scholarly journals A comprehensive anatomical and phylogenetic evaluation of Dilophosaurus wetherilli (Dinosauria, Theropoda) with descriptions of new specimens from the Kayenta Formation of northern Arizona

2020 ◽  
Vol 94 (S78) ◽  
pp. 1-103 ◽  
Author(s):  
Adam D. Marsh ◽  
Timothy B. Rowe
Keyword(s):  
Phylogenetic Analyses ◽  
Cervical Vertebrae ◽  
Pop Culture ◽  
Single Species ◽  
Axial Skeleton ◽  
Late Triassic ◽  
Monophyletic Clade ◽  
Navajo Nation ◽  
Northern Arizona ◽  
Nasal Process

AbstractDilophosaurus wetherilli was the largest animal known to have lived on land in North America during the Early Jurassic. Despite its charismatic presence in pop culture and dinosaurian phylogenetic analyses, major aspects of the skeletal anatomy, taxonomy, ontogeny, and evolutionary relationships of this dinosaur remain unknown. Skeletons of this species were collected from the middle and lower part of the Kayenta Formation in the Navajo Nation in northern Arizona. Redescription of the holotype, referred, and previously undescribed specimens of Dilophosaurus wetherilli supports the existence of a single species of crested, large-bodied theropod in the Kayenta Formation. The parasagittal nasolacrimal crests are uniquely constructed by a small ridge on the nasal process of the premaxilla, dorsoventrally expanded nasal, and tall lacrimal that includes a posterior process behind the eye. The cervical vertebrae exhibit serial variation within the posterior centrodiapophyseal lamina, which bifurcates and reunites down the neck. Iterative specimen-based phylogenetic analyses result in each of the additional specimens recovered as the sister taxon to the holotype. When all five specimens are included in an analysis, they form a monophyletic clade that supports the monotypy of the genus. Dilophosaurus wetherilli is not recovered as a ceratosaur or coelophysoid, but is instead a non-averostran neotheropod in a grade with other stem-averostrans such as Cryolophosaurus ellioti and Zupaysaurus rougieri. We did not recover a monophyletic ‘Dilophosauridae.’ Instead of being apomorphic for a small clade of early theropods, it is more likely that elaboration of the nasals and lacrimals of stem-averostrans is plesiomorphically present in early ceratosaurs and tetanurans that share those features. Many characters of the axial skeleton of Dilophosaurus wetherilli are derived compared to Late Triassic theropods and may be associated with macropredation and an increase in body size in Theropoda across the Triassic-Jurassic boundary.

A study of molecular sequences, sexuality, and morphological variation in Plagiomnium carolinianum, P. maximoviczii, and P. rhynchophorum (Bryophyta, Mniaceae)

Phytotaxa ◽  
2018 ◽  
Vol 375 (1) ◽  
pp. 81
Author(s):  
YAN-JUN YI ◽  
ZHEN-WEI SUN ◽  
SI HE ◽  
MAMTIMIN SULAYMAN
Keyword(s):  
Phylogenetic Analyses ◽  
Single Species ◽  
Molecular Study ◽  
Geographic Range ◽  
Similar Species ◽  
Monophyletic Clade ◽  
Closely Related Species ◽  
Molecular Phylogenetic ◽  
Different Populations ◽  
Rps4 Gene

Morphologically, recognition of the genus Plagiomnium may be relatively easy. Yet identifications of closely related species have met great difficulties. The contemporary species delimitations of P. carolinianum, P. maximoviczii, and P. rhynchophorum largely based on sexuality as the sole distinction have not been satisfactory. As shown from literature, character variations among these three taxa were continuous and intergraded within or among different populations throughout a wide geographic range. No gametophytic characters could be reliably used to distinguish them from each other. Molecular phylogenetic analyses using ITS2 and rps4 gene were undertaken to resolve delineations for these three morphologically similar species. The results suggest that they form a well support monophyletic clade, which can be defined as representing one single species with two subspecies, i.e. P. rhynchophorum subsp. maximoviczii and P. rhynchophorum subsp. rhynchophorum. The present molecular study supports the treatment of P. carolinianum as synonym of P. rhynchophorum as purposed previously by Koponen based on morphology.

A new aetosaur genus (Archosauria: Pseudosuchia) from the early Late Triassic of southern Brazil

Zootaxa ◽  
2012 ◽  
Vol 3166 (1) ◽  
pp. 1 ◽  
Author(s):  
JULIA B. DESOJO ◽  
MARTÍN D. EZCURRA ◽  
EDIO E. KISCHLAT
Keyword(s):  
Cervical Vertebrae ◽  
Cladistic Analysis ◽  
Axial Skeleton ◽  
Late Triassic ◽  
South American ◽  
Southern Brazil ◽  
Caudal Vertebra ◽  
Caudal Vertebrae ◽  
Santa Maria ◽  
Early Late

We describe the new aetosaur Aetobarbakinoides brasiliensis gen. et sp. nov. from the early Late Triassic (late Carnian-early Norian) Brazilian Santa Maria Formation. The holotype is composed of a partial postcranium including several cer-vical and dorsal vertebrae and ribs, one anterior caudal vertebra, right scapula, right humerus, right tibia, partial right pes,and anterior and mid-dorsal paramedian osteoderms. Aetobarbakinoides is differentiated from other aetosaurs by the pres-ence of cervical vertebrae with widely laterally extended prezygapophyses, mid-cervical vertebrae with anterior articularfacet width more than 1.2 times wider than the posterior one, anterior caudal vertebrae with extremely anteroposteriorlyshort prezygapophyses, elongated humerus and tibia in relation to the axial skeleton, and paramedian osteoderms with aweakly raised anterior bar. A cladistic analysis recovered the new species as more derived than the South American generaAetosauroides (late Carnian-early Norian) and Neoaetosauroides (late Norian-Rhaetian), and it is nested as the sister-tax-on of an unnamed clade, composed of Typothoracisinae and Desmatosuchinae, due to the absence of a ventral keel in thecervical vertebrae. Aetobarbakinoides presents a skeletal anatomy previously unknown among South American aetosaurs,with the combination of presacral vertebrae with hyposphene, anteroposteriorly short and unkeeled cervical vertebrae,gracile limbs, and paramedian osteoderms with a weakly raised anterior bar. Aetobarbakinoides is among the oldest knownaetosaurs together with Aetosauroides from Argentina and Brazil and Stagonolepis robertsoni from Scotland, indicatinga widely distributed early record for the group. In addition, the recognition of a suite of derived features in Aetobarbaki-noides, which is one of the oldest known aetosaurs, is in agreement with an older origin for the group, as it is expected by the extensive ghost lineages at the base of the main pseudosuchian clades.

scholarly journals Homeotic shift at the dawn of the turtle evolution

2017 ◽  
Vol 4 (4) ◽  
pp. 160933 ◽  
Author(s):  
Tomasz Szczygielski
Keyword(s):  
Vertebral Column ◽  
Phylogenetic Analyses ◽  
Cervical Vertebrae ◽  
Expression Patterns ◽  
Cervical Vertebra ◽  
Late Triassic ◽  
Cervical Region ◽  
Crown Group ◽  
Dorsal Vertebra ◽  
Shift Hypothesis

All derived turtles are characterized by one of the strongest reductions of the dorsal elements among Amniota, and have only 10 dorsal and eight cervical vertebrae. I demonstrate that the Late Triassic turtles, which represent successive stages of the shell evolution, indicate that the shift of the boundary between the cervical and dorsal sections of the vertebral column occurred over the course of several million years after the formation of complete carapace. The more generalized reptilian formula of at most seven cervicals and at least 11 dorsals is thus plesiomorphic for Testudinata. The morphological modifications associated with an anterior homeotic change of the first dorsal vertebra towards the last cervical vertebra in the Triassic turtles are partially recapitulated by the reduction of the first dorsal vertebra in crown-group Testudines, and they resemble the morphologies observed under laboratory conditions resulting from the experimental changes of Hox gene expression patterns. This homeotic shift hypothesis is supported by the, unique to turtles, restriction of Hox-5 expression domains, somitic precursors of scapula, and brachial plexus branches to the cervical region, by the number of the marginal scute-forming placodes, which was larger in the Triassic than in modern turtles, and by phylogenetic analyses.

scholarly journals Linking morphological and molecular sources to disentangle the case of Xylodon australis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Javier Fernández-López ◽  
M. Teresa Telleria ◽  
Margarita Dueñas ◽  
Mara Laguna-Castro ◽  
Klaus Schliep ◽  
...  
Keyword(s):  
New Zealand ◽  
Phylogenetic Analyses ◽  
Single Species ◽  
R Package ◽  
Molecular Data ◽  
Historical Collections ◽  
Close Relationship ◽  
Kinship Relations ◽  
History Of ◽  
Different Sources

AbstractThe use of different sources of evidence has been recommended in order to conduct species delimitation analyses to solve taxonomic issues. In this study, we use a maximum likelihood framework to combine morphological and molecular traits to study the case of Xylodon australis (Hymenochaetales, Basidiomycota) using the locate.yeti function from the phytools R package. Xylodon australis has been considered a single species distributed across Australia, New Zealand and Patagonia. Multi-locus phylogenetic analyses were conducted to unmask the actual diversity under X. australis as well as the kinship relations respect their relatives. To assess the taxonomic position of each clade, locate.yeti function was used to locate in a molecular phylogeny the X. australis type material for which no molecular data was available using morphological continuous traits. Two different species were distinguished under the X. australis name, one from Australia–New Zealand and other from Patagonia. In addition, a close relationship with Xylodon lenis, a species from the South East of Asia, was confirmed for the Patagonian clade. We discuss the implications of our results for the biogeographical history of this genus and we evaluate the potential of this method to be used with historical collections for which molecular data is not available.

scholarly journals Delimitation, new species and teleomorph-anamorph relationships in Codinaea, Dendrophoma, Paragaeumannomyces and Striatosphaeria (Chaetosphaeriaceae)

MycoKeys ◽  
2020 ◽  
Vol 74 ◽  
pp. 17-74
Author(s):  
Martina Réblová ◽  
Jana Nekvindová ◽  
Jacques Fournier ◽  
Andrew N. Miller
Keyword(s):  
New Species ◽  
Type Species ◽  
Morphological Traits ◽  
Phylogenetic Analyses ◽  
Axenic Culture ◽  
Monophyletic Clade ◽  
Morphological Comparison ◽  
The Family ◽  
Terrestrial Habitats ◽  
First Time

The Chaetosphaeriaceae are a diverse group of pigmented, predominantly phialidic hyphomycetes comprised of several holomorphic genera including Chaetosphaeria, the most prominent genus of the family. Although the morphology of the teleomorphs of the majority of Chaetosphaeria is rather uniform, their associated anamorphs primarily exhibit the variability and evolutionary change observed in the genus. An exception from the morphological monotony among Chaetosphaeria species is a group characterised by scolecosporous, hyaline to light pink, multiseptate, asymmetrical ascospores and a unique three-layered ascomatal wall. Paragaeumannomyces sphaerocellularis, the type species of the genus, exhibits these morphological traits and is compared with similar Chaetosphaeria with craspedodidymum- and chloridium-like synanamorphs. Morphological comparison and phylogenetic analyses of the combined ITS-28S sequences of 35 isolates and vouchers with these characteristics revealed a strongly-supported, morphologically well-delimited clade in the Chaetosphaeriaceae containing 16 species. The generic name Paragaeumannomyces is applied to this monophyletic clade; eight new combinations and five new species, i.e. P. abietinussp. nov., P. eleganssp. nov., P. granulatussp. nov., P. sabinianussp. nov. and P. smokiensissp. nov., are proposed. A key to Paragaeumannomyces is provided. Using morphology, cultivation studies and phylogenetic analyses of ITS and 28S rDNA, two additional new species from freshwater and terrestrial habitats, Codinaea paniculatasp. nov. and Striatosphaeria castaneasp. nov., are described in the family. A codinaea-like anamorph of S. castanea forms conidia with setulae at each end in axenic culture; this feature expands the known morphology of Striatosphaeria. A chaetosphaeria-like teleomorph is experimentally linked to Dendrophoma cytisporoides, a sporodochial hyphomycete and type species of Dendrophoma, for the first time.

Aestuariisphingobium litorale Li et al. 2020 is a later heterotypic synonym of Chakrabartia godavariana Jani et al. 2019

2021 ◽  
Vol 71 (8) ◽  
Author(s):  
Peng Wang ◽  
Yuxin Gao
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Phylogenetic Analyses ◽  
Single Species ◽  
Rrna Gene ◽  
Genomic Comparison ◽  
Content Type ◽  
Link Type ◽  
Type Strains

Chakrabartia godavariana PRB40T was compared with Aestuariisphingobium litorale SYSU M10002T to examine the taxonomic relationship between the two type strains. The 16S rRNA gene sequence of C. godavariana PRB40T had high similarity (99.8 %) to that of A. litorale SYSU M10002T. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the two strains formed a tight cluster within the genus Chakrabartia . A draft genomic comparison between the two strains revealed an average nucleotide identity of 97.3 % and a digital DNA–DNA hybridization estimate of 79.5±2.9 %, strongly indicating that the two strains represented a single species. In addition, neither strain displayed any striking differences in metabolic, physiological or chemotaxonomic features. Therefore, we propose that Aestuariisphingobium litorale is a later heterotypic synonym of Chakrabartia godavariana .

Ichthyosaurs from the Upper Triassic (Carnian–Norian) of the New Siberian Islands, Russian Arctic, and their implications for the evolution of the ichthyosaurian basicranium and vertebral column

2021 ◽  
pp. 1-24
Author(s):  
Nikolay G. ZVERKOV ◽  
Dmitry V. GRIGORIEV ◽  
Andrzej S. WOLNIEWICZ ◽  
Alexey G. KONSTANTINOV ◽  
Evgeny S. SOBOLEV
Keyword(s):  
Vertebral Column ◽  
Cervical Vertebrae ◽  
Upper Triassic ◽  
Late Triassic ◽  
Phylogenetic Position ◽  
New Taxon ◽  
Russian Arctic ◽  
Micro Computed Tomography ◽  
New Siberian Islands ◽  
Group Relationships

ABSTRACT The first ichthyosaurian specimens discovered from the Upper Triassic of the Russian Arctic (Kotelny Island, New Siberian Islands) are described herein. They include the remains of large- to small-bodied ichthyosaurians originating from six stratigraphic levels spanning the lower Carnian to middle Norian. The material is mostly represented by isolated vertebrae and ribs, which are not possible to accurately diagnose, but also includes specimens comprising associated vertebrae and a fragmentary skeleton that preserves cranial remains (parabasisphenoid, fragmentary quadrate, partial mandible and hyoids). Based on vertebral and rib morphology, we identify the specimens as representatives of the following taxonomic groups: large-bodied shastasaurids, medium-sized indeterminate ichthyosaurians with a single rib facet in the presacral centra, and small euichthyosaurians with double rib facets present throughout the presacral vertebrae that likely represent toretocnemids and/or basal parvipelvians. In addition, the cranial and mandibular remains preserved in one of the specimens, ZIN PH 5/250, were studied using micro-computed tomography. Its mandible is highly similar to that of toretocnemids, whereas the parabasisphenoid demonstrates a peculiar combination of both plesiomorphic and derived character states, providing the first detailed data on this cranial element in a Late Triassic ichthyosaurian. Furthermore, the specimen also demonstrates a distinctive condition of rib articulation in the anteriormost presacral (cervical) vertebrae, which together with other features allows for the erection of a new taxon – Auroroborealia incognita gen. et sp. nov. Although the phylogenetic position of this taxon is uncertain due to its fragmentary nature, its anatomy, indicating toretocnemid or parvipelvian affinities, further supports the previously hypothesised sister-group relationships between these two clades. The morphology of the parabasisphenoid and vertebral column of the new taxon is discussed in broader contexts of the patterns of evolution of these skeletal regions in ichthyosaurs.

Intraspecific variation in the axial skeleton of Aetosauroides scagliai (Archosauria: Aetosauria) and its implications for the aetosaur diversity of the Late Triassic of Brazil

2021 ◽  
Vol 93 (suppl 2) ◽  
Author(s):  
VOLTAIRE D. PAES-NETO ◽  
JULIA BRENDA DESOJO ◽  
ANA CAROLINA B. BRUST ◽  
CESAR LEANDRO SCHULTZ ◽  
ÁTILA AUGUSTO S. DA-ROSA ◽  
...  
Keyword(s):  
Intraspecific Variation ◽  
Axial Skeleton ◽  
Late Triassic

The locomotor system

2013 ◽  
Author(s):  
Martin E. Atkinson
Keyword(s):  
Vertebral Column ◽  
Cervical Vertebrae ◽  
Lumbar Vertebrae ◽  
Posterior Wall ◽  
Axial Skeleton ◽  
Intervertebral Discs ◽  
Central Canal ◽  
The Body ◽  
Thoracic Vertebrae ◽  
Locomotor System

The locomotor system comprises the skeleton, composed principally of bone and cartilage, the joints between them, and the muscles which move bones at joints. The skeleton forms a supporting framework for the body and provides the levers to which the muscles are attached to produce movement of parts of the body in relation to each other or movement of the body as a whole in relation to its environment. The skeleton also plays a crucial role in the protection of internal organs. The skeleton is shown in outline in Figure 2.1A. The skull, vertebral column, and ribs together constitute the axial skeleton. This forms, as its name implies, the axis of the body. The skull houses and protects the brain and the eyes and ears; the anatomy of the skull is absolutely fundamental to the understanding of the structure of the head and is covered in detail in Section 4. The vertebral column surrounds and protects the spinal cord which is enclosed in the spinal canal formed by a large central canal in each vertebra. The vertebral column is formed from 33 individual bones although some of these become fused together. The vertebral column and its component bones are shown from the side in Figure 2.1B. There are seven cervical vertebrae in the neck, twelve thoracic vertebrae in the posterior wall of the thorax, five lumbar vertebrae in the small of the back, five fused sacral vertebrae in the pelvis, and four coccygeal vertebrae—the vestigial remnants of a tail. Intervertebral discs separate individual vertebrae from each other and act as a cushion between the adjacent bones; the discs are absent from the fused sacral vertebrae. The cervical vertebrae are small and very mobile, allowing an extensive range of neck movements and hence changes in head position. The first two cervical vertebrae, the atlas and axis, have unusual shapes and specialized joints that allow nodding and shaking movements of the head on the neck. The thoracic vertebrae are relatively immobile. combination of thoracic vertebral column, ribs, and sternum form the thoracic cage that protects the thoracic organs, the heart, and lungs and is intimately involved in ventilation (breathing).

The Axial Skeletons of Sunghir 1, 2, and 3

2014 ◽  
Author(s):  
Erik Trinkaus ◽  
Alexandra P. Buzhilova ◽  
Maria B. Mednikova ◽  
Maria V. Dobrovolskaya
Keyword(s):  
Radiocarbon Dating ◽  
Cervical Vertebrae ◽  
Costal Cartilage ◽  
Lumbar Vertebrae ◽  
Axial Skeleton ◽  
Age At Death ◽  
Vertebral Bodies ◽  
Length Scaling

Given their burial positions, on their backs with the trunks and limbs extended, the Sunghir 1 to 3 individuals should have retained major portions of their axial skeletons. This is the case for Sunghir 2 and 3, both of whom retain all of the cervical vertebrae, most of their thoracic and lumbar vertebrae, and major portions of their sacra. Sunghir 2 preserves portions of 23 of the 24 ribs, and Sunghir 3 retains at least a small piece of each of her 24 ribs. Moreover her left fifth and sixth ribs lack only their costal cartilage surfaces. Only Sunghir 3 preserves any elements of the sternum, two partial and separated sternebral segments. In contrast, despite the apparent presence of major portions of the axial skeleton in situ, little remains of the Sunghir 1 vertebrae, ribs, or sternum. The cervical vertebrae are absent, unless pieces of them are mixed with the collection of what appear to be thoracic and lumbar fragments. Only two vertebrae remain reasonably intact, the T1 and T2. There are eight pieces of vertebral bodies, one of which has a pathological growth (chapter 17). The ribs consist of small pieces, except for a largely intact left first rib. Although evident in the in situ photographs, nothing remains of the manubrium. There is also a piece of distal middle rib, which is of use for the age-at-death assessment. Some of the vertebral and rib pieces have been sacrificed over the years for direct radiocarbon dating (e.g., Kuzmin et al. 2004). Others pieces, heavily fissured and hence probably descending into fragments during excavation, were only partially retained. There are nonetheless a few aspects of the Sunghir axial skeletons, beyond age assessments (chapter 6), the pathological lesions on the Sunghir 1 vertebrae (chapter 17), use of the sacra in the pelves (chapter 14), and body length scaling for Sunghir 2 and 3 (chapter 11), that are of interest.

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