scholarly journals Peculiar macrophagous adaptations in a new Cretaceous pliosaurid

2015 ◽  
Vol 2 (12) ◽  
pp. 150552 ◽  
Author(s):  
Valentin Fischer ◽  
Maxim S. Arkhangelsky ◽  
Ilya M. Stenshin ◽  
Gleb N. Uspensky ◽  
Nikolay G. Zverkov ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Fossil Record ◽  
Late Jurassic ◽  
Phylogenetic Analyses ◽  
Consensus Methods ◽  
Ancestral State ◽  
Ecological Diversity ◽  
Apex Predator ◽  
State Reconstruction ◽  
Marine Reptile

During the Middle and Late Jurassic, pliosaurid plesiosaurs evolved gigantic body size and a series of craniodental adaptations that have been linked to the occupation of an apex predator niche. Cretaceous pliosaurids (i.e. Brachaucheninae) depart from this morphology, being slightly smaller and lacking the macrophagous adaptations seen in earlier forms. However, the fossil record of Early Cretaceous pliosaurids is poor, concealing the evolution and ecological diversity of the group. Here, we report a new pliosaurid from the Late Hauterivian (Early Cretaceous) of Russia. Phylogenetic analyses using reduced consensus methods recover it as the basalmost brachauchenine. This pliosaurid is smaller than other derived pliosaurids, has tooth alveoli clustered in pairs and possesses trihedral teeth with complex serrated carinae. Maximum-likelihood ancestral state reconstruction suggests early brachauchenines retained trihedral teeth from their ancestors, but modified this feature in a unique way, convergent with macrophagous archosaurs or sphenacodontoids. Our findings indicate that Early Cretaceous marine reptile teeth with serrated carinae cannot be unequivocally assigned to metriorhynchoid crocodylomorphs. Furthermore, they extend the known diversity of dental adaptations seen in Sauropterygia, the longest lived clade of marine tetrapods.

scholarly journals Improvements in the fossil record may largely resolve current conflicts between morphological and molecular estimates of mammal phylogeny

2018 ◽  
Vol 285 (1893) ◽  
pp. 20181632 ◽  
Author(s):  
Robin M. D. Beck ◽  
Charles Baillie
Keyword(s):  
Maximum Likelihood ◽  
Fossil Record ◽  
Morphological Character ◽  
Phylogenetic Analyses ◽  
Molecular Data ◽  
Morphological Data ◽  
Ancestral State ◽  
Case Scenario ◽  
State Reconstruction ◽  
Consensus View

Phylogenies of mammals based on morphological data continue to show several major areas of conflict with the current consensus view of their relationships, which is based largely on molecular data. This raises doubts as to whether current morphological character sets are able to accurately resolve mammal relationships. We tested this under a hypothetical ‘best case scenario’ by using ancestral state reconstruction (under both maximum parsimony and maximum likelihood) to infer the morphologies of fossil ancestors for all clades present in a recent comprehensive DNA sequence-based phylogeny of mammals, and then seeing what effect the subsequent inclusion of these predicted ancestors had on unconstrained phylogenetic analyses of morphological data. We found that this resulted in topologies that are highly congruent with the current consensus phylogeny, at least when the predicted ancestors are assumed to be well preserved and densely sampled. Most strikingly, several analyses recovered the monophyly of clades that have never been found in previous morphology-only studies, such as Afrotheria and Laurasiatheria. Our results suggest that, at least in principle, improvements in the fossil record—specifically the discovery of fossil taxa that preserve the ancestral or near-ancestral morphologies of the nodes in the current consensus—may be sufficient to largely reconcile morphological and molecular estimates of mammal phylogeny, even using current morphological character sets.

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.

scholarly journals A turiasaurian sauropod dinosaur from the Early Cretaceous Wealden Supergroup of the United Kingdom

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6348
Author(s):  
Philip D. Mannion
Keyword(s):  
Early Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Western Europe ◽  
Phylogenetic Analyses ◽  
Neural Spine ◽  
Faunal Turnover ◽  
The United Kingdom ◽  
The Usa ◽  
The Uk

The Jurassic/Cretaceous (J/K) boundary, 145 million years ago, has long been recognised as an extinction event or faunal turnover for sauropod dinosaurs, with many ‘basal’ lineages disappearing. However, recently, a number of ‘extinct’ groups have been recognised in the Early Cretaceous, including diplodocids in Gondwana, and non-titanosauriform macronarians in Laurasia. Turiasauria, a clade of non-neosauropod eusauropods, was originally thought to have been restricted to the Late Jurassic of western Europe. However, its distribution has recently been extended to the Late Jurassic of Tanzania (Tendaguria tanzaniensis), as well as to the Early Cretaceous of the USA (Mierasaurus bobyoungi and Moabosaurus utahensis), demonstrating the survival of another ‘basal’ clade across the J/K boundary. Teeth from the Middle Jurassic–Early Cretaceous of western Europe and North Africa have also tentatively been attributed to turiasaurs, whilst recent phylogenetic analyses recovered Late Jurassic taxa from Argentina and China as further members of Turiasauria. Here, an anterior dorsal centrum and neural arch (both NHMUK 1871) from the Early Cretaceous Wealden Supergroup of the UK are described for the first time. NHMUK 1871 shares several synapomorphies with Turiasauria, especially the turiasaurs Moabosaurus and Tendaguria, including: (1) a strongly dorsoventrally compressed centrum; (2) the retention of prominent epipophyses; and (3) an extremely low, non-bifid neural spine. NHMUK 1871 therefore represents the first postcranial evidence for Turiasauria from European deposits of Early Cretaceous age. Although turiasaurs show clear heterodont dentition, only broad, characteristically ‘heart’-shaped teeth can currently be attributed to Turiasauria with confidence. As such, several putative turiasaur occurrences based on isolated teeth from Europe, as well as the Middle Jurassic and Early Cretaceous of Africa, cannot be confidently referred to Turiasauria. Unequivocal evidence for turiasaurs is therefore restricted to the late Middle Jurassic–Early Cretaceous of western Europe, the Late Jurassic of Tanzania, and the late Early Cretaceous of the USA, although remains from elsewhere might ultimately demonstrate that the group had a near-global distribution.

scholarly journals Comparative Mitogenomics of Fungal Species in Stachybotryaceae Provides Evolutionary Insights into Hypocreales

2021 ◽  
Vol 22 (24) ◽  
pp. 13341
Author(s):  
Li-Yuan Ren ◽  
Shu Zhang ◽  
Yong-Jie Zhang
Keyword(s):  
State Estimation ◽  
Early Cretaceous ◽  
Gene Order ◽  
Phylogenetic Analyses ◽  
Fungal Species ◽  
Stachybotrys Chartarum ◽  
Ancestral State ◽  
Intron Insertion ◽  
Dominant Pattern ◽  
The Family

Stachybotrys chartarum is one of the world’s ten most feared fungi within the family Stachybotryaceae, although to date, not a single mitogenome has been documented for Stachybotryaceae. Herein, six mitogenomes of four different species in Stachybotryaceae are newly reported. The S. chartarum mitogenome was 30.7 kb in length and contained two introns (one each in rnl and cox1). A comparison of the mitogenomes of three different individuals of S. chartarum showed few nucleotide variations and conservation of gene content/order and intron insertion. A comparison of the mitogenomes of four different Stachybotryaceae species (Memnoniella echinata, Myrothecium inundatum, S. chartarum, and S. chlorohalonata), however, revealed variations in intron insertion, gene order/content, and nad2/nad3 joining pattern. Further investigations on all Hypocreales species with available mitogenomes showed greater variabilities in gene order (six patterns) and nad2/nad3 joining pattern (five patterns) although a dominant pattern always existed in each case. Ancestral state estimation showed that in each case the dominant pattern was always more ancestral than those rare patterns. Phylogenetic analyses based on mitochondrion-encoded genes supported the placement of Stachybotryaceae in Hypocreales. The crown age of Stachybotryaceae was estimated to be approximately the Early Cretaceous (141–142 Mya). This study greatly promotes our understanding of the evolution of fungal species in Hypocreales.

scholarly journals Tip dating supports novel resolutions of controversial relationships among early mammals

2020 ◽  
Vol 287 (1928) ◽  
pp. 20200943
Author(s):  
Benedict King ◽  
Robin M. D. Beck
Keyword(s):  
Early Cretaceous ◽  
Late Jurassic ◽  
Morphological Evolution ◽  
Phylogenetic Analyses ◽  
Late Triassic ◽  
Crown Group ◽  
Jehol Biota ◽  
Rates Of Evolution ◽  
Mammal Evolution ◽  
Minimum Divergence

The estimation of the timing of major divergences in early mammal evolution is challenging owing to conflicting interpretations of key fossil taxa. One contentious group is Haramiyida, the earliest members of which are from the Late Triassic. Many phylogenetic analyses have placed haramiyidans in a clade with multituberculates within crown Mammalia, thus extending the minimum divergence date for the crown group deep into the Triassic. A second taxon of interest is the eutherian Juramaia from the Middle–Late Jurassic Yanliao Biota, which is morphologically very similar to eutherians from the Early Cretaceous Jehol Biota and implies a very early origin for therian mammals. Here, we apply Bayesian tip-dated phylogenetic methods to investigate these issues. Tip dating firmly rejects a monophyletic Allotheria (multituberculates and haramiyidans), which are split into three separate clades, a result not found in any previous analysis. Most notably, the Late Triassic Haramiyavia and Thomasia are separate from the Middle Jurassic euharamiyidans. We also test whether the Middle–Late Jurassic age of Juramaia is ‘expected’ given its known morphology by assigning an age prior without hard bounds. Strikingly, this analysis supports an Early Cretaceous age for Juramaia , but similar analyses on 12 other mammaliaforms from the Yanliao Biota return the correct, Jurassic age. Our results show that analyses incorporating stratigraphic data can produce results very different from other methods. Early mammal evolution may have involved multiple instances of convergent morphological evolution (e.g. in the dentition), and tip dating may be a method uniquely suitable to recognizing this owing to the incorporation of stratigraphic data. Our results also confirm that Juramaia is anomalous in exhibiting a much more derived morphology than expected given its age, which in turn implies very high rates of evolution at the base of therian mammals.

Convergent evolution and possible constraint in the posterodorsal retraction of the external nares in pelagic crocodylomorphs

2020 ◽  
Vol 189 (2) ◽  
pp. 494-520 ◽  
Author(s):  
Mark T Young ◽  
Sven Sachs ◽  
Pascal Abel ◽  
Davide Foffa ◽  
Yanina Herrera ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Convergent Evolution ◽  
Posterior Margin ◽  
Late Jurassic ◽  
Anterior Margin ◽  
Phylogenetic Analyses ◽  
Marine Reptiles

Abstract Amongst Mesozoic marine reptiles, metriorhynchid crocodylomorphs were unique in evolving into pelagically adapted forms with little-to-no posterodorsal retraction of the external nares. Narial retraction is a common adaptation seen in sustained swimmers, notably occurring during cetacean evolution. Mesosaurids and the basalmost known members of ichthyosauriforms, thalattosaurians, saurosphargids, sauropterygians, pleurosaurids and mosasauroids had the external nares divided by an ossified bar, bound by multiple cranial bones and were positioned back from the tip of the rostrum. However, metriorhynchids evolved from taxa with a single external naris bound solely by the premaxilla, and positioned near the tip of an elongate rostrum. We posit that metriorhynchids were uniquely disadvantaged in evolving into sustained swimmers. Herein we describe three Late Jurassic metriorhynchid cranial rostra that display differing degrees of narial retraction. In our new phylogenetic analyses, the backwards migration of the narial fossa posterior margin occurred independently at least four times in Metriorhynchidae, whereas the backwards migration of the anterior margin only occurred twice. Although Rhacheosaurini share the backwards migration of the anterior and posterior narial margins, posterodorsal retraction occurred differently along three lineages. This culminated in the Early Cretaceous, where a rhacheosaurin evolved nares bound by the premaxilla and maxilla, and significantly posterodorsally retracted.

scholarly journals Valanginian occurrence of Pelomedusoides turtles in northern South America: revision of this hypothesis based on a new fossil remain

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9810
Author(s):  
Edwin-Alberto Cadena
Keyword(s):  
South America ◽  
Early Cretaceous ◽  
Fossil Record ◽  
Late Jurassic ◽  
Diverse Group ◽  
Fossil Remains ◽  
Molecular Phylogenetic ◽  
Northern South America ◽  
Phylogenetic Hypotheses

Pelomedusoides constitutes the most diverse group of Mesozoic and Cenozoic side-necked turtles. However, when it originated is still being poorly known and controversial. Fossil remains from the Early Cretaceous (Valanginian) Rosa Blanca Formation of Colombia were described almost a decade ago as potentially belonging to Podocnemidoidea (a large subclade inside Pelomedusoides) and representing one of the earliest records of this group of turtles. Here, I revise this hypothesis based on a new fragmentary specimen from the Rosa Blanca Formation, represented by a right portion of the shell bridge, including the mesoplastron and most of peripherals 5 to 7. The equidimensional shape of the mesoplatron allows me to support its attribution as belonging to Pelomedusoides, a group to which the previously podocnemidoid material is also attributed here. Although the Valanginian pelomesudoid material from Colombia is still too fragmentary as to be considered the earliest indisputable record of the Pelomedusoides clade, their occurrence is at least in agreement with current molecular phylogenetic hypotheses that suggest they split from Chelidae during the Jurassic and should occur in the Late Jurassic and Early Cretaceous fossil record.

scholarly journals Refining the marine reptile turnover at the Early–Middle Jurassic transition

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10647
Author(s):  
Valentin Fischer ◽  
Robert Weis ◽  
Ben Thuy
Keyword(s):  
Middle Jurassic ◽  
Fossil Record ◽  
Late Jurassic ◽  
Western Europe ◽  
Marine Ecosystems ◽  
Taxonomic Composition ◽  
Restricted Area ◽  
Marine Reptile ◽  
Geological Formations ◽  
Geological Period

Even though a handful of long-lived reptilian clades dominated Mesozoic marine ecosystems, several biotic turnovers drastically changed the taxonomic composition of these communities. A seemingly slow paced, within-geological period turnover took place across the Early–Middle Jurassic transition. This turnover saw the demise of early neoichthyosaurians, rhomaleosaurid plesiosaurians and early plesiosauroids in favour of ophthalmosaurid ichthyosaurians and cryptoclidid and pliosaurid plesiosaurians, clades that will dominate the Late Jurassic and, for two of them, the entire Early Cretaceous as well. The fossil record of this turnover is however extremely poor and this change of dominance appears to be spread across the entire middle Toarcian–Bathonian interval. We describe a series of ichthyosaurian and plesiosaurian specimens from successive geological formations in Luxembourg and Belgium that detail the evolution of marine reptile assemblages across the Early–Middle Jurassic transition within a single area, the Belgo–Luxembourgian sub-basin. These fossils reveal the continuing dominance of large rhomaleosaurid plesiosaurians, microcleidid plesiosaurians and Temnodontosaurus-like ichthyosaurians up to the latest Toarcian, indicating that the structuration of the upper tier of Western Europe marine ecosystems remained essentially constant up to the very end of the Early Jurassic. These fossils also suddenly record ophthalmosaurid ichthyosaurians and cryptoclidid plesiosaurians by the early Bajocian. These results from a geographically-restricted area provide a clearer picture of the shape of the marine reptile turnover occurring at the early–Middle Jurassic transition. This event appears restricted to the sole Aalenian stage, reducing the uncertainty of its duration, at least for ichthyosaurians and plesiosaurians, to 4 instead of 14 million years.

scholarly journals Improvements in the fossil record may largely resolve the conflict between morphological and molecular estimates of mammal phylogeny

2018 ◽  
Author(s):  
Robin M. D. Beck ◽  
Charles Baillie
Keyword(s):  
Maximum Likelihood ◽  
Molecular Phylogeny ◽  
Fossil Record ◽  
Morphological Character ◽  
Molecular Data ◽  
Morphological Data ◽  
Ancestral State ◽  
Case Scenario ◽  
State Reconstruction ◽  
Consensus View

AbstractMorphological phylogenies of mammals continue to show major conflicts with the robust molecular consensus view of their relationships. This raises doubts as to whether current morphological character sets are able to accurately resolve mammal relationships, particularly for fossil taxa for which, in most cases, molecular data is unlikely to ever become available. We tested this under a hypothetical “best case scenario” by using ancestral state reconstruction (under both maximum parsimony and maximum likelihood) to infer the morphologies of fossil ancestors for all clades present in a recent comprehensive molecular phylogeny of mammals, and then seeing what effect inclusion of these predicted ancestors had on unconstrained analyses of morphological data. We found that this resulted in topologies that are highly congruent with the molecular consensus, even when simulating the effect of incomplete fossilisation. Most strikingly, several analyses recovered monophyly of clades that have never been found in previous morphology-only studies, such as Afrotheria and Laurasiatheria. Our results suggest that, at least in principle, improvements in the fossil record may be sufficient to largely reconcile morphological and molecular phylogenies of mammals, even with current morphological character sets.

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