Pine-site myiasis: a rare complication of halo orthosis

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Intramedullary melanotic schwannoma

We present a case of an intramedullary melanotic schwannoma (IMS) of the thoracic spinal cord. To our knowledge, this is the seventh reported case of an IMS of the central nervous system. Schwannomas are benign nerve sheath tumors of neural crest origin composed entirely of well differentiated Schwann cells that typically occur in peripheral nerves. Both the intramedullary location and the melanotic component of the reported lesion make it exceedingly rare. We will present our case, theories as to the origin of these tumors, clues in radiographic identification, and current clinical follow-up recommendations

Phylogenomic Analysis Resolves the Interordinal Relationships and Rapid Diversification of the Laurasiatherian Mammals

Although great progress has been made in resolving the relationships of placental mammals, the position of several clades in Laurasiatheria remain controversial. In this study, we performed a phylogenetic analysis of 97 orthologs (46,152 bp) for 15 taxa, representing all laurasiatherian orders. Additionally, phylogenetic trees of laurasiatherian mammals with draft genome sequences were reconstructed based on 1608 exons (2,175,102 bp). Our reconstructions resolve the interordinal relationships within Laurasiatheria and corroborate the clades Scrotifera, Fereuungulata, and Cetartiodactyla. Furthermore, we tested alternative topologies within Laurasiatheria, and among alternatives for the phylogenetic position of Perissodactyla, a sister-group relationship with Cetartiodactyla receives the highest support. Thus, Pegasoferae (Perissodactyla + Carnivora + Pholidota + Chiroptera) does not appear to be a natural group. Divergence time estimates from these genes were compared with published estimates for splits within Laurasiatheria. Our estimates were similar to those of several studies and suggest that the divergences among these orders occurred within just a few million years

Hystricognathy vs Sciurognathy in the Rodent Jaw: A New Morphometric Assessment of Hystricognathy Applied to the Living Fossil Laonastes (Diatomyidae)

While exceptional for an intense diversification of lineages, the evolutionary history of the order Rodentia comprises only a limited number of morphological morphotypes for the mandible. This situation could partly explain the intense debates about the taxonomic position of the latest described member of this clade, the Laotian rock rat Laonastes aenigmamus (Diatomyidae). This discovery has re-launched the debate on the definition of the Hystricognathi suborder identified using the angle of the jaw relative to the plane of the incisors. Our study aims to end this ambiguity. For clarity, it became necessary to revisit the entire morphological diversity of the mandible in extant and extinct rodents. However, current and past rodent diversity brings out the limitations of the qualitative descriptive approach and highlights the need for a quantitative approach. Here, we present the first descriptive comparison of the masticatory apparatus within the Ctenohystrica clade, in combining classic comparative anatomy with morphometrical methods. First, we quantified the shape of the mandible in rodents using 3D landmarks. Then, the analysis of osteological features was compared to myological features in order to understand the biomechanical origin of this morphological diversity. Among the morphological variation observed, the mandible of Laonastes aenigmamus displays an intermediate association of features that could be considered neither as sciurognathous nor as hystricognathous

Mammalian Molecular Systematics with Emphasis on the Insectivore Order Lipotyphla

Insectivore classification has been one of the most controversial problems in mammalian systematics. Evolutionary relationships among the six extant families, Talpidae (moles), Soricidae (shrews), Erinaceidae (hedgehogs), Tenrecidae (tenrecs), Chryosochloridae (golden moles), and Solenodontidae (solenodons), have remained uncertain based on morphological data. Animals classified within the order Lipotyphla have been considered to be among the most primitive living eutherian mammals. However, the six extant families are speciose, geographically widespread and adapted to a wide range of ecological niches. The combination of "primitive" and various specialized morphological characters has made classification of lipotyphlans particularly difficult. This work addressed the phylogenetic relationships among the Talpidae, Soricidae, Erinaceidae, and Tenrecidae based on mitochondrial (mt) DNA sequence data. Complete mt genome sequences of a European mole (Talpa europaea) and a lesser hedgehog tenrec (Echinops telfairi) were determined, as well as the cytochrome b (cyt b) and partial NADH5 mt gene sequences of a shrew (Sorex araneus). Three methods of phylogenetic analysis were used: maximum parsimony, neighbor joining and maximum likelihood (ML). The effect of rate heterogeneity on tree topology and branch lengths was explored under ML. In addition, the complete mt genome of an African cane rat (Thryonomys swinderianus) was sequenced to address the issue of the phylogenetic position of Erinaceidae at the base of Eutheria. Monophyly of Lipotyphla was not supported based on analyses of 12 mt protein coding genes. Talpidae was found as an outgroup to the Cetferungulata rather than as an ancient lineage in Eutheria. Analyses of cyt b and NADH5 data indicated strong support for a sister taxon relationship between Talpidae and Soricidae (superfamily Soricoidea). Chiroptera was outgroup to Soricoidea, forming the clade Volantiterranea, new. A sister taxon relationship between Tenrecidae and Talpidae was significantly rejected. There was moderate support for the placement of the Tenrecidae within Afrotheria together with Tubulidentata (aardvark) and Proboscidea (elephant). The basal position of Erinaceidae was supported by all approaches except ML + rate heterogeneity. The discrete gamma model of rate heterogeneity disproportionately increased the long branches at the base of Eutheria relative to those at the top of the tree highlighting the potential for misleading results and the need for more dense taxon sampling near the base of the tree