scholarly journals Before trilobite legs: Pygmaclypeatus daziensis reconsidered and the ancestral appendicular organization of Cambrian artiopods

2021 ◽  
Author(s):  
Michel Schmidt ◽  
Xianguang Hou ◽  
Dayou Zhai ◽  
Huijuan Mai ◽  
Jelena Belojevic ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Feeding Strategy ◽  
Small Body ◽  
Functional Ecology ◽  
Evolutionary Significance ◽  
Small Body Size ◽  
Micro Computed Tomography ◽  
Mode Of Life ◽  
Chengjiang Biota ◽  
High Degree

The Cambrian Stage 3 Chengjiang biota in South China is one of the most influential Konservat Lagerstatten worldwide thanks to the fossilization of diverse nonbiomineralizing organisms through pyritization. Despite their contributions to understanding the evolution of early animals, several Chengjiang species remain poorly known due to their scarcity and/or incomplete preservation. Here, we use micro-computed tomography to reveal in detail the ventral appendage organization of the enigmatic non-trilobite artiopod Pygmaclypeatus daziensis, one of the rarest euarthropods in Chengjiang, and explore its functional ecology and broader evolutionary significance. P. daziensis possesses a set of uniramous antennae and 14 pairs of post-antennal biramous appendages, the latter of which show an unexpectedly high degree of heteronomy based on the localized differentiation of the protopodite, endopod and exopod along the antero-posterior body axis. The small body size (less than 2 cm), presence of delicate spinose endites, and well-developed exopods with multiple paddle-shaped lamellae on the appendages of P. daziensis indicate a nekto-benthic mode of life, and a scavenging/detritus feeding strategy. P. daziensis shows that appendage heteronomy is phylogenetically widespread within Artiopoda, the megadiverse clade that includes trilobites and their relatives with nonbiomineralizing exoskeletons and suggests that a single exopod lobe with paddle like lamellae is ancestral for this clade.

Cortical and trabecular bone parameters from HR-Pqct images at the Tibia: a local comparison with synchrotron radiation micro-computed tomography

2013 ◽  
Author(s):  
Agnes Ostertag ◽  
Francoise Peyrin ◽  
Sylvie Fernandez ◽  
Jean-Denis Laredo ◽  
Vernejoul Marie-Christine De ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Synchrotron Radiation ◽  
Trabecular Bone ◽  
Micro Computed Tomography ◽  
Bone Parameters ◽  
Local Comparison

Morphology and Affinities of Ampelocissites Seeds (Vitaceae: Ampelopsis clade) from the Paleogene of Texas, USA

2020 ◽  
Vol 45 (3) ◽  
pp. 478-482
Author(s):  
Steven R. Manchester
Keyword(s):  
Computed Tomography ◽  
Cross Sections ◽  
Seed Coat ◽  
Ct Scanning ◽  
Seed Morphology ◽  
Early Eocene ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Fossil Seeds ◽  
Fossil Genus

Abstract—The type material on which the fossil genus name Ampelocissites was established in 1929 has been reexamined with the aid of X-ray micro-computed tomography (μ-CT) scanning and compared with seeds of extant taxa to assess the relationships of these fossils within the grape family, Vitaceae. The specimens were collected from a sandstone of late Paleocene or early Eocene age. Although originally inferred by Berry to be intermediate in morphology between Ampelocissus and Vitis, the newly revealed details of seed morphology indicate that these seeds represent instead the Ampelopsis clade. Digital cross sections show that the seed coat maintains its thickness over the external surfaces, but diminishes quickly in the ventral infolds. This feature, along with the elliptical chalaza and lack of an apical groove, indicate that Ampelocissites lytlensis Berry probably represents Ampelopsis or Nekemias (rather than Ampelocissus or Vitis) and that the generic name Ampelocissites may be useful for fossil seeds with morphology consistent with the Ampelopsis clade that lack sufficient characters to specify placement within one of these extant genera.

INVESTIGATION OF AUBRITES THROUGH INTEGRATION OF 3D MODAL MINERALOGY WITH X-RAY MICRO-COMPUTED TOMOGRAPHY AND GEOCHEMISTRY

2018 ◽  
Author(s):  
Zoë E. Wilbur ◽  
◽  
Arya Udry ◽  
Arya Udry ◽  
Daniel M. Coleff ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Micro Computed Tomography ◽  
X Ray

scholarly journals Micro-Computed Tomography Analysis of Subchondral Bone Regeneration Using Osteochondral Scaffolds in an Ovine Condyle Model

2021 ◽  
Vol 11 (3) ◽  
pp. 891
Author(s):  
Taylor Flaherty ◽  
Maryam Tamaddon ◽  
Chaozong Liu
Keyword(s):  
Computed Tomography ◽  
Bone Regeneration ◽  
Subchondral Bone ◽  
Volume Ratio ◽  
Bone Volume ◽  
Osteochondral Defects ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Trabecular Thickness ◽  
Osteochondral Scaffold

Osteochondral scaffold technology has emerged as a promising therapy for repairing osteochondral defects. Recent research suggests that seeding osteochondral scaffolds with bone marrow concentrate (BMC) may enhance tissue regeneration. To examine this hypothesis, this study examined subchondral bone regeneration in scaffolds with and without BMC. Ovine stifle condyle models were used for the in vivo study. Two scaffold systems (8 mm diameter and 10 mm thick) with and without BMC were implanted into the femoral condyle, and the tissues were retrieved after six months. The retrieved femoral condyles (with scaffold in) were examined using micro-computed tomography scans (micro-CT), and the micro-CT data were further analysed by ImageJ with respect to trabecular thickness, bone volume to total volume ratio (BV/TV) ratio, and degree of anisotropy of bone. Statistical analysis compared bone regeneration between scaffold groups and sub-set regions. These results were mostly insignificant (p < 0.05), with the exception of bone volume to total volume ratio when comparing scaffold composition and sub-set region. Additional trends in the data were observed. These results suggest that the scaffold composition and addition of BMC did not significantly affect bone regeneration in osteochondral defects after six months. However, this research provides data which may guide the development of future treatments.

scholarly journals High degree of non-genetic phenotypic variation in the vascular system of crayfish: a discussion of possible causes and implications

Zoomorphology ◽  
2021 ◽  
Author(s):  
Stephan Scholz ◽  
Torben Göpel ◽  
Stefan Richter ◽  
Christian S. Wirkner
Keyword(s):  
Phenotypic Variation ◽  
Genetic Factors ◽  
Vascular System ◽  
Micro Computed Tomography ◽  
Causal Factors ◽  
Developmental Variation ◽  
Branching Patterns ◽  
Phenotypic Variations ◽  
Marbled Crayfish ◽  
High Degree

AbstractIn this study, the hemolymph vascular system (HVS) in two cambarid crayfishes, i.e. the Marbled Crayfish, Procambarus virginalis Lyko, 2017 and the Spiny Cheek Crayfish, Faxonius limosus (Rafinesque, 1817), is investigated in regard of areas of non-genetic phenotypic variation. Despite their genetic identity, specimens of P. virginalis show variability in certain features of the HVS. Thus, we describe varying branching patterns, sporadic anastomoses, and different symmetry states in the vascular system of the marbled crayfish. We visualize our findings by application of classical and modern morphological methods, e.g. injection of casting resin, micro-computed tomography and scanning electron microscopy. By comparing our findings for P. virginalis to the vasculature in sexually reproducing crayfishes, i.e. F. limosus and Astacus astacus, we discuss phenotypic variation of the HVS in arthropods in general. We conclude that constant features of the HVS are hereditary, whereas varying states identified by study of the clonal P. virginalis must be caused by non-genetic factors and, that congruent variations in sexually reproducing F. limosus and A. astacus are likely also non-genetic phenotypic variations. Both common causal factors for non-genetic phenotypic variation, i.e., phenotypic plasticity and stochastic developmental variation are discussed along our findings regarding the vascular systems. Further aspects, such as the significance of non-genetic phenotypic variation for phylogenetic interpretations are discussed.

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