scholarly journals New material of the ‘microsaur’ Llistrofus from the cave deposits of Richards Spur, Oklahoma and the paleoecology of the Hapsidopareiidae

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6327 ◽  
Author(s):  
Bryan M. Gee ◽  
Joseph J. Bevitt ◽  
Ulf Garbe ◽  
Robert R. Reisz
Keyword(s):  
Evolutionary History ◽  
Substantial Reduction ◽  
Sister Group ◽  
Phylogenetic Position ◽  
Neutron Tomography ◽  
Early Permian ◽  
Cave Deposits ◽  
Internal Structures ◽  
History Of ◽  
New Material

The Hapsidopareiidae is a group of “microsaurs” characterized by a substantial reduction of several elements in the cheek region that results in a prominent, enlarged temporal emargination. The clade comprises two markedly similar taxa from the early Permian of Oklahoma, Hapsidopareion lepton and Llistrofus pricei, which have been suggested to be synonymous by past workers. Llistrofus was previously known solely from the holotype found near Richards Spur, which consists of a dorsoventrally compressed skull in which the internal structures are difficult to characterize. Here, we present data from two new specimens of Llistrofus. This includes data collected through the use of neutron tomography, which revealed important new details of the palate and the neurocranium. Important questions within “Microsauria” related to the evolutionary transformations that likely occurred as part of the acquisition of the highly modified recumbirostran morphology for a fossorial ecology justify detailed reexamination of less well-studied taxa, such as Llistrofus. Although this study eliminates all but one of the previous features that differentiated Llistrofus and Hapsidopareion, the new data and redescription identify new features that justify the maintained separation of the two hapsidopareiids. Llistrofus possesses some of the adaptations for a fossorial lifestyle that have been identified in recumbirostrans but with a lesser degree of modification (e.g., reduced neurocranial ossification and mandibular modification). Incorporating the new data for Llistrofus into an existing phylogenetic matrix maintains the Hapsidopareiidae’s (Llistrofus + Hapsidopareion) position as the sister group to Recumbirostra. Given its phylogenetic position, we contextualize Llistrofus within the broader “microsaur” framework. Specifically, we propose that Llistrofus may have been fossorial but was probably incapable of active burrowing in the fashion of recumbirostrans, which had more consolidated and reinforced skulls. Llistrofus may represent an earlier stage in the step-wise acquisition of the derived recumbirostran morphology and paleoecology, furthering our understanding of the evolutionary history of “microsaurs.”

The amphibamiform Nanobamus macrorhinus from the early Permian of Texas

2019 ◽  
Vol 94 (2) ◽  
pp. 366-377 ◽  
Author(s):  
Bryan M. Gee ◽  
Robert R. Reisz
Keyword(s):  
Phylogenetic Analysis ◽  
Evolutionary History ◽  
Phylogenetic Position ◽  
Early Permian ◽  
Larval Form ◽  
Terrestrial Environments ◽  
History Of ◽  
Insight Into

AbstractNanobamus macrorhinus Schoch and Milner, 2014 is a small amphibamiform temnospondyl from the early Permian Arroyo Formation of Texas. It is most readily characterized by an elongate and partially subdivided naris. This condition is superficially reminiscent of that seen in the coeval trematopids, the group to which N. macrorhinus was originally referred to under an interpretation of the holotype as a larval form. This was discounted by later workers, but the amphibamiform affinities of the specimen were not formalized until recently. The specimen has never been described in the context of its amphibamiform affinities and remains poorly characterized, never having been sampled in a phylogenetic analysis. Here we present a complete, updated osteological description of N. macrorhinus, including an improved characterization of its unique mosaic of plesiomorphic and apomorphic features and clarification of the taxon's autapomorphies. Our analysis of the taxon's phylogenetic position within Amphibamiformes shows that N. macrorhinus was recovered as diverging after basal amphibamiforms, e.g., the micropholids, and before derived amphibamiforms, e.g., the amphibamids. This is supported by the unique mixture of retained plesiomorphies, e.g., nonforeshortened postparietals and an oval choana, and apomorphies, e.g., a narrow interorbital region and slender palatal rami of the pterygoid. These results reflect the complexity of terrestrial amphibamiform diversity and provide further insight into the evolutionary history of the lissamphibian stem in terrestrial environments.

scholarly journals The palate and choanae structure of the cf. Susisuchus (Crocodyliformes, Eusuchia): phylogenetic implications

2018 ◽  
Author(s):  
Karla J Leite ◽  
Daniel C Fortier
Keyword(s):  
Lower Cretaceous ◽  
Evolutionary History ◽  
Ventral View ◽  
Sister Group ◽  
Phylogenetic Position ◽  
Phylogenetic Implications ◽  
History Of

Crocodyliformes have undergone few modifications in their morphology since they have emerged. The change in the position of the choana was important during the evolutionary history of this group. Such character is relevant in the phylogenetic position of many crocodyliforms. The Susisuchidae clade has been placed in different phylogenetic positions: as a sister group of Eusuchia, advanced Neosuchia and in Eusuchia. In Isisfordia there are reports that the choana of this taxon is or not fully enclosed by pterygoid. A new skull of cf. Susisuchus from the Crato Formation of the Santana Group (Lower Cretaceous) is described and we recover Susisuchidae in a new phylogenetic position within Eusuchia. The preservation in the ventral view of FPH-243-V allows character encoding not yet observed for the species. The new specimen shows a typical eusuchian palate for Susisuchus, in which the choana is fully enclosed by the pterygoid. The encoding of the ventral characters of Susisuchus places Susisuchidae in Eusuchia. However, this position must be further studied, since the matrices showed fragility in the reconstitution of the Neosuchia-Eusuchia transition.

scholarly journals Detailed anatomy of the braincase ofMacelognathus vagansMarsh, 1884 (Archosauria, Crocodylomorpha) using high resolution tomography and new insights on basal crocodylomorph phylogeny

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e2801 ◽  
Author(s):  
Juan Martin Leardi ◽  
Diego Pol ◽  
James Matthew Clark
Keyword(s):  
Late Jurassic ◽  
Sister Group ◽  
Phylogenetic Position ◽  
Micro Ct ◽  
Internal Structures ◽  
Postcranial Remains ◽  
New Material ◽  
Anatomical Information ◽  
Early Late ◽  
Ct Studies

BackgroundMacelognathus vagansMarsh, 1884 from the Late Jurassic Morrison Fm. of Wyoming was originally described as a dinosaur by Marsh and in 1971 Ostrom suggested crocodilian affinities. In 2005, Göhlich and collaborators identified new material of this species from Colorado as a basal crocodylomorph. However, a partial skull found in association with mandibular and postcranial remains was not described.MethodsDue to the small size and delicate structures within the braincase, micro CT studies were performed on this specimen. The new anatomical information was incorporated in a phylogenetic dataset, expanding both character and taxon sampling.ResultsThis new material reinforces the non-crocodyliform crocodylomorph affinities ofMacelognathusas it bears a large otic aperture, unfused frontals and lacks ornamentation on the dorsal cranial bones. The internal structures also support these affinities as this specimen bears traits (i.e., heavily pneumatized and expanded basisphenoid; the presence of additional pneumatic features on the braincase; and the otoccipital-quadrate contact) not present in most basal crocodylomorphs. Furthermore, the presence of a wide supraoccipital and a cranioquadrate passage are traits shared withAlmadasuchusfrom the early Late Jurassic of Argentina.Macelognathuswas recovered as one of the closest relatives of crocodyliforms, forming a clade (Hallopodidae) with two other Late Jurassic taxa (AlmadasuchusandHallopus).DiscussionThe clade formed byAlmadasuchus+Hallopus+Macelognathus, the Hallopodidae, is characterized by a higher degree of suturing of the braincase, posteriorly closed otic aperture (paralleled in mesoeucrocodylians) and cursorial adaptations. Also, the phylogenetic position of this lineage of derived crocodylomorphs as the sister group of Crocodyliformes implies a large amount of unsampled record (ghost lineage), at least 50 million years.

scholarly journals The palate and choanae structure of theSusisuchusanatoceps(Crocodyliformes, Eusuchia): phylogenetic implications

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5372 ◽  
Author(s):  
Karla J. Leite ◽  
Daniel C. Fortier
Keyword(s):  
Lower Cretaceous ◽  
Fossil Record ◽  
Evolutionary History ◽  
Morphological Changes ◽  
Ventral View ◽  
Structural Evolution ◽  
Sister Group ◽  
Phylogenetic Position ◽  
Phylogenetic Implications ◽  
History Of

Crocodyliformes is a group with a broad fossil record, in which several morphological changes have been documented. Among known transformations the most iconic is perhaps the series of changes seen in the structural evolution of the choanae. The change in the position of the choanae was important during the evolutionary history of the Crocodyliformes. This structure is relevant in the phylogenetic position of many crocodyliforms. The new skull ofSusisuchus anatocepsfrom the Crato Formation of the Santana Group (Lower Cretaceous) is described and the preservation in the ventral view allows character encoding not yet observed for the species. The new specimen shows a typical eusuchian palate forSusisuchus anatoceps, in which the choana is fully enclosed by the pterygoid. The Susisuchidae clade has been placed in different phylogenetic positions: as a sister group of Eusuchia, advanced Neosuchia and in Eusuchia. InIsisfordiathere are reports that the choana of this taxon is or is not fully enclosed by the pterygoid. The encoding of the ventral characters ofS.anatocepsplaces Susisuchidae in Eusuchia. However, this position must be further studied, since the matrices showed fragility in the reconstitution of the Neosuchia–Eusuchia transition.

scholarly journals The palate and choanae structure of the cf. Susisuchus (Crocodyliformes, Eusuchia): phylogenetic implications

2018 ◽  
Author(s):  
Karla J Leite ◽  
Daniel C Fortier
Keyword(s):  
Lower Cretaceous ◽  
Evolutionary History ◽  
Ventral View ◽  
Sister Group ◽  
Phylogenetic Position ◽  
Phylogenetic Implications ◽  
History Of

Crocodyliformes have undergone few modifications in their morphology since they have emerged. The change in the position of the choana was important during the evolutionary history of this group. Such character is relevant in the phylogenetic position of many crocodyliforms. The Susisuchidae clade has been placed in different phylogenetic positions: as a sister group of Eusuchia, advanced Neosuchia and in Eusuchia. In Isisfordia there are reports that the choana of this taxon is or not fully enclosed by pterygoid. A new skull of cf. Susisuchus from the Crato Formation of the Santana Group (Lower Cretaceous) is described and we recover Susisuchidae in a new phylogenetic position within Eusuchia. The preservation in the ventral view of FPH-243-V allows character encoding not yet observed for the species. The new specimen shows a typical eusuchian palate for Susisuchus, in which the choana is fully enclosed by the pterygoid. The encoding of the ventral characters of Susisuchus places Susisuchidae in Eusuchia. However, this position must be further studied, since the matrices showed fragility in the reconstitution of the Neosuchia-Eusuchia transition.

scholarly journals Nephromyces represents a diverse and novel lineage of the Apicomplexa that has retained apicoplasts

2019 ◽  
Author(s):  
Sergio A Muñoz-Gómez ◽  
Keira Durnin ◽  
Laura Eme ◽  
Christopher Paight ◽  
Christopher E Lane ◽  
...  
Keyword(s):  
Life Style ◽  
Metabolic Pathways ◽  
Evolutionary History ◽  
Phylogenetic Analyses ◽  
Phylogenetic Position ◽  
Biosynthetic Pathways ◽  
History Of ◽  
Sea Squirts ◽  
Shed Light ◽  
Apicoplast Genome

Abstract A most interesting exception within the parasitic Apicomplexa is Nephromyces, an extracellular, probably mutualistic, endosymbiont found living inside molgulid ascidian tunicates (i.e., sea squirts). Even though Nephromyces is now known to be an apicomplexan, many other questions about its nature remain unanswered. To gain further insights into the biology and evolutionary history of this unusual apicomplexan, we aimed to (1) find the precise phylogenetic position of Nephromyces within the Apicomplexa, (2) search for the apicoplast genome of Nephromyces, and (3) infer the major metabolic pathways in the apicoplast of Nephromyces. To do this, we sequenced a metagenome and a metatranscriptome from the molgulid renal sac, the specialized habitat where Nephromyces thrives. Our phylogenetic analyses of conserved nucleus-encoded genes robustly suggest that Nephromyces is a novel lineage sister to the Hematozoa, which comprises both the Haemosporidia (e.g., Plasmodium) and the Piroplasmida (e.g., Babesia and Theileria). Furthermore, a survey of the renal sac metagenome revealed 13 small contigs that closely resemble the genomes of the non-photosynthetic reduced plastids, or apicoplasts, of other apicomplexans. We show that these apicoplast genomes correspond to a diverse set of most closely related but genetically divergent Nephromyces lineages that co-inhabit a single tunicate host. In addition, the apicoplast of Nephromyces appears to have retained all biosynthetic pathways inferred to have been ancestral to parasitic apicomplexans. Our results shed light on the evolutionary history of the only probably mutualistic apicomplexan known, Nephromyces, and provide context for a better understanding of its life style and intricate symbiosis.

Phylogenetic position and evolutionary history of the turtle and whale barnacles (Cirripedia: Balanomorpha: Coronuloidea)

2013 ◽  
Vol 67 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Ryota Hayashi ◽  
Benny K.K. Chan ◽  
Noa Simon-Blecher ◽  
Hiromi Watanabe ◽  
Tamar Guy-Haim ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Phylogenetic Position ◽  
History Of

scholarly journals Three new Cenomanian conifers from El Chango (Chiapas, Mexico) offer a snapshot of the geographic mosaic of the Mesozoic conifer decline

2021 ◽  
Author(s):  
Ixchel Gonzalez-Ramirez ◽  
Sergio RS Cevallos-Ferriz ◽  
Carl Rothfels
Keyword(s):  
Evolutionary History ◽  
Mixed Forest ◽  
Freshwater Ecosystems ◽  
Total Evidence ◽  
Morphological Data ◽  
Phylogenetic Position ◽  
Dominant Group ◽  
Geographic Mosaic ◽  
History Of ◽  
Rare Opportunity

Premise of study: El Chango is a recently discovered quarry that contains extremely well preserved fossils. The Cenomanian age of the locality corresponds to a time when the global flora was transitioning from gymnosperm- to angiosperm-dominated, yet conifers predominate in this locality. These fossils thus provide a rare opportunity to understand the replacement of conifers by angiosperms as the dominant group of plants. Methods: We collected material from El Chango in annual expeditions (2010 to 2014). We selected the three most abundant and best preserved conifer morphotypes and conducted a total-evidence (i.e., including molecular and morphological data) phylogenetic analysis of a sample of 72 extant conifer species plus the three fossils. We use these results to inform our taxonomic decisions. Results: We obtained four equally most-parsimonious trees (consistency index = 44.1%, retention index = 78.8%). Despite ambiguous relationships among some extant taxa, the three fossil conifers had the same phylogenetic position in all four most parsimonious trees; we describe these species as new: Sequoiadendron helicalancifolium sp. nov. (Cupressaceae), and Microcachrys rhomboidea sp. nov. and Dacrydium bifoliosus sp. nov (Podocarpaceae). The ecosystem is interpreted as a coastal humid mixed forest. Conclusions: Our findings contribute to the understanding of Cenomanian equatorialregions, and support the hypothesis of a geographically and ecologically structured rise of angiosperms, with conifers remaining dominant in brackish-water and angiosperms becoming dominant in freshwater-ecosystems. These fossils fill in gaps in the evolutionary history of lineages like Microcachrys, which we demonstrate occurred in the Northern hemisphere before becoming restricted to its current range (Tasmania).

Wood anatomy of the Mascarene Dombeyoideae: Systematic and ecological implications

IAWA Journal ◽  
2011 ◽  
Vol 32 (4) ◽  
pp. 493-519 ◽  
Author(s):  
Anaïs Boura ◽  
Timothée Le Péchon ◽  
Romain Thomas
Keyword(s):  
Evolutionary History ◽  
Wood Anatomy ◽  
Sister Group ◽  
Biological Data ◽  
Sister Group Relationship ◽  
Anatomical Features ◽  
Ecological Implications ◽  
History Of ◽  
Mascarene Islands ◽  
Almost All

The Dombeyoideae (Malvaceae) are one of the most diversified groups of plants in the Mascarene Islands. Species of Dombeya Cav., Ruizia Cav. and Trochetia DC. are distributed in almost all parts of the archipelago and show a wide diversity in their growth forms. This study provides the first wood anatomical descriptions of 17 out of the 22 Mascarene species of Dombeyoideae. Their wood anatomy is similar to that of previously described species: wide vessels, presence of both apotracheal and paratracheal parenchyma, and storied structure. In addition, we also found a second wood anatomical pattern with narrower vessels, high vessel frequency and thick-walled fibres. The two aforementioned wood patterns are considered in a phylogenetic context and used to trace the evolutionary history of several wood anatomical features. For example, the pseudoscalariform pit arrangement supports a sister group relationship between Trochetia granulata Cordem. and T. blackburniana Bojer ex Baker and may be a new synapomorphy of the genus Trochetia. Finally, wood variability is evaluated in relation to geographic, climatic and biological data. Despite the juvenile nature of some of the specimens studied, we discuss how the habit, but also factors related to humidity, influence the variability observed in the Mascarene Dombeyoideae wood structure.

scholarly journals Origin of raptorial feeding in juvenile euarthropods revealed by a Cambrian radiodontan

2018 ◽  
Vol 5 (6) ◽  
pp. 863-869 ◽  
Author(s):  
Jianni Liu ◽  
Rudy Lerosey-Aubril ◽  
Michael Steiner ◽  
Jason A Dunlop ◽  
Degan Shu ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Feeding Habits ◽  
Phylogenetic Position ◽  
Early Developmental Stage ◽  
Rapid Rise ◽  
Juvenile Instar ◽  
History Of ◽  
Dietary Ecology ◽  
Chengjiang Biota ◽  
Early Developmental

Abstract The rapid rise of arthropods during the Cambrian quickly established some clades, such as the euarthropod stem-group called Radiodonta, as the dominant and most diverse predators in marine ecosystems. Recent discoveries have shown that the size and dietary ecology of radiodontans are far more diverse than previously thought, but little is known about the feeding habits of juveniles. Here, we document a very small (∼18-mm-long), near-complete specimen of the radiodontan Lyrarapax unguispinus from the early Cambrian Chengjiang Biota of China. This specimen is the smallest radiodontan individual known, representing a juvenile instar. Its adult-like morphology—especially the fully developed spinose frontal appendages and tetraradial oral cone—indicates that L. unguispinus was a well-equipped predator at an early developmental stage, similar to modern raptorial euarthropods, such as mantises, mantis shrimps and arachnids. This evidence, coupled with the basal phylogenetic position of radiodontans, confirms that raptorial feeding habits in juvenile euarthropods appeared early in the evolutionary history of the group.

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