Tail feather strength in tail-assisted climbing birds is achieved through geometric, not material change.

Birds encompass vast ecomorphological diversity and practise numerous distinct locomotor modes. One oft-cited feature seen in climbing birds is an increase in tail 'stiffness', yet it remains unclear to what extent these feathers are altered, and the specific mechanism by which differences in functional performance are attained. We collected a broad taxonomic sample of tail feathers (6525 total, from 774 species representing 21 avian orders and ranging in size from approximately 3 g to greater than 11 kg) and present data on their material properties, cross-sectional geometry and morphometrics. Ordinary and phylogenetic least-squares regressions of each variable versus body mass were conducted to assess scaling relationships and demonstrate that tail-supported climbers exhibit longer tail feathers with a wider rachis base and tip, and a greater second moment of area and maximum bending moment. However, no differences were observed in the material properties of the keratin itself. This suggests that tail-supported arboreal climbing birds of multiple orders have independently adopted similar morphologies. Moreover, these geometric relationships follow the same allometric scaling relationships as seen in the long bones of mammalian limbs, suggesting that the morphology of these developmentally and evolutionarily distinct structures are governed by similar functional constraints of weight support.

Developmental origin underlies evolutionary rate variation across the placental skull.

The placental skull has evolved into myriad forms, from longirostrine whales to globular primates, and with a diverse array of appendages from antlers to tusks. This disparity has recently been studied from the perspective of the whole skull, but the skull is composed of numerous elements that have distinct developmental origins and varied functions. Here, we assess the evolution of the skull's major skeletal elements, decomposed into 17 individual regions. Using a high-dimensional morphometric approach for a dataset of 322 living and extinct eutherians (placental mammals and their stem relatives), we quantify patterns of variation and estimate phylogenetic, allometric and ecological signal across the skull. We further compare rates of evolution across ecological categories and ordinal-level clades and reconstruct rates of evolution along lineages and through time to assess whether developmental origin or function discriminate the evolutionary trajectories of individual cranial elements. Our results demonstrate distinct macroevolutionary patterns across cranial elements that reflect the ecological adaptations of major clades. Elements derived from neural crest show the fastest rates of evolution, but ecological signal is equally pronounced in bones derived from neural crest and paraxial mesoderm, suggesting that developmental origin may influence evolutionary tempo, but not capacity for specialisation. This article is part of the theme issue 'The mammalian skull: development, structure and function'.

Attenuated evolution of mammals through the Cenozoic.

The Cenozoic diversification of placental mammals is the archetypal adaptive radiation. Yet, discrepancies between molecular divergence estimates and the fossil record fuel ongoing debate around the timing, tempo, and drivers of this radiation. Analysis of a three-dimensional skull dataset for living and extinct placental mammals demonstrates that evolutionary rates peak early and attenuate quickly. This long-term decline in tempo is punctuated by bursts of innovation that decreased in amplitude over the past 66 million years. Social, precocial, aquatic, and herbivorous species evolve fastest, especially whales, elephants, sirenians, and extinct ungulates. Slow rates in rodents and bats indicate dissociation of taxonomic and morphological diversification. Frustratingly, highly similar ancestral shape estimates for placental mammal superorders suggest that their earliest representatives may continue to elude unequivocal identification.

Experimental approaches to assess the effect of composition of abrasives in the cause of dental microwear.

Dental microwear is used to investigate feeding ecology. Animals ingest geological material in addition to food. The full effect of geological abrasives on tooth wear is unknown. To evaluate mineralogical abrasives as tooth wear agents, rats were fed food manufactured with quartz silt, diatomaceous earth, and calcium carbonate. Rats were assigned to treatments and fed for 15 days. Molars were scanned with a Sensofar Plu Neox confocal microscope and evaluated using ISO-25178-2 parameters and traditional microwear variables using light microscopy. Using a pellet-diet as the control, all treatments had influence on microwear and discriminant function analyses indicated that unique surface textures had been produced. ISO variables with high discriminatory values were correlated to scratch and pit frequencies, but more ISO parameters identified changes associated with numbers of scratches than changes associated with pits. The microwear changes associated with the abrasive inclusions were co-dependent on the type of diet that the abrasives had been added to. The abrasives had less effect with pellets but produced more modified and more differentiated microwear when added to the transgenic dough. Although abrasives produce distinctive surface textures, some knowledge of the properties of food with the abrasives is needed to identify the abrasive agent.

The tempo of cetacean cranial evolution.

The evolution of cetaceans (whales and dolphins) represents one of the most extreme adaptive transitions known, from terrestrial mammals to a highly specialized aquatic radiation that includes the largest animals alive today. Many anatomical shifts in this transition involve the feeding, respiratory, and sensory structures of the cranium, which we quantified with a high-density, three-dimensional geometric morphometric analysis of 201 living and extinct cetacean species spanning the entirety of their ∼50-million-year evolutionary history. Our analyses demonstrate that cetacean suborders occupy distinct areas of cranial morphospace, with extinct, transitional taxa bridging the gap between archaeocetes (stem whales) and modern mysticetes (baleen whales) and odontocetes (toothed whales). This diversity was obtained through three key periods of rapid evolution: first, the initial evolution of archaeocetes in the early to mid-Eocene produced the highest evolutionary rates seen in cetaceans, concentrated in the maxilla, frontal, premaxilla, and nasal; second, the late Eocene divergence of the mysticetes and odontocetes drives a second peak in rates, with high rates and disparity sustained through the Oligocene; and third, the diversification of odontocetes, particularly sperm whales, in the Miocene (∼18-10 Mya) propels a final peak in the tempo of cetacean morphological evolution. Archaeocetes show the fastest evolutionary rates but the lowest disparity. Odontocetes exhibit the highest disparity, while mysticetes evolve at the slowest pace, particularly in the Neogene. Diet and echolocation have the strongest influence on cranial morphology, with habitat, size, dentition, and feeding method also significant factors impacting shape, disparity, and the pace of cetacean cranial evolution.

Regional variation in the density of Meissner's corpuscles in human fingers.

Manual therapies in medicine rely on a physician's ability to sense and respond to tactile cues from their hands to inform them of symptoms within the patient. Sensory cues through skin may not be equally sensitive among all people, and little is known about the variation in distribution of sensory corpuscles in the human hand. Variation of corpuscle numbers studied in living people are limited to less invasive techniques, limiting their accuracy. Body-donor studies that thoroughly sample the distribution throughout the hand are extremely rare, usually only including a small number of sites around the hand and only a small number of individuals. Does the distribution of Meissner's corpuscles vary greater between individuals, between fingers, along the finger, or at specialized regions of the fingers themselves (pads, over interphalangeal joints, tips)? We tested whether there were significant differences between finger regions (fingertips vs. pads, vs. interphalangeal joints), or from proximal to distal, or between digits, or between individuals by histologically sampling human body-donors to science. There were significant differences in the quantity of Meissner's corpuscles between finger regions, from proximal to distal regions along digits, between individuals, but not between digits. Specifically, fingertips demonstrated higher counts of Meissner's corpuscles than pads and interphalangeal joints, more distally located regions (i.e. tips and distal pads) demonstrated higher Meissner's corpuscles than more proximal regions, and most individuals demonstrated significantly different average amounts of total Meissner's corpuscles from each other. Our results suggest that variability exists in the amounts and distribution of Meissner's corpuscles both between and within fingers of human subjects.

Surface metrology of bone surface attachments of knee ligaments.

OBJECTIVES: Textural differences between entheses reflect biomechanical activities of the musculoskeletal system. Methods used to measure these surfaces have limitations. Here, the surface metrology of roughness of articular and entheseal surfaces of the knee are investigated with an optical profiler. METHODS: Osteological specimens of six femora and seven tibiae were prepared from cadavers. Measurements were obtained to surrogate body mass. Specimens were molded with polyvinylsiloxane and casts prepared with resin, which were scanned using a white light optical profiler. Scans were processed by a computer program. Each scan produced 32 variables, categorized into 6 groups for each location. RESULTS: The distribution of data was mostly normal. Analysis of variance (ANOVA) identified Ssk significant (p-value .002); post hoc Tukey testing indicated significance between femoral PCL and tibial ACL entheses groups (p-value .007), and between tibial ACL and tibial entheses groups (p-value .002) suggesting the ability to differentiate anterior and posterior cruciate ligament entheses. Sku was found significant with a t test between articular and entheseal surfaces. Correlation coefficients were significant between surface metrology parameters and measurements related to body mass. CONCLUSIONS: This study distinguished differences between entheses of the anterior and posterior cruciate ligaments, with the Ssk parameter most useful. Differences in articular and entheseal surfaces were found with the Sku parameter most useful. Correlations indicated a relationship between body mass and surface metrology parameters. Finally, these findings suggest this method can be used for further investigation of spondyloarthropathies.

Organ histopathological associations with hyperostosis frontalis interna in humans / Asociaciones histopatológicas de órganos con hiperostosis frontal interna en humanos

SUMMARY: An increased thickening of the frontal bone by irregular laminar additions on the inner surface just deep to the dura mater have been known in the archaeological and medical record as hyperostosis frontalis interna (HFI). The distribution of this is idiosyncratically restricted to the frontal and has no known etiology. The prevalence among post-menopausal females and rarity in males suggests that it is hormonally driven. Here we report histopathological findings of particularly hormonally active organs (pituitaries, gonads and liver) from a geriatric cadaveric sample in which HFI is assessed. HFI was present in 50 % of males (7/14) and 95 % (21/22) of females. All males with HFI had testicular atrophy or had testes absent. Males with HFI category C or D had moderate to severe testicular atrophy. Decreased numbers of interstitial cells (Leydig cells) were present in 83.3 % of males with HFI. All but one female (21/22) from this study exhibited evidence of HFI, and ovarian pathologies were unevenly distributed (fibromas in two) and most exhibited signs of being healthy and post-menopausal. Liver pathologies had opposite patterns between the sexes, with more liver pathologies occurring among males without HFI (particularly passive congestion and bile stasis). The only exceptions were that the one case of liver neoplasia was found in a male with HFI and steotosis was found in two cases with HFI and one case without HFI. In females all cases of liver pathologies (steotosis, hepatitis, passive congestion, fibrosis, and bile stasis) were associated with HFI. It appears that gonadal pathology is most closely associated with HFI in males but not females, suggesting that the role of estradiol in this unusual growth of bone in geriatric humans may be worth investigating further.

RESUMEN: Un aumento del engrosamiento del hueso frontal, por adiciones laminares irregulares en la superficie interna, justo en la profundidad de la duramadre, se conoce en los registros arqueológicos y médicos como hiperostosis frontal interna (HFI). La distribución de ésta, se restringe idiosincráticamente al hueso frontal y no tiene etiología conocida. La prevalencia entre las mujeres posmenopáusicas y la rareza en los hombres sugiere que se debe a las hormonas. Aquí informamos los hallazgos histopatológicos de órganos hormonalmente activos (hipófisis, gónadas e hí- gado) de una muestra de cadáveres geriátricos en la que se evaluó HFI. La HFI estuvo presente en el 50 % de los hombres (7/14) y el 95 % (21/22) de las mujeres. Todos los hombres con HFI tenían atrofia testicular o no tenían testículos. En los hombres con HFI categoría C o D se observó atrofia testicular de moderada a grave. Hubo una disminución en el número de células intersticiales (células de Leydig) en el 83,3 % de los hombres con HFI. En 21de 22 mujeres se observó evidencia de HFI, y las patologías ováricas se distribuyeron de manera desigual (fibromas en dos) y la mayoría exhibió signos de estar sana y posmenopáusica. Las patologías hepáticas tenían patrones opuestos entre los sexos, con más patologías hepáticas entre los hombres sin HFI (particularmente congestión pasiva y estasis biliar). Las excepciones fueron que el único caso de neoplasia hepática se encontró en un varón con HFI y se presentó esteatosis en dos casos con HFI y un caso sin HFI. En las mujeres, todos los casos de patologías hepáticas (esteatosis, hepatitis, congestión pasiva, fibrosis y estasis biliar) se asociaron con HFI. Al parecer la patología gonadal está más estrechamente asociada con la HFI en los hombres que en las mujeres, lo que sugiere un rol del estradiol en este crecimiento inusual de hueso en hombres de avanzada edad. Sería importante realizar investigaciones más detalladas precisas respecto a la hiperostosis frontal interna.

Convergent Evolution of Swimming Adaptations in Modern Whales Revealed by a Large Macrophagous Dolphin from the Oligocene of South Carolina.

Modern whales and dolphins are superbly adapted for marine life, with tail flukes being a key innovation shared by all extant species. Some dolphins can exceed speeds of 50 km/h, a feat accomplished by thrusting the flukes while adjusting attack angle with their flippers [1]. These movements are driven by robust axial musculature anchored to a relatively rigid torso consisting of numerous short vertebrae, and controlled by hydrofoil-like flippers [2-7]. Eocene skeletons of whales illustrate the transition from semiaquatic to aquatic locomotion, including development of a fusiform body and reduction of hindlimbs [8-11], but the rarity of Oligocene whale skeletons [12, 13] has hampered efforts to understand the evolution of fluke-powered, but forelimb-controlled, locomotion. We report a nearly complete skeleton of the extinct large dolphin Ankylorhiza tiedemani comb. n. from the Oligocene of South Carolina, previously known only from a partial rostrum. Its forelimb is intermediate in morphology between stem cetaceans and extant taxa, whereas its axial skeleton displays incipient rigidity at the base of the tail with a flexible lumbar region. The position of Ankylorhiza near the base of the odontocete radiation implies that several postcranial specializations of extant cetaceans, including a shortened humerus, narrow peduncle, and loss of radial tuberosity, evolved convergently in odontocetes and mysticetes. Craniodental morphology, tooth wear, torso vertebral morphology, and body size all suggest that Ankylorhiza was a macrophagous predator that could swim relatively fast, indicating that it was one of the few extinct cetaceans to occupy a niche similar to that of killer whales.

Surface Replication, Fidelity and Data Loss in Traditional Dental Microwear and Dental Microwear Texture Analysis.

Dental microwear studies often analyze casts rather than original surfaces, although the information loss associated with reproduction is rarely considered. To investigate the sensitivity of high magnification (150x) microwear analysis to common surface replication materials and methods, we compared areal surface texture parameters (ISO 25178-2) and traditional microwear variables (pits and scratches) generated from teeth and casts of rat molars exposed to experimental diets involving hard and soft foods in which abrasive materials had been added. Although the data from the original and replicated surfaces were correlated, many significant differences were found between the resulting data of the casts and original teeth. Both areal surface texture parameters and traditional microwear variables showed diminished ability to discriminate between the eight diet treatments when casts were analyzed. When areal surface texture parameters and traditional microwear variables were combined into a single discriminant function analysis, the cast data and original data produced the most similar results. Microwear researchers tend to favor either texture analysis or traditional microwear methods, better results may be generated by combining them. Although surface textures were not accurately reproduced by the casts, they retained sufficient information to discriminate between microwear of the experimental diets to a degree similar to the original teeth.

A long-forgotten 'dinosaur' bone from a museum cabinet, uncovered to be a Japan's iconic extinct mammal, Paleoparadoxia (Desmostylia, Mammalia).

Here, we report a new 'discovery' of a desmostylian fossil in the geological collection at a national university in Japan. This fossil was unearthed over 60 years ago and donated to the university. Owing to the original hand-written note kept with the fossil in combination with interview investigation, we were able to reach two equally possible fossil sites in the town of Tsuchiyu Onsen, Fukushima. Through the interviews, we learned that the fossil was discovered during construction of a debris flow barrier and that it was recognized as a 'dinosaur' bone among the locals and displayed in the Village Hall before/until the town experienced a fire disaster in 1954. As scientific findings, the fossil was identified to be a right femur of Paleoparadoxia (Desmostylia), which shows well-preserved muscle scars on the surface. The age was estimated to be 15.9 Ma or younger in zircon-dating. This study shows an excellent case that historical and scientific significances could be extracted from long-forgotten uncatalogued specimens as long as the original information is retained with the specimens.

Evolution of cranial telescoping in echolocating whales (Cetacea: Odontoceti).

Odontocete (echolocating whale) skulls exhibit extreme posterior displacement and overlapping of facial bones, here referred to as retrograde cranial telescoping. To examine retrograde cranial telescoping across 40 million years of whale evolution, we collected 3D scans of whale skulls spanning odontocete evolution. We used a sliding semilandmark morphometric approach with Procrustes superimposition and PCA to capture and describe the morphological variation present in the facial region, followed by Ancestral Character State Reconstruction (ACSR) and evolutionary model fitting on significant components to determine how retrograde cranial telescoping evolved. The first PC score explains the majority of variation associated with telescoping and reflects the posterior migration of the external nares and premaxilla alongside expansion of the maxilla and frontal. The earliest diverging fossil odontocetes were found to exhibit a lesser degree of cranial telescoping than later diverging but contemporary whale taxa. Major shifts in PC scores and centroid size are identified at the base of Odontoceti, and early burst and punctuated equilibrium models best fit the evolution of retrograde telescoping. This indicates that the Oligocene was a period of unusually high diversity and evolution in whale skull morphology, with little subsequent evolution in telescoping.

The Origin of Filter Feeding in Whales.

As the largest known vertebrates of all time, mysticetes depend on keratinous sieves called baleen to capture enough small prey to sustain their enormous size [1]. The origins of baleen are controversial: one hypothesis suggests that teeth were lost during a suction-feeding stage of mysticete evolution and that baleen evolved thereafter [2-4], whereas another suggests that baleen evolved before teeth were lost [5]. Here we report a new species of toothed mysticete, Coronodon havensteini, from the Oligocene of South Carolina that is transitional between raptorial archaeocete whales and modern mysticetes. Although the morphology and wear on its anterior teeth indicate that it captured large prey, its broad, imbricated, multi-cusped lower molars frame narrow slots that were likely used for filter feeding. Coronodon havensteini is a basal, if not the most basal, mysticete, and our analysis suggests that it is representative of an initial stage of mysticete evolution in which teeth were functional analogs to baleen. In later lineages, the diastema between teeth increased-in some cases, markedly so [6]-and may mark a stage at which the balance of the oral fissure shifted from mostly teeth to mostly baleen. When placed in a phylogenetic context, our new taxon indicates that filter feeding was preceded by raptorial feeding and that suction feeding evolved separately within a clade removed from modern baleen whales.

Peripheral Arteries May Be Reliable Indicators of Coronary Vascular Disease.

Atherosclerosis is a stronger predictor for ischemic cardiovascular events than traditional risk factors such as race, age, sex, history, and metabolic profile. Previous research had primarily used ultrasound; however, we performed a study using histopathology to more accurately grade atherosclerosis development using the American Heart Association's grading scale. We cross-sectioned 13 different arteries from 48 cadavers and placed them into three separate groups based on anatomic location: central arteries, peripheral arteries, and carotid arteries. The central artery group included arteries that are non-palpable and commonly lead to ischemic diseases when occluded. The peripheral artery group included arteries that are accessible to palpation. The carotid artery group included branches of the carotid artery. We investigated whether a centrally located atherosclerotic vessel was associated with atherosclerosis of a specific peripheral artery. We hypothesized a correlation between carotid, peripheral and central arteries that may point to specific arteries that are more effective to analyze clinically when assessing cardiovascular risk. We observed a correlation between pathology in the left coronary artery and bifurcation of the carotid artery (r = 0.37 P ≤ 0.016), two arteries known to be implicated in ischemic stroke and ischemic heart disease. Importantly, our study demonstrates that the radial artery, a peripheral vessel, exhibited a positive correlation between both the pathologic left coronary (r = 0.33 P ≤ 0.041) and bifurcation of the carotid arteries (r = 0.34 P ≤ 0.025). Therefore, we propose investigating the radial artery as a clinically accessible location to monitor with ultrasound when assessing a patient's risk for ischemic cardiovascular disease. Anat Rec, 300:1230-1239, 2017. © 2017 Wiley Periodicals, Inc.

Postembryonic Nephrogenesis and Persistence of Six2-Expressing Nephron Progenitor Cells in the Reptilian Kidney.

New nephron formation (nephrogenesis) ceases in mammals around birth and is completely absent in adults. In contrast, postembryonic nephrogenesis is well documented in the mesonephric kidneys of fishes and amphibians. The transient mesonephros in reptiles (including birds) and mammals is replaced by the metanephros during embryogenesis. Thus, one may speculate that postembryonic nephrogenesis is restricted to the mesonephric kidney. Previous reports have suggested the metanephros of non-avian reptiles (hereafter reptiles) may continually form nephrons throughout life. We investigated the presence of adult nephrogenesis in reptiles by examining adult kidneys from several species including Trachemys scripta, Chrysemys picta, Boa constrictor, Tupinambis tegu, Anolis carolinensis, and Alligator mississipiensis among others. We found that all major reptilian groups (Testudines, Crocodylia, and Squamates) showed the presence of adult nephrogenesis. The total amount of nephrogenesis varied greatly between species with turtles displaying the highest density of nephrogenesis. In contrast, we were unable to detect adult nephrogenesis in monotremes, and in the iguanid A. carolinensis. Nephron progenitor cells express the transcription factor Six2, which in mammals, becomes downregulated as the progenitor cell population is exhausted and nephrogenesis ends. Using the alligator as a model, we were able to detect Six2-positive cap mesenchyme cells in the adult kidney, which spatially correlated with areas of nephrogenesis. These results suggest that the metanephric kidney of reptiles has maintained the ability to continually grow new nephrons during postembryonic life, a process lost early in mammalian evolution, likely due to the persistence of a Six2-expressing progenitor cell population.

Graphene-Molybdenum Disulfide-Graphene Tunneling Junctions with Large-Area Synthesized Materials.

Tunneling devices based on vertical heterostructures of graphene and other 2D materials can overcome the low on-off ratios typically observed in planar graphene field-effect transistors. This study addresses the impact of processing conditions on two-dimensional materials in a fully integrated heterostructure device fabrication process. In this paper, graphene-molybdenum disulfide-graphene tunneling heterostructures were fabricated using only large-area synthesized materials, unlike previous studies that used small exfoliated flakes. The MoS2 tunneling barrier is either synthesized on a sacrificial substrate and transferred to the bottom-layer graphene or synthesized directly on CVD graphene. The presence of graphene was shown to have no impact on the quality of the grown MoS2. The thickness uniformity of MoS2 grown on graphene and SiO2 was found to be 1.8 ± 0.22 nm. XPS and Raman spectroscopy are used to show how the MoS2 synthesis process introduces defects into the graphene structure by incorporating sulfur into the graphene. The incorporation of sulfur was shown to be greatly reduced in the absence of molybdenum suggesting molybdenum acts as a catalyst for sulfur incorporation. Tunneling simulations based on the Bardeen transfer Hamiltonian were performed and compared to the experimental tunneling results. The simulations show the use of MoS2 as a tunneling barrier suppresses contributions to the tunneling current from the conduction band. This is a result of the observed reduction of electron conduction within the graphene sheets.

Regional quantitative histological variations in human oral mucosa.

Oral mucosa demonstrates regional variations that reflect contact with food during mastication. Though known qualitatively, our aim was to quantitatively assess regions to establish a measurable baseline from which one could compare in pathological and comparative studies, in which the abrasiveness of diets may differ. We assessed variations in the epithelial-connective tissue junction (rete ridges counts), collagen organization within the lamina propria, and elastin composition of the lamina propria of 15 regions of the labial (buccal) gingiva, lingual gingiva, vestibule, and palate. All characteristics varied more between regions within the same individual than between individuals. Lingual gingiva had high rete ridges counts, high level of collagen organization, and moderate elastin composition compared to other regions. The labial gingiva had few rete ridges, high collagen organization, and low elastin. The vestibule had the fewest average of rete ridges, least organized collagen, and high elastin. The hard palate had the highest average of rete ridges, high collagen organization, and the lowest elastin content. The soft palate conversely had the smallest average of rete ridges, moderate collagen organization, and the highest elastin composition. Our results indicate that comparison of these quantitative histological differences is warranted only for collagen organization and elastin composition. Differences in rete ridges counts were not statistically significant. Most histological characteristics observed were not significantly different between dentulous and edentulous cadavers, and the group containing all individuals. An exception was the level of collagen fiber organization within the lamina propria, which was higher in most regions when teeth were present.

Bony outgrowths on the jaws of an extinct sperm whale support macroraptorial feeding in several stem physeteroids.

Several extinct sperm whales (stem Physeteroidea) were recently proposed to differ markedly in their feeding ecology from the suction-feeding modern sperm whales Kogia and Physeter. Based on cranial, mandibular, and dental morphology, these Miocene forms were tentatively identified as macroraptorial feeders, able to consume proportionally large prey using their massive teeth and robust jaws. However, until now, no corroborating evidence for the use of teeth during predation was available. We report on a new specimen of the stem physeteroid Acrophyseter, from the late middle to early late Miocene of Peru, displaying unusual bony outgrowths along some of the upper alveoli. Considering their position and outer shape, these are identified as buccal maxillary exostoses. More developed along posterior teeth and in tight contact with the high portion of the dental root outside the bony alveoli, the exostoses are hypothesized to have developed during powerful bites; they may have worked as buttresses, strengthening the teeth when facing intense occlusal forces. These buccal exostoses further support a raptorial feeding technique for Acrophyseter and, indirectly, for other extinct sperm whales with a similar oral apparatus (Brygmophyseter, Livyatan, Zygophyseter). With a wide size range, these Miocene stem physeteroids were major marine macropredators, occupying ecological niches nowadays mostly taken by killer whales.

A histological investigation into the correlation of central retinal artery atherosclerosis with the systemic circulation.

Current research suggests that retinal arterial changes such as arteriovenous nicking and arterial narrowing are pathologically distinct from atherosclerosis. Other studies have found a positive correlation between retinal changes and systemic atherosclerosis. However, limited recent histopathologic evidence assessing atherosclerosis in the central retinal artery exists. We investigated atherosclerosis in the central retinal artery and how it correlates to atherosclerosis in the carotid and coronary arteries. Twenty-two cadavers (12 males, 10 females) were dissected, obtaining one orbit, one carotid artery, and one coronary artery from each. The specimens were sectioned and stained for histologic analysis by light microscopy using hematoxylin and eosin, Verhoeff's elastic, and Gomori's trichrome stains. The degree of atherosclerosis was graded from absent, or I (least severe) to VIII (most severe) based on the current American Heart Association guidelines. Atherosclerotic changes were present in the central retinal, coronary, and carotid arteries. A positive correlation was found between the central retinal artery and the carotid artery (r = 0.23, P = 0.15), the central retinal artery and the coronary artery (r = 0.31, P = 0.08), and the carotid artery and the coronary artery (r = 0.45, P = 0.02). The presence of low-grade atherosclerosis in the central retinal artery is prevalent in a population of advanced vascular disease. However, central retinal artery atherosclerotic lesion severity is poorly correlated with disease severity in the carotid and coronary arteries.