scholarly journals The anatomy and palaeobiology of the early armoured dinosaur Scutellosaurus lawleri (Ornithischia: Thyreophora) from the Kayenta Formation (Lower Jurassic) of Arizona

2021 ◽  
Vol 8 (7) ◽  
pp. 201676
Author(s):  
Benjamin T. Breeden ◽  
Thomas J. Raven ◽  
Richard J. Butler ◽  
Timothy B. Rowe ◽  
Susannah C. R. Maidment
Keyword(s):  
Large Body ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Phylogenetic Position ◽  
Character State ◽  
Large Body Size ◽  
Faunal Diversity ◽  
State Changes ◽  
First Time ◽  
Shed Light

The armoured dinosaurs, Thyreophora, were a diverse clade of ornithischians known from the Early Jurassic to the end of the Cretaceous. During the Middle and Late Jurassic, the thyreophorans radiated to evolve large body size, quadrupedality, and complex chewing mechanisms, and members of the group include some of the most iconic dinosaurs, including the plated Stegosaurus and the club-tailed Ankylosaurus ; however, the early stages of thyreophoran evolution are poorly understood due to a paucity of relatively complete remains from early diverging thyreophoran taxa. Scutellosaurus lawleri is generally reconstructed as the earliest-diverging thyreophoran and is known from over 70 specimens from the Lower Jurassic Kayenta Formation of Arizona, USA. Whereas Scutellosaurus lawleri is pivotal to our understanding of character-state changes at the base of Thyreophora that can shed light on the early evolution of the armoured dinosaurs, the taxon has received limited study. Herein, we provide a detailed account of the osteology of Scutellosaurus lawleri , figuring many elements for the first time. Scutellosaurus lawleri was the only definitive bipedal thyreophoran. Histological studies indicate that it grew slowly throughout its life, possessing lamellar-zonal tissue that was a consequence neither of its small size nor phylogenetic position, but may instead be autapomorphic, and supporting other studies that suggest thyreophorans had lower basal metabolic rates than other ornithischian dinosaurs. Faunal diversity of the Kayenta Formation in comparison with other well-known Early Jurassic-aged dinosaur-bearing formations indicates that there was considerable spatial and/or environmental variation in Early Jurassic dinosaur faunas.

A new species of the subgenus Scheloribates (Topobates) (Acari: Oribatida: Scheloribatidae) from Panama

2020 ◽  
Vol 29 (2) ◽  
pp. 278-283
Author(s):  
S.G. Ermilov
Keyword(s):  
New Species ◽  
Body Size ◽  
Leaf Litter ◽  
Related Species ◽  
Large Body ◽  
Oribatid Mite ◽  
Neotropical Region ◽  
Large Body Size ◽  
First Time ◽  
A New Species

The oribatid mite subgenus Scheloribates (Topobates) Grandjean, 1958, is recorded from the Neotropical region for the first time. A new species of this subgenus is described from the leaf litter collected in Cayo Agua Island, Panama. Scheloribates (Topobates) panamaensis sp. nov. differs from its related species by the very large body size and presence of a strong ventrodistal process on the leg femora II–IV.

scholarly journals A revision of the early neotheropod genus Sarcosaurus from the Early Jurassic (Hettangian–Sinemurian) of central England

2020 ◽  
Vol 191 (1) ◽  
pp. 113-149 ◽  
Author(s):  
Martín D Ezcurra ◽  
Richard J Butler ◽  
Susannah C R Maidment ◽  
Ivan J Sansom ◽  
Luke E Meade ◽  
...  
Keyword(s):  
Type Species ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
Early Jurassic ◽  
Late Triassic ◽  
Valid Species ◽  
Character State ◽  
New Information ◽  
Evolutionary Radiation ◽  
Nomina Dubia

Abstract Neotheropoda represents the main evolutionary radiation of predatory dinosaurs and its oldest records come from Upper Triassic rocks (c. 219 Mya). The Early Jurassic record of Neotheropoda is taxonomically richer and geographically more widespread than that of the Late Triassic. The Lower Jurassic (upper Hettangian–lower Sinemurian) rocks of central England have yielded three neotheropod specimens that have been assigned to two species within the genus Sarcosaurus, S. woodi (type species) and S. andrewsi. These species have received little attention in discussions of the early evolution of Neotheropoda and recently have been considered as nomina dubia. Here, we provide a detailed redescription of one of these specimens (WARMS G667–690) and reassess the taxonomy and phylogenetic relationships of the genus Sarcosaurus. We propose that the three neotheropod specimens from the Early Jurassic of central England represent a single valid species, S. woodi. The second species of the genus, ‘S. andrewsi’, is a subjective junior synonym of the former. A quantitative phylogenetic analysis of early theropods recovered S. woodi as one of the closest sister-taxa to Averostra and provides new information on the sequence of character state transformations in the lead up to the phylogenetic split between Ceratosauria and Tetanurae.

Uncommon preservation of dinosaur footprints in a tidal breccia: Eubrontes giganteus from the Early Jurassic Mongisty tracksite of Aveyron, southern France

2021 ◽  
pp. 1-18
Author(s):  
Jean-David Moreau ◽  
Jacques Sciau ◽  
Georges Gand ◽  
Emmanuel Fara
Keyword(s):  
Scale Up ◽  
Lower Jurassic ◽  
Depositional Environments ◽  
Early Jurassic ◽  
Coarse Grained ◽  
Southern France ◽  
Fine Grained ◽  
The North ◽  
Dinosaur Tracks ◽  
First Time

Abstract A recent excavation yielded 118 large tridactyl footprints in the Lower Jurassic Dolomitic Formation of the Causses Basin, at Mongisty in southern France. Most of the tracks are ascribed to Eubrontes giganteus Hitchcock, 1845. They are preserved on a surface of 53 m2 and form parallel rows with a preferential orientation towards the north. Such an abundance and density of E. giganteus is observed for the first time in the Early Jurassic from the Causses Basin. Sedimentological and ichnotaphonomical analyses show that the footprints were made at different time intervals, thus excluding the passage of a large group. In contrast to all other tracksites from the Dolomitic Formation, where tracks are preserved in fine-grained sediments corresponding to low-energy depositional palaeoenvironments, the tracks from Mongisty are preserved in coarse-grained sediment which is a matrix- to clast-supported breccia. Clasts consist of angular to sub-rounded, millimetric to centimetric-scale (up to 2 cm), poorly sorted, randomly oriented, homogeneous dolostone intraclasts floating in a dolomudstone matrix. Sedimentological analysis shows that the depositional environments of Mongisty varied from subtidal to intertidal/supratidal settings in a large and protected flat marsh. The lithology of the track-bearing surfaces indicates that the mudflat of the Causses Basin was sporadically affected by large mud flows that reworked and redeposited mudstone intraclasts coming from the erosion of upstream, dry and partially lithified mud beds. Throughout the world, this type of preservation of dinosaur tracks in tidal matrix- to clast-supported breccias remains rare.

scholarly journals Multi-modal locomotor costs explain sexual size but not shape dimorphism in a leaf-mimicking insect

2021 ◽  
Author(s):  
Romain P. Boisseau ◽  
Thies H. Buscher ◽  
Lexi J. Klawitter ◽  
Stanislav N. Gorb ◽  
Douglas J. Emlen ◽  
...  
Keyword(s):  
Body Size ◽  
Body Shape ◽  
Large Body ◽  
Flight Performance ◽  
Large Body Size ◽  
Empirical Measures ◽  
Substrate Adhesion ◽  
Flight Costs ◽  
Lift And Drag ◽  
Shed Light

In most arthropods, adult females are larger than males, and male competition is a race to quickly locate and mate with scattered females (scramble competition polygyny). In this context, smaller males may be favored due to more efficient locomotion leading to higher mobility during mate searching while larger males may benefit from increased speed and higher survivorship. Understanding how body size affects different aspects of the locomotor performance of males is therefore essential to shed light on the evolution of this widespread mating system. Using a combination of empirical measures of flight performance and substrate adhesion, and modelling of body aerodynamics, we show that large body size impairs both flight and landing (attachment) performance in male leaf insects (Phyllium philippinicum), a species where relatively small and skinny males fly through the canopy in search of large sedentary females. Smaller males were more agile in the air, ascended more rapidly during flight, and had a lower risk of detaching from the substrates on which they walk and land. Our models revealed variation in body shape affected body lift and drag, but tradeoffs with weight meant that effects were negligible, suggesting that flight costs do not explain the evolution of strong sexual dimorphism in body shape in this species.

scholarly journals The postcranial skeleton of the erythrosuchid archosauriform Garjainia prima from the Early Triassic of European Russia

2020 ◽  
Vol 7 (12) ◽  
pp. 201089
Author(s):  
Susannah C. R. Maidment ◽  
Andrey G. Sennikov ◽  
Martín D. Ezcurra ◽  
Emma M. Dunne ◽  
David J. Gower ◽  
...  
Keyword(s):  
Body Size ◽  
Mass Extinction ◽  
Middle Triassic ◽  
Large Body ◽  
The Body ◽  
European Russia ◽  
Early Triassic ◽  
Postcranial Skeleton ◽  
Large Body Size ◽  
First Time

Erythrosuchidae were large-bodied, quadrupedal, predatory archosauriforms that dominated the hypercarnivorous niche in the aftermath of the Permo-Triassic mass extinction. Garjainia , one of the oldest members of the clade, is known from the late Olenekian of European Russia. The holotype of Garjainia prima comprises a well-preserved skull, but highly incomplete postcranium. Recent taxonomic reappraisal demonstrates that material from a bone bed found close to the type locality, previously referred to as ‘ Vjushkovia triplicostata ', is referable to G. prima. At least, seven individuals comprising cranial remains and virtually the entire postcranium are represented, and we describe this material in detail for the first time. An updated phylogenetic analysis confirms previous results that a monophyletic Garjainia is the sister taxon to a clade containing Erythrosuchus, Shansisuchus and Chalishevia . Muscle scars on many limb elements are clear, allowing reconstruction of the proximal locomotor musculature. We calculate the body mass of G. prima to have been 147–248 kg, similar to that of an adult male lion. Large body size in erythrosuchids may have been attained as part of a trend of increasing body size after the Permo-Triassic mass extinction and allowed erythrosuchids to become the dominant carnivores of the Early and Middle Triassic.

scholarly journals New faunistical and taxonomic data on oribatid mites (Acari: Oribatida) of Taiwan

Acarologia ◽  
2021 ◽  
Vol 61 (2) ◽  
pp. 297-320
Author(s):  
Sergey G. Ermilov ◽  
Jhih-Rong Liao
Keyword(s):  
New Species ◽  
Morphological Traits ◽  
Large Body ◽  
Oribatid Mite ◽  
Large Body Size ◽  
Medium Length ◽  
Notogastral Seta ◽  
Two New Species ◽  
Lateral Branches ◽  
First Time

The present study is based on oribatid mite material collected in Taiwan in 2017–2019. A list of identified taxa, including 141 species/subspecies from 88 genera and 47 families is provided; of these, 36 species/subspecies, 13 genera and five families are recorded for the first time in the Taiwan fauna, and eight species and one genus are recorded for the first time in the Oriental region. Two new species are described. Tyrphonothrus nivnu n. sp. (description based on adult) is similar to Tyrphonothrus altissimus (Piffl, 1971), T. cajamarcensis (Hammer, 1961) and T. wallworki (Starý and Block, 1995) in general morphological traits (notogastral ridges developed; tridactylous legs; notogastral setae e2, h1, h2, and p2 long, setiform, with attenuate tip, other setae of medium length, setiform; high number of genital setae; absence of notogastral ornamentation; and comparatively large body size), but differs from these listed species by the barbed notogastral setae and comparatively long notogastral setae c1, c2, c3, and e1. Jacotella puyuma n. sp. (description based on adult and tritonymph) is similar to Jacotella neonominata Subías, 2004 in general morphological traits (centrodorsal notogastral part with two longitudinal ridges, posteriorly fused, each ridge with two lateral transverse branches; absence of notogastral ornamentation; notogastral seta h1 distinctly longer than other notogastral setae), but differs from the latter by the narrowly elongate bothridial head, flagellate notogastral setae h1 and p1, the length of notogastral setae, and the absence of additional longitudinal ridges connected lateral branches of median ridges (in adult); and by the long gastronotic seta h1 similar in length to bothridial seta, seta h2 similar to h3 and lp and seta dm clearly longer than da on larval exuvium (in tritonymph).

The imaginal and detailed nymphal characters of Cincticostella fusca (Kang & Yang, 1995) (Ephemeroptera: Ephemerellidae)

Zootaxa ◽  
2020 ◽  
Vol 4729 (2) ◽  
pp. 277-285 ◽  
Author(s):  
WEI ZHANG ◽  
NA HAN ◽  
MIN ZHANG ◽  
YIN-FANG WANG ◽  
CHANG-FA ZHOU
Keyword(s):  
Body Size ◽  
Large Body ◽  
Early Spring ◽  
Large Body Size ◽  
Southeastern China ◽  
First Time

Among the 17 known species of the genus Cincticostella, only five of them have been reported as both nymphs and imagoes, which does not include the Chinese species C. fusca Kang et Yang (1995). Here the nymphs are redescribed and reared imagoes are reported for the first time, based on material collected from southeastern China. Morphologically, the nymph is unique because of its large body size, expanded genae, pale median stripe on the anterior of the head, and dark tarsi. The male imago can be differentiated from congeners by its large body size, pigmented forewings, and the mesothoracic scutellum having a pair of membranous lamellae. More importantly, its penes are distinct, being fused for most of their length and having complex ventral projections. Adults emerge in early spring (March to April). 

scholarly journals The most complete enantiornithine from North America and a phylogenetic analysis of the Avisauridae

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5910 ◽  
Author(s):  
Jessie Atterholt ◽  
J. Howard Hutchison ◽  
Jingmai K. O’Connor
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
New Genus ◽  
Large Body ◽  
Cladistic Analysis ◽  
South American ◽  
New Taxon ◽  
Large Body Size ◽  
First Time ◽  
North And South

The most complete known North American enantiornithine was collected in 1992 but never formally described. The so-called “Kaiparowits avisaurid” remains one of the most exceptional Late Cretaceous enantiornithine fossils. We recognize this specimen as a new taxon, Mirarce eatoni (gen. et sp. nov.), and provide a complete anatomical description. We maintain that the specimen is referable to the Avisauridae, a clade previously only known in North America from isolated tarsometatarsi. Information from this specimen helps to clarify evolutionary trends within the Enantiornithes. Its large body size supports previously observed trends toward larger body mass in the Late Cretaceous. However, trends toward increased fusion of compound elements across the clade as a whole are weak compared to the Ornithuromorpha. The new specimen reveals for the first time the presence of remige papillae in the enantiornithines, indicating this feature was evolved in parallel to dromaeosaurids and derived ornithuromorphs. Although morphology of the pygostyle and (to a lesser degree) the coracoid and manus appear to remain fairly static during the 65 million years plus of enantiornithine evolution, by the end of the Mesozoic at least some enantiornithine birds had evolved several features convergent with the Neornithes including a deeply keeled sternum, a narrow furcula with a short hypocleidium, and ulnar quill knobs—all features that indicate refinement of the flight apparatus and increased aerial abilities. We conduct the first cladistic analysis to include all purported avisuarid enantiornithines, recovering an Avisauridae consisting of a dichotomy between North and South American taxa. Based on morphological observations and supported by cladistic analysis, we demonstrate Avisaurus to be paraphyletic and erect a new genus for “A. gloriae,” Gettyia gen. nov.

Moonshine worms (Diopatra aciculata: Onuphidae, Annelida) in the Knysna Estuary, South Africa; taxonomy and distribution

2020 ◽  
Vol 100 (6) ◽  
pp. 897-907
Author(s):  
H. van Rensburg ◽  
C. A. Matthee ◽  
C. A. Simon
Keyword(s):  
South Africa ◽  
Large Body ◽  
Ecological Impacts ◽  
Population Estimate ◽  
Morphological Description ◽  
Low Density ◽  
Large Body Size ◽  
First Time ◽  
Shell Fragments ◽  
Scanning Electron

AbstractMoonshine worms are a popular bait species used for fishing. The taxon was not detected during surveys of the macrobenthos conducted in Knysna in the 1940s and 1990s, and was first reported as a harvested bait species in the mid-2000s, suggesting that it appeared for the first time in the estuary in the last three decades. A previous molecular analysis identified the worms as Diopatra aciculata, a species first described from Australia. This study provides an updated detailed morphological description of D. aciculata in South Africa to facilitate future identifications and also investigates the species' distribution and population size in the Knysna Estuary. Specimens were examined by scanning electron, stereo- and compound microscopes. Diopatra aciculata has tubes that protrude from the sediment in sandy areas, often decorated with algae and shell fragments; a large body size, up to 600 mm long and 11.5 mm wide. It has 10–18 rings on ceratophores; 5–10 teeth on pectinate chaetae; uni- and bidentate pseudo-compound falcigers and dorsal cirri approximately as long as branchiae. Diopatra aciculata was detected up to 12 km from the mouth of the Knysna Estuary with densities measured at 18 sampled sites. Statistical analysis retrieved high and low density groups that were significantly different from one another (Kruskal-Wallis H(14, 800) = 376.55; P = 0.01), but distribution of high density sites was patchy. We estimate that the population comprises 20–24 million individuals. Given the size of individual worms and the population estimate, this species can be expected to have significant ecological impacts in the estuary.

scholarly journals Early Jurassic (middle Hettangian) marine gastropods from the Pogibshi Formation (Alaska) and their paleobiogeographical significance

2020 ◽  
Vol 47 (3) ◽  
pp. 559
Author(s):  
Mariel Ferrari ◽  
Robert B. Blodgett ◽  
Montana S. Hodges ◽  
Christopher L. Hodges
Keyword(s):  
North America ◽  
South America ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Time Range ◽  
South American ◽  
Kenai Peninsula ◽  
South Central ◽  
First Occurrence ◽  
First Time

A middle Hettangian marine gastropod assemblage is reported from the Kenai Peninsula of south-central Alaska supplying new paleontological evidence of this group in Lower Jurassic rocks of North America. Pleurotomaria pogibshiensis sp. nov. is described from the middle Hettangian marine succession informally known as Pogibshi formation, being the first occurrence of the genus in the Kenai Peninsula and the oldest occurrence of the genus in present-day Alaska and North America. One species of the genus Lithotrochus, namely Lithotrochus humboldtii (von Buch), is also reported for the first time from the Kenai Peninsula. Lithotrochus has been considered as endemic to South America for a time range from the early Sinemurian to the late Pliensbachian. The newest occurrence of Lithotrochus in rocks of the Pogibshi formation extends the paleobiogeographical and chronostratigraphical distribution of the genus into the present-day Northern Hemisphere. However, the Southern Hemisphere affinities are consistent with the hypothetical interpretations (although supported both by paleobiogeographical and paleomagnetic data) that the Peninsular terrane of south-central Alaska is far-traveled and may have originated at much more southerly paleolatitudes than its present-day position. Two other Early Jurassic caenogastropods typical of the Andean region of South America and of the Tethyan epicontinental seas are described for the first time in the Pogibshi formation, and these are Pseudomelania sp. and Pictavia sp. The new gastropod assemblage reported here shows close affinities with coeval South American and European gastropod faunas, supplying new evidence to interpret their distribution during the Early Jurassic.

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