show a low nuchal crest and their exoccipitals meet and form a bar on the dorsal border of the foramen magnum, excluding the supraoccipital from this border. Specimens M4 and MN25 do not present any nuchal crest and the supraoccipital participates in the dorsal border of the foramen magnum. Both braincases M4 and MN25 are therefore attributable to Rhabdodon. Specimens M4 and MN25 have been compared to the occiput of a juvenile Tenontosaurus tilletti (fig. 6 : MCZ 4205, conserved in the Museum of Comparative Zoology, Harvard University). This reveals that Tenontosaurus and Rhabdodon share numerous characters : (1) the exoccipitals form the lateral borders of the foramen magnum, its ventral border being occupied by the basioccipital; (2) the occipital condyle is partly constituted by the exoccipitals, and in the same proportions; (3) the supraoccipital is rostrally oriented; (4) the suture line located between the prootic and the laterosphenoid shows the same outline; (5) the cresta prootica starts within the paroccipital process and extends onto the opisthotic; (6) the cresta prootica is transversal and non-horizontal; (7) the distribution of the cranial nerves is homologuous along the lateral surface of the braincase. Nevertheless, the braincase of Tenontosaurus differs from that of Rhabdodon in several significant respects : (1) the exoccipitals are dorsally connected, excluding the supraoccipital from the dorsal border of the foramen magnum; (2) two small dorsal humps are present at the level of the suture of the exoccipitals; (3) the supraoccipital is excluded from the dorsal border of the foramen magnum, which gives it a triangular shape; (4) the paroccipital processes are short, laterally flattened, and wing-shaped, and are more mediodorsally oriented than in Rhabdodon; (5) the cresta prootica follows a concave line and ends up on the prootic, at the level of the opening of the trigeminal nerve; (6) the external curve of the laterosphenoids is stronger; (7) the suture between the basioccipital and the opisthotic is very clear. The first of these unshared characters suggests that Rhabdodon belongs to Norman’s [1984] ‘hypsilophodontoid’ clade and Tenontosaurus to the more evolved ‘iguanodontoid’ clade. The fusion of the exoccipitals on the dorsal border of the foramen magnum, together with other cranial adaptations, may have reduced the stress caused by a more elaborate mastication. Rhabdodon appears to have had a more primitive type of mastication. The strip formed by the reunion of the exoccipitals is less expanded dorsoventrally in Tenontosaurus tilletti than in the ‘iguanodontoid’ and ‘hadrosauroid’ clades. Tenontosaurus may therefore represent an intermediate group between the ‘hypsilophodontoid’ and ‘iguanodontoid’ clades.

Sign in / Sign up

Export Citation Format

Share Document