scholarly journals Comparative cranial osteology of subadult eucentrosauran ceratopsid dinosaurs from the Two Medicine Formation, Montana, indicates sequence of ornamentation development and complex supraorbital ontogenetic change

2021 ◽  
Vol 66 ◽  
Author(s):  
John Wilson ◽  
John Scannella
Keyword(s):  
Ontogenetic Change ◽  
Cranial Osteology

Brief description of prey selectivity and ontogenetic changes in the diet of the invasive lionfish Pterois volitans (Actinopterygii, Scorpaenidae) in the Mexican Caribbean

2018 ◽  
Author(s):  
Juan Carlos Villaseñor-Derbez
Keyword(s):  
Stomach Contents ◽  
Ontogenetic Change ◽  
Prey Selectivity ◽  
Ontogenetic Changes ◽  
Pterois Volitans ◽  
Mexican Caribbean ◽  
Invasive Lionfish

Stomach contents were analyzed from 109 individuals. A total of 4 Genera and 14 Species were identified. Crustaceans accounted for %N=67.39% , %IRI= 86.37% of the total identified taxa and Teleosts %N=32.61% (%IRI = 13.63%). An ontogenetic change was observed in P. volitans diet.

scholarly journals Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics

2012 ◽  
Vol 8 (4) ◽  
pp. 660-664 ◽  
Author(s):  
K. T. Bates ◽  
P. L. Falkingham
Keyword(s):  
Body Size ◽  
Feeding Behaviour ◽  
Ontogenetic Change ◽  
Positive Allometry ◽  
Musculoskeletal Models ◽  
Terrestrial Animal ◽  
Body Dynamics ◽  
Mode Of Life ◽  
Scaling Analyses ◽  
Multi Body

Bite mechanics and feeding behaviour in Tyrannosaurus rex are controversial. Some contend that a modest bite mechanically limited T. rex to scavenging, while others argue that high bite forces facilitated a predatory mode of life. We use dynamic musculoskeletal models to simulate maximal biting in T. rex . Models predict that adult T. rex generated sustained bite forces of 35 000–57 000 N at a single posterior tooth, by far the highest bite forces estimated for any terrestrial animal. Scaling analyses suggest that adult T. rex had a strong bite for its body size, and that bite performance increased allometrically during ontogeny. Positive allometry in bite performance during growth may have facilitated an ontogenetic change in feeding behaviour in T. rex , associated with an expansion of prey range in adults to include the largest contemporaneous animals.

scholarly journals An assessment of the taxonomic validity of three species of marsupial frogs (Anura: Hemiphractidae: Gastrotheca) from the Yungas of Bolivia based on external morphology and cranial osteology

Zootaxa ◽  
2021 ◽  
Vol 5068 (2) ◽  
pp. 211-239
Author(s):  
CLAUDIA LANSAC ◽  
RODRIGO AGUAYO ◽  
IGNACIO DE LA RIVA
Keyword(s):  
Principal Component ◽  
Taxonomic Status ◽  
Ct Scanning ◽  
Developmental State ◽  
Morphological Characters ◽  
Biological Entity ◽  
Nominal Species ◽  
Linear Discriminant ◽  
Morphological Studies ◽  
Cranial Osteology

The genus Gastrotheca (Anura: Hemiphractidae) is a group of marsupial frogs particularly diverse in Andean regions. Several taxonomic studies of this genus have been conducted in the humid cloud forests—or Yungas—of the Andean eastern slopes of central Bolivia (departments of Cochabamba and Santa Cruz). Yet, the distinction among three species that occur sympatrically in these forests, G. lauzuricae (proposed as a junior synonym of G. coeruleomaculatus in 2015), G. piperata, and G. splendens, remains unclear since the morphological characters that purportedly support their differentiation are variable and partly shared among them. We have carried out external morphological studies, including multivariate morphometric analyses, to assess how they support the taxonomic status of these three species. We also evaluated characters of the cranial osteology of a sample of six individuals using micro CT-scanning. Principal component and linear discriminant analyses resulted in a great overlap among the putative species. Cranial osteological comparisons did not reveal highly significant differences among them, but suggested that different degrees of hyperossification could be related to the developmental state of individuals. Our results indicate that most morphological and osteological reported differences between the three species likely represent intraspecific variation. Thus, we propose that the three nominal species belong to a single biological entity, for which the name Gastrotheca splendens (Schmidt, 1857) has priority. We also restrict the name Gastrotheca coeruleomaculatus (Werner, 1899) to externally similar congeneric populations from the Yungas forests of department of La Paz, but highlighting the need of a detailed evaluation of their taxonomic identity.  

scholarly journals New interpretation of the cranial osteology of the Early Cretaceous turtle Arundelemys dardeni (Paracryptodira) based on a CT-based re-evaluation of the holotype

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11495
Author(s):  
Serjoscha W. Evers ◽  
Yann Rollot ◽  
Walter G. Joyce
Keyword(s):  
Early Cretaceous ◽  
Computer Tomography ◽  
Mass Extinction ◽  
Early Evolution ◽  
New Interpretation ◽  
Phylogenetic Hypotheses ◽  
Initial Description ◽  
Cranial Osteology ◽  
Anatomical Information

Arundelemys dardeni is an Early Cretaceous paracryptodire known from a single, incomplete, but generally well-preserved skull. Phylogenetic hypotheses of paracryptodires often find Arundelemys dardeni as an early branching baenid. As such, it has a central role in understanding the early evolution of the successful clade Baenidae, which survived the Cretaceous–Paleogene mass extinction, as well as the diversification of Paracryptodira into its subclades, which recent research suggests to perhaps include helochelydrids, compsemydids, pleurosternids, and baenids. Computer tomography scans of the holotype material that were produced for the initial description of Arundelemeys dardeni reveal several errors in the initial anatomical description of the species, which we correct based on element-by-element segmentation. In addition, we provide entirely novel anatomical information, including descriptions of several previously undescribed cranial bones, the endosseous labyrinth, and the cranial scutes, the latter of which are unknown for most paracryptodires. We provide an interpretation of cranial scutes which homologizes the scutes of Arundelemys dardeni with those of other stem turtles.

scholarly journals First nearly complete skull of Gallotia auaritae (lower-middle Pleistocene, Squamata, Gallotiinae) and a morphological phylogenetic analysis of the genus Gallotia

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Penélope Cruzado-Caballero ◽  
Carolina Castillo Ruiz ◽  
Arnau Bolet ◽  
Juan Ramón Colmenero ◽  
Julio De la Nuez ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Cranial Morphology ◽  
Middle Pleistocene ◽  
Phylogenetic Position ◽  
Fossil Species ◽  
La Palma ◽  
Computed Microtomography ◽  
X Ray Computed ◽  
Cranial Osteology ◽  
First Time

Abstract The Canary Islands are an Atlantic archipelago known for its high number of endemic species. Among the most known endemic vertebrate species are the giant lizards of the genus Gallotia. We describe the cranial osteology of the first almost complete and articulated fossil skull of the taxon Gallotia auaritae, recovered from the lower-middle Pleistocene of the La Palma island. In this work, X-ray computed microtomography images were used to perform an exhaustive phylogenetic analysis where most of the extant and fossil species of the genus Gallotia were included for first time. This analysis recovered a monophyletic Gallotia clade with similar topology to that of molecular analyses. The newly described specimen shares some characters with the group formed by G. bravoana, G. intermedia and G. simonyi, G. auaritae, and its position is compatible with a referral to the latter. Our study adds new important data to the poorly known cranial morphology of G. auaritae, and the phylogenetic analysis reveals an unexpected power of resolution to obtain a morphology-based phylogeny for the genus Gallotia, for inferring the phylogenetic position of extinct species and for helping in the identification of fossil specimens.

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