Squamosal Research Articles

The osteology of the lacertid genus Darevskia Arribas, 1999 (Squamata, Lacertidae)

A total of 230 cleared and alizarin stained and 136 radiographed specimens of Darevskia belonging to 47 nominal taxa (species, subspecies or singular clades) including the seven parthenogenetic ones and a triploid hybrid were studied. Sixteen osteological characters in all the tried species were analyzed. These characters by corporal regions were: skull characters: 1.—number of premaxillary teeth; 2.—number of maxillary teeth; 3.—number of dentary teeth; 4.—teeth morphology; 5.—presence of anterolateral process in the postfrontal bone; 6.—presence of anteromedial process in the postorbital bone; 7.—comparative lengths of the postorbital and postfrontal bones; 8.—overlap degree between the postorbital and the squamosal bones. Postcranial characters: 9.—existence of visible (ossified) ribs associated with the third presacral vertebrae; 10.—sternal/xiphisternal costal formula and presence of inscriptional ribs; 11.—number of presacral vertebrae; 12.—number of posterior dorsal vertebrae (short presacral ribs); 13.—presence and form of the sternal fontanelle; 14.—form of the clavicles (emarginated or marginated); 15.—interclavicle form; 16.—morphology of first autotomic vertebrae of the tail. Our goals were to characterize osteologically the different species of Darevskia, to contrast their relationships traced from osteological traits with the available genetic-derived phylogenies of the group, to compare the osteological characteristics of the parthenogenetic species with their bisexual parental species, and to comment on their parentage and character polarity. Finally, we aimed to search for osteological characteristics of the different groups within Darevskia, diagnosing them for the first time. The results, commented on by characters, are available in the main text, and taxa characteristics are easily consultable and condensed in Table 1. Osteological characteristics of Darevskia, together with available phylogenetic trees, have permitted us to define some new groups within Darevskia (raddei, chlorogaster, defilippi, and parvula new groups) (Appendix 3), which are reciprocally monophyletic and have diagnostic characteristics. All of them are diagnosed and named as subgenera to be used if necessary, instead of the partial, old and not always comprehensive groups.

Using the methyl cellulose poultice method to remove plaster and burlap - A case study on Triceratops bone

The dinosaur collection at the Natural History Museum, London (NHM) includes a Triceratops skull (NHMUK PV R 3886), purchased from Charles Sternberg in 1909. While most of the skull is on public display in the Dinosaurs gallery, two large sections of the frill (the squamosal bones) had been replicated for the display and the originals left in storage. With much of the fossil bone obscured by plaster of Paris, the original frill sections were deemed of limited use to science in their current form. A work request was received to strip away as much artificial material as possible to determine the extent of the original fossil material. An air scribe fitted with a chisel stylus proved initially effective, but soon revealed an additional obstacle – layers of hessian underneath. The methyl cellulose poultice method was used to swell the hessian, aiding softening of the plaster, and allowing layers to be torn off in strips. The fine layer of plaster remaining on the bone was removed, where possible, with a Split-V ultrasonic tool. This sequence of treatments can be utilised at minimal risk to specimens in similar situations when a hessian and plaster jacket has been applied but a separator layer has been omitted.

Isotopic ecology of Hawaiian green sea turtles (Chelonia mydas) and reliability of δ13C, δ15N, and δ34S analyses of unprocessed bone samples for dietary studies

This study conducted stable isotope analysis (δ13C, δ15N, and δ34S) on the epidermis and two skeletal elements (rib and squamosal bones) of Hawaiian green turtles (Chelonia mydas) and putative diet items obtained from two neritic sites: the Kona/Kohala coast and Oahu. Turtle tissues were collected in 2018–2020 and diet samples in 2018, 2019, and 2021. The effect of body size and sampling locality on individual bulk tissue isotope values was evaluated, and stable isotope mixing models based on δ13C, δ15N, and δ34S values from those tissues and four groups of food sources were used to reconstruct diet histories of the turtles. Mixing models indicated that green turtles along the Kona/Kohala coast consumed an omnivorous diet, whereas those from Oahu had an herbivorous diet. These diet make-ups are consistent with published gut content analyses. However, mixing models using the stable isotope ratios in rib and squamosal bone failed to yield reasonable diet histories, probably due to inadequacies of the applied trophic discrimination factor (TDF), a key model parameter. These results further establish that stable isotope ratios in the epidermis can be used effectively to study green turtle diet, but also reveal that more validation—and establishment of appropriate TDFs—is needed before bone can be used reliably to assess green turtle diet.

Differentiation of skull morphology and cranial kinesis in common toads

We examined the cranial morphology and cranial kinesis of the common toads Bufo bufo and B. spinosus with micro-computed tomography and geometric morphometrics and compared the results with published data for related species in a phylogenetic context. The species significantly diverge in skull shape. The skull of B. spinosus is shorter and higher, with a ventral arm of the squamosal bone and the jaw articulation point positioned perpendicular to the braincase, in comparison with a more lateral position in B. bufo. In either species, females have a shorter snout and a higher and wider skull at the jaw articulation point that is positioned more posteriorly, in comparison with conspecific males. High variation in the amount of bone ossification was recorded in both species, ranging from scarcely ossified and loosely connected bones to highly ossified and firmly connected bones. We also found that skull shape and inferred kinetic properties of the skull are highly variable across the Bufonini tribe. However, sample sizes are mostly small and intraspecific variation is high, which might compromise the analyses. Overall, the results suggest that developmental plasticity produces high variation in ossification and cranial kinesis, affecting individuals’ feeding performances. At the population level, this variation supports an efficient exploitation of the habitat and may promote morphological adaptation in a changing environment.

Histological and chemical diagnosis of a combat lesion in Triceratops

In the collective imagination derived from scientific and popular literature, Triceratops often faced each other in combat. Thus, from the second half of the twentieth century, these ceratopsids were described as pugnacious animals. This arises primarily from the interpretation of extracranial fenestrae in ceratopsids being the result of combat trauma. However, the diagnosis of the traumatic nature of these anatomical variants of their neck frill requires evidence of bone healing and remodelling by microscopy analysis. Here, we present the case of the Triceratops horridus known as Big John, which is one of the largest specimens discovered in the Hell Creek Formation (Upper Cretaceous; South Dakota, USA). Its right squamosal bone shows an extrafenestra with irregular margins and signs of inflammation. Microscopy analysis revealed newly formed and healing bone, with histological signs typical of the bone remodelling phase. Chemical analysis revealed sulphur that was derived from glycosaminoglycan’s and sulphated glycoproteins of the preosseous osteoid substance present in the healing phases of a bone trauma. Histological and microanalytical analyses confirm that the squamosal fenestra of Big John is the result of a traumatic event, which might indeed have occurred during combat with another Triceratops.

Osteology, relationships and functional morphology of Weigeltisaurus jaekeli (Diapsida, Weigeltisauridae) based on a complete skeleton from the Upper Permian Kupferschiefer of Germany.

BackgroundWeigeltisauridae is a clade of small-bodied diapsids characterized by a horned cranial frill, slender trunk and limbs, and a patagium supported by elongated bony rods. Partial skeletons and fragments are definitively known only from upper Permian (Lopingian) rocks in England, Germany, Madagascar and Russia. Despite these discoveries, there have been few detailed descriptions of weigeltisaurid skeletons, and the homologies of many skeletal elements—especially the rods supporting the patagium—remain the subject of controversy.Materials & MethodsHere, we provide a detailed description of a nearly complete skeleton of Weigeltisaurus jaekeli from the upper Permian (Lopingian: Wuchiapingian) Kupferschiefer of Lower Saxony, Germany. Briefly addressed by past authors, the skeleton preserves a nearly complete skull, postcranial axial skeleton, appendicular skeleton, and patagial supports. Through comparisons with extant and fossil diapsids, we examine the hypotheses for the homologies of the patagial rods. To examine the phylogenetic position of Weigeltisauridae and characterize the morphology of the clade, we integrate the material and other weigeltisaurids into a parsimony-based phylogenetic analysis focused on Permo-Triassic non-saurian Diapsida and early Sauria (61 taxa, 339 characters).ResultsWe recognize a number of intriguing anatomical features in the weigeltisaurid skeleton described here, including hollow horns on the post-temporal arch, lanceolate teeth in the posterior portion of the maxilla, the absence of a bony arch connecting the postorbital and squamosal bones, elongate and slender phalanges that resemble those of extant arboreal squamates, and patagial rods that are positioned superficial to the lateral one third of the gastral basket. Our phylogenetic study recovers a monophyletic Weigeltisauridae including Coelurosauravus elivensis, Weigeltisaurus jaekeli, and Rautiania spp. The clade is recovered as the sister taxon to Drepanosauromorpha outside of Sauria (=Lepidosauria + Archosauria).ConclusionsOur anatomical observations and phylogenetic analysis show variety of plesiomorphic diapsid characters and apomorphies of Weigeltisauridae in the specimen described here. We corroborate the hypothesis that the patagial ossifications are dermal bones unrelated to the axial skeleton. The gliding apparatus of weigeltisaurids was constructed from dermal elements unknown in other known gliding diapsids. SMNK-PAL 2882 and other weigeltisaurid specimens highlight the high morphological disparity of Paleozoic diapsids already prior to their radiation in the early Mesozoic.

A Case of a Nonpetrous Cholesterol Granuloma Presenting as a Temporal Mass

Objective A case of a skull base cholesterol granuloma (CG) of the squamosal temporal bone. This is the first ever reported case of CG in a well-pneumatized squamous temporal bone. Design Case report and review of the literature. Discussion. CG is a cystic mass typically found in the petrous apex and occasionally in the paranasal sinuses and orbit. Experience with the treatment of these expansile and inflammatory processes has largely been garnered from those occurring in the petrous apex, where they are surgically drained, via a transtympanic, transmastoid, or middle fossa approach. We report a case of cholesterol granuloma situated in the temporal fossa presenting as a temporal mass. The accessible location of this particular lesion made it amenable to total excision, avoiding the need for surgical drainage and possibility for recurrence. Conclusion This case supports the theory of pathogenesis of such lesions typically occurring where pneumatized air spaces interface with bone marrow, in this case, where the reaches of pneumatized cells in the squamous portion of the temporal bone meet diploic bone.

Selection of Superior Quality Annona Species by Means of Bioactive Compounds and Antioxidant Capacity

Present study evaluated different parts of (leaves, seeds, bark, roots, ripen fruits, unripen fruits) 6 species of Annona (Annona cherimola, Annona muricata L., Annona reticulata L., Annona squamosa L (green and red varieties) and Annona glabra L. by means of total antioxidant capacity (TAC), total phenolic content (TPC) and total flavonoid content (TFC) in order to select superior quality species of Annona for commercial cultivation. TAC, TPC and TFC were determined using Ferric Reducing Antioxidant Power (FRAP) assay, Folin-Ciocalteu method and colorimetric method, respectively. It was observed that all tested parts of all tested species contained appreciable amount of TAC, TPC and TFC. Significantly higher TPC were recorded in roots of custard apple (82.08±0.74a mg GAE/g DW) followed by roots of soursop (73.10±0.72b mg GAE/g DW), leaves of soursop (55.18±0.18a mg GAE/g DW) respectively. It was interesting to see that the highest TAC was observed in root extracts of soursop (194.98 mg TE/g DW followed by bark extracts of pond apple (134.37 mg TE/g DW) and leaf extracts of soursop (122.67 mg TE/g DW respectively. Total flavonoid content of leaf extracts of six different species were varied as soursops>sugar apple R>pond apple>sugar apple G> custard apple >cherimoya respectively. Strong positive correlations were observed between TAC values and TPCs of leaves, seeds, barks and roots (R² = 0.78; p<0.001). Based on the results of bioactive molecules present in different species and their parts, it could be concluded that soursop and custard apple could be recommended as superior quality Annona species for commercial cultivation.

Tribal allocation and biogeographical significance of one of the largest sigmodontine rodent, the extinct Galápagos Megaoryzomys (Cricetidae)

ABSTRACT One of the largest members of Sigmodontinae, the extinct Megaoryzomys curioi from Santa Cruz Island in the Galápagos Archipelago (Ecuador), is traditionally treated as a representative of Thomasomyini. We contrasted this hypothesis based on a direct study of craniodental material of M. curioi, including a well-preserved skull assessed through CT-scan examination, within a broader sampling of brachydonts sigmodontines. M. curioi lacks or presents a poorly expressed suspensory process of the squamosal bone, while in Thomasomyini this structure is well developed. In the same way, M. curioi does not exhibit the condition in the dorsal aperture of the ectotympanic displayed by the Thomasomyini, and the morphology of the mandible also contrasts with the widespread condition shown by Thomasomyini. Besides, the procingulum of the first lower molar in M. curioi lacks the typical pattern of Thomasomyini composed of two defined conulids. Overall craniodental morphology in M. curioi favours its allocation to the Oryzomyini. This alternative hypothesis resolves two biogeographical issues connected with the target genus: (1) Galápagos Islands were colonised by members of a single sigmodontine tribe (i.e., Oryzomyini) and (2) within the sigmodontine radiation; members of the Oryzomyini were uniquely capable of reaching oceanic islands.

Stapes fixation to the promontory and fallopian canal in a case of chronic otitis media: Implications on development and etiology

Embryology of stapes has long been a topic of controversy. There are theories stating a single source to the dual origin of stapes. Chronic otitis media is also known to cause various acquired bony ossicular fixations. We present a case of an 11-year-old female with right chronic otitis media, active squamosal with cerebellar abscess who underwent drainage of cerebellar abscess followed by tympanomastoidectomy as a two-staged procedure. Intraoperatively, there were stapes suprastructure fusion to the fallopian canal and one crural attachment to the promontory. There are no clear criteria to differentiate bony fixation of congenital origin from acquired causes. This case also highlights the need to add a new subclass in the classification of minor middle ear anomalies given by Cremer, and our findings also support the dual origin for stapes development.

S13-05 SESSION 13: HYPERTELORISM / CRANIOFACIAL CLEFTS A NOVEL ORBITO ENCEPHALO CRANIAL DYSPLASIA VARIANT TESSIER 9 FACIAL CLEFT

Introduction: We present a group of patients with dysplasia involving mesencephalon, prosencephalon, calvarium, scalp, hairline and lateral orbit. These features are classifiable as a variant Tessier 9 cleft. Clinical and radiologic findings are presented, as well as outcomes of treatment. Methods: Retrospective chart review, clinical photographs, 3D CT and MRI exams. Results: 15 patients were included. 9 patients were treated for congenital hydrocephalus due to aqueductal stenosis, and 7/9 had residual craniomegaly. Radiologic findings include pontine or quadrigeminal plate “lipoma” (n=4), squamosal bone dysplasia (n=3), Supernumerary intra-parietal suture (n=7), partial or total synotosis of the coronal or lambdoid sutures (n=5). Hairline findings include a pathognomonic temporal hairline “Omega-dot” or “atoll-like” deformity (n=12), temporal hairline peak (n=2), interrupted lateral eyebrow (n=6) and absent frontal process of the zygomatic bone (n=1). Using the following diagnostic algorithm: 2 findings = possible/tentative diagnosis, 3 or more findings = positive/confirmed diagnosis, our group was divided into 13 positive and 2 possible diagnoses. Conclusion: These patients display a constellation of rare/pathognomonic clinical symptoms with associated radiologic findings and prognostic implications. Patients with congenital hydrocephalus that harbor this anomaly may retain a craniomegalic skull when treated with standard protocols. We present the diagnostic criteria used in this series. Further radiologic examination of brain anomalies and genetic sequencing are ongoing.

Anatomical and Radiographic Study on the Skull and Mandible of the Common Opossum (Didelphis Marsupialis Linnaeus, 1758) in the Caribbean.

Common opossums (Didelphis marsupialis) are found throughout the Caribbean island of Trinidad and Tobago. The present work was conducted on 10 skulls and mandibles of the common opossum to describe the osteology and foramina of these skulls and mandibles grossly and radiographically. The information that is garnered can be used to detect, diagnose, and treat head affections, as well as for comparative studies with the skulls and mandibles of other similar species. The skulls and mandibles were prepared and cleaned using standard method. All of the characteristic features of various standards views of the skulls bones, including dorsal, lateral, caudal and midsagittal, and the lateral and caudal views of the mandibles as well as the foramina of the skulls and mandibles were described and discussed. Each skull was divided into long facial and short cranial regions. No supraorbital foramen was observed in the skulls. The tympanic bulla was absent while there was the tympanic process of the alisphenoid. The temporal process of the zygomatic bone, zygomatic process of maxilla, and zygomatic process of the squamosal bone formed the zygomatic arch. The dental formula was confirmed. The bones and foramina of the skull and mandible were similar to other marsupial species and were homologue to that of other mammals.

Kir2.1 is important for efficient BMP signaling in mammalian face development

Mutations that disrupt the inwardly rectifying potassium channel Kir2.1 lead to Andersen-Tawil syndrome that includes periodic paralysis, cardiac arrhythmia, cognitive deficits, craniofacial dysmorphologies and limb defects. The molecular mechanism that underlies the developmental consequences of inhibition of these channels has remained a mystery. We show that while loss of Kir2.1 function does not affect expression of several early facial patterning genes, the domain in which Pou3f3 is expressed in the maxillary arch is reduced. Pou3f3 is important for development of the jugal and squamosal bones. The reduced expression domain of Pou3f3 is consistent with the reduction in the size of the squamosal and jugal bones in Kcnj2KO/KO animals, however it does not account for the diverse craniofacial defects observed in Kcnj2KO/KO animals. We show that Kir2.1 function is required in the cranial neural crest for morphogenesis of several craniofacial structures including palate closure. We find that while the palatal shelves of Kir2.1-null embryos elevate properly, they are reduced in size due to decreased proliferation of the palatal mesenchyme. While we find no reduction in expression of BMP ligands, receptors, and associated Smads in this setting, loss of Kir2.1 reduces the efficacy of BMP signaling as shown by the reduction of phosphorylated Smad 1/5/8 and reduced expression of BMP targets Smad6 and Satb2.

Evolution of skull shape in the family Salamandridae (Amphibia: Caudata).

We carried out a comparative morphometric analysis of 56 species of salamandrid salamanders, representing 19 out of 21 extant genera, with the aim of uncovering the major patterns of skull shape diversification, and revealing possible trends and directions of evolutionary change. To do this we used micro-computed tomography scanning and three-dimensional geometric morphometrics, along with a well-resolved molecular phylogeny. We found that allometry explains a relatively small amount of shape variation across taxa. Congeneric species of salamandrid salamanders are more similar to each other and cluster together producing distinct groups in morphospace. We detected a strong phylogenetic signal and little homoplasy. The most pronounced changes in the skull shape are related to the changes of the frontosquamosal arch, a unique feature of the cranial skeleton for the family Salamandridae, which is formed by processes arising from the frontal and squamosal bones that arch over the orbits. By mapping character states over the phylogeny, we found that a reduction of the frontosquamosal arch occurs independently in three lineages of the subfamily Pleurodelinae. This reduction can probably be attributed to changes in the development and ossification rates of the frontosquamosal arch. In general, our results are similar to those obtained for caecilian amphibians, with an early expansion into the available morphospace and a complex history characterizing evolution of skull shape in both groups. To evaluate the specificity of the inferred evolutionary trajectories and Caudata-wide trends in the diversity of skull morphology, information from additional groups of tailed amphibians is needed.

Loading and Form in the Mammalian Jaw Joint

The synovial articulation between the dentary and squamosal bones, usually referred to as the temporomandibular joint (TMJ), is a defining feature of the Class Mammalia. The mandibular component of this joint is a secondary cartilage that develops in a membranous matrix and contributes to growth of the mandible. While resembling the growth cartilage of long bones, the mandibular condylar cartilage differs in that it also must function as the articular surface of the mammalian jaw joint, a function mediated by a fibrous thickening of the perichondrium. Another difference from typical growth cartilage is that cells are closely packed and not aligned in columns. This feature permits the direction of growth to be altered. Perhaps because of its origin from membranous tissue, the mandibular condyle is notably sensitive to mechanical loading, particularly during the period of growth. Loading of the TMJ arises from contraction of the jaw muscles, but the magnitude and orientation of loading vary according to the muscle combination used. In this contribution we summarize and synthesize studies on condylar loading assessed using strain gages affixed to the condylar neck of rabbits (Oryctolagus cuniculus) and pigs (Sus scrofa) under normal and altered conditions, correlating the findings with condylar morphology. During normal mastication young adult rabbits evince nearly vertical compressive strain on the condylar neck. Reduction of muscle force using botulinum toxin diminished and reoriented the strain, and these changes were accompanied by a striking loss of bone in the condylar head and neck. The paralyzed side condyle tended to be smaller than that of the healthy side, suggesting that condylar surface area did not increase normally, but the thickness of the cartilage layer was unaffected, implying no change in length of the cartilage process. Like rabbits, pigs show compressive strain on the condylar neck during mastication. During the growth process, the orientation of masticatory compressive strain alters from posterior‐superior in younger animals to anterior‐superior in older pigs. Studies correlating condylar strain with cartilage proliferation showed a tendency for proliferation to decrease as condylar compressive strain increased. A procedure (distraction osteogenesis) used clinically to increase mandibular length was found to lower the magnitude and reorient condylar strain. Unlike the adult rabbits, these juvenile pigs responded to lowered loads with increased growth, but the direction was altered in correspondence with the reorientation of masticatory strain. Collectively, these studies illustrate the dependence of mandibular morphology on the specifics of species, age, and especially masticatory mechanics.Support or Funding InformationSupported by DE08513, DE14336, DE018142 from NIDCR.

Present scenario of microbiological pattern in chronic suppurative otitis media and its management guidelines

AIMS: Chronic suppurative otitis media (CSOM) is a common infectious chronic ear disease in India resulting in serious complications, especially hearing impairment. Irrational use of antibiotics for its management has led to the emergence of multidrug-resistant bacterial strains. Considering this, this study was conducted to know the pattern of causative organisms associated with CSOM and their antimicrobial sensitivity. Materials and Methods: Ear discharge from 200 clinically diagnosed cases of CSOM was collected by suction using sterile techniques in a sterilised test tube on wash bottle principle consisting of a glass tube made air tight with the help of a cork with an inlet and outlet facility. All samples were processed in the department of microbiology for the identification of bacterial and fungal isolates and their antimicrobial sensitivity testing. Results: Among the 200 samples of ear discharge, 127 were from ear having tubotympanic (mucosal or safe) type of CSOM while 73 were from ear with attico-antral (squamosal or unsafe) CSOM. Among aerobic isolates, Pseudomonas aeruginosa (35%) was most common followed by Staphylococcus aureus. Other aerobes isolated were Klebsiella spp., coagulase-negative Staphylococcus, Proteus spp. and Escherichia coli. Fungus was isolated in tubotympanic (9.45%) CSOM only. Among anaerobic isolates, Peptostreptococcus (1%) was most common. Conclusion: Monomicrobial isolates, especially P. aeruginosa and Staphylococcus species, were found to be most common in our study. Therefore, evaluation of microbiological pattern and their antibiotic sensitivity pattern in local area becomes helpful in prescribing empirical antibiotics for successful treatment of CSOM.

A new mountain lizard from Montes de León (NW Iberian Peninsula):Iberolacerta monticola astur ssp. nov. (Squamata: Lacertidae).

Iberolacerta populations from the Northern Montes de Leon (NML) were studied by means of external morphology (scalation and biometry), osteology and genetics (mtDNA and microsatellites), searching for their homogeneity ("intrazonalanalysis") and, once verified, comparing them with Iberolacerta monticola s. str. (from Central Cantabrian Mountains)and/. gal ani (from Southern Montes de Leon) ("extrazonal analysis") from neighboring areas.Our "intrazonal analysis" revealed discordances between the different approaches, especially the patterns of variation of nuclear microsatellites (congruent with external morphology) and mtDNA, namely a very low nuclear differentiation between relatively highly differentiated mtDNA lineages. The morphological approach was unable to discriminate any of the populations as significantly different from the others in the NML. Mitochondrial DNA revealed a haplotype lineage closely related to I. galani (MNL-II in our text) in some specimens of Sierra de Villabandfn and Suspiron, but these populations are morphologically indistinguishable from the main part of the other populations that belong to lineage NML-1,phylogenetically closer to/. monticola. After a separation from I. manti cola ca. 1.8 Mya, the populations in this geographic region must have suffered at least two different waves of gene flow from I. gal ani, the second one not much later than 0.5 Mya. Microsatellite results indicate that all the NML populations are genetically similar in terms of their nuclear genomes,independently of their mitochondrial differentiation (NML-I vs. NML-II haplotype groups). Since all the morphological and microsatellite evidences point towards the fact that, independently of the mitochondrial haplotypes that they bear (NML-1 or NML-II), there is only one taxon in the area, we describe it as: Iberolacerta monticola astur ssp. nov.Concerning the relationships of I. m. astur ssp. nov. with I. monticola s. str. and I. gal ani ("extra zonal analysis"), in the female analyses the new taxon centroid is closer to I. monticola s. str. than to I. gal ani (more similarity with I manticolas.str.), whereas in the male analyses the relationship is just the contrary (closer to I. gal ani, paralleling the direction of the hypothesized past hybridization). Moreover, in both sexes' ANOVA, I. m. astur ssp. nov. results more similar (lessP<0.05 differences) to I. galani than to I. monticola s. str. Osteologically, I. m. astur ssp. nov. is slightly more similar toI. monticola s. str. than to I. galani, especially in the squamosal bone, which is regularly arched (primitive shape). Genetically,as indicated above, the NML populations can be subdivided in two groups according to their mitochondrial DNA,namely NML-I (bearing clearly differentiated haplotypes, phylogenetically closer to I. monticola) and NML-II (whose haplotypes could have been mistaken for those of an I. gal ani population). This mitochondrial subdivision has at most a subtle nuclear correlate, however. According to the nuclear microsatellite markers, all the NML populations belong to a single group(/. m. astur ssp. nov.), which would be more similar to I. gal ani than to I monticola, with NML-II populations lying closer to I. galani than those from the NML-I group and, correspondingly, more distant from I. monticola. The discordant phylogenetic signal of mitochondrial and nuclear markers is discussed in terms of past introgression events and sex-biases in phylopatry and dispersion in these species. Iberolacerta manti cola astur ssp. nov., inhabits the Northern Montes de Leon (Sierra de Gistreo sensu latissimo ): Gistredo,Catoute, Tambaron, Nevadfn, Villabandfn (or Macizo del Alto de Ia Canada), Arcos del Agua (or Fernan Perez),Tiendas and Suspiron, mainly in quartzite and slate rock substrates. Its current distribution, cornered in the NW of theNorthern part of the Montes de Leon, suggests a possible competitive exclusion between this taxon and/. galani, as the galani haplotypes (NML-II) appear cornered in the most harsh and continental areas, speaking also about a, even in the past, very limited presence of this species in the area that probably was soon absorbed by I. m. astur ssp. nov. (with NMLI haplotypes). Variation in watershed limits (especially with l montico/a s. str. in the North) and Pleistocene climatic oscillations(with I. gal ani in the South) probably played a crucial role in isolation of the different Iberolacerta colonizationwaves in this zone. These changes in the boundaries among watersheds limited the contact between the NML and the main Cantabrian Mountains, restricting to narrow points (different along time) the contact between the two ranges, and thus,the areas for possible contact between I. m. astur ssp. nov. and I. monticola s. str. (see Fig. lB). The origin of this tax on dates back to the end of Pliocene or Lower Pleistocene (around 1.8 Mya), according to mtDNA divergence. On the other side, climatic oscillations allowed expansion and contact with the more continental harsh climate-dwelling I. gal ani.

Old and new hypotheses about the homology of the compound bones from the cheek and otico-occipital regions of the anuran skull

We studied the larval development of compound bones from the otico-occipital and cheek regions in species of the neobatrachian genera Batrachyla, Hylorina, Leptodactylus, Odontophrynus and Pleurodema. Comparisons were made using a set of Ambystoma spp. (Caudata) and Ceratophrys ornata (Anura; Ceratophryidae) larvae. As suggested by previous studies, we verified the compound nature of the exoccipital (two centers, anurans only), frontoparietal (one center, most anurans and Ambystoma; three centers, some anurans), and squamosal (two centers, all anurans and Ambystoma) bones. We discuss old and new homology hypotheses for each of the compound bone centers in the context of the most widely accepted scenario of lissamphibian origins and relationships, i.e., monophyletic Lissamphibia that includes the clade Batrachia (Caudata+Anura) and the most divergent Gymnophiona. Our findings have a direct impact on our understanding of the composition of the skull in Lissamphibia. We recognized the presence of the following bones: (i) opisthotic (fused to the exoccipital) and tabular (fused to the squamosal) in Batrachia (Anura+Caudata) and (ii) supratemporal (fused to the parietal portion of the frontoparietal) in Anura. Separate centers of the parietal were found only in Pleurodema.

Temporal Bones of the Gekkota Support Molecular Relationships within the Pygopodoidea

Abstract Although molecular phylogenetic studies strongly support the monophyly of the Pygopodoidea, which comprise the gekkotan families Diplodactylidae, Carphodactylidae, and Pygopodidae, relationships among these constituent families are less robust. Morphological evidence for a particular three-taxon statement of pygopodoid relationships is hindered by the highly derived postcranial and trophic anatomy of limbless pygopodids relative to limbed gekkotans. We discuss variation in the temporal region of the gekkotan skull and identify a posteriorly dilated squamosal bone with a medially directed process, a character that is shared uniquely within Gekkota and more broadly within extant Squamata, by carphodactylids and pygopodids. The pygopodoid relationships (Diplodactylidae [Carphodactylidae, Pygopodidae]) implied by squamosal morphology are consistent with those receiving the greatest support from the most complete nuclear gene phylogenies.

Evidence of Combat in Triceratops

BackgroundThe horns and frill of Triceratops and other ceratopsids (horned dinosaurs) are interpreted variously as display structures or as weapons against conspecifics and predators. Lesions (in the form of periosteal reactive bone, healing fractures, and alleged punctures) on Triceratops skulls have been used as anecdotal support of intraspecific combat similar to that in modern horned and antlered animals. If ceratopsids with different cranial morphologies used their horns in such combat, this should be reflected in the rates of lesion occurrence across the skull.Methodology/Principal FindingsWe used a G-test of independence to compare incidence rates of lesions in Triceratops (which possesses two large brow horns and a smaller nasal horn) and the related ceratopsid Centrosaurus (with a large nasal horn and small brow horns), for the nasal, jugal, squamosal, and parietal bones of the skull. The two taxa differ significantly in the occurrence of lesions on the squamosal bone of the frill (P = 0.002), but not in other cranial bones (P>0.20).Conclusions/SignificanceThis pattern is consistent with Triceratops using its horns in combat and the frill being adapted as a protective structure for this taxon. Lower pathology rates in Centrosaurus may indicate visual rather than physical use of cranial ornamentation in this genus, or a form of combat focused on the body rather than the head.