scholarly journals A basal thunnosaurian from Iraq reveals disparate phylogenetic origins for Cretaceous ichthyosaurs

2018 ◽  
Author(s):  
Valentin Fischer ◽  
Darren Naish ◽  
Jeff Liston ◽  
Robert M Appleby ◽  
James B Riding ◽  
...  
Keyword(s):  
Middle East ◽  
Early Cretaceous ◽  
Late Jurassic ◽  
Evolutionary History ◽  
Early Jurassic ◽  
Late Triassic ◽  
Low Diversity ◽  
History Of

Cretaceous ichthyosaurs have typically been considered a small, homo- geneous assemblage sharing a common Late Jurassic ancestor. Their low diversity and disparity have been interpreted as indicative of a decline lead- ing to their Cenomanian extinction. We describe the first post-Triassic ichthyosaur from the Middle East, Malawania anachronus gen. et sp. nov. from the Early Cretaceous of Iraq, and re-evaluate the evolutionary history of parvipelvian ichthyosaurs via phylogenetic and cladogenesis rate ana- lyses. Malawania represents a basal grade in thunnosaurian evolution that arose during a major Late Triassic radiation event and was previously thought to have gone extinct during the Early Jurassic. Its pectoral mor- phology appears surprisingly archaic, retaining a forefin architecture similar to that of its Early Jurassic relatives. After the initial latest Triassic radiation of early thunnosaurians, two subsequent large radiations pro- duced lineages with Cretaceous representatives, but the radiation events themselves are pre-Cretaceous. Cretaceous ichthyosaurs therefore include distantly related lineages, with contrasting evolutionary histories, and appear more diverse and disparate than previously supposed.

scholarly journals A basal thunnosaurian from Iraq reveals disparate phylogenetic origins for Cretaceous ichthyosaurs

2013 ◽  
Vol 9 (4) ◽  
pp. 20130021 ◽  
Author(s):  
Valentin Fischer ◽  
Robert M. Appleby ◽  
Darren Naish ◽  
Jeff Liston ◽  
James B. Riding ◽  
...  
Keyword(s):  
Middle East ◽  
Early Cretaceous ◽  
Late Jurassic ◽  
Evolutionary History ◽  
Early Jurassic ◽  
Late Triassic ◽  
Low Diversity ◽  
History Of

Cretaceous ichthyosaurs have typically been considered a small, homogeneous assemblage sharing a common Late Jurassic ancestor. Their low diversity and disparity have been interpreted as indicative of a decline leading to their Cenomanian extinction. We describe the first post-Triassic ichthyosaur from the Middle East, Malawania anachronus gen. et sp. nov. from the Early Cretaceous of Iraq, and re-evaluate the evolutionary history of parvipelvian ichthyosaurs via phylogenetic and cladogenesis rate analyses. Malawania represents a basal grade in thunnosaurian evolution that arose during a major Late Triassic radiation event and was previously thought to have gone extinct during the Early Jurassic. Its pectoral morphology appears surprisingly archaic, retaining a forefin architecture similar to that of its Early Jurassic relatives. After the initial latest Triassic radiation of early thunnosaurians, two subsequent large radiations produced lineages with Cretaceous representatives, but the radiation events themselves are pre-Cretaceous. Cretaceous ichthyosaurs therefore include distantly related lineages, with contrasting evolutionary histories, and appear more diverse and disparate than previously supposed.

scholarly journals Mesozoic Intracontinental Orogeny in the Tectonic History of the Kolyvan’– Tomsk Folded Zone (Southern Siberia): a Synthesis of Geological Data and results of Apatite Fission Track Analysis

2021 ◽  
Vol 62 (9) ◽  
pp. 1006-1020
Author(s):  
F.I. Zhimulev ◽  
E.V. Vetrov ◽  
I.S. Novikov ◽  
G. Van Ranst ◽  
S. Nachtergaele ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Fission Track ◽  
Early Jurassic ◽  
Late Triassic ◽  
Apatite Fission Track ◽  
History Of ◽  
Paleozoic Rocks ◽  
Orogenic Events

Abstract —The Kolyvan’–Tomsk folded zone (KTFZ) is a late Permian collisional orogen in the northwestern section of the Central Asian Orogenic Belt. The Mesozoic history of the KTFZ area includes Late Triassic–Early Jurassic and Late Jurassic–Early Cretaceous orogenic events. The earlier event produced narrow deep half-ramp basins filled with Early–Middle Jurassic molasse south of the KTFZ, and the later activity rejuvenated the Tomsk thrust fault, whereby the KTFZ Paleozoic rocks were thrust over the Early–Middle Jurassic basin sediments. The Mesozoic orogenic events induced erosion and the ensuing exposure of granitoids (Barlak complex) that were emplaced in a within-plate context after the Permian collisional orogeny. Both events were most likely associated with ocean closure, i.e., the Paleothetys Ocean in the Late Triassic–Early Jurassic and the Mongol–Okhotsk Ocean in the Late Jurassic–Early Cretaceous. The apatite fission track (AFT) ages of granitoids from the Ob’ complex in the KTFZ range between ~120 and 100 Ma (the Aptian and the Albian). The rocks with Early Cretaceous AFT ages were exhumed as a result of denudation and peneplanation of the Early Cretaceous orogeny, which produced a vast Late Cretaceous–Paleogene planation surface. The tectonic pattern of the two orogenic events, although being different in details, generally inherited the late Paleozoic primary collisional structure of the Kolyvan’–Tomsk zone.

scholarly journals Triassic–Jurassic mass extinction as trigger for the Mesozoic radiation of crocodylomorphs

2013 ◽  
Vol 9 (3) ◽  
pp. 20130095 ◽  
Author(s):  
Olja Toljagić ◽  
Richard J. Butler
Keyword(s):  
Mass Extinction ◽  
Evolutionary History ◽  
Morphological Diversity ◽  
Early Jurassic ◽  
Late Triassic ◽  
Time Interval ◽  
Significant Shift ◽  
History Of ◽  
Larger Sample ◽  
Lineage Diversity

Pseudosuchia, one of the two main clades of Archosauria (Reptilia: Diapsida), suffered a major decline in lineage diversity during the Triassic–Jurassic (TJ) mass extinction (approx. 201 Ma). Crocodylomorpha, including living crocodilians and their extinct relatives, is the only group of pseudosuchians that survived into the Jurassic. We reassess changes in pseudosuchian morphological diversity (disparity) across this time interval, using considerably larger sample sizes than in previous analyses. Our results show that metrics of pseudosuchian disparity did not change significantly across the TJ boundary, contrasting with previous work suggesting low pseudosuchian disparity in the Early Jurassic following the TJ mass extinction. However, a significant shift in morphospace occupation between Late Triassic and Early Jurassic taxa is recognized, suggesting that the TJ extinction of many pseudosuchian lineages was followed by a major and geologically rapid adaptive radiation of crocodylomorphs. This marks the onset of the spectacularly successful evolutionary history of crocodylomorphs in Jurassic and Cretaceous ecosystems.

scholarly journals A new stem turtle from the Middle Jurassic of Scotland: new insights into the evolution and palaeoecology of basal turtles

2008 ◽  
Vol 276 (1658) ◽  
pp. 879-886 ◽  
Author(s):  
Jérémy Anquetin ◽  
Paul M Barrett ◽  
Marc E.H Jones ◽  
Scott Moore-Fay ◽  
Susan E Evans
Keyword(s):  
Middle Jurassic ◽  
Late Jurassic ◽  
Evolutionary History ◽  
Sister Group ◽  
Late Triassic ◽  
Sister Group Relationship ◽  
New Taxon ◽  
Crown Group ◽  
History Of ◽  
Isle Of Skye

The discovery of a new stem turtle from the Middle Jurassic (Bathonian) deposits of the Isle of Skye, Scotland, sheds new light on the early evolutionary history of Testudinata. Eileanchelys waldmani gen. et sp. nov. is known from cranial and postcranial material of several individuals and represents the most complete Middle Jurassic turtle described to date, bridging the morphological gap between basal turtles from the Late Triassic–Early Jurassic and crown-group turtles that diversify during the Late Jurassic. A phylogenetic analysis places the new taxon within the stem group of Testudines (crown-group turtles) and suggests a sister-group relationship between E. waldmani and Heckerochelys romani from the Middle Jurassic of Russia. Moreover, E. waldmani also demonstrates that stem turtles were ecologically diverse, as it may represent the earliest known aquatic turtle.

scholarly journals The evolutionary history of polycotylid plesiosaurians

2018 ◽  
Vol 5 (3) ◽  
pp. 172177 ◽  
Author(s):  
V. Fischer ◽  
R. B. J. Benson ◽  
P. S. Druckenmiller ◽  
H. F. Ketchum ◽  
N. Bardet
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Phylogenetic Relationships ◽  
Evolutionary History ◽  
Phylogenetic Analyses ◽  
Neck Length ◽  
Ecological Release ◽  
Holotype Specimen ◽  
Low Diversity ◽  
History Of

Polycotylidae is a clade of plesiosaurians that appeared during the Early Cretaceous and became speciose and abundant early in the Late Cretaceous. However, this radiation is poorly understood. Thililua longicollis from the Middle Turonian of Morocco is an enigmatic taxon possessing an atypically long neck and, as originally reported, a series of unusual cranial features that cause unstable phylogenetic relationships for polycotylids. We reinterpret the holotype specimen of Thililua longicollis and clarify its cranial anatomy. Thililua longicollis possesses an extensive, foramina-bearing jugal, a premaxilla–parietal contact and carinated teeth. Phylogenetic analyses of a new cladistic dataset based on first-hand observation of most polycotylids recover Thililua and Mauriciosaurus as successive lineages at the base of the earliest Late Cretaceous polycotyline radiation. A new dataset summarizing the Bauplan of polycotylids reveals that their radiation produced an early burst of disparity during the Cenomanian–Turonian interval, with marked plasticity in relative neck length, but this did not arise as an ecological release following the extinction of ichthyosaurs and pliosaurids. This disparity vanished during and after the Turonian, which is consistent with a model of ‘early experimentation/late constraint’. Two polycotylid clades, Occultonectia clade nov. and Polycotylinae, survived up to the Maastrichtian, but with low diversity.

scholarly journals Thai amber: insights into early diatom history?

2020 ◽  
Vol 191 ◽  
pp. 23
Author(s):  
Vincent Girard ◽  
Simona Saint Martin ◽  
Eric Buffetaut ◽  
Jean-Paul Saint Martin ◽  
Didier Néraudeau ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Fossil Record ◽  
Late Jurassic ◽  
Molecular Data ◽  
Early Jurassic ◽  
Coastal Environments ◽  
Potential Bias ◽  
Fossil Evidence ◽  
History Of

The origin of the diatoms still remains enigmatic. Their fossil record is scarce until the Late Cretaceous and great divergences exist between molecular data and the earliest fossil evidence. While molecular data indicate an origin during the Triassic or Early Jurassic, early fossil evidence is only from the Late Jurassic-Early Cretaceous. The discovery of diatoms in French mid-Cretaceous amber by the end of the 2000s already suggested a potential bias in the diatom fossil record as it made older many diatom lineages, the record of which hitherto began at the end of the Cretaceous. The Jurassic/Early Cretaceous fossil record of diatoms is extremely sparse and any new occurrence is important for retracing the evolutionary, palaeogeographical and palaeoenvironmental history of diatoms. Thai amber has yielded a new diatom specimen that has been attributed to the genus Hemiaulus. Fossil assemblages and sedimentological data indicate that Thai amber and its Hemiaulus specimen are Late Jurassic in age. This discovery represents the oldest hitherto known specimen of Hemiaulus and so extends the fossil record of the bipolar diatoms and of the genus Hemiaulus by several dozens of millions of years and brings closer the fossil evidence and molecular data (that estimated an origin of the bipolar diatoms about 150 Ma ago). It reinforces the hypothesis of a pre-Cretaceous fossil diatom records and also supports an origin of the diatoms in shallow coastal environments.

scholarly journals A new stem turtle from the Middle Jurassic of Scotland: new insights into the evolution and palaeoecology of basal turtles

2017 ◽  
Author(s):  
Jérémy Anquetin ◽  
Paul M. Barrett ◽  
Marc E. H. Jones ◽  
Scott Moore-Fay ◽  
Susan E. Evans
Keyword(s):  
Middle Jurassic ◽  
Late Jurassic ◽  
Evolutionary History ◽  
Sister Group ◽  
Late Triassic ◽  
Sister Group Relationship ◽  
New Taxon ◽  
Crown Group ◽  
History Of ◽  
Isle Of Skye

The discovery of a new stem turtle from the Middle Jurassic (Bathonian) deposits of the Isle of Skye, Scotland, sheds new light on the early evolutionary history of Testudinata. Eileanchelys waldmani gen. et sp. nov. is known from cranial and postcranial material of several individuals and represents the most complete Middle Jurassic turtle described to date, bridging the morphological gap between basal turtles from the Late Triassic–Early Jurassic and crown-group turtles that diversify during the Late Jurassic. A phylogenetic analysis places the new taxon within the stem group of Testudines (crown-group turtles) and suggests a sister-group relationship between E. waldmani and Heckerochelys romani from the Middle Jurassic of Russia. Moreover, E. waldmani also demonstrates that stem turtles were ecologically diverse, as it may represent the earliest known aquatic turtle.

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.

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.

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