Changes In Facial Morphology Research Articles

Increasing Vertical Dimension of a Case with Full Mouth Rehabilitation: Case Report.

Introduction: Bruxism is one of the most frequent causes for occlusal tooth wear, with the loss of tooth structure caused by mechanical wear between maxillary and mandibular tooth surfaces, case report was conducted to improve the patient oral health, and to maintain the new vertical dimension since it was lost by teeth clenching. Case description: this paper presents a 50 years old male suffering from severe bruxism, which implicated the appearance and function of the patient, he was transferred to TIU dental hospital for full mouth rehabilitation treatment. Discussion: The rehabilitation of patients with extensive occlusal wear is complex and difficult to solve, becoming thus one of the biggest challenges of dentistry, a proper planning of a prosthetic rehabilitation should not attribute the re-establishing of occlusal vertical dimension (OVD) to new prostheses at the risk of the patient doesn’t adapt to a new condition of vertical dimension. Conclusion: Tooth wear causes dimensional changes in facial morphology and OVD decrease. The correct determination of occlusal vertical dimension represents a factor of success in the rehabilitation treatment. Keywords: Vertical Dimension, Rehabilitation, Full Mouth, Bruxism.

Impact of orthodontic-induced facial morphology changes on aesthetic evaluation: a retrospective study

BackgroundThe profound influence of orthodontic treatments on facial aesthetics has been a topic of increasing interest. This study delves into the intricate interplay between orthodontic treatments, facial feature alterations, and aesthetic perceptions.MethodsA total of 73 patients who had undergone orthodontic treatment were included in this study. Facial photographs were taken before and after treatment. Ten orthodontists provided facial aesthetic ratings (FAR) for each patient's frontal, profile, and overall views. 48 facial landmarks were manually placed by the orthodontists and normalized using Generalized Procrustes analysis (GPA). Two types of phenotypes were derived from facial landmarks. Global facial phenotypes were then extracted using principal component analysis (PCA). Additionally, 37 clinical features related to aesthetics and orthodontics were extracted. The association between facial features and changes in FAR after orthodontic treatment was determined using these two types of phenotypes.ResultsThe FAR exhibited a high correlation among orthodontic experts, particularly in the profile view. The FAR increased after orthodontic treatment, especially in profile views. Extraction of premolars and orthognathic surgery were found to result in higher FAR change. For global facial phenotypes, the most noticeable changes in the frontal and profile views associated with FAR occurred in the lip area, characterized by inward retraction of the lips and slight chin protrusion in the profile view, as well as a decrease in lip height in the frontal view. The changes observed in the profile view were statistically more significant than those in the frontal view. These facial changes were consistent with the changes from orthodontic treatment. For clinical features, two profile features, namely pg.sm.hori and pg.n.ls, were found to be associated with FAR following orthodontic treatment. The highest FAR scores were achieved when pg.sm.hori was at 80° and pg.n.ls was at 8°. On the other hand, frontal clinical features had a subtle effect on FAR during orthodontic treatment.ConclusionsThis study demonstrated that orthodontic treatment improves facial aesthetics, particularly at lip aera in the profile view. Profile clinical features, such as pg.sm.hori and pg.n.ls, are essential in orthodontic treatment which could increase facial aesthetics.

Assessment of the Cosmetic Effect of Eye Bag Surgery on Facial Morphology Changes

Assessment of the Cosmetic Effect of Eye Bag Surgery on Facial Morphology Changes

Photometric analysis of the relationship between craniovertebral angle and facial profile in children aged 10–12 years

BackgroundHead posture deviation is seen in 52.5 % of children aged 6–15 years. Studies have shown that poor posture habits can impair muscle function during craniofacial growth and development. A muscle imbalance causes abnormal positioning of dental and skeletal structures, a condition that exerts negative impacts, such as changes in facial morphology. ObjectiveTo determine through photometric analysis the relationship between craniovertebral angle as a function of head posture and glabella-subnasale-pogonion (G-Sn-Pg) angle as a function of facial profile in 10–12-year-old children, and the results will help to avoid facial development issues. MethodsThirty-three subjects met the inclusion criteria. Their craniovertebral angles and facial profiles were measured using lateral photometry and ImageJ. The craniovertebral angle was determined by connecting the tragus and C7 with a horizontal line, whereas the facial profile angle was determined by connecting the glabella, subnasale, and pogonion. The relationship between the craniovertebral and G-Sn-Pg angle values was analyzed using the Pearson correlation test. ResultsA significant relationship was observed between the craniovertebral angle and the G-Sn- Pg angle (p < 0.05), although such a relationship was weak (r = 0.373). ConclusionA more forward head posture is associated with a more convex facial profile, and this relationship is useful for the early prevention and treatment.

The combined application of bleomycin with triamcinolone acetonide in port wine stains: inhibiting proliferation and recurrence of port wine stains

BackgroundPort wine stains slowly grow thicker over time, nodules appear on the surface, and the color slowly deepens from pink to purple. Even after laser treatment, some port wine stains will recur and slowly grow, and the erythema appears again. The purpose of this study was to investigate the effectiveness of bleomycin in combination with triamcinolone acetonide in the treatment of inhibiting the proliferation and recurrence of port wine stains.ResultsHistopathological change: Before treatment, dense capillaries were distributed within the lesion, and blood fills the lumen. Lack of normal skin structure: After bleomycin and triamcinolone acetonide injection, the number of capillaries was significantly reduced, and fibrosis occurred in tissues. Changes in facial morphology: After treatment, the port wine stains became thinner, the asymmetry of the face was effectively improved, and the appearance have been significantly improved. After 5 years of follow-up, there were no recurrent cases.ConclusionBleomycin and triamcinolone acetonide injection can effectively inhibit the proliferation of port wine stains and prevent port wine stains from recurring after treatment.

Perception gap of aged facial appearance; self-perception is younger than actual status due to angle of viewing.

Facial morphology changes with aging, resulting in an aged appearance that is a great matter of concern for people. However, it is not clear whether people perceive their own facial appearance accurately, in part because there are few methods to evaluate this. The aim of this study is firstly to establish an evaluation system for the perception gap of aged facial appearance between the self-perceived status and the actual status, and then to use this evaluation system to quantify the perception gap and to clarify the mechanism of this gap METHOD: Thirty-six middle-aged female volunteers were first asked to rate their facial aging-related morphology according to a 6-grade set of photos taken at a 45° angle from the front showing progressive stages of sagging severity, without looking either in a mirror or at photos of themselves (self- or "subjective" perception). Then they were shown photos of their face taken at a 45° angle from the front, and asked again to rate their sagging grade based on these photos ("objective" rating). In addition, facial photos taken from several angles from the front to the side were evaluated for sagging severity by trained evaluators. This system for analyzing perception gap revealed that the self-perception of aged appearance was significantly younger than the actual situation in three facial areas, namely the cheek, around the eyes and the facial contour, and the gap corresponded to an age difference of as much as 8 years in middle-aged females. Trained evaluators found that the severity of sagging judged from photos taken from a frontal direction was significantly less than in photos of the same subject taken from side angles. This suggests that recognition of sagging is more difficult from the front, which is the direction from which people view their own face in daily life. Indeed, viewing photos taken from the side, a rare viewing angle of one's own face, increased the motivation to improve aged appearance in more than 70% of the subjects in a questionnaire survey. The results suggest that people perceive their own facial appearance as less aged than it actually is. The reason for this appears to be that viewing from the front, the usual viewing angle of one's own face in daily life, results in lower perceived sagging severity, likely due to reduced depth perception.

ZFACE: facial analytics from a coordinate extrapolation system for morphometric phenotyping of developing zebrafish.

Facial development requires a complex and coordinated series of cellular events, that when perturbed, can lead to structural birth defects. A quantitative approach to quickly assess morphological changes could address how genetic or environmental inputs lead to differences in facial shape and promote malformations. Here we report on a method to rapidly analyze craniofacial development in zebrafish embryos using Facial Analytics based on a Coordinate Extrapolation system, termed zFACE. Confocal images capture facial structures and morphometric data is quantified based on anatomical landmarks present during development. The quantitative morphometric data can detect phenotypic variation and informs on changes in facial morphology. We applied this approach to show that loss of smarca4a in developing zebrafish leads to craniofacial anomalies, microcephaly and alterations in brain morphology. These changes are characteristic of Coffin-Siris syndrome (CSS), a rare human genetic disorder associated with mutations in SMARCA4. Multivariate analysis of zFACE data facilitated the classification of smarca4a mutants based on changes in specific phenotypic characteristics. Together, zFACE provides a way to rapidly and quantitatively assess the impact of genetic alterations on craniofacial development in zebrafish.

Predicting the Future Appearances of Lost Children for Information Forensics with Adaptive Discriminator-Based FLM GAN

This article proposes an adaptive discriminator-based GAN (generative adversarial network) model architecture with different scaling and augmentation policies to investigate and identify the cases of lost children even after several years (as human facial morphology changes after specific years). Uniform probability distribution with combined random and auto augmentation techniques to generate the future appearance of lost children’s faces are analyzed. X-flip and rotation are applied periodically during the pixel blitting to improve pixel-level accuracy. With an anisotropic scaling, the images were generated by the generator. Bilinear interpolation was carried out during up-sampling by setting the padding reflection during geometric transformation. The four nearest data points used to estimate such interpolation at a new point during Bilinear interpolation. The color transformation applied with the Luma flip on the rotation matrices spread log-normally for saturation. The luma-flip components use brightness and color information of each pixel as chrominance. The various scaling and modifications, combined with the StyleGan ADA architecture, were implemented using NVIDIA V100 GPU. The FLM method yields a BRISQUE score of between 10 and 30. The article uses MSE, RMSE, PSNR, and SSMIM parameters to compare with the state-of-the-art models. Using the Universal Quality Index (UQI), FLM model-generated output maintains a high quality. The proposed model obtains ERGAS (12 k–23 k), SCC (0.001–0.005), RASE (1 k–4 k), SAM (0.2–0.5), and VIFP (0.02–0.09) overall scores.

Changes in Cat Facial Morphology Are Related to Interaction with Humans.

We aimed to clarify the changes in facial morphology of cats in relation to their interactions with humans. In Study 1, we compared the facial morphology of cats (feral mixed breed, owned domestic mixed breed, and owned domestic purebreds) with that of African wildcats. After collecting 3295 photos, we found that owned domestic cats' noses were significantly shorter than those of African wildcats and feral mixed breed, and there were no significant differences between the latter two. The eye angles were significantly more gradual in owned domestic purebreds than in the other groups. In Study 2, we examined the correlation between facial morphology and years with the owner, and found that the former is not affected by the latter. This suggests that changes in facial morphology are possibly transgenerational changes. The difference in facial morphology between wildcats and owned cats might be caused by domestication, and that between feral cats and owned cats might be due to feralization. In Study 3, we investigated whether cats' facial features affect cuteness ratings. We asked human participants to evaluate the cuteness of cats' face images and found that faces with shorter nose lengths were considered cuter. This suggests that owned domestic cats' facial morphology is preferred by humans.

Fat infiltration into dermal layer induces aged facial appearance by decreasing dermal elasticity.

Facial morphology changes with aging, producing an aged appearance, but the mechanisms involved are not fully established. We recently showed that subcutaneous fat infiltrates into the dermal layer with aging, but it is not yet clear whether and how this drastic change of the dermal layer influences facial appearance. We aimed to establish the role of fat infiltration in producing an aged facial appearance and to clarify the mechanism involved. We analyzed the severity of fat infiltration in cheek skin of 30 middle-aged female volunteers by means of ultrasonography. Severity of the nasolabial fold, an established age-related morphology, was evaluated based on our photographic grading criteria as a measure of aged appearance. Skin elasticity was measured with a Cutometer. Fat infiltration to the dermal layer was detected at the cheek skin noninvasively by means of ultrasonography. Fat infiltration severity, measured as the minimum depth of the fat inside the dermal layer from the skin surface, was positively correlated with the magnitude of the nasolabial fold. Further, fat infiltration severity was significantly negatively correlated with dermal elasticity. Our results suggest that fat infiltration into the dermal layer is a critical factor inducing aged appearance of the face. The infiltrated fat decreases the dermal elasticity, which exacerbates nasolabial folds, namely producing an aged facial appearance.

Psychosocial Maternal Perception of the Outcome of Pre Surgical Infant Orthopedics in Infants Born with Cleft Lip and Palate.

The setback of having a child with cleft lip and palate deeply affects the parents psychology. The Pre Surgical Infant Orthopaedics(PSIO) is a promising procedure for improvement in facial morphology prior to primary lip repair. The current study examines the perception of effects of PSIO procedures on the facial appearance of newborns with cleft lip/palate by their mothers and finds its correlation if any, with the change in psychosocial status of the mothers. The mothers of 50 infants(0-6 months) born with cleft lip/palate rated the nasal morphology, extent of cleft defect and overall facial morphology on a Likert's scale before and after PSIO procedure. This was correlated with changes in mother's depression, anxiety and stress levels by using the validated Hindi-version of Depression Anxiety and Stress scale(DASS-42) index before and after PSIO. The mothers reported a significant improvement in all the morphological parameters for their infants with PSIO which correlated well with significant reduction in the DASS scores from 22.54(severe) to 7.10(normal) for depression, 20.64(extremely severe) to 6.46(normal) for anxiety and 24.7(severe) to 8.4(normal) for stress. The changes in facial morphology by PSIO procedures are well perceived by mothers and significantly improves their depression, anxiety and stress levels.

Wnt Signaling Drives Correlated Changes in Facial Morphology and Brain Shape.

Canonical Wnt signaling plays multiple roles critical to normal craniofacial development while its dysregulation is known to be involved in structural birth defects of the face. However, when and how Wnt signaling influences phenotypic variation, including those associated with disease, remains unclear. One potential mechanism is via Wnt signaling’s role in the patterning of an early facial signaling center, the frontonasal ectodermal zone (FEZ), and its subsequent regulation of early facial morphogenesis. For example, Wnt signaling may directly alter the shape and/or magnitude of expression of the sonic hedgehog (SHH) domain in the FEZ. To test this idea, we used a replication-competent avian sarcoma retrovirus (RCAS) encoding Wnt3a to modulate its expression in the facial mesenchyme. We then quantified and compared ontogenetic changes in treated to untreated embryos in the three-dimensional (3D) shape of both the SHH expression domain of the FEZ, and the morphology of the facial primordia and brain using iodine-contrast microcomputed tomography imaging and 3D geometric morphometrics (3DGM). We found that increased Wnt3a expression in early stages of head development produces correlated variation in shape between both structural and signaling levels of analysis. In addition, altered Wnt3a activation disrupted the integration between the forebrain and other neural tube derivatives. These results show that activation of Wnt signaling influences facial shape through its impact on the forebrain and SHH expression in the FEZ, and highlights the close relationship between morphogenesis of the forebrain and midface.

Soft tissue facial changes among adult females during alignment stage of orthodontic treatment: a 3D geometric morphometric study

BackgroundTo investigate changes in facial morphology during the first six months of orthodontic treatment among adult females receiving orthodontic treatment.Methods43 adult females receiving orthodontic treatment were randomly recruited. 3D facial images were taken at baseline (T0), three months (T1), and six months (T2) after treatment initiation. Spatially dense facial landmarks were digitized to allow for sufficient details in characterization of facial features. 3D geometric morphometrics and multivariate statistics were used to investigate changes in mean and variance of facial shape and facial form associated with treatment.ResultsWe observed statistically significant changes in facial shape across the three treatment stages (p = 0.0022). Pairwise comparisons suggested significant changes from T0 to T1 (p = 0.0045) and from T0 to T2 (p = 0.0072). Heatmap visualization indicated that the buccal and temporal region were invaginated while the labial region became protruded with treatment. The magnitude of shape change was 0.009, 0.004, and 0.010 from T0 to T1, T1 to T2, and T0 to T2, respectively, in unit of Procrustes distance. The average magnitude of change per-landmark was 1.32 mm, 0.21 mm, and 1.34 mm, respectively. Changes in mean facial form were not statistically significant (p = 0.1143). No changes in variance of facial shape were observed across treatment stages (p > 0.05).ConclusionRate of facial changes was twice as fast during the first three months as that during fourth to sixth month. Buccal and temporal region became invaginated while labial region became protruded with treatment.

Considerations in occlusal vertical dimension rehabilitation

The vertical dimension is one of the important aspects that affect facial appearance, because it is related in facial height ratio. The vertical occlusal dimension is the height of the lower face measured from two points (infra-nasal and gnation points) when the maxillary and mandibular teeth were occlusion in the maximum intercuspal position. In complex cases, tooth wear can result in a decrease in facial height because the predominant wear on the anterior teeth encourages downward movement of the condyles when the intercuspal is maximum so that the vertical di-mension decreases. In addition, factors that cause a decrease in the vertical dimension are loss of posterior teeth accompanied by skeletal disharmony or accompanied by tooth abrasion and migration. The purpose of this paper is to explain how to restore the decreased occlusal vertical dimensions. Things that need to be considered are di-vided into two, extraorally and intraorally. Extraoral considerations are in the form of a large reduction in OVD, fa-cial esthetics and conditions of the temporomandibular joint. The parameters considered intraoral were the remain-ing tooth structure and occlusion. It was concluded that tooth wear due to functional and parafunctional activities can result in dimensional changes in facial morphology as well as a decrease in the occlusal vertical dimension. Correct OVD rehabilitation is an important factor in the success of rehabilitation treatment.

A Cross-Sectional Study to Understand 3D Facial Differences in a Population of African Americans and Caucasians.

Objective The purpose of this cross-sectional retrospective study was to use three-dimensional surface imaging to determine gender dimorphism and facial morphological changes from adolescence to adulthood in African American and Caucasian populations. Materials and Methods Three-dimensional images were captured and the total sample size included 371 subjects. Images were combined using Rapidform 2006 Plus Pack 2 software to produce a male and female facial average for each population. Comparisons were conducted within the following categories: (1) gender comparison within each race, (2) adult and adolescent comparison within each race, and (3) adult and adolescent comparison between the races. Results Adolescent gender comparisons within each race showed high percentages of similarity. However, adult females in both races showed more prominent periorbital, malar, and nasolabial regions and less prominent lower forehead, nose, and lower face compared with adult males of the same race. African American adult females showed increase in length and width of the face, increased nasal tip projection, and decreased periorbital regions compared with African American adolescent females. Welsh adult females had an increase in the nose and chin projection compared with Welsh adolescent females. Adult males of both races had increase in nose and chin projection, increase in length and width of the face, and decreased periorbital, malar, and nasolabial regions compared with adolescent males of the same race. African American adolescents had a wider alar base, more protrusive lips, and periorbital regions, and less prominent nose and chin compared with the Welsh adolescents. African American adults also had a wider alar base; more protrusive lips and periorbital regions; a broader face; and more retrusive chin, nose, nasolabial region; and lower forehead compared with Welsh adults. Conclusions Few differences were noted between genders within the same racial groups during adolescence. However, changes became more distinct in adulthood. From adolescence to adulthood, facial morphologies were similarly matched within the gender for females; however, there were significant changes for males. Lastly, facial morphology patterns tend to be established early in life.

Developmental shape changes in facial morphology: Geometric morphometric analyses based on a prospective, population-based, Chinese cohort in Hong Kong.

BackgroundThorough understanding of developmental changes of human facial shape is lacking. The present study aimed to evaluate developmental shape changes of facial morphology based on a prospective, population-representative, Chinese cohort in Hong Kong.MethodsA population-representative sample of Chinese in Hong Kong was followed. Serial facial images of over 260 participants were obtained at age 12, 15, and 18 years. Facial landmarks were digitized and the corresponding coordinates were submitted for Generalized Procrustes Analysis. The resultant Procrustes shape coordinates, which captured shape information encoded by the facial landmarks, were then used for statistical shape analyses.ResultsSmall but significant developmental changes in mean facial shape were observed (p < 0.0001 for all pairwise comparisons). Significant age-related changes in the magnitude of variance of facial shape were also observed (p < 0.05). Phenotypic growth trajectories representing developmental shape changes were similar in size (p > 0.05) between sexes but differed in direction (p < 0.05) in shape space and trajectory shape (p < 0.05). The magnitude of shape differences between sexes remained constant from 12 to 18 years. Results of frontal facial shape analyses after removing the effect of allometry were similar to results obtained before removal of allometry. For lateral facial configurations, allometric trajectories among the age-by-sex groups were similar in slope (p > 0.05) but varied in directions in the multidimensional shape space.ConclusionsOur findings suggested significant age-related changes in facial shape and provided a dynamic view of developmental changes in sexual dimorphism of facial shape. Allometry contributed minimally to developmental changes in frontal facial shape. In addition, the allometric trajectories for lateral facial configurations were similar in rate of shape change but differed in their directions in shape space.

Anthropocephalometric Aspects of Frontoethmoid Encephalocele Patients

Frontoethmoid encephalocele (FEE) causes maxillofacial structural abnormalities and also covers some bony landmarks, especially in the glabella region. This study examined the faces of frontoethmoid encephalocele patients before undergoing corrective surgery with the aim of identifying and assessing their facial morphological differences. This was a cross-sectional study from January 1, 2016 to June 31, 2017. A simple anthropocephalometric measurement was performed on the patient's face who would undergo surgery. Periorbital and mid-face measurements showed differences between the patients and normal groups. The midface structure of the patients clearly changed. The age when the procedure was taken also had effect. Preoperative 3DCT is proposed to describe the facial anatomy of EFE patients. Further studies in this field are suggested to produce a comprehensive database of facial morphology changes in FEE populations, both pre- and post-operatively, with the intention of producing a redefinition of FEE cases based on anthropo-cephalometric principles.

Growing patients with Duchenne muscular dystrophy: longitudinal changes in their dentofacial morphology and orofacial functional capacities.

The aim of this study was to describe the longitudinal changes in facial morphology, dental arch alterations and oral functional capacities that occur in growing patients with Duchenne muscular dystrophy (DMD) in order to identify the effects of the progression of the disease. Twelve DMD patients (6.5-17.5 years of age) and 12 matched controls were screened on two different occasions (T1 and T2), 2 years apart. Dental casts, lateral cephalometric radiographs, maximal posterior bite force and labial force were measured to determine changes in their functional capacities and dentofacial morphology. Furthermore, the thickness and echogenicity of the masseter muscle were measured during clenching. Unpaired t-tests were performed to evaluate the differences between the DMD patients and their healthy matched controls; paired t-tests were used to assess the changes that occurred within each group between T1 and T2. Between T1 and T2 the following changes were observed: widening of the lower dental arch for the DMD patients of 2.6mm (±0.9mm) compared to a slight reduction of -0.1mm (±0.8mm) for the control group (P = 0.001). We found a statistically significant reduction of the sagittal skeletal intermaxillary relationship (ANB-angle) of 2.0° (±2.0°) in the DMD group (P = 0.012). In T1 and T2, the maximal posterior bite force and the labial force were lower for the DMD patients compared to the control group (P = 0.001), who showed an increase during this period. The results indicate that DMD influences the facial morphology, dental arch dimensions and oral functional capacities. The longitudinal perspective of this study revealed that the worsening of most of the measured parameters is associated with the progression of the disease. Besides the expected deterioration of the functional measurements, we found in all patients, a marked transverse increase of the posterior part of the dental arches, more in the lower than in the upper, resulting in posterior crossbites, as well as a tendency towards a skeletal Class III relationship.

Analysis of morphological changes after facial massage by a novel approach using three-dimensional computed tomography.

Photograph-based visual scoring has been used for evaluation of facial morphological changes. Here, we describe a three-dimensional computed tomography (3D-CT) method for objective analysis of facial and intra-facial (subcutaneous) changes. The effects of facial massage were examined using both methods. Subjects were 12 healthy female volunteers without facial scars or deformation (age 30-54 years, mean 39.4 years). Photograph-based scoring of massage-induced morphological changes was done at the nasolabial folds, upper, lower and lateral cheeks and lower eyelids. For 3D-CT evaluation, the virtual center axis (VCA) was set as the cranio-caudal longitudinal line, and the VCA-skin surface distances (VSDs) were measured. Massage-induced changes of VSD were calculated (facial massage-induced change rate, FMCR). Intra-facial (subcutaneous) changes were also evaluated. Photograph-based scoring revealed marked morphological changes of the nasolabial folds after facial massage, and changes of the lower, upper and lateral cheeks and lower eyelid were also observed in more than half of the subjects. FMCR values were significantly changed in the paranasal area, nasolabial fold area and cranial part of the mandibular area. Photograph-based scores at the lower cheek and lower eyelid were well correlated with FMCR in the inferior part of the nasolabial fold and the mandibular area, respectively. Massage-induced changes of subcutaneous fat tissues and facial expression muscles were also apparent on CT images. 3D-CT imaging is useful for objective evaluation of the effects of facial massage, including anatomical changes in subcutaneous structures.

New beaked whales from the late Miocene of Peru and evidence for convergent evolution in stem and crown Ziphiidae (Cetacea, Odontoceti).

The Ziphiidae (beaked whales) represent a large group of open-ocean odontocetes (toothed cetaceans), whose elusive and deep diving behavior prevents direct observation in their natural habitat. Despite their generally large body size, broad geographical distribution, and high species number, ziphiids thus remain poorly known. Furthermore, the evolutionary processes that have led to their extreme adaptations and impressive extant diversity are still poorly understood. Here we report new fossil beaked whales from the late Miocene of the Pisco Formation (southern Peru). The best preserved remains here described are referred to two new genera and species, the Messinian Chavinziphius maxillocristatus and the Tortonian Chimuziphius coloradensis, based on skull remains from two marine vertebrate-rich localities: Cerro Los Quesos and Cerro Colorado, respectively. C. maxillocristatus is medium sized retains a complete set of functional lower teeth, and bears robust rostral maxillary crests similar to those of the extant Berardius. By contrast, C. coloradensis is small and characterized by large triangular nasals and moderately thickened premaxillae that dorsally close the mesorostral groove. Both species confirm the high past diversity of Ziphiidae, the richest cetacean family in terms of the number of genera and species. Our new phylogenetic and biogeographical analyses depart markedly from earlier studies in dividing beaked whales into two major clades: the Messapicetus clade, which, along with other stem ziphiids, once dominated the southeastern Pacific and North Atlantic; and crown Ziphiidae, the majority of which are found in deep-water regions of the Southern Ocean, with possible subsequent dispersal both globally (Mesoplodon and Ziphius) and to the cooler waters of the northern oceans (Berardius and Hyperoodon). Despite this relatively clear separation, both lineages seem to follow similar evolutionary trends, including (1) a progressive reduction of dentition; (2) an increase in the compactness and thickness of the rostral bones; (3) similar changes in facial morphology (e.g., elevation of the vertex); and (4) an increase of body size. We suggest that these trends may be linked to a convergent ecological shift to deep diving and suction feeding.