scholarly journals A new Late Eocene primate from the Krabi Basin (Thailand) and the diversity of Palaeogene anthropoids in southeast Asia

2013 ◽  
Vol 280 (1771) ◽  
pp. 20132268 ◽  
Author(s):  
Yaowalak Chaimanee ◽  
Olivier Chavasseau ◽  
Vincent Lazzari ◽  
Adélaïde Euriat ◽  
Jean-Jacques Jaeger
Keyword(s):  
Phylogenetic Relationships ◽  
Evolutionary History ◽  
Middle Eocene ◽  
Late Eocene ◽  
The Other ◽  
Crown Group ◽  
Phylogenetic Relations ◽  
Stem Group ◽  
Morphological Adaptations ◽  
Anthropoid Primates

According to the most recent discoveries from the Middle Eocene of Myanmar and China, anthropoid primates originated in Asia rather than in Africa, as was previously considered. But the Asian Palaeogene anthropoid community remains poorly known and inadequately sampled, being represented only from China, Myanmar, Pakistan and Thailand. Asian Eocene anthropoids can be divided into two distinct groups, the stem group eosimiiforms and the possible crown group amphipithecids, but the phylogenetic relationships between these two groups are not well understood. Therefore, it is critical to understand their evolutionary history and relationships by finding additional fossil taxa. Here, we describe a new small-sized fossil anthropoid primate from the Late Eocene Krabi locality in Thailand, Krabia minuta , which shares several derived characters with the amphipithecids. It displays several unique dental characters, such as extreme bunodonty and reduced trigon surface area, that have never been observed in other Eocene Asian anthropoids. These features indicate that morphological adaptations were more diversified among amphipithecids than was previously expected, and raises the problem of the phylogenetic relations between the crown anthropoids and their stem group eosimiiforms, on one side, and the modern anthropoids, on the other side.

scholarly journals Influence of mass on tarsus shape variation: a morphometrical investigation among Rhinocerotidae (Mammalia: Perissodactyla)

2020 ◽  
Vol 129 (4) ◽  
pp. 950-974 ◽  
Author(s):  
Cyril Etienne ◽  
Christophe Mallet ◽  
Raphaël Cornette ◽  
Alexandra Houssaye
Keyword(s):  
Body Weight ◽  
Body Mass ◽  
Evolutionary History ◽  
The Body ◽  
The Other ◽  
Upright Posture ◽  
Centroid Size ◽  
Shape Variation ◽  
Morphological Adaptations ◽  
Both Bones

Abstract Many tetrapod lineages show extreme increases in body mass in their evolutionary history, associated with important osteological changes. The ankle joint, essential for foot movement, is assumed to be particularly affected in this regard. We investigated the morphological adaptations of the astragalus and the calcaneus in Rhinocerotidae, and analysed them in light of a comparative analysis with other Perissodactyla. We performed 3D geometric morphometrics and correlated shape with centroid size of the bone and body mass of the species. Our results show that mass has an influence on bone shape in Rhinocerotidae and in Perissodactyla, but this is not as strong as expected. In heavy animals the astragalus has a flatter trochlea, orientated more proximally, associated with a more upright posture of the limb. The calcaneus is more robust, possibly to sustain the greater tension force exerted by the muscles during plantarflexion. Both bones show wider articular facets, providing greater cohesion and better dissipation of the loading forces. The body plan of the animals also has an influence. Short-legged Teleoceratina have a flatter astragalus than the other rhinocerotids. Paraceratherium has a thinner calcaneus than expected. This study clarifies adaptations to high body weight among Rhinocerotidae and calls for similar investigations in other groups with massive forms.

Crocodilian diversity in space and time: the role of climate in paleoecology and its implication for understanding K/T extinctions

Paleobiology ◽  
1998 ◽  
Vol 24 (4) ◽  
pp. 470-497 ◽  
Author(s):  
Paul J. Markwick
Keyword(s):  
Northern Hemisphere ◽  
Middle Eocene ◽  
Temporal Trends ◽  
Late Eocene ◽  
High Rate ◽  
Mass Extinctions ◽  
Crown Group ◽  
Climatic Effects ◽  
General Decline

The taxonomic diversity of crocodilians (Crocodylia) through the last 100 million years shows a general decline in the number of genera and species to the present day. But this masks a more complex pattern. This is investigated here using a comprehensive database of fossil crocodilians that provides the opportunity to examine spatial and temporal trends, the influence of sampling, and the role of climate in regulating biodiversity.Crown-group crocodilians, comprising the extant families Alligatoridae, Crocodylidae, and Gavialidae, show the following trend: an initial exponential diversification through the Late Cretaceous and Paleocene that is restricted to the Northern Hemisphere until after the K/T boundary; relatively constant diversity from the Paleocene into the middle Eocene that may be an artifact of sampling, which might mask an actual decline in numbers; low diversity during the late Eocene and Oligocene; a second exponential diversification during the Miocene and leveling off in the late Miocene and Pliocene; and a precipitous drop in the Pleistocene and Recent. The coincidence of drops in diversity with global cooling is suggestive of a causal link—during the initial glaciation of Antarctica in the Eocene and Oligocene and the Northern Hemisphere glaciation at the end of the Pliocene. However, matters are complicated in the Northern Hemisphere by the climatic effects of regional uplift.Although the global trend of diversification is unperturbed at the K/T boundary, this is largely due to the exceptionally high rate of origination in the early Paleocene. Nonetheless, the survival of such a demonstrably climate-sensitive group strongly suggests that a climatic explanation for the K/T mass extinctions, especially the demise of the dinosaurs, must be reconsidered.

scholarly journals An early fossil remora (Echeneoidea) reveals the evolutionary assembly of the adhesion disc

2013 ◽  
Vol 280 (1766) ◽  
pp. 20131200 ◽  
Author(s):  
Matt Friedman ◽  
Zerina Johanson ◽  
Richard C. Harrington ◽  
Thomas J. Near ◽  
Mark R. Graham
Keyword(s):  
Evolutionary History ◽  
Body Plan ◽  
The Other ◽  
Ontogenetic Changes ◽  
Dorsal Fin ◽  
Early Oligocene ◽  
Stem Group ◽  
History Of ◽  
And Migration ◽  
Fin Spines

The adhesion disc of living remoras (Echeneoidea: Echeneidae) represents one of the most remarkable structural innovations within fishes. Although homology between the spinous dorsal fin of generalized acanthomorph fishes and the remora adhesion disc is widely accepted, the sequence of evolutionary—rather than developmental—transformations leading from one to the other has remained unclear. Here, we show that the early remora † Opisthomyzon (Echeneoidea: †Opisthomyzonidae), from the early Oligocene (Rupelian) of Switzerland, is a stem-group echeneid and provides unique insights into the evolutionary assembly of the unusual body plan characteristic of all living remoras. The adhesion disc of † Opisthomyzon retains ancestral features found in the spiny dorsal fins of remora outgroups, and corroborates developmental interpretations of the homology of individual skeletal components of the disc. † Opisthomyzon indicates that the adhesion disc originated in a postcranial position, and that other specializations (including the origin of pectination, subdivision of median fin spines into paired lamellae, increase in segment count and migration to a supracranial position) took place later in the evolutionary history of remoras. This phylogenetic sequence of transformation finds some parallels in the order of ontogenetic changes to the disc documented for living remoras.

scholarly journals Sakhalinencyrtus leleji Simutnik gen. et sp. nov. of earliest Encyrtidae (Hymenoptera, Chalcidoidea) from Sakhalinian amber

2021 ◽  
Vol 84 ◽  
pp. 361-372
Author(s):  
Serguei A. Simutnik ◽  
Evgeny E. Perkovsky ◽  
Dmitry V. Vasilenko
Keyword(s):  
New Genus ◽  
Middle Eocene ◽  
Late Eocene ◽  
Apical Position ◽  
Male Specimen ◽  
Stem Group ◽  
Filum Spinosum ◽  
The Family

Another earliest representative of the family Encyrtidae, Sakhalinencyrtus leleji Simutnik gen. et sp. nov., is described and illustrated based on a male specimen from the middle Eocene Sakhalinian amber. Similarly to other Encyrtidae from Sakhalinian amber, the new fossil fundamentally differs from encyrtids from late Eocene European ambers as well as from modern ones. Moreover, it probably belongs to a stem group of the family. The new genus is characterized by extremely apical position of cerci, long veins of the forewing with expanded parastigma, stigmal vein with long uncus, and absence of filum spinosum. The forewing venation of the new genus is very similar to that of Sugonjaevia Simutnik, 2015, but these genera differ by the structure of Mt8, hypopygium, genitalia, and clava.

Taxonomic and systematic implications of the revision of the phylogenetic relations in the genus Ectinogonia Spinola 1837 (Coleoptera: Buprestidae) of Central Chile

Zootaxa ◽  
2019 ◽  
Vol 4603 (1) ◽  
pp. 159
Author(s):  
SIMÓN ANGUITA-SALINAS ◽  
RODRIGO M. BARAHONA-SEGOVIA ◽  
ELIE POULIN ◽  
ÁLVARO ZÚÑIGA-REINOSO
Keyword(s):  
Phylogenetic Relationships ◽  
Morphological Variability ◽  
Haplotype Network ◽  
Species Level ◽  
The Other ◽  
Nominal Species ◽  
Central Chile ◽  
Phylogenetic Relations ◽  
Taxonomic History ◽  
Traditional Taxonomy

Ectinogonia Spinola 1837 is composed of 22 species to date, but its taxonomic history has been complex and is still unresolved. The species of the Santiagan Province of Central Chile are particularly complex because they show important morphological variability and overlapping traits, making species identification and delimitation difficult. The main goal of the present study is to show the phylogenetic relationships among species of Ectinogonia of the Santiagan province and discuss the taxonomic and systematic implications of our findings. Phylogeny reconstructions as well as a haplotype network disclosed four groups, partially inconsistent with the traditional taxonomy. Actually, the two Ectinogonia speciosa subspecies (E. speciosa speciosa (Germain 1856) and E. speciosa oscuripennis Cobos 1954) belong to two distinct clades, which are not reciprocally monophyletic, meaning that Ectinogonia speciosa is polyphyletic. On the other hand, the two other clades each contain, two nominal species (E. buquetii (Spinola 1837) and E. vidali Moore & Guerrero 2017, and E. isamarae Moore 1994 and E. speciosa oscuripennis Cobos 1954) without reciprocal haplotype sorting. These results suggest that: (1) E. speciosa oscuripennis should be raised to species level and (2) the following new synonymies are proposed: E. isamarae Moore 1994 is synonymised with E. oscuripennis Cobos 1954 and E. vidali Moore & Guerrero 2017 is synonymised with E. buquetii (Spinola 1837).

scholarly journals A Mesozoic clown beetle myrmecophile (Coleoptera: Histeridae)

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Yu-Lingzi Zhou ◽  
Adam Ślipiński ◽  
Dong Ren ◽  
Joseph Parker
Keyword(s):  
Evolutionary History ◽  
Host Switching ◽  
Crown Group ◽  
Deep Time ◽  
Ant Colonies ◽  
Burmese Amber ◽  
Major Clade ◽  
Behavioral Adaptations ◽  
Stem Group ◽  
History Of

Complex interspecies relationships are widespread among metazoans, but the evolutionary history of these lifestyles is poorly understood. We describe a fossil beetle in 99-million-year-old Burmese amber that we infer to have been a social impostor of the earliest-known ant colonies. Promyrmister kistneri gen. et sp. nov. belongs to the haeteriine clown beetles (Coleoptera: Histeridae), a major clade of ‘myrmecophiles’—specialized nest intruders with dramatic anatomical, chemical and behavioral adaptations for colony infiltration. Promyrmister reveals that myrmecophiles evolved close to the emergence of ant eusociality, in colonies of stem-group ants that predominate Burmese amber, or with cryptic crown-group ants that remain largely unknown at this time. The clown beetle-ant relationship has been maintained ever since by the beetles host-switching to numerous modern ant genera, ultimately diversifying into one of the largest radiations of symbiotic animals. We infer that obligate behavioral symbioses can evolve relatively rapidly, and be sustained over deep time.

scholarly journals Sedimentary Basin Reconstruction and Tectonic Development of Paleocene-Eocene Succession, Southern Iraq, by Geohistory Analysis

2021 ◽  
pp. 1213-1225
Author(s):  
Mahdi Ali Menshed ◽  
Aiad Ali Hussien Al-Zaidy
Keyword(s):  
Middle Eocene ◽  
Late Eocene ◽  
Oil Field ◽  
Transitional Period ◽  
The Other ◽  
Arabian Plate ◽  
The West ◽  
Tectonic Lineament ◽  
Western Side ◽  
Tectonic Boundary

The Paleocene-Early Eocene sequence is represented by Aliji and Umm Er Radhuma formations, while the Middle-Late Eocene sequence is represented by Jaddala and Dammam formations. The Rus Formation has been described and its basin was analyzed separately because it was deposited during the regression period (Middle Eocene), which is a transitional period between these two cycles.   This study includes analysis of the geohistory of this succession,  interpretation of the changes of the accumulation, and calculation of subsidence rates. The results were compared with the space available to explain the basin development. The study site included the boreholes of Garraf-84 and 92, Halfaya-1, Nasirya-13 and 40, and Noor-5 at the Mesopotamian Block, in addition to the  Ratawi-8, Tuba-15, Rumaila-217, Zubair-45, and West Qurna-60 at the Basra Block.      The Aliji basin was characterized by the decrease in accommodation values to the northeast direction and the increase in all the other parts of the study area. A comparison of the setting of this basin with the Umm Er Radhuma basin gives a clear evidence of the tectonic impact coming from the northeast. During the Middle Eocene stage, we notice that the basin was affected by comprehensive uplifting processes. This led to the generation of a very shallow basin (Rus basin) with the exposure of the northern part of the basin during the regression stage.      The Middle-Late Eocene basin is represented by a transgression stage with high subsidence, where the sea level had been raised and covered the northeastern and eastern parts of the studied area by deep sea deposits (Jaddala Formation). While the other parts of the study area were characterized by shallow sediments of Dammam Formation. This period ended with a clear tectonic uplift occurring in the northeastern parts and decreasing towards the southwest. This confirms the reactivation of the tectonic action from the northeast, represented by the continental collision. All these sources of evidence indicate that the study area is divided into a northern part and a southern part. Both of these parts are separated by a major tectonic lineament extending from the West Qurna oil field to the Nasiriya oil field, which confirms the presence of the tectonic boundary between the Mesopotamian block and the Basra block. In addition, there exists a secondary tectonic boundary that divides the Mesopotamian block into two parts, the first is to the east and the other is to the west. The results showed that the eastern side was most affected by the collision of the Iranian Plate with the Arabian Plate, which led to its uplift, while the western side was less affected by this tectonics evidence.

scholarly journals Common origin of ornithine–urea cycle in opisthokonts and stramenopiles

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Aleš Horák ◽  
Andrew E. Allen ◽  
Miroslav Oborník
Keyword(s):  
Gene Transfer ◽  
Phylogenetic Relationships ◽  
Evolutionary History ◽  
Urea Cycle ◽  
Common Origin ◽  
The Other ◽  
Urea Synthesis ◽  
Genes Encoding ◽  
Different Origins ◽  
The Impact

Abstract Eukaryotic complex phototrophs exhibit a colorful evolutionary history. At least three independent endosymbiotic events accompanied by the gene transfer from the endosymbiont to host assembled a complex genomic mosaic. Resulting patchwork may give rise to unique metabolic capabilities; on the other hand, it can also blur the reconstruction of phylogenetic relationships. The ornithine–urea cycle (OUC) belongs to the cornerstone of the metabolism of metazoans and, as found recently, also photosynthetic stramenopiles. We have analyzed the distribution and phylogenetic positions of genes encoding enzymes of the urea synthesis pathway in eukaryotes. We show here that metazoan and stramenopile OUC enzymes share common origins and that enzymes of the OUC found in primary algae (including plants) display different origins. The impact of this fact on the evolution of stramenopiles is discussed here.

Extinct crane-like birds (Eogruidae and Ergilornithidae) from the Cenozoic of Central Asia are indeed ostrich precursors

The Auk ◽  
2021 ◽  
Author(s):  
Gerald Mayr ◽  
Nikita Zelenkov
Keyword(s):  
Central Asia ◽  
Cervical Vertebrae ◽  
Late Eocene ◽  
Progressive Reduction ◽  
Crown Group ◽  
Stem Group ◽  
Characteristic Features ◽  
New Perspective ◽  
Second Toe

Abstract We describe new fossils from the late Eocene of Mongolia, which show that the crane-like Eogruidae and Ergilornithidae are stem group representatives of the Struthioniformes (ostriches). Currently, both taxa are unanimously assigned to the neognathous Gruiformes (cranes and allies). However, ergilornithids show a progressive reduction of the second toe, and a few earlier authors likened these birds to ostriches, which are the only extant birds with just 2 toes. So far, eogruids and ergilornithids were mainly known from hindlimb bones from the Cenozoic of Asia, and here we provide important new data on the skeletal anatomy of these birds. A partial skull exhibits characteristic features of palaeognathous birds, and ostriches in particular. In its distinctive shape, it furthermore closely resembles the skull of the Eocene palaeognathous Palaeotididae, which are here also considered to be stem group representatives of the Struthioniformes. A femur from the late Eocene of Mongolia likewise corresponds to that of ostriches in derived traits, whereas cervical vertebrae exhibit features of neognathous birds. The fossils suggest that true ostriches (crown group Struthionidae) originated in Asia, and the Neognathae-like morphology of some bones opens a new perspective on the evolution of skeletal characteristics of palaeognathous birds.

scholarly journals Description of a new genus of primitive ants from Canadian amber, with the study of relationships between stem- and crown-group ants (Hymenoptera: Formicidae)

2016 ◽  
Author(s):  
Leonid H. Borysenko
Keyword(s):  
Statistical Analysis ◽  
Morphometric Analysis ◽  
New Genus ◽  
Statistical Study ◽  
The Other ◽  
Taxonomic Position ◽  
Crown Group ◽  
Stem Group ◽  
Evolution Of Eusociality

AbstractA detailed study of the holotype ofSphecomyrma canadensisWilson, 1985 from Canadian amber has led to the conclusion that the specimen belongs to a new genus, here namedBoltonimeciagen.n. Since the taxonomy of stem-group ants is not well understood, in order to find the taxonomic position of this genus, it is necessary to review the classification of stem-group ants in a study of their relation to crown-group ants. In the absence of data for traditional taxonomic approaches, a statistical study was done based on a morphometric analysis of antennae. Scape elongation is believed to play an important role in the evolution of eusociality in ants; however, this hypothesis has never been confirmed statistically. The statistical analysis presented herein lends support to the view that antennal morphology reliably distinguishes stem-group ants from crown-group ants to determine whether a species belongs to one or the other group. This, in turn, may indicate a relationship exists between eusociality and scape elongation. A review of Cretaceous records of ants is made and the higher classification of Formicidae with definitions of stem and crown groups is proposed. Newly obtained data are discussed focusing particularly on the origin, evolution and diversity of ants.

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