scholarly journals The oldest ceratosaurian (Dinosauria: Theropoda), from the Lower Jurassic of Italy, sheds light on the evolution of the three-fingered hand of birds

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5976 ◽  
Author(s):  
Cristiano Dal Sasso ◽  
Simone Maganuco ◽  
Andrea Cau
Keyword(s):  
Marine Invertebrates ◽  
First Record ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Ancestral State ◽  
Theropod Dinosaurs ◽  
Sea Bottom ◽  
Fourth Finger ◽  
Primary Axis ◽  
Digit Position

The homology of the tridactyl hand of birds is a still debated subject, with both paleontological and developmental evidence used in support of alternative identity patterns in the avian fingers. With its simplified phalangeal morphology, the Late Jurassic ceratosaurian Limusaurus has been argued to support a II–III–IV digital identity in birds and a complex pattern of homeotic transformations in three-fingered (tetanuran) theropods. We report a new large-bodied theropod, Saltriovenator zanellai gen. et sp. nov., based on a partial skeleton from the marine Saltrio Formation (Sinemurian, lowermost Jurassic) of Lombardy (Northern Italy). Taphonomical analyses show bone bioerosion by marine invertebrates (first record for dinosaurian remains) and suggest a complex history for the carcass before being deposited on a well-oxygenated and well-illuminated sea bottom. Saltriovenator shows a mosaic of features seen in four-fingered theropods and in basal tetanurans. Phylogenetic analysis supports sister taxon relationships between the new Italian theropod and the younger Early Jurassic Berberosaurus from Morocco, in a lineage which is the basalmost of Ceratosauria. Compared to the atrophied hand of later members of Ceratosauria, Saltriovenator demonstrates that a fully functional hand, well-adapted for struggling and grasping, was primitively present in ceratosaurians. Ancestral state reconstruction along the avian stem supports 2-3-4-1-X and 2-3-4-0-X as the manual phalangeal formulae at the roots of Ceratosauria and Tetanurae, confirming the I–II–III pattern in the homology of the avian fingers. Accordingly, the peculiar hand of Limusaurus represents a derived condition restricted to late-diverging ceratosaurians and cannot help in elucidating the origin of the three-fingered condition of tetanurans. The evolution of the tridactyl hand of birds is explained by step-wise lateral simplification among non-tetanuran theropod dinosaurs, followed by a single primary axis shift from digit position 4 to 3 at the root of Tetanurae once the fourth finger was completely lost, which allowed independent losses of the vestigial fourth metacarpal among allosaurians, tyrannosauroids, and maniraptoromorphs. With an estimated body length of 7.5 m, Saltriovenator is the largest and most robust theropod from the Early Jurassic, pre-dating the occurrence in theropods of a body mass approaching 1,000 Kg by over 25 My. The radiation of larger and relatively stockier averostran theropods earlier than previously known may represent one of the factors that ignited the trend toward gigantism in Early Jurassic sauropods.

First record of the early Mesozoic sphenodontian Clevosaurus (Lepidosauria: Rhynchocephalia) from the Southern Hemisphere

1995 ◽  
Vol 69 (1) ◽  
pp. 123-126 ◽  
Author(s):  
Hans-Dieter Sues ◽  
Robert R. Reisz
Keyword(s):  
Nova Scotia ◽  
Southern Hemisphere ◽  
Southern Africa ◽  
First Record ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Red Beds ◽  
Early Mesozoic

An incomplete skull of a small sphenodontian lepidosaur from the upper part of the Stormberg Group of southern Africa is referable to Clevosaurus Swinton, 1939. It is most closely related to C. bairdi from the McCoy Brook Formation (Lower Jurassic) of Nova Scotia (Canada) and C. mcgilli from the Dark Red Beds of the Lower Lufeng Formation (Lower Jurassic) of Yunnan (China). The new specimen is important because it represents the first record of Clevosaurus from the Southern Hemisphere. Like many other taxa of Early Jurassic continental tetrapods (crocodylomorph archosaurs, dinosaurs, synapsids), Clevosaurus had an apparently Pangaean distribution.

Provenance of Jurassic sedimentary rocks of south-central Quesnellia, British Columbia: implications for paleogeography

2004 ◽  
Vol 41 (1) ◽  
pp. 103-125 ◽  
Author(s):  
Nathan T Petersen ◽  
Paul L Smith ◽  
James K Mortensen ◽  
Robert A Creaser ◽  
Howard W Tipper
Keyword(s):  
Detrital Zircon ◽  
Middle Jurassic ◽  
Sedimentary Rocks ◽  
Source Area ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Late Triassic ◽  
Nd Isotopes ◽  
South Central ◽  
History Of

Jurassic sedimentary rocks of southern to central Quesnellia record the history of the Quesnellian magmatic arc and reflect increasing continental influence throughout the Jurassic history of the terrane. Standard petrographic point counts, geochemistry, Sm–Nd isotopes and detrital zircon geochronology, were employed to study provenance of rocks obtained from three areas of the terrane. Lower Jurassic sedimentary rocks, classified by inferred proximity to their source areas as proximal or proximal basin are derived from an arc source area. Sandstones of this age are immature. The rocks are geochemically and isotopically primitive. Detrital zircon populations, based on a limited number of analyses, have homogeneous Late Triassic or Early Jurassic ages, reflecting local derivation from Quesnellian arc sources. Middle Jurassic proximal and proximal basin sedimentary rocks show a trend toward more evolved mature sediments and evolved geochemical characteristics. The sandstones show a change to more mature grain components when compared with Lower Jurassic sedimentary rocks. There is a decrease in εNdT values of the sedimentary rocks and Proterozoic detrital zircon grains are present. This change is probably due to a combination of two factors: (1) pre-Middle Jurassic erosion of the Late Triassic – Early Jurassic arc of Quesnellia, making it a less dominant source, and (2) the increase in importance of the eastern parts of Quesnellia and the pericratonic terranes, such as Kootenay Terrane, both with characteristically more evolved isotopic values. Basin shale environments throughout the Jurassic show continental influence that is reflected in the evolved geochemistry and Sm–Nd isotopes of the sedimentary rocks. The data suggest southern Quesnellia received material from the North American continent throughout the Jurassic but that this continental influence was diluted by proximal arc sources in the rocks of proximal derivation. The presence of continent-derived material in the distal sedimentary rocks of this study suggests that southern Quesnellia is comparable to known pericratonic terranes.

Jurassic evolution of the Qaidam Basin in western China: Constrained by stratigraphic succession, detrital zircon U-Pb geochronology and Hf isotope analysis

2021 ◽  
Author(s):  
Tao Qian ◽  
Zongxiu Wang ◽  
Yu Wang ◽  
Shaofeng Liu ◽  
Wanli Gao ◽  
...  
Keyword(s):  
Late Jurassic ◽  
Qaidam Basin ◽  
Isotope Analysis ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Hf Isotope ◽  
Western China ◽  
Small Scale ◽  
Altyn Tagh ◽  
Stratigraphic Succession

The formation and evolution of an intracontinental basin triggered via the subduction or collision of plates at continental margins can record intracontinental tectonic processes. As a typical intracontinental basin during the Jurassic, the Qaidam Basin in western China records how this extensional basin formed and evolved in response to distant subduction or collisional processes and tectonism caused by stresses transmitted from distant convergent plate margins. The Jurassic evolution of the Qaidam Basin, in terms of basin-filling architecture, sediment dispersal pattern and basin properties, remains speculative; hence, these uncertainties need to be revisited. An integrated study of the stratigraphic succession, conglomerates, U-Pb geochronology, and Hf isotopes of detrital zircons was adopted to elucidate the Jurassic evolutionary process of the Qaidam Basin. The results show that a discrete Jurassic terrestrial succession characterized by alluvial fan, braided stream, braided river delta, and lacustrine deposits developed on the western and northern margins of the Qaidam Basin. The stratigraphic succession, U-Pb age dating, and Hf isotope analysis, along with the reconstructed provenance results, suggest small-scale distribution of Lower Jurassic sediments deposited via autochthonous sedimentation on the western margin of the basin, with material mainly originating from the Altyn Tagh Range. Lower Jurassic sediments in the western segment of the northern basin were shed from the Qilian Range (especially the South Qilian) and Eastern Kunlun Range. And coeval sediments in the eastern segment of the northern basin were originated from the Quanji massif. During the Middle-Late Jurassic, the primary source areas were the Qilian Range and Eastern Kunlun Range, which fed material to the whole basin. The Jurassic sedimentary environment in the Qaidam Basin evolved from a series of small-scale, scattered, and rift-related depressions distributed on the western and northern margins during the Early Jurassic to a larger, extensive, and unified depression occupying the whole basin in the Middle Jurassic. The Altyn Tagh Range rose to a certain extent during the Early Jurassic but lacked large-scale strike-slip tectonism throughout the Jurassic. At that time, the North Qaidam tectonic belt had not yet been uplifted and did not shed material into the basin during the Jurassic. The Qaidam Basin experienced intracontinental extensional tectonism with a northeast-southwest trend throughout the Jurassic in response to far-field effects driven by the sequential northward or northeastward amalgamation of blocks to the southern margin of the Qaidam Block and successive accretion of the Qiangtang Block and Lhasa Block onto the southern Eurasian margin during the Late Triassic−Early Jurassic and Late Jurassic−Early Cretaceous, respectively.

New Lower Jurassic ammonite faunas from the Fernie Formation, southern Canadian Rocky Mountains

1987 ◽  
Vol 24 (8) ◽  
pp. 1688-1704 ◽  
Author(s):  
Russell L. Hall
Keyword(s):  
British Columbia ◽  
North American ◽  
Rocky Mountains ◽  
Red Deer ◽  
First Record ◽  
Lower Jurassic ◽  
Canadian Rocky Mountains ◽  
Poker Chip

New ammonite faunas are described from sections along Bighorn and Scalp creeks in central-western Alberta where Lower Jurassic parts of the Fernie Formation are exposed. The first record of the upper Sinemurian Obtusum Zone from the Fernie is based on the occurrence of Asteroceras cf. stellare and Epophioceras cf. breoni in the basal pebbly coquina on Bighorn Creek. The overlying Red Deer Member has yielded Amaltheus cf. stokesi, representing the upper Pliensbachian Margaritatus Zone; in immediately superjacent strata the first North American examples of ?Amauroceras occur together with Protogrammoceras and ?Aveyroniceras. In the basal parts of the overlying Poker Chip Shale a fauna including Harpoceras cf. falciferum, Harpoceratoides, Polyplectus cf. subplanatus, Hildaites cf. serpentiniformis, and Dactylioceras cf. athleticum is correlated with the lower Toarcian Falciferum Zone.The upper parts of the Poker Chip Shale on Fording River in southeastern British Columbia contain a fauna representing some part of the upper Toarcian, but owing to poor preservation, generic identifications are only tentatively made.

A Lower Jurassic heteroporid bryozoan and associated biota, Turnagain Lake, British Columbia

1981 ◽  
Vol 18 (3) ◽  
pp. 457-468 ◽  
Author(s):  
C. M. Henderson ◽  
D. G. Perry
Keyword(s):  
British Columbia ◽  
North America ◽  
Green Alga ◽  
Marine Environment ◽  
High Energy ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Associated Fauna ◽  
North Central ◽  
Commensal Relationship

Late Early Jurassic heteroporid bryozoa occur in arenaceous carbonates near Turnagain Lake, north-central British Columbia. The occurrence of Heteropora tipperi n. sp. marks the first documentation of Early Jurassic cyclostome bryozoa in North America. The associated fauna, comprising the ammonite Harpoceras, the foraminifer Reinholdella, and the pelecypod Weyla, establish the age as Early Toarcian. Other associated biota include an endolithic green alga(e), which is demonstrated to have a commensal relationship with H. tipperi n. sp. Sedimentologic and biotic data from the host strata point to a shallow, temperate, high-energy, normal marine environment.

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 Ngwevu intloko: a new early sauropodomorph dinosaur from the Lower Jurassic Elliot Formation of South Africa and comments on cranial ontogeny in Massospondylus carinatus

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7240 ◽  
Author(s):  
Kimberley E.J. Chapelle ◽  
Paul M. Barrett ◽  
Jennifer Botha ◽  
Jonah N. Choiniere
Keyword(s):  
South Africa ◽  
New Species ◽  
Sexual Dimorphism ◽  
New Genus ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Adult Size ◽  
Minimum Age ◽  
Cranial Ontogeny ◽  
Morphological Differences

Our knowledge of Early Jurassic palaeobiodiversity in the upper Elliot Formation of South Africa has increased markedly in recent years with the discovery of new fossils, re-assessments of previously collected material and a better understanding of Stormberg Group stratigraphy. Here, Ngwevu intloko, a new genus of upper Elliot basal sauropodomorph is named on the basis of a complete skull and partial skeleton (BP/1/4779) previously assigned to Massospondylus carinatus. It can be distinguished from all other basal sauropodomorphs by a combination of 16 cranial and six postcranial characters. The new species is compared to a small ontogenetic series of M. carinatus as well as to a range of closely related taxa. Taphonomic deformation, sexual dimorphism and ontogeny are rejected as possible explanations for the morphological differences present between BP/1/4779 and other taxa. Osteohistological examination reveals that BP/1/4779 had nearly reached adult size at the time of its death at a minimum age of 10 years.

scholarly journals Upper Karoo vertebrate assemblages (Late Triassic/Early Jurassic) of the Lake Kariba region, Zimbabwe

2017 ◽  
Author(s):  
Paul M Barrett ◽  
Tim Broderick ◽  
Kimberley Chapelle ◽  
Jonah Choiniere ◽  
Steve Edwards ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Southern Africa ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Type Locality ◽  
Late Triassic ◽  
Lake Kariba ◽  
Aquatic Fauna ◽  
Mudstone Facies

Southern Africa provides critical information on Late Triassic–Early Jurassic terrestrial tetrapod faunas. Most of the localities in this region are in South Africa and Lesotho, but preliminary work in Zimbabwe has revealed significant potential. Early Jurassic Zimbabwean localities have yielded the basal sauropodomorph Massospondylus, the early sauropod Vulcanodon and theropod material. Late Triassic localities are also known, but have yielded only fragmentary specimens thus far. In early 2017, a joint South African-Zimbabwean-UK team conducted fieldwork in the upper Karoo-aged deposits along the shores of Lake Kariba, northern Zimbabwe (Mid-Zambesi Basin). We relocated the Vulcanodon type locality on Island 126/127 and found that, contrary to previous reports suggesting a Toarcian age, the quarry was in a horizon pre-dating the onset of Drakensburg volcanism (= Batoka Basalts). It is situated instead within the earlier Lower Jurassic Forest Sandstone. This indicates that Vulcanodon is 10–15 million years older than thought previously, recalibrating several nodes within Sauropoda and indicating extensive overlap between true sauropods and 'prosauropods'. Other new vertebrate localities show that sauropodomorphs are present in the Forest Sandstone and upper Tashinga (Late Triassic) formations, but a grey mudstone facies within the Pebbly Arkose Member of the latter unit yields a more aquatic fauna, including lungfish and phytosaurs, but lacking sauropodomorphs. The phytosaur occurrence is the first in Africa south of the Sahara. Faunal and sedimentological evidence indicates that the Late Triassic and Early Jurassic sites in this region were deposited under more mesic environments than their lateral equivalents in South Africa.

The oldest representative of the family Austropanorpidae (Mecoptera) from the Lower Jurassic of Siberia

2016 ◽  
Vol 107 (2-3) ◽  
pp. 151-155 ◽  
Author(s):  
Wiesław Krzemiński ◽  
Agnieszka Soszyńska-Maj ◽  
Katarzyna Kopeć ◽  
Irena D. Sukatsheva
Keyword(s):  
Lower Jurassic ◽  
Early Jurassic ◽  
Paleontological Institute ◽  
Russian Academy Of Sciences ◽  
The Family ◽  
Academy Of Sciences

ABSTRACTThe family Austropanorpidae (Mecoptera) was described by Willmann in 1977 from the Eocene of Australia, based on one genus and species, Austropanorpa australis Riek, 1952. During a restudy of the collection of the Paleontological Institute, Russian Academy of Sciences in Moscow, a second and much older representative of this family was found. This specimen, described as Orthophlebia martynovae Sukatsheva, 1985 from Siberia (Russia), was considered until now to be a member of family Orthophlebiidae. We transfer this species to the Austropanorpidae, extending the age of this family back to the Early Jurassic. An updated diagnoses of the family Austropanorpidae and genus Austropanorpa are presented here.

scholarly journals The phylogenetic position of the solitary zoanthid genus Sphenopus (Cnidaria: Hexacorallia)

2012 ◽  
Vol 81 (1) ◽  
pp. 43-54 ◽  
Author(s):  
James D. Reimer ◽  
Meifang Lin ◽  
Takuma Fujii ◽  
David J.W. Lane ◽  
Bert W. Hoeksema
Keyword(s):  
Marine Invertebrates ◽  
Phylogenetic Analyses ◽  
Solid Substrate ◽  
Ancestral State Reconstruction ◽  
Phylogenetic Position ◽  
Ancestral State ◽  
State Reconstruction ◽  
Unique Character ◽  
The Family ◽  
Southern Taiwan

The zoanthid genus Sphenopus (Cnidaria: Anthozoa: Zoantharia), like many other brachycnemic zoanthids, is found in shallow subtropical and tropical waters, but is uniquely unitary (solitary, monostomatous), azooxanthellate, and free-living. With sparse knowledge of its phylogenetic position, this study examines the phylogenetic position of Sphenopus within the family Sphenopidae utilizing specimens from southern Taiwan and Brunei collected in 1999-2011, and furthermore analyzes the evolution of its unique character set via ancestral state reconstruction analyses. Phylogenetic analyses surprisingly show Sphenopus to be phylogenetically positioned within the genus Palythoa, which is colonial (polystomatous), zooxanthellate, and attached to solid substrate. Ancestral state reconstruction strongly indicates that the unique characters of Sphenopus have evolved recently within Palythoa and only in the Sphenopuslineage. These results indicate that zoanthid body plans can evolve with rapidity, as in some other marine invertebrates, and that the traditional definitions of zoanthid genera may need reexamination.

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