scholarly journals Issi saaneq gen. et sp. nov.—A New Sauropodomorph Dinosaur from the Late Triassic (Norian) of Jameson Land, Central East Greenland

Diversity ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 561
Author(s):  
Victor Beccari ◽  
Octávio Mateus ◽  
Oliver Wings ◽  
Jesper Milàn ◽  
Lars B. Clemmensen
Keyword(s):  
Phylogenetic Analysis ◽  
Intraspecific Variation ◽  
Late Stage ◽  
Late Triassic ◽  
Middle Stage ◽  
East Greenland ◽  
Sister Clade ◽  
New Findings ◽  
Stage Juvenile ◽  
Small Foramen

The Late Triassic (Norian) outcrops of the Malmros Klint Formation, Jameson Land (Greenland) have yielded numerous specimens of non-sauropod sauropodomorphs. Relevant fossils were briefly reported in 1994 and were assigned to Plateosaurus trossingensis. However, continuous new findings of early non-sauropod sauropodomorphs around the globe facilitate comparisons and allow us to now revise this material. Here, the non-sauropod sauropodomorph Issi saaneq gen. et sp. nov. is described based on two almost complete and articulated skulls. The two skulls represent a middle-stage juvenile and a late-stage juvenile or subadult. Issi saaneq differs from all other sauropodomorphs by several unique traits: (1) a small foramen at the medial surface of the premaxilla; (2) an anteroposteriorly elongated dorsoposterior process of the squamosal; (3) a relatively high quadrate relative to rostrum height; (4) a well-developed posterodorsal process of the articular. These features cannot be explained by taphonomy, ontogeny, or intraspecific variation. Issi saaneq shows affinities to Brazilian plateosaurids and the European Plateosaurus, being recovered as the sister clade of the latter in our phylogenetic analysis. It is the northernmost record of a Late Triassic sauropodomorph, and a new dinosaur species erected for Greenland. Issi saaneq broadens our knowledge about the evolution of plateosaurid sauropodomorphs.

scholarly journals Intraspecific variation in the Cambrian: new observations on the morphology of the Chengjiang euarthropod Sinoburius lunaris

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Michel Schmidt ◽  
Yu Liu ◽  
Xianguang Hou ◽  
Joachim T. Haug ◽  
Carolin Haug ◽  
...  
Keyword(s):  
Intraspecific Variation ◽  
Southwest China ◽  
3D Models ◽  
Morphological Characters ◽  
Open Questions ◽  
New Findings ◽  
Unique Shape ◽  
Variable Species ◽  
Chengjiang Biota ◽  
3D Software

Abstract Background The Chengjiang biota from southwest China (518-million-years old, early Cambrian) has yielded nearly 300 species, of which more than 80 species represent early chelicerates, crustaceans and relatives. The application of µCT-techniques combined with 3D software (e.g., Drishti), has been shown to be a powerful tool in revealing and analyzing 3D features of the Chengjiang euarthropods. In order to address several open questions that remained from previous studies on the morphology of the xandarellid euarthropod Sinoburius lunaris, we reinvestigated the µCT data with Amira to obtain a different approach of visualization and to generate new volume-rendered models. Furthermore, we used Blender to design 3D models showing aspects of intraspecific variation. Results New findings are: (1) antennulae consist of additional proximal articles that have not been detected before; (2) compared to other appendages, the second post-antennular appendage has a unique shape, and its endopod is comprised of only five articles (instead of seven); (3) the pygidium bears four pairs of appendages which are observed in all specimens. On the other hand, differences between specimens also have been detected. These include the presence/absence of diplotergites resulting in different numbers of post-antennular appendages and tergites and different distances between the tip of the hypostome and the anterior margin of the head shield. Conclusions Those new observations reveal intraspecific variation among Chengjiang euarthropods not observed before and encourage considerations about possible sexual dimorphic pairs or ontogenetic stages. Sinoburius lunaris is a variable species with respect to its morphological characters, cautioning that taxon-specific variabilities need to be considered when exploring new species.

scholarly journals Evolutionary significance of the blastozoan Eumorphocystis and its pseudo-arms

2020 ◽  
pp. 1-17
Author(s):  
Thomas E. Guensburg ◽  
James Sprinkle ◽  
Rich Mooi ◽  
Bertrand Lefebvre
Keyword(s):  
Phylogenetic Analysis ◽  
Sister Taxon ◽  
Evolutionary Significance ◽  
Coelomic Cavity ◽  
Anatomical Features ◽  
New Findings ◽  
Solid Block ◽  
Cover Plates

Abstract Twelve specimens of Eumorphocystis Branson and Peck, 1940 provide the basis for new findings and a more informed assessment of whether this blastozoan (a group including eocrinoids, blastoids, diploporites, rhombiferans) constitutes the sister taxon to crinoids, as has been recently proposed. Both Eumorphocystis and earliest-known crinoid feeding appendages express longitudinal canals, a demonstrable trait exclusive to these taxa. However, the specimen series studied here shows that Eumorphocystis canals constrict proximally and travel within ambulacrals above the thecal cavity. This relationship is congruent with a documented blastozoan pattern but very unlike earliest crinoid topology. Earliest crinoid arm cavities lie fully beneath floor plates; these expand and merge directly with the main thecal coelomic cavity at thecal shoulders. Other associated anatomical features echo this contrasting comparison. Feeding appendages of Eumorphocystis lack two-tiered cover plates, podial basins/pores, and lateral arm plating, all features of earliest crinoid ‘true arms.’ Eumorphocystis feeding appendages are buttressed by solid block-like plates added during ontogeny at a generative zone below floor plates, a pattern with no known parallel among crinoids. Eumorphocystis feeding appendages express brachioles, erect extensions of floor plates, also unknown among crinoids. These several distinctions point to nonhomology of most feeding appendage anatomy, including longitudinal canals, removing Eumorphocystis and other blastozoans from exclusive relationship with crinoids. Eumorphocystis further differs from crinoids in that thecal plates express diplopores, respiratory structures not present among crinoids, but ubiquitous among certain groups of blastozoans. Phylogenetic analysis places Eumorphocystis as a crownward blastozoan, far removed from crinoids.

scholarly journals A review of Palaeozoic and Mesozoic tetrapods from Greenland

2018 ◽  
Vol 66 ◽  
pp. 21-46 ◽  
Author(s):  
Marco Marzola ◽  
Octávio Mateus ◽  
Jesper Milàn ◽  
Lars B. Clemmensen
Keyword(s):  
Late Jurassic ◽  
Early Jurassic ◽  
Late Carboniferous ◽  
Late Triassic ◽  
Late Devonian ◽  
Early Triassic ◽  
Shallow Marine ◽  
East Greenland ◽  
Marine Deposits ◽  
Theropod Dinosaurs

This article presents a synthesis of Palaeozoic and Mesozoic fossil tetrapods from Greenland, including an updated review of the holotypes and a new photographic record of the main specimens. All fossil tetrapods found are from East Greenland, with at least 30 different known taxa: five stem tetrapods (Acanthostega gunnari, Ichthyostega eigili, I. stensioi, I. watsoni, and Ymeria denticulata) from the Late Devonian of the Aina Dal and Britta Dal Formations; four temnospondyl amphibians (Aquiloniferus kochi, Selenocara groenlandica, Stoschiosaurus nielseni, and Tupilakosaurus heilmani) from the Early Triassic of the Wordie Creek Group; two temnospondyls (Cyclotosaurus naraserluki and Gerrothorax cf. pulcherrimus), one testudinatan (cf. Proganochelys), two stagonolepids (Aetosaurus ferratus and Paratypothorax andressorum), the eudimorphodontid Arcticodactylus, undetermined archosaurs (phytosaurs and both sauropodomorph and theropod dinosaurs), the cynodont Mitredon cromptoni, and three mammals (Haramiyavia clemmenseni, Kuehneotherium, and cf. ?Brachyzostrodon), from the Late Triassic of the Fleming Fjord Formation; one plesiosaur from the Early Jurassic of the Kap Stewart Formation; one plesiosaur and one ichthyosaur from the Late Jurassic of the Kap Leslie Formation, plus a previously unreported Late Jurassic plesiosaur from Kronprins Christian Land. Moreover, fossil tetrapod trackways are known from the Late Carboniferous (morphotype Limnopus) of the Mesters Vig Formation and at least four different morphologies (such as the crocodylomorph Brachychirotherium, the auropodomorph Eosauropus and Evazoum, and the theropodian Grallator) associated to archosaurian trackmakers are known from the Late Triassic of the Fleming Fjord Formation. The presence of rich fossiliferous tetrapod sites in East Greenland is linked to the presence of well-exposed continental and shallow marine deposits with most finds in terrestrial deposits from the Late Devonian and the Late Triassic.

scholarly journals Anomalously high variation in postnatal development is ancestral for dinosaurs but lost in birds

2016 ◽  
Vol 113 (51) ◽  
pp. 14757-14762 ◽  
Author(s):  
Christopher T. Griffin ◽  
Sterling J. Nesbitt
Keyword(s):  
Postnatal Development ◽  
Intraspecific Variation ◽  
Early Jurassic ◽  
Late Triassic ◽  
Growth Trajectories ◽  
Low Levels ◽  
Triassic Period ◽  
Rates Of Growth

Compared with all other living reptiles, birds grow extremely fast and possess unusually low levels of intraspecific variation during postnatal development. It is now clear that birds inherited their high rates of growth from their dinosaurian ancestors, but the origin of the avian condition of low variation during development is poorly constrained. The most well-understood growth trajectories of later Mesozoic theropods (e.g.,Tyrannosaurus,Allosaurus) show similarly low variation to birds, contrasting with higher variation in extant crocodylians. Here, we show that deep within Dinosauria, among the earliest-diverging dinosaurs, anomalously high intraspecific variation is widespread but then is lost in more derived theropods. This style of development is ancestral for dinosaurs and their closest relatives, and, surprisingly, this level of variation is far higher than in living crocodylians. Among early dinosaurs, this variation is widespread across Pangaea in the Triassic and Early Jurassic, and among early-diverging theropods (ceratosaurs), this variation is maintained for 165 million years to the end of the Cretaceous. Because the Late Triassic environment across Pangaea was volatile and heterogeneous, this variation may have contributed to the rise of dinosaurian dominance through the end of the Triassic Period.

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

scholarly journals New perspectives on the Late Triassic vertebrates of East Greenland: preliminary results of a Polish−Danish palaeontological expedition

2014 ◽  
Vol 35 (4) ◽  
pp. 541-552 ◽  
Author(s):  
Tomasz Sulej ◽  
Andrzej Wolniewicz ◽  
Niels Bonde ◽  
Błażej Błażejowski ◽  
Grzegorz Niedźwiedzki ◽  
...  
Keyword(s):  
21St Century ◽  
Current Knowledge ◽  
Taxonomic Diversity ◽  
Trace Fossils ◽  
Skeletal Remains ◽  
Late Triassic ◽  
East Greenland ◽  
Terrestrial Vertebrates ◽  
Preliminary Results ◽  
Dinosaur Tracks

Abstract The Fleming Fjord Formation (Jameson Land, East Greenland) documents a diverse assemblage of terrestrial vertebrates of Late Triassic age. Expeditions from the turn of the 21st century have discovered many important fossils that form the basis of our current knowledge of Late Triassic Greenlandic faunas. However, due to the scarcity and incompleteness of the fossils and their insufficient study, our understanding of the taxonomic diversity of the Fleming Fjord Formation is hindered. Here, we report the preliminary findings of a Polish-Danish expedition to the Fleming Fjord Formation that took place in 2014. Three areas were visited – the fairly well known MacKnight Bjerg and Wood Bjerg and the virtually unexplored Liasryggen. MacKnigth Bjerg and Liasryggen yielded fossils which promise to significantly broaden our knowledge of vertebrate evolution in the Late Triassic. Stem-mammal remains were discovered at Liasryggen. Other fossils found at both sites include remains of actinopterygians, sarcopterygians, temnospondyl amphibians and various archosaurs (including early dinosaurs). Numerous vertebrate trace fossils, including coprolites, pseudosuchian footprints, theropod and sauropodomorph dinosaur tracks, were also discovered. Newly discovered skeletal remains as well as abundant trace fossils indicate higher tetrapod diversity in the Late Triassic of Greenland than previously thought. Trace fossils also allow inferences of early theropod and sauropodomorph dinosaur behaviour.

Fossil Plant Relative Abundances Indicate Sudden Loss of Late Triassic Biodiversity in East Greenland

Science ◽  
2009 ◽  
Vol 324 (5934) ◽  
pp. 1554-1556 ◽  
Author(s):  
J. C. McElwain ◽  
P. J. Wagner ◽  
S. P. Hesselbo
Keyword(s):  
Late Triassic ◽  
Fossil Plant ◽  
East Greenland ◽  
Sudden Loss ◽  
Relative Abundances

A revision of Herennia (Araneae:Nephilidae:Nephilinae), the Australasian 'coin spiders'

2005 ◽  
Vol 19 (5) ◽  
pp. 391 ◽  
Author(s):  
Matjaž Kuntner
Keyword(s):  
Phylogenetic Analysis ◽  
Sexual Size Dimorphism ◽  
Solomon Islands ◽  
The Philippines ◽  
The Other ◽  
Size Dimorphism ◽  
Island Endemics ◽  
Sister Clade ◽  
New Synonymy ◽  
New Britain

The nephilid ‘coin spiders’ (Herennia Thorell) are known for their arboricolous ladder webs, extreme sexual size dimorphism and peculiar sexual biology. This paper revises Herennia taxonomy, systematics, biology and biogeography. The widespread Asian Herennia multipuncta (Doleschall) ( = H. sampitana Karsch, new synonymy; = H. mollis Thorell, new synonymy) is synanthropic and invasive, whereas the other 10 species are narrowly distributed Australasian island endemics: H. agnarssoni, sp. nov. is known from Solomon Islands; H. deelemanae, sp. nov. from northern Borneo; H. etruscilla, sp. nov. from Java; H. gagamba, sp. nov. from the Philippines; H. jernej, sp. nov. from Sumatra; H. milleri, sp. nov. from New Britain; H. oz, sp. nov. from Australia; H. papuana Thorell from New Guinea; H. sonja, sp. nov. from Kalimantan and Sulawesi; and H. tone, sp. nov. from the Philippines. A phylogenetic analysis of seven species of Herennia, six nephilid species and 15 outgroup taxa scored for 190 morphological and behavioural characters resulted in 10 equally parsimonious trees supporting the monophyly of Nephilidae, Herennia, Nephila, Nephilengys and Clitaetra, but the sister-clade to the nephilids is ambiguous. Coin spiders do not fit well established biogeographic lines (Wallace, Huxley) dividing Asian and Australian biotas, but the newly drawn ‘Herennia line’ suggests an all-Australasian speciation in Herennia. To explain the peculiar male sexual behaviour (palpal mutilation and severance) known in Herennia and Nephilengys, three specific hypotheses based on morphological and behavioural data are proposed: (1) broken embolic conductors function as mating plugs; (2) bulb severance following mutilation is advantageous for the male to avoid hemolymph leakage; and (3) the eunuch protects his parental investment by fighting off rival males.

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