Displasia fibrosa maxilar. Del diagnóstico al tratamiento. Reporte de caso / Maxillary fibrous dysplasia. From diagnosis to treatment: Case report / Displasia fibrosa maxilar. Do diagnóstico ao tratamento: Relato de caso

La displasia fibrosa se puede presentar, en cualquier persona, por una mutación en los primeros meses de gestación. Se trata de lesiones óseas benignas en pacientes jóvenes, en las que el tejido óseo normal es sustituido por tejido conectivo fibroso, debido a una alteración funcional de las células, siendo esta la antesala de una neoplasia. El objetivo de éste artículo es presentar un caso local de Displasia Fibrosa Maxilar, enfatizando el manejo clínico, radiográfico, pre y postoperatorio más pertinente. Por lo tanto, se describe el caso de un paciente adolescente de género masculino, afectado por displasia fibrosa en hemimaxilar derecho, a quien le fueron realizados los estudios imagenológicos e histopatológicos necesarios para obtener el diagnóstico definitivo y decidir el abordaje menos invasivo posible cumpliendo con estándares de estética facial; se realizó abordaje intrabucal para shaving óseo, con sedación consciente bajo estricta vigilancia de la especialista en anestesiología y reanimación. Una vez logrado el contorno deseado mediante el uso de piezas de mano de alta y baja velocidad, se realizó la sutura de los tejidos y el paciente egresó ambulante y con buen estado general de salud.

Fibrous dysplasia can occur in any person due to a mutation in the first months of gestation. These are benign bone lesions in young patients, in which the normal bone tissue is replaced by fibrous connective tissue, due to a functional alteration of the cells, being this the prelude to a neoplasm. The aim of this article is to present a local case of Maxillary Fibrous Dysplasia, emphasizing the most relevant clinical, radiographic, pre and postoperative management. Therefore, we describe the case of an adolescent male patient, affected by fibrous dysplasia in the right hemimaxillary, who underwent the necessary imaging and histopathological studies to obtain the definitive diagnosis and decide the least invasive approach possible in compliance with facial aesthetic standards; an intraoral approach was performed for bone shaving, with conscious sedation under strict supervision of the specialist in anesthesiology and resuscitation. Once the desired contour was achieved through the use of high and low speed handpieces, the tissues were sutured and the patient was discharged ambulatory and in good general health.

A displasia fibrosa pode ocorrer em qualquer pessoa devido a uma mutação nos primeiros meses de gestação. São lesões ósseas benignas em pacientes jovens, nas quais o tecido ósseo normal é substituído por tecido conjuntivo fibroso, devido a uma alteração funcional das células, sendo esse o prelúdio de uma neoplasia. O objetivo deste artigo é apresentar um caso local de Displasia Fibrosa Maxilar, enfatizando o manejo clínico, radiográfico, pré e pós-operatório mais pertinente. Portanto, descrevemos o caso de um paciente adolescente do sexo masculino, afetado por displasia fibrosa no hemimaxilar direito, que foi submetido aos exames de imagem e histopatológicos necessários para obter um diagnóstico definitivo e decidir sobre a abordagem menos invasiva possível, em conformidade com os padrões estéticos faciais; foi realizada uma abordagem intraoral para raspagem óssea, com sedação consciente sob estrita supervisão do especialista em anestesiologia e ressuscitação. Depois que o contorno desejado foi obtido com o uso de peças de mão de alta e baixa velocidade, os tecidos foram suturados e o paciente recebeu alta ambulatorial em bom estado geral de saúde.

Pampean megamammals in Europe: the fossil collections from Santiago Roth.

Santiago Roth was a Swiss fossil finder, naturalist, and paleontologist that emigrated to Argentina in 1866. His work largely influenced the discipline in the country at the end of the twentieth century, particularly the stratigraphy of the Pampean region. Some of his collections of Pampean fossils were sold to museums and private collectors in Europe and were accompanied by elaborated catalogues. Fossils in the Roth's catalogues N° 2 and 3 are housed today in the Natural History Museum of Denmark, fossils from catalogues N° 4 to 6, were sold to Swiss museums, with Catalogue N° 5 currently housed at the Department of Paleontology, Universität Zürich. Here, we provide a general framework on the stratigraphy from the Roth's Pampean fossil sites, summarize the history of the Pampean fossils in Europe originally collected by Roth, and provide historical and curatorial details of the Roth's collection at the Department of Paleontology, Universität Zürich. Supplementary Information: The online version contains supplementary material available at 10.1186/s13358-023-00283-5.

Santiago Roth fue un buscador de fósiles, naturalista y paleontólogo suizo que emigró a la Argentina en 1866. Su obra influyó en gran medida en la disciplina del país a fines del siglo XX, con algunos aportes que son pilares, en particular aquellos para la comprensión de la estratigrafía de la Región Pampeana. Algunas de sus colecciones de fósiles pampeanos fueron vendidas a museos y coleccionistas privados en Europa y estaban acompañadas de catálogos elaborados. Los fósiles de los catálogos N° 2 y 3 de Roth se encuentran hoy en el Museo de Historia Natural de Dinamarca, los fósiles de los catálogos N° 4 a 6 fueron vendidos a museos suizos, mientras que el Catálogo N° 5 en particular está alojado actualmente en el Departamento de Paleontología, Universidad de Zurich. Aquí proporcionamos un marco general sobre la estratigrafía de los sitios de los fósiles pampeanos de Roth, resumimos la historia de los fósiles pampeanos en Europa colectados originalmente por Roth y brindamos detalles históricos y curatoriales de la colección de Roth del Departamento de Paleontología, Universidad de Zurich.

Pliocene sigmodontine rodents (Mammalia: Cricetidae) in northernmost South America: test of biogeographic hypotheses and revised evolutionary scenarios.

We document the first occurrence of Sigmodontinae (Mammalia, Rodentia, Cricetidae) from the Pliocene of northern South America, from the San Gregorio Formation of northwestern Venezuela. The recovered isolated molars are identified as Oligoryzomys sp. and Zygodontomys sp., two currently widespread sigmodontines in South America. These records constitute the oldest representatives of these genera, potentially new species, and the first Pliocene occurrence for Oryzomyini and the whole subfamily outside Argentina. Hypotheses on the historical biogeography of sigmodontines have been constructed almost exclusively using genetic data and the fossils we report provide a new kind of evidence. The occurrence of Oligoryzomys sp. and Zygodontomys sp. in Venezuela provides novel information for the diversification models suggested for Oligoryzomys, by supporting a potential eastern corridor of open environments from northern to southern South America. The presence of sigmodontines from the locality home of the new reports, Norte Casa Chiguaje, is consistent with the palaeoenvironmental conditions originally proposed for it based on mammals and botanical records, being characterized as mixed open grassland/forest areas surrounding permanent freshwater systems. The new sigmodontine evidence is used to discuss the putative scenarios of the ancient evolution of the subfamily in South America, favouring a model in which open areas (savannahs) to the east of the Andes played crucial role aiding or obstructing Late Miocene-Pliocene sigmodontine dispersion southwards.

Sperm whales (Physeteroidea) from the Pisco Formation, Peru, and their trophic role as fat sources for late Miocene sharks.

Shark-cetacean trophic interactions, preserved as bite marks in the fossil record, mostly correspond to isolated or fragmentary findings that bear limited information about major trophic patterns or roles. Here, we provide evidence of focalized foraging by sharks in the form of tooth bite marks over physeteroids fossil bones from the late Miocene of Peru. These findings indicate that sharks were targeting the forehead of coeval physeteroids to actively feed on their lipid-rich nasal complexes. Miocene physeteroids displayed a broad diversity, including giant predatorial forms, small benthic foragers and suction feeders. Like their extant relatives, these animals exhibited enlarged fatty forehead organs responsible for their sound production capabilities, thus evolving taxon-specific cranial architecture. Bite marks are found on the cranial bones where these structures were attached, indicating that sharks actively targeted this region; but also, in areas that would only be accessible following the consumption of the surrounding soft tissues. The shape of the bite marks and their distribution suggests a series of consecutive scavenging events by individuals of different shark species. Similar bite patterns can be recognized on other Miocene physeteroids fossils from across the globe, suggesting that sharks actively exploited physeteroid carcasses as fat sources.

A new hybodontiform shark (Strophodus Agassiz 1838) from the Lower Cretaceous (Valanginian-Hauterivian) of Colombia.

The vertebrate marine faunas that inhabited northern South America during the Cretaceous are still poorly known. This study is a contribution to a growing wave of new studies on Lower Cretaceous vertebrates from Colombia. Here we report and describe a new species of a hybodontiform shark of the genus Strophodus, which we named Strophodus rebecae sp. nov., based on isolated teeth, that were collected in Valanginian-Hauterivian rocks of the Rosa Blanca Formation (Carrizal and El Sapo Members) near the town of Zapatoca, Santander Department, Andes of Colombia. In addition, we describe two other fragmented teeth assigned to Strophodus sp. from the Rosa Blanca Fm. The new species from Colombia represents the only Cretaceous record of Strophodus from Gondwana, offering new insights into the paleogeographic distribution of the genus, as well as increasing the knowledge about the scarce hybodontiform paleodiversity known from South America. The presence of Strophodus in the Rosa Blanca Formation suggests that these durophagous (shell-crushing) fishes played an important role as predators of the abundant and diverse invertebrate fauna present in these ancient tropical coastal ecosystems of Gondwana.

A fossil assemblage from the mid-late Maastrichtian of Gavdos Island, Greece, provides insights into the pre-extinction pelagic ichthyofaunas of the Tethys.

The global body-fossil record of marine 'fishes' from the time interval immediately preceding the Cretaceous-Paleogene Extinction is markedly poor. This deficiency appears to be further exacerbated with regards to offshore and deep-water taxa, obscuring our understanding of the state and composition of corresponding vertebrate faunas at the onset of this major extinction event. Recent fieldwork in the mid-late Maastrichtian exposures of the Pindos Unit in Gavdos Island, Greece, yielded a small but informative sample of fossil 'fishes', which inhabited the Tethys approximately three to four million years before the extinction. In this work we describe this sample, which comprises between eight and nine discrete morphotypes of various size classes, belonging to †Ichthyodectoidei, Aulopiformes (†Dercetidae, †Enchodontidae, †Ichthyotringidae), cf. †Sardinioididae, as well as the hexanchid shark †Gladioserratus sp. The new material expands the faunal list for the Maastrichtian of Gavdos Island, and the Pindos Unit as a whole, and further allows for the description of a new genus and species of †Enchodontidae and a new species of †Ichthyotringidae. The two new taxa are found to be widespread in the Maastrichtian of the Pindos Unit. The overall character of the assemblage agrees with previous interpretations of an offshore and rather deep depositional environment for the fossiliferous horizons. Furthermore, it exhibits a higher diversity than, and little taxonomic overlap with penecontemporaneous teleost assemblages from the Tethys, and informs on the otherwise poorly known Maastrichtian offshore and deep-water marine ichthyofaunas of the region.

A Pliocene-Pleistocene continental biota from Venezuela.

The Pliocene-Pleistocene transition in the Neotropics is poorly understood despite the major climatic changes that occurred at the onset of the Quaternary. The San Gregorio Formation, the younger unit of the Urumaco Sequence, preserves a fauna that documents this critical transition. We report stingrays, freshwater bony fishes, amphibians, crocodiles, lizards, snakes, aquatic and terrestrial turtles, and mammals. A total of 49 taxa are reported from the Vergel Member (late Pliocene) and nine taxa from the Cocuiza Member (Early Pleistocene), with 28 and 18 taxa reported for the first time in the Urumaco sequence and Venezuela, respectively. Our findings include the first fossil record of the freshwater fishes Megaleporinus, Schizodon, Amblydoras, Scorpiodoras, and the pipesnake Anilius scytale, all from Pliocene strata. The late Pliocene and Early Pleistocene ages proposed here for the Vergel and Cocuiza members, respectively, are supported by their stratigraphic position, palynology, nannoplankton, and 86Sr/88Sr dating. Mammals from the Vergel Member are associated with the first major pulse of the Great American Biotic Interchange. In contrast to the dry conditions prevailing today, the San Gregorio Formation documents mixed open grassland/forest areas surrounding permanent freshwater systems, following the isolation of the northern South American basin from western Amazonia. These findings support the hypothesis that range contraction of many taxa to their current distribution in northern South America occurred rapidly during at least the last 1.5 million years.

Equatorial pliosaurid from Venezuela marks the youngest South American occurrence of the clade.

Pliosaurids were the dominant macropredators in aquatic environments at least since the Middle Jurassic until their extinction in the early Late Cretaceous. Until very recently, the Cretaceous record of Pliosauridae has been poor and difficult to interpret from the taxonomic and phylogenetic perspective. Despite that the knowledge of Cretaceous pliosaurids improved in recent years, numerous aspects of their evolutionary history still remain only poorly known. Here, we report the first pliosaurid material from Venezuela. The taxon is most likely earliest Cenomanian in age, thus representing the youngest occurrence of Pliosauridae from South America. The Venezuelan taxon is based on a well-preserved tooth crown whose morphology and outer enamel structural elements appear to resemble especially those observable in the giant pliosaurid Sachicasaurus vitae from the Lower Cretaceous of Colombia. The new discovery extends the pliosaurid record on the continent by more than 10 million years and likely marks the southernmost Upper Cretaceous occurrence of Pliosauridae, worldwide. We also briefly discuss the affinities of the enigmatic Venezuelan elasmosaurid Alzadasaurus tropicus and highlight similarities to elasmosaurids from the Western Interior Seaway.

A stem delphinidan from the Caribbean region of Venezuela.

The dense Miocene record of cetaceans is known from localities along the coasts of all continents, mostly in the northern Atlantic or the eastern Pacific regions, but Antarctica. Fossils from the Caribbean region are few and include of a couple of findings from Panama and Venezuela. Here, we report a partly complete skull from the Caujarao Formation (middle Miocene), Falcon State, Caribbean region of Venezuela. Our phylogenetic analyses indicate that the Caujarao specimen is a 'stem delphinidan', a group that includes several taxa of early diverging odontocetes whose phylogenetic affinities remain a matter of debate. The fossil record has shown that this group of stem delphinidans was taxonomically diverse, but displayed a somewhat homogeneous cranial patterning, with most of the variations being found within the mandible or tympanoperiotic characters. As other stem delphinidans the Caujarao odontocete displays an enlarged temporal fossa and a fairly symmetrical cranium. Because the skull is missing several key diagnostic characters due to the preservation state of the specimen, a more precise taxonomic identification is not possible. Despite this, the finding of this specimen highlights the importance of the fossil record from the Neogene of Venezuela, and the importance of the area to understand cetacean evolution in the proto-Caribbean.

Anterior-Posterior (AP) Calcaneal Profile View: A Novel Radiographic Image to Assess Varus Malalignment.

BACKGROUND: Assessing and correcting malalignment is important when treating calcaneus fractures. The Harris axial view is commonly utilized to assess varus deformity but may be inherently inaccurate due to its tangential nature. The anterior-posterior (AP) calcaneal profile view is a novel radiographic view that is easily obtained with demonstrated increased accuracy for assessing calcaneal axial alignment. METHODS: Five nonpaired ankle cadaveric specimens were used in this investigation. Oblique osteotomies were created in relation to the long axis, and varus deformities were produced by inserting solid radiolucent wedges into the osteotomies to create models of 10, 20, and 30 degrees of angulation of the calcaneal tuberosity. Specimens were imaged using both the Harris axial view and the AP calcaneal profile view. RESULTS: For cadavers with 10 degrees of actual varus angulation, the mean Harris axial view angle and the AP calcaneal profile view angle were 10.9 ± 4.8 (range, 5.5-16.0) degrees and 13.0 ± 5.5 (range, 7.3-20.9) degrees, respectively. For cadavers with 20 degrees of actual varus angulation, the mean Harris view angle and the AP calcaneal profile view angle were 11.5 ± 2 (range, 8.2-13.6) degrees and 18.1 ± 4.8 (range, 11.7-23.5) degrees, respectively (P = .005). On pairwise comparison with Bonferroni correction, there was a significant difference between the Harris axial view angle and both the AP calcaneal profile view angle (P = .012) and actual angulation (P = .011). For cadavers with 30 degrees of actual varus angulation, the mean Harris axial view angle and the AP calcaneal profile view angle were 18.3 ± 4.3 (range, 13.3-23.6) degrees and 28.3 ± 2.9 (range, 24.4-31.1) degrees, respectively (P < .001). On pairwise comparison with Bonferroni correction, there was a significant difference between the Harris axial view angle and both the AP calcaneal profile view angle (P = .001) and actual angulation (P < .001). There was no significant difference between the AP calcaneal profile view angle and actual angulation (P > .999). CONCLUSION: The AP calcaneal profile view is a novel radiographic view that is easily obtained with demonstrated increased accuracy for assessing calcaneal axial alignment. While both views demonstrated similar measurement error for lesser degrees of varus malalignment, the AP calcaneal profile view demonstrated more accurate measurement of increasing heel varus compared with the Harris view. CLINICAL RELEVANCE: The AP calcaneal profile view could be used in addition to other radiographic views when treating displaced, intra-articular calcaneus fractures to help optimize correction of hindfoot alignment.

Diversity and paleoenvironmental implications of an elasmobranch assemblage from the Oligocene-Miocene boundary of Ecuador.

The occurrence and diversity of elasmobranchs from the Oligocene-Miocene boundary from Tropical America is poorly known in comparison with the paleodiversity from younger Neogene intervals of the region. Here we describe a new elasmobranch assemblage from the rich fossil site of Montañita-Olón (Dos Bocas Formation, Santa Elena, Ecuador), where other vertebrates have already been described: for example, sea turtles and cetaceans. We report a total of 27 elasmobranch taxa, 19 of which are new fossil records for Ecuador, 10 new records for the Central Eastern Pacific and four new records for South America. Additionally, in order to reconstruct the environment where these marine remains were deposited, we performed abundance, paleobathymetric and habitat preference analyses, concluding that they were likely deposited in an outer neritic (open shelf) environment. The study of Oligocene and early Miocene marine elasmobranchs faunas in Tropical America is key to addressing the issues in the evolutionary history of this group.

Peri-implant fractures around hindfoot fusion nails: A systematic literature review and classification system.

BACKGROUND: Tibio-talo calcaneal (TTC) arthrodesis is increasingly performed for hindfoot arthrosis and other indications. Peri-implant fracture around hindfoot fusion nails has been previously reported and can be problematic to treat given multiple surgical considerations including the status of hindfoot arthrodesis at time of fracture. We present a systematic review of the literature regarding peri-implant fractures around hindfoot fusion nails and propose a classification system to help guide treatment based on findings from the current literature as well as the collective experience of the senior authors. METHODS: A review of the literature was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to identify clinical investigations in which peri-implant fractures or other hardware failures were observed as complications following TTC arthrodesis using hindfoot nails. The electronic database of PubMed/Medline/Cochrane Library was explored using specific search terms. Inclusion criteria was any clinical investigation that reported on outcomes after TTC arthrodesis using a hindfoot nail in at least one patient. Cadaveric and non-clinical investigations were excluded. RESULTS: A total of 36 studies were identified which met inclusion criteria and reported clinical outcomes after TTC arthrodesis using a hindfoot fusion nail. Of the 36 studies, there was a total of 13 intraoperative fractures, 43 tibial stress fractures and 24 peri-implant fractures recorded in 12 of the 36 studies. CONCLUSION: Peri-implant fracture following tibio-talo calcaneal arthrodesis using a hindfoot intramedullary nail is an uncommon but problematic condition to treat. General heterogeneity of patients and indications as well as a lack of descriptive detail in the current literature makes meta-analysis difficult. Given the lack of consensus on treatment, a classification system may be helpful to guide clinical practice.

Gunshot-Related Injuries to the Foot & Ankle: Review Article.

Gunshot-related injuries remain a significant and important cause of global morbidity and cost. The foot and ankle has certain anatomic and functional considerations that make gunshot-related injuries challenging to manage. While the scientific literature regarding gunshot-related injuries is extensive, little of the existing literature focuses on the foot and ankle. While principles of management can be somewhat extrapolated from the current literature, an understanding of the body of work specific to the foot and ankle is valuable. Therefore, this review provides an overview of ballistic injuries to the foot and ankle as well as specific guidelines to aid surgeons in treating these difficult injuries. Level of Evidence: Level V, expert opinion.

Complications after Metatarsal Osteotomies for Hallux Valgus: Malunion, Nonunion, Avascular Necrosis, and Metatarsophalangeal Osteoarthritis.

Avascular necrosis (AVN), nonunion, malunion, and metatarsophalangeal (MTP) osteoarthritis following hallux valgus osteotomies, as well as pathophysiology, diagnosis, prevention strategies, and treatment are discussed in this article. AVN and nonunion are very infrequent, and they can be effectively prevented taking into consideration local anatomy preservation, biomechanics, and patient comorbidities. Shortening, elevation, plantarflexion, varus/valgus, and rotational of the first metatarsal are the most common types of malunion. They can lead to pain, stiffness, deformity recurrence, and transfer metatarsalgia. MTP osteoarthritis can develop after metatarsal malunion or AVN. Treatment options include cheilectomy, osteotomies to correct malunions, and MTP arthrodesis.

Subtle Lisfranc Injuries: Fix It, Fuse It, or Bridge It?

The management of Lisfranc injuries is challenging considering the broad spectrum of energy involved and highly variable clinical presentation. Despite the advances in surgical techniques, subtle Lisfranc injuries can lead to chronic pain and permanent disability. Surgical treatment is mandatory for all the unstable injuries; however, the best surgical technique remains controversial. The most predictive factor for a successful outcome is the maintenance of anatomic alignment; therefore, the selection of the appropriate surgical technique is of paramount importance. This article reviews the current treatment options and describes the selection of the surgical technique based on the different clinical presentations.

Assessment of variables that influence agreement between reviewers for Foot & Ankle International.

INTRODUCTION: A common criticism of the peer-review process is the often disparate nature of reviewer recommendations when a decision is rendered which belies the supposed uniformity of the process. The purpose of this investigation was to examine level of agreement between reviewers for Foot & Ankle International (FAI) and analyze variables which may have influenced agreement in order to better understand the peer-review process. METHODS: Approval to conduct this investigation was obtained from the Executive Board and Editor in Chief of FAI. All manuscripts submitted to FAI during the calendar year 2016 which underwent formal peer-review were included in the analysis. For each reviewed manuscript, demographic data was collected regarding specific reviewer and manuscript characteristics in a de-identified manner. RESULTS: 442 manuscripts underwent formal blinded peer-review by two independent reviewers during the study period. Only 199 manuscripts (45%) had a decision rendered in which both reviewers agreed on the same initial recommendation. There were no differences in demographic characteristics between the group of reviewers who agreed as compared to those who disagreed on the initial round of peer review. A similar number of indexed peer-reviewed publications between reviewers correlated with increased levels of agreement. CONCLUSIONS: During the study period, there was 45% initial agreement between reviewers for FAI when assessing the same manuscript. Aside from research productivity, no other reviewer-specific variables examined in this investigation were found to correlate with agreement. Specific recommendations and changes may be considered to increase the efficiency and effectiveness of the peer-review process.

Syndesmotic Fixation Utilizing a Novel Screw: A Retrospective Case Series Reporting Early Clinical and Radiographic Outcomes.

Background. Syndesmotic disruption occurs in 20% of ankle fractures and requires anatomical reduction and stabilization to maximize outcomes. Although screw breakage is often asymptomatic, the breakage location can be unpredictable and result in painful bony erosion. The purpose of this investigation is to report early clinical and radiographic outcomes of patients who underwent syndesmotic fixation using a novel metal screw designed with a controlled break point. Methods. We performed a retrospective review of all patients who underwent syndesmotic fixation utilizing the R3lease Tissue Stabilization System (Paragon 28, Denver, CO) over a 12-month period. Demographic and screw-specific data were obtained. Postoperative radiographs were reviewed, and radiographic parameters were measured. Screw loosening or breakage was documented. Results. 18 patients (24 screws) met inclusion criteria. The mean follow-up was 11.7 months (range = 6.0-14.7 months). 5/24 screws (21%) fractured at the break point. No screw fractured at another location, nor did any fracture prior to resumption of weight bearing; 19 screws did not fracture, with 8/19 intact screws (42.1%) demonstrating loosening. There was no evidence of syndesmotic diastasis or mortise malalignment on final follow-up. No screws required removal during the study period. Conclusion. This study provides the first clinical data on a novel screw introduced specifically for syndesmotic fixation. At short-term follow up, there were no complications and the R3lease screw provided adequate fixation to allow healing and prevent diastasis. Although initial results are favorable, longer-term follow-up with data on cost comparisons and rates of hardware removal are needed to determine cost-effectiveness relative to similar implants.Level of Evidence: Level IV: Retrospective case series.

Giant extinct caiman breaks constraint on the axial skeleton of extant crocodylians.

The number of precaudal vertebrae in all extant crocodylians is remarkably conservative, with nine cervicals, 15 dorsals and two sacrals, a pattern present also in their closest extinct relatives. The consistent vertebral count indicates a tight control of axial patterning by Hox genes during development. Here we report on a deviation from this pattern based on an associated skeleton of the giant caimanine Purussaurus, a member of crown Crocodylia, and several other specimens from the Neogene of the northern neotropics. P. mirandai is the first crown-crocodylian to have three sacrals, two true sacral vertebrae and one non-pathological and functional dorsosacral, to articulate with the ilium (pelvis). The giant body size of this caiman relates to locomotory and postural changes. The iliosacral configuration, a more vertically oriented pectoral girdle, and low torsion of the femoral head relative to the condyles are hypothesized specializations for more upright limb orientation or weight support.

The Neogene fossil record of Aetomylaeus (Elasmobranchii, Myliobatidae) from the southeastern Pacific.

The presence of eagle rays of the genus Aetomylaeus in the Neogene of the Temperate Pacific coast of South America (TPSA) still is ambiguous, although the fossil record of elasmobranch fishes (sharks, rays, and skates) from this area is quite good. Here, we present the first unmistakable fossil remains of Aetomylaeus from the Neogene of the TPSA. The material comprises 13 dental plates from one site in Peru and six localities in Chile ranging in age from Miocene to Pliocene and was compared with dental plates of extant species. Our study reveals that the number of tooth rows and the shape of lateral teeth in extant species are seemingly very variable and need to be established before fossil specimens can be confidently identified. Consequently, we do not assign the fossil specimens from the Neogene of the TPSA to any species but leave them as Aetomylaeus. Moreover, we recognized that only the shape of medial teeth provides reliable diagnostic characters in our material, whereas the shape and number of lateral teeth are highly variable, similar to the condition seen in extant species.