scholarly journals A New Early Cretaceous lizard in Myanmar Amber with Exceptionally Preserved Integument

2021 ◽  
Author(s):  
Andrej Čerňanský ◽  
Edward L. Stanley ◽  
Juan D. Daza ◽  
Arnau Bolet ◽  
J. Salvador Arias ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Morphological Analysis ◽  
Sister Taxon ◽  
Phylogenetic Position ◽  
Pectoral Girdle ◽  
New Taxon ◽  
Anterior Portion ◽  
External Appearance ◽  
Rare Opportunity ◽  
Rule Out

Abstract We here report on a well-preserved juvenile lizard specimen in Albian amber (ca. 110 mya) from the Hkamti site in Myanmar. This new taxon, Retinosaurus hkamtiensis gen. et sp. nov., is represented by an articulated skull and the anterior portion of the trunk, including the pectoral girdle and forelimbs. The ocular skeleton (scleral ossicles) and eyelid are also visible, and the specimen exhibits pristine detail of the integument (of both head and body). In a combined molecular and morphological analysis, Retinosaurus was consistently recovered as a scincoid lizard (i.e. Scinciformata), as the sister taxon to the Mexican Cretaceous genus Tepexisaurus + Xantusiidae. However, the phylogenetic position of Retinosaurus should be interpreted with caution. We cannot not rule out the possibility that Retinosaurus represents a separate lineage of uncertain phylogenetic position, as it is the case for many Jurassic and Cretaceous taxa. Nonetheless, this fossil offers a rare opportunity to glimpse the external appearance of one group of lizards during the Early Cretaceous.

scholarly journals A new Barremian (Early Cretaceous) ichthyosaur from western Russia

2018 ◽  
Author(s):  
Valentin Fischer ◽  
Edwige Masure ◽  
Maxim S. Arkhangelsky ◽  
Pascal Godefroit
Keyword(s):  
Phylogenetic Analysis ◽  
Early Cretaceous ◽  
Sister Taxon ◽  
New Taxon ◽  
Skull Roof

A new ophthalmosaurid ichthyosaur, Sveltonectes insolitus, gen. et sp. nov., is described from a sub-complete and three-dimensionally preserved specimen from the late Barremian of western Russia. This new taxon is supported by 11 cranial, dental, and postcranial autapomorphies, and is also characterized by features previously considered as autapomorphic for some other Ophthalmosauridae, such as a processus narialis on the prefrontal and relatively long hind fins with pre- and postaxial accessory digits. We conducted a new phylogenetic analysis of Thunnosauria, which supports a ‘Stenopterygius’ origin for Ophthalmosauridae. Sveltonectes is regarded as the sister taxon of Aegirosaurus, which shares a similar skull roof construction. Contrary to most other Cretaceous ichthyosaurs, Sveltonectes is characterized by delicate and sharply pointed teeth, confirming that the ophthalmosaurids were ecologically highly diversified during the Early Cretaceous.

Cyclotella deceusteriana, a new centric diatom species (Bacillariophyta) from the sub-Antarctic Region

Phytotaxa ◽  
2018 ◽  
Vol 333 (1) ◽  
pp. 108 ◽  
Author(s):  
BART VAN DE VIJVER ◽  
STEVEN DESSEIN
Keyword(s):  
New Species ◽  
Morphological Analysis ◽  
Central Area ◽  
Centric Diatom ◽  
New Taxon ◽  
Antarctic Region ◽  
Distribution And Ecology ◽  
Electron Microscopical ◽  
A New Species ◽  
Freshwater Diatom

During a survey of the freshwater diatom flora of the sub-Antarctic region (Iles Kerguelen and Iles Crozet) in the southern Indian Ocean, an unknown Cyclotella taxon was observed that was formerly identified as the presumed cosmopolitan C. meneghinana. Detailed morphological analysis based on light and scanning electron microscopical observations and comparison with several similar Cyclotella taxa worldwide justified the description of this unknown taxon as a new species: Cyclotella deceusteriana sp. nov. The new taxon is characterized by the presence of marginal fultoportulae on every costa, hyaline furrows between the raised marginal parts on which the striae are located, 2, occasionally 1, 3 or 4 central fultoportulae and an entirely flat, smooth, relatively small central area. The new species is described and compared with other Cyclotella taxa. Notes on its distribution and ecology are added.

A giant within Carpocorini (Hemiptera: Heteroptera: Pentatomidae): Description of Adustonotus graziae sp. nov.

Zootaxa ◽  
2021 ◽  
Vol 4958 (1) ◽  
pp. 489-502
Author(s):  
FILIPE MICHELS BIANCHI
Keyword(s):  
Morphological Characters ◽  
The Other ◽  
Total Evidence ◽  
Valid Species ◽  
Phylogenetic Position ◽  
New Taxon ◽  
Large Size ◽  
Internal Genitalia ◽  
Evidence Analysis ◽  
Heteroptera Pentatomidae

The Carpocorini are distributed worldwide, and it is one of the most speciose tribes within the Pentatomidae with 127 genera and more than 500 valid species. Recently, Adustonotus Bianchi was described to contain eight species formerly placed within Euschistus Dallas. Among them, Adustonotus grandis (Rolston) and Adustonotus latus (Dallas) are remarkable for their large size. Herein, the phylogenetic position of a new taxon is inferred by a total evidence analysis based on 85 morphological characters and four molecular markers. Adustonotus graziae sp. nov. is described, and is recovered in a polytomic lineage, including A. grandis and A. latus. These species share a solid combination of features that enable them to be separated from the other Adustonotus species (e.g., large size, the humeral angles spatulate and exceptionally produced, and the capsula seminalis shortened). Illustrations of external and internal genitalia, and a distributional map are provided. 

scholarly journals Three new Cenomanian conifers from El Chango (Chiapas, Mexico) offer a snapshot of the geographic mosaic of the Mesozoic conifer decline

2021 ◽  
Author(s):  
Ixchel Gonzalez-Ramirez ◽  
Sergio RS Cevallos-Ferriz ◽  
Carl Rothfels
Keyword(s):  
Evolutionary History ◽  
Mixed Forest ◽  
Freshwater Ecosystems ◽  
Total Evidence ◽  
Morphological Data ◽  
Phylogenetic Position ◽  
Dominant Group ◽  
Geographic Mosaic ◽  
History Of ◽  
Rare Opportunity

Premise of study: El Chango is a recently discovered quarry that contains extremely well preserved fossils. The Cenomanian age of the locality corresponds to a time when the global flora was transitioning from gymnosperm- to angiosperm-dominated, yet conifers predominate in this locality. These fossils thus provide a rare opportunity to understand the replacement of conifers by angiosperms as the dominant group of plants. Methods: We collected material from El Chango in annual expeditions (2010 to 2014). We selected the three most abundant and best preserved conifer morphotypes and conducted a total-evidence (i.e., including molecular and morphological data) phylogenetic analysis of a sample of 72 extant conifer species plus the three fossils. We use these results to inform our taxonomic decisions. Results: We obtained four equally most-parsimonious trees (consistency index = 44.1%, retention index = 78.8%). Despite ambiguous relationships among some extant taxa, the three fossil conifers had the same phylogenetic position in all four most parsimonious trees; we describe these species as new: Sequoiadendron helicalancifolium sp. nov. (Cupressaceae), and Microcachrys rhomboidea sp. nov. and Dacrydium bifoliosus sp. nov (Podocarpaceae). The ecosystem is interpreted as a coastal humid mixed forest. Conclusions: Our findings contribute to the understanding of Cenomanian equatorialregions, and support the hypothesis of a geographically and ecologically structured rise of angiosperms, with conifers remaining dominant in brackish-water and angiosperms becoming dominant in freshwater-ecosystems. These fossils fill in gaps in the evolutionary history of lineages like Microcachrys, which we demonstrate occurred in the Northern hemisphere before becoming restricted to its current range (Tasmania).

scholarly journals A new iguanodontian (Dinosauria: Ornithopoda) from the Early Cretaceous of Mongolia

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5300
Author(s):  
Terry A. Gates ◽  
Khishigjav Tsogtbaatar ◽  
Lindsay E. Zanno ◽  
Tsogtbaatar Chinzorig ◽  
Mahito Watabe
Keyword(s):  
Phylogenetic Analysis ◽  
Growth Stage ◽  
Phylogenetic Analyses ◽  
Type Specimen ◽  
Sister Taxon ◽  
New Taxon ◽  
Time Of Death ◽  
The North ◽  
Unusual Combination ◽  
Relationship Of

We describe a new iguanodontian ornithopod,Choyrodon barsboldigen. et sp. nov. from the Albian-aged Khuren Dukh Formation of Mongolia based on several partial skeletons interpreted to represent a subadult growth stage based on osteohistological features. This new taxon is diagnosed by many autapomorphies of the maxilla, nasal, lacrimal, opisthotic, predentary, and surangular.Choyrodondisplays an unusual combination of traits, possessing an open antorbital fenestra (a primitive ornithopod trait) together with derived features such as a downturned dentary and enlarged narial fenestra. Histological imaging suggests that the type specimen ofChoyrodonwould have been a subadult at the time of death. Phylogenetic analysis of two different character matrices do not positChoyrodonto be the sister taxon or to be more primitive than the iguanodontianAltirhinus kurzanovi, which is found in the same formation. The only resolved relationship of this new taxon is that it was hypothesized to be a sister-taxon with the North American speciesEolambia caroljonesa. Though discovered in the same formation andChoyrodonbeing smaller-bodied thanAltirhinus, it does not appear that the former species is an ontogimorph of the latter. Differences in morphology and results of the phylogenetic analyses support their distinction although more specimens of both species will allow better refinement of their uniqueness.

A new taxon of birds (Aves) from the Early Cretaceous of Western Siberia, Russia

2011 ◽  
Vol 9 (1) ◽  
pp. 109-117 ◽  
Author(s):  
Evgeny N. Kurochkin ◽  
Nikita V. Zelenkov ◽  
Alexandr O. Averianov ◽  
Sergei V. Leshchinskiy
Keyword(s):  
Early Cretaceous ◽  
Western Siberia ◽  
New Taxon

The phylogenetic position of the tuatara, Sphenodon (Sphenodontida, Amniota), as indicated by cladistic analysis of the ultrastructure of spermatozoa

1992 ◽  
Vol 335 (1274) ◽  
pp. 207-219 ◽  
Keyword(s):  
Cladistic Analysis ◽  
Sister Group ◽  
Sister Taxon ◽  
Phylogenetic Position ◽  
Sister Group Relationship ◽  
Usual Concept ◽  
Cladistic Analyses ◽  
Relationship Of

Sphenodon has traditionally been regarded as a little changed survivor of the Permo-Triassic thecodont or eosuchian ‘stem reptiles’ but has alternatively been placed in the Lepidosauria as the plesiomorphic or even apomorphic sister-taxon of the squamates. A cladistic analysis of 16 characters from spermatozoal ultrastructure of Sphenodon and other amniotes unequivocally confirms its exceedingly primitive status. The analysis suggests that monotremes are the sister-group of birds; squamates form the sister-group of a bird + monotreme clade while the three sister-groups successively below the bird + monotreme + squa- mate assemblage are the caiman, the tuatara and the outgroup (turtles). The monotreme + bird couplet, supports the concept of the Haemothermia, but can only be regarded heuristically. The usual concept of mammals as a synapsid-derived outgroup of all other extant amniotes is not substantiated spermatologically. All cladistic analyses made, and a separate consideration of apomorphies, indicate that Sphenodon is spermatologically the most primitive amniote, excepting the Chelonia. It is advanced (apomorphic) for the amniotes in only two of the 16 spermatozoal characters considered. A close, sister-group relationship of Sphenodon with squamates is not endorsed.

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.

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