Establishment of some clade names for Amphiesmenoptera (Insecta: Holometabola)

The Hamitidae are a family of mid–Cretaceous heteromorph ammonites including lineages leading to four other families. Problems are outlined in trying to describe the phylogeny of completely extinct groups such as these heteromorph ammonites using the existing cladistic terminology, which is largely concerned with extant taxa and their ancestors. To solve these problems, two new terms are proposed: †crown groups and †stem groups, which are equivalent to crown and stem groups in terms of the evolutionary history of a clade, but are not defined on the basis of extant taxa. Instead they are defined by the topology of the phylogenetic tree, the †crown group being a clade defined by synapomorphies but which gave rise to no descendants. A †stem group is a branch of a phylogenetic tree which comprises the immediate sister groups of a given †crown group but is not itself a clade. Examples of these terms are described here with reference to the phylogeny of the Hamitidae and their descendants. The Hamitidae are paraphyletic and form †stem groups to a number of †crown groups, namely the Anisoceratidae, Baculitidae, Scaphitidae, and Turrilitidae. The definitions of the genera and subgenera are refined with respect to the type species and the clades within which they occur, and four new genera are described: Eohamites, Helicohamites, Sziveshamites, and Planohamites.

BackgroundThe purpose of this study was to investigate the fracture strength and stress distribution of four ceramic restorations.MethodsForty human mandibular first molars were collected and randomized into four groups after establishing the distal defect: full crown group with 4 mm axial wall height (AWH) (FC4); short AWH crown group with 2 mm AWH (SC2); occlusal veneer group with 0 mm AWH (OV0); occlusal distal veneer group with only the distal surface prepared, and 4 mm AWH (OD4). The teeth were prepared according to the groups and the ceramic restorations were completed using celtra duo ceramic blocks. The ceramic thickness of the occlusal surface is about 1.5 mm and the edge is about 1 mm. The failure load values and fracture modes of each group were detected by mechanical test in vitro. According to the groups to establish three-dimensional finite element analysis (FEA) models, a 600 N loading force was applied vertically using a hemispherical indenter with a diameter of 6 mm. and compare the stress distribution under the condition of different restorations.ResultsIn vitro mechanical tests showed that the failure load values were SC2 (3232.80 ± 708.12 N) > OD4 (2886.90 ± 338.72 N) > VO0 (2133.20 ± 376.15 N) > FC4(1635.40 ± 413.05 N). The failure load values of the short AWH crown and occlusal distal veneer were significantly higher than that of occlusal veneer and full crown (P<0.05). The fracture modes of the full crown and occlusal veneer groups were mainly ceramic fractures and some were restorable tooth fractures. The short AWH crown and occlusal distal veneer groups presented with three fracture modes, the proportion of non-restorable tooth fracture was higher. The results of FEA show that under the spherical loading condition, the stress of ceramic was concentrated in the contact area of the loading head, the maximum von Mises stress values were FC4 (356.2 MPa) > VO0 (214.3 MPa) > OD4 (197.9 MPa) > SC2 (163.1 MPa). The stress of enamel was concentrated in the area where the remaining enamel was thinner, the maximum von Mises stress values was OD4 (246.2 MPa) ≈ FC4 (212.4 MPa) > VO0 (61.8 MPa) ≈ SC2 (45.81 MPa). The stress of dentin is concentrated in the root furcation and the upper third region of the root. However, stress concentration was observed at the tooth cervix in the full crown.ConclusionUnder certain conditions, the occlusal distal veneer shows better performance than the full crown.

Purpose: Cusp fractures are among the major reasons for the extractions of root-treated teeth. With the intention of increasing information about the mechanical behavior of minimally invasive cusp coverage restorations, the aim of current study was to evaluate the fracture resistance and failure modes of endodontically treated maxillary premolars restored with onlays employing various cusp reduction designs (anatomic, horizontal and beveled) to identify the optimum design and to assess whether these designs influence the restorable fracture rate.Materials and methods: Fifty defect-free maxillary premolar teeth were divided into 5 groups: onlay with anatomic occlusal reduction design (OA), onlay with horizontal occlusal reduction design (OH), onlay with beveled occlusal reduction design (OB), full-coverage crown (CR) and non-restored sound teeth (NR). In OA, OH, OB and CR groups, the access cavities were sealed using bonded composite after endodontic treatment. For OA, OH and OB groups, cusps were prepared with anatomic, horizontal and beveled designs. Except for NR group, all teeth were restored with resin-infiltrated ceramic restorations. After thermal aging for 10000 cycles between 5°C and 50 °C, all specimens were submitted to compressive axial load at a crosshead speed of 1 mm min-1 till failure. The data were analyzed using ANOVA test.Results: The highest load to fracture values (N) was recorded in control non-restored group (1657±167.7N), followed by CR, OA, OB and OH groups where the mean values were 887.5±40.3, 789.4±54.8, 722.2±46.2 and 634.8±74.2N respectively. Significant differences were found among fracture values of test groups (p<.05). The intact teeth predominantly fractured with favorable fracture patterns followed by CR group; while both OB and OH groups showed the heights non-favorable pattern of fracture. Group OA represented moderate percentage of favorable fracture.Conclusions: Root treated teeth restored with anatomic cusp reduction design displayed greater fracture resistance and greater rates of restorable fractures than root treated teeth submitted to horizontal and beveled reduction deigns.

All known post-Paleozoic asteroids belong to the crown group, and no crown-group asteroid is known from the Paleozoic. A scanty fossil record provides limited data on morphology of both Paleozoic stem-group sister lineages and on the Triassic crown group diversification. Timing of events is weakly constrained. Interpretations based on this meager record are tentative.Within limitations of the record, recent work suggests that skeletal arrangement of the ventral surface offers apomorphies of crown-group diversification. Enlarged disk size is common in the crown group. Large disks are constructed in part by addition of many ventral and ventral-lateral so-called “actinal” ossicles. Actinals in the crown group are comparatively uniform in size, shape, and arrangement within each species. Actinal alignment is of one of two patterns, parallel to adambulacrals or parallel to marginals. Actinals in the crown group are tentatively considered to be an apomorphy of the crown group, although the incomplete fossil record leads to uncertainty.Enlarged disks are found in some Paleozoic (stem-group) asteroids. Axillary ossicles, marginal series extending onto ventral interbrachia, and enlarged disk adambulacrals are modes of disk size increase known only from Paleozoic asteroids. Actinal ossicles are found in a few stem-group species but arrangements are unlike those of the crown group.Certain Carboniferous and Permian genera share aspects of ambulacral column construction with the crown group, but lack actinal apomorphies. Actinal arrangement is available for two of the three known Triassic genera. In certain ways, patterns are intermediate between stem-group and Jurassic and younger crown-group asteroids.

A gap exists between paleontological and neontological approaches to ruminant phylogenetics, despite great increases in phylogenetic resolution through molecular work of the last three decades, and a large and growing fossil record. This gap is reflected in differing methodological approaches, with insufficient integration of the large fossil record by molecular studies on the one hand, and insufficient consideration of highly resolved genomic work by paleontological studies on the other. Both paleontological and molecular approaches seek to answer similar broad evolutionary questions, and a synthetic approach is in the interest of all. I demonstrate this by reviewing the development of each field, noting many examples in which paleontological or molecular approaches to ruminant phylogenetics are, on their own, inadequate compared to an approach which considers all sources of data together. In particular, cases such as those of Bison, Capra, and Pelea have shown that integration of genomic and anatomical data presents better resolution of relationships, and I suggest Antilocapra and Moschus may benefit from a similar approach, especially with the integration of fossil taxa into a combined (supermatrix) analysis. I present preliminary results of a new and large (in progress) morphological matrix that is intended to be used for the incorporation of anatomical data and fossil taxa into a combined analysis. The new matrix is much larger than previous morphological matrices assembled for ruminant phylogenetics, meaning it can support a larger number of fossil taxa than was previously possible. Preliminary analysis with 18 taxa recovers a highly supported tree that is mostly compatible with both traditional and molecular phylogenies, although problems of convergence remain, such as between Antilocapra and Bovidae. Finally, I propose standardization of ruminant clade names in order to limit miscommunication between paleontological and neontological workers. I propose phylogenetic definitions based on crown (extant) clades for the names Ruminantia and Pecora, and the use of Pan-Ruminantia and Pan-Pecora to accommodate each respective crown clade plus its stem group.

Burmese amber is well known for preserving unique extinct lineages of insects. Here, we describe a new fossil beetle in its larval stage from Burmese amber. Bayesian and parsimony phylogenetic analysis of 50 morphological characters support this fossil as being sister to both the tribes Dineutini and Orectochilini, representing an extinct stem lineage in Gyrininae. It is described here as a new genus and species of whirligig beetle, Chimerogyrus gigagalea gen. & sp. nov., a taxon that preserves remarkable intermediate features between the whirligig beetle tribe Gyrinini and the crown Orectochilini and Dineutini. This new taxon preserves key features for studying the evolution of characters within the larval stage of the Gyrinidae and highlights the importance of Burmese amber for preserving both stem and crown lineages present during the mid-Cretaceous, before the end-Cretaceous mass extinction event.

Abstract. DNA-based divergence time estimates suggested major changes in the composition of epiphyte lineages of liverworts during the Cretaceous; however, evidence from the fossil record is scarce. We present the first Cretaceous fossil of the predominantly epiphytic leafy liverwort genus Radula in ca. 100 Myr old Burmese amber. The fossil's exquisite preservation allows first insights into the morphology of early crown group representatives of Radula occurring in gymnosperm-dominated forests. Ancestral character state reconstruction aligns the fossil with the crown group of Radula subg. Odontoradula; however, corresponding divergence time estimates using the software BEAST lead to unrealistically old age estimates. Alternatively, assignment of the fossil to the stem of subg. Odontoradula results in a stem age estimate of Radula of 227.8 Ma (95 % highest posterior density (HPD): 165.7–306.7) and a crown group estimate of 176.3 Ma (135.1–227.4), in agreement with analyses employing standard substitution rates (stem age 235.6 Ma (142.9–368.5), crown group age 183.8 Ma (109.9–289.1)). The fossil likely belongs to the stem lineage of Radula subg. Odontoradula. The fossil's modern morphology suggests that switches from gymnosperm to angiosperm phorophytes occurred without changes in plant body plans in epiphytic liverworts. The fossil provides evidence for striking morphological homoplasy in time. Even conservative node assignments of the fossil support older rather than younger age estimates of the Radula crown group, involving origins for most extant subgenera by the end of the Cretaceous and diversification of their crown groups in the Cenozoic.

Introduction: The aim of this study is to determine the shear bond strength (SBS) of ceramic brackets bonded to three different porcelain surfaces. Materials and Methods: A total of 36 porcelain crowns were used in this study. Porcelain crowns were allocated to the three groups as follows: Conventional porcelain-fused-to-metal crowns, IPS e.max ceramic crowns, and porcelain-fused-to-zirconia crowns. Porcelain surfaces were etched with 9.6% hydrofluoric acid and rinsed with a water/spray combination. Then, ceramic brackets were bonded with a light-cured composite resin. All the specimens were stored in distilled water at 37°C for 24 hours and thermocycled and loaded into a universal testing machine for testing. Any adhesive that remained after debonding was assessed and scored according to the modified adhesive remnant index (ARI). Statistical Analysis: One-way analysis of variance (ANOVA) and Tukey's test were used to compare the SBS of the groups. The Chi-square test was used to determine the ARI scores among the groups. Results: No statistically significant difference between the ARI scores for the three types of crowns was observed. In the conventional porcelain-fused-to-metal crown group (7.09 MPa), the lowest values of bond strength were obtained. Although similar values of bond strength were found in the IPS e.max ceramic crown (8.60 MPa) and porcelain-fused-to-zirconia crown (8.93 MPa) groups, the statistically significant differences in values of shear bond strength have observed between the other groups. Conclusions: SBS of ceramic brackets bonded to different porcelain surfaces may produce different results due to the type of porcelain crown.

Tardigrades as ‘Stem-Group Arthropods’: The Evidence from the Cambrian Fauna

ObjectiveTo compare the survival rate against fracture of endodontically treated anterior teeth (ETT) affected by cervical (class V) lesions with pulpal involvement restored with resin composite or a post/core and crown, and to identify the prognostic factors for fracture.MethodsDental records and radiographs of ETT affected by cervical lesions with pulpal involvement restored with resin composite or a post/core and crown during a recall period from 2009–2022 were selected according to the inclusion and exclusion criteria. The number of tooth fracture, the restorability after fracture and any possible risk factors were identified. The survival rate against ETT fracture were analyzed and compared between the two restoration groups by Kaplan-Meier survival analysis and the Tarone-Ware test. Non-proportional hazard models were used to identify the prognostic factors. The sub-analysis in each restoration group was also performed.ResultsThe study comprised 175 ETT restored with resin composite (n=125) or a crown (n=50). With a mean recall period of 32.9±15.8 months, the survival rate against ETT fracture with resin composite (85.6%) was not significantly different from those with a crown (88%) (p≥0.05). The most frequent mode of fracture was crown-root fracture, which accounted for 78% and 83.30% of the fractures in the resin composite and crown groups, respectively. A significant prognostic factor for ETT fracture affected by cervical lesions with pulpal involvement was additional tooth structure loss from a class III, class IV or another class V lesion on the opposite side (p<0.05). The ETT affected by cervical lesions with pulpal involvement combined with additional tooth structure loss had a 7.25-fold higher risk of fracture than those with single-surface affected by cervical lesions with pulpal involvement (hazard ratio [HR] = 7.25; 95% confidence interval [CI], 1.68–31.30). The sub-analysis in the crown and resin composite groups revealed that the survival rates of ETT with single-surface affected by cervical lesions with pulpal involvement was 100% and 96.15%, respectively, which were significantly higher than those of ETT with additional tooth loss at 80.65% and 78.08%, respectively (p<0.05).ConclusionWith a mean 33-month recall period, the survival rate against ETT fracture affected by cervical lesions with pulpal involvement restored with resin composite or crown were not significantly different. Additional tooth structure loss was a significant prognostic factor for fracture.

This study describes a specimen that extends the oldest fossil evidence of Pinus L. to the Early Cretaceous Wealden Formation of Yorkshire, UK (131–129 million years ago), and prompts a critical reevaluation of criteria that are employed to identify crown group genera of Pinaceae from anatomically preserved seed cones. The specimen, described as Pinus yorkshirensis sp. nov., is conical, 5 cm long, and 3.1 cm in maximum diameter. Bract/scale complexes are helically arranged and spreading. Vasculature of the axis forms a complete cylinder with few resin canals in the wood, and the inner cortex is dominated by large resin canals. Bracts are short, with two resin canals, and separate from the scale base laterally. Distally, the ovuliferous scales broaden and thicken to form a rhomboidal apophysis with a dorsal umbo, characters found only in the genus Pinus among living conifers. Resin canals enter the ovuliferous scale abaxial to the vascular tissue, which divides distally to form a row of adaxially convex bundles. A short interseminal ridge separates two inverted and winged seeds on the adaxial surface of the ovuliferous scale. Seeds contain megagametophyte tissue and polycotyledonary embryos. Numerical cladistic analysis of anatomically preserved seed cones yields a well-resolved phylogeny of crown and stem group Pinaceae that is roughly concordant with the results of analyses that include living species only. All of the included species of Pinus form a clade with three very Pinus-like species that currently are assigned to the stem genus Pityostrobus. These results call to question the utility of traditional methods for assigning fossil seed cones to Pinus, resolve relationships among stem and crown group genera, and highlight the unnatural circumscription of Pityostrobus. This suggests that some species of Pityostrobus may actually represent the genus Pinus, and it demonstrates that the evolutionary diversification of Pinaceae began earlier than previously recognized from fossil evidence.

The known fossil record of crown-group amniotes begins in the late Carboniferous with the sauropsid trackmaker Notalacerta1,2 and the sauropsid body fossil Hylonomus1, 2, 3–4. The earliest body fossils of crown-group tetrapods are mid-Carboniferous, and the oldest trackways are early Carboniferous5, 6–7. This suggests that the tetrapod crown group originated in the earliest Carboniferous (early Tournaisian), with the amniote crown group appearing in the early part of the late Carboniferous. Here we present new trackway data from Australia that challenge this widely accepted timeline. A track-bearing slab from the Snowy Plains Formation of Victoria, Taungurung Country, securely dated to the early Tournaisian8,9, shows footprints from a crown-group amniote with clawed feet, most probably a primitive sauropsid. This pushes back the likely origin of crown-group amniotes by at least 35–40 million years. We also extend the range of Notalacerta into the early Carboniferous. The Australian tracks indicate that the amniote crown-group node cannot be much younger than the Devonian/Carboniferous boundary, and that the tetrapod crown-group node must be located deep within the Devonian; an estimate based on molecular-tree branch lengths suggests an approximate age of early Frasnian for the latter. The implications for the early evolution of tetrapods are profound; all stem-tetrapod and stem-amniote lineages must have originated during the Devonian. It seems that tetrapod evolution proceeded much faster, and the Devonian tetrapod record is much less complete, than has been thought.

The Genomic Record of Humankind's Evolutionary Roots

Phylogenetic signal detection from an ancient rapid radiation: Effects of noise reduction, long-branch attraction, and model selection in crown clade Apocynaceae

Recent efforts have led to the development of extremely sophisticated methods for incorporating tree-wide data and accommodating uncertainty when estimating the temporal patterns of phylogenetic trees, but assignment of prior constraints on node age remains the most important factor. This depends largely on understanding substantive disagreements between specialists (paleontologists, geologists, and comparative anatomists), which are often opaque to phylogeneticists and molecular biologists who rely on these data as downstream users. This often leads to misunderstandings of how the uncertainty associated with node age minima arises, leading to inappropriate treatments of that uncertainty by phylogeneticists. In order to promote dialogue on this subject, we here review factors (phylogeny, preservational megabiases, spatial and temporal patterns in the tetrapod fossil record) that complicate assignment of prior node age constraints for deep divergences in the tetrapod tree, focusing on the origin of crown-group Amniota, crown-group Amphibia, and crown-group Tetrapoda. We find that node priors for amphibians and tetrapods show high phylogenetic lability and different phylogenetic treatments identifying disparate taxa as the earliest representatives of these crown groups. This corresponds partially to the well-known problem of lissamphibian origins but increasingly reflects deeper instabilities in early tetrapod phylogeny. Conversely, differences in phylogenetic treatment do not affect our ability to recognize the earliest crown-group amniotes but do affect how diverse we understand the earliest amniote faunas to be. Preservational megabiases and spatiotemporal heterogeneity of the early tetrapod fossil record present unrecognized challenges in reliably estimating the ages of tetrapod nodes; the tetrapod record throughout the relevant interval is spatially restricted and disrupted by several major intervals of minimal sampling coincident with the emergence of all three crown groups. Going forward, researchers attempting to calibrate the ages for these nodes, and other similar deep nodes in the metazoan fossil record, should consciously consider major phylogenetic uncertainty, preservational megabias, and spatiotemporal heterogeneity, preferably examining the impact of working hypotheses from multiple research groups. We emphasize a need for major tetrapod collection effort outside of classic European and North American sections, particularly from the southern hemisphere, and suggest that such sampling may dramatically change our timelines of tetrapod evolution.