scholarly journals A redescription of the Late Jurassic (Tithonian) turtle Uluops uluops and a new phylogenetic hypothesis of Paracryptodira

2021 ◽  
Vol 140 (1) ◽  
Author(s):  
Yann Rollot ◽  
Serjoscha W. Evers ◽  
Walter G. Joyce
Keyword(s):  
Computed Tomography ◽  
Phylogenetic Analysis ◽  
Late Jurassic ◽  
Internal Carotid ◽  
Circulation System ◽  
Phylogenetic Hypothesis ◽  
Micro Computed Tomography ◽  
Future Studies ◽  
Computed Tomography Scans ◽  
Palatine Artery

AbstractWe study the Late Jurassic (Tithonian) turtle Uluops uluops using micro-computed tomography scans to investigate the cranial anatomy of paracryptodires, and provide new insights into the evolution of the internal carotid artery and facial nerve systems, as well as the phylogenetic relationships of this group. We demonstrate the presence of a canalis caroticus lateralis in Uluops uluops, the only pleurosternid for which a palatine artery canal can be confidently identified. Our phylogenetic analysis retrieves Uluops uluops as the earliest branching pleurosternid, Helochelydridae within Pleurosternidae, and Compsemydidae including Kallokibotion bajazidi within Baenidae, which suggests at least two independent losses of the palatine artery within paracryptodires. We expect future studies will provide additional insights into the evolution of the circulation system of paracryptodires, as well as clarifying relationships along the turtle stem.

scholarly journals A dataset comprising four micro-computed tomography scans of freshly fixed and museum earthworm specimens

GigaScience ◽  
2014 ◽  
Vol 3 (1) ◽  
Author(s):  
Jennifer Lenihan ◽  
Sebastian Kvist ◽  
Rosa Fernández ◽  
Gonzalo Giribet ◽  
Alexander Ziegler
Keyword(s):  
Computed Tomography ◽  
Micro Computed Tomography ◽  
Computed Tomography Scans

scholarly journals Volumetric analysis of the cranial and nasal cavity from micro-computed tomography scans in the rabbit

2020 ◽  
Vol 79 (2) ◽  
pp. 333-338
Author(s):  
C. Bakıcı ◽  
R. O. Akgun ◽  
O. Ekım ◽  
C. Soydal ◽  
C. Oto
Keyword(s):  
Computed Tomography ◽  
Nasal Cavity ◽  
Volumetric Analysis ◽  
Micro Computed Tomography ◽  
Computed Tomography Scans

scholarly journals The five digits of the giraffe metatarsal

2020 ◽  
Vol 131 (3) ◽  
pp. 699-705
Author(s):  
Laurel R Yohe ◽  
Nikos Solounias
Keyword(s):  
Computed Tomography ◽  
High Resolution ◽  
Fossil Record ◽  
The Other ◽  
Micro Computed Tomography ◽  
Common Assumption ◽  
Internal Morphology ◽  
Computed Tomography Scans ◽  
The Common ◽  
Taxonomic Groups

Abstract Evolution has shaped the limbs of hoofed animals in specific ways. In artiodactyls, it is the common assumption that the metatarsal is composed of the fusion of digits III and IV, whereas the other three digits have been lost or are highly reduced. However, evidence from the fossil record and internal morphology of the metatarsal challenges these assumptions. Furthermore, only a few taxonomic groups have been analysed. In giraffes, we discovered that all five digits are present in the adult metatarsal and are highly fused and modified rather than lost. We examined high-resolution micro-computed tomography scans of the metatarsals of two mid and late Miocene giraffid fossils and the extant giraffe and okapi. In all the Giraffidae analysed, we found a combination of four morphologies: (1) four articular facets; (2) four or, in most cases, five separate medullary cavities internally; (3) a clear, small digit I; and (4) in the two fossil taxa of unknown genus, the presence of external elongated grooves where the fusions of digits II and V have taken place. Giraffa and Okapia, the extant Giraffidae, show a difference from all the extinct taxa in having more flattened digits tightly packed together, suggesting convergent highly fused digits despite divergent ecologies and locomotion. These discoveries provide evidence that enhances our understanding of how bones fuse and call into question current hypotheses of digit loss.

scholarly journals Ontogenetic braincase development in Psittacosaurus lujiatunensis (Dinosauria: Ceratopsia) using micro-computed tomography

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7217 ◽  
Author(s):  
Claire M. Bullar ◽  
Qi Zhao ◽  
Michael J. Benton ◽  
Michael J. Ryan
Keyword(s):  
Computed Tomography ◽  
Semicircular Canal ◽  
Morphological Changes ◽  
Relative Reduction ◽  
Growth Stages ◽  
Ontogenetic Changes ◽  
Micro Computed Tomography ◽  
Horizontal Semicircular Canal ◽  
Computed Tomography Scans ◽  
Key Events

Ontogenetic sequences are relatively rare among dinosaurs, with Ceratopsia being one of the better represented clades, and especially among geologically earlier forms, such as Psittacosaurus. Psittacosaurus is a small, bipedal basal ceratopsian abundant in the Lower Cretaceous deposits of Asia, whose cranial and endocranial morphology has been well studied, but only cursory details have been published on the bones surrounding the brain. Using reconstructions created from micro-computed tomography scans of well-preserved skulls from the Barremian–Aptian Yixian Formation, China, we document morphological changes in the braincase of Psittacosaurus lujiatunensis through three growth stages, hatchling, juvenile, and adult, thus providing the first detailed study of ceratopsian braincase morphology through ontogeny. Notable ontogenetic changes in the braincase of P. lujiatunensis include a dramatic relative reduction in size of the supraoccipital, an increase in the lateral expansion of the paroccipital processes and a decrease in the angle between the lateral semicircular canal and the palatal plane. These ontogenetic morphological changes in the braincase relate to expansion of the cranium and brain through growth, as well as reflecting the switch from quadrupedal juveniles to bipedal adults as documented in the changing orientation of the horizontal semicircular canal through ontogeny. Recognition of these patterns in a basal ceratopsian has implications for understanding key events in later ceratopsian evolution, such as the development of the parieto-squamosal frill in derived neoceratopsians.

scholarly journals New skulls and skeletons of the Cretaceous legged snake Najash, and the evolution of the modern snake body plan

2019 ◽  
Vol 5 (11) ◽  
pp. eaax5833 ◽  
Author(s):  
Fernando F. Garberoglio ◽  
Sebastián Apesteguía ◽  
Tiago R. Simões ◽  
Alessandro Palci ◽  
Raúl O. Gómez ◽  
...  
Keyword(s):  
Fossil Record ◽  
Body Plan ◽  
Transient Phase ◽  
Phylogenetic Hypothesis ◽  
Micro Computed Tomography ◽  
Molecular Analyses ◽  
Initial Sequence ◽  
Intermediate Morphology ◽  
Computed Tomography Scans ◽  
Shed Light

Snakes represent one of the most dramatic examples of the evolutionary versatility of the vertebrate body plan, including body elongation, limb loss, and skull kinesis. However, understanding the earliest steps toward the acquisition of these remarkable adaptations is hampered by the very limited fossil record of early snakes. Here, we shed light on the acquisition of the snake body plan using micro–computed tomography scans of the first three-dimensionally preserved skulls of the legged snake Najash and a new phylogenetic hypothesis. These findings elucidate the initial sequence of bone loss that gave origin to the modern snake skull. Morphological and molecular analyses including the new cranial data provide robust support for an extensive basal radiation of early snakes with hindlimbs and pelves, demonstrating that this intermediate morphology was not merely a transient phase between limbed and limbless body plans.

scholarly journals A new plesiosaurian from the Jurassic–Cretaceous transitional interval of the Slottsmøya Member (Volgian), with insights into the cranial anatomy of cryptoclidids using computed tomography

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8652 ◽  
Author(s):  
Aubrey Jane Roberts ◽  
Patrick S. Druckenmiller ◽  
Benoit Cordonnier ◽  
Lene L. Delsett ◽  
Jørn H. Hurum
Keyword(s):  
Computed Tomography ◽  
Phylogenetic Analysis ◽  
High Resolution ◽  
Early Cretaceous ◽  
Late Jurassic ◽  
New Genus ◽  
Pectoral Girdle ◽  
High Latitudes ◽  
New Genus And Species ◽  
Major Clade

Cryptoclidids are a major clade of plesiosauromorph plesiosaurians best known from the Middle—Late Jurassic, but little is known regarding their turnover into the Early Cretaceous. Of the known cryptoclidid genera, most preserve only a limited amount of cranial material and of these Cryptoclidus eurymerus, displays the most complete, but compressed cranium. Thus, the lack of knowledge of the cranial anatomy of this group may hinder the understanding of phylogenetic interrelationships, which are currently predominantly based on postcranial data. Here we present a nearly complete adult cryptoclidid specimen (PMO 224.248) representing a new genus and species Ophthalmothule cryostea gen et sp. nov., from the latest Jurassic to earliest Cretaceous part of the Slottsmøya Member, of central Spitsbergen. The holotype material preserves a complete cranium, partial mandible, complete and articulated cervical, pectoral and anterior to middle dorsal series, along with the pectoral girdle and anterior humeri. High resolution microcomputed tomography reveals new data on the cranial anatomy of this cryptoclidid, including new internal features of the braincase and palate that are observed in other cryptoclidids. A phylogenetic analysis incorporating new characters reveals a novel tree topology for Cryptoclididae and particularly within the subfamily Colymbosaurinae. These results show that at least two cryptoclidid lineages were present in the Boreal Region during the latest Jurassic at middle to high latitudes.

scholarly journals A review of the carotid artery and facial nerve canal systems in extant turtles

PeerJ ◽  
2021 ◽  
Vol 8 ◽  
pp. e10475
Author(s):  
Yann Rollot ◽  
Serjoscha W. Evers ◽  
Walter G. Joyce
Keyword(s):  
Facial Nerve ◽  
Morphometric Study ◽  
Circulation System ◽  
Geniculate Ganglion ◽  
Carotid Canal ◽  
Computed Tomography Scans ◽  
Canal Systems ◽  
Carotid Circulation ◽  
Palatine Artery ◽  
Shed Light

The cranial circulation and innervation systems of turtles have been studied for more than two centuries and extensively used to understand turtle systematics. Although a significant number of studies related to these structures exists, a broader comprehension of variation across the tree has been hindered by poor sampling and a lack of synthetic studies that addressed both systems together. We here provide new insights regarding the carotid circulation and facial nerve innervation systems in a broad set of extant turtles using CT (computed tomography) scans, which allow us to trace the canals these structures form in bone and understand the interaction between both systems. We document that the palatine artery, including the lateral carotid canal, is absent in all pleurodires and carettochelyids and was likely reduced or lost several times independently within Testudinoidea. We also highlight osteological correlates for the location of the mandibular artery. We finally summarize variation regarding the placement of the mandibular artery, location of the geniculate ganglion, placement of the hyomandibular and vidian nerves, and situations where we recommend caution when assessing canals in fossils. A morphometric study confirms that the relative sizes of the carotid canals are correlated with one another. Our results have the potential for building new phylogenetic characters and investigating the circulation systems of fossil taxa, which are expected to shed light on the evolution of the circulation system of turtles and clarify some unresolved relationships between fossil turtle clades.

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