A new small baurioid therocephalian from the Lower Triassic Jiucaiyuan Formation, Xinjiang, China

Several therocephalian species,mainly represented by cranial material from the late Permian,have been reported from China in recent years.Here we describe a tiny new baurioid therocephalian,Jiucaiyuangnathus confusus gen.et sp.nov.,from the Jiucaiyuan Formation,Xinjiang,China.The new taxon is represented by a partial snout with occluded partial lower jaw and two postcranial skeletons.Although juvenile in stage,the new species is diagnosed by the following features:round pit in middle of lateral surface of maxilla;lacrimal contact nasal;fossa for dentary tooth on the posterior end of the premaxilla,lateral to the anterior choana;two small vertical triangular ridges extending dorsally and ventrally on the vomerine anterior portion,and bordering a thin vomerine foramen laterally;anterior projection of the lateral part of the frontal on the nasal;symphyseal region of the dentary projected anteriorly;5 upper premaxillary teeth,upper and lower canines absent,diastema between the last premaxillary upper incisor and first maxillary tooth present,no diastema separating anterior from posterior dentition in the mandible,10 maxillary teeth and 12 dentary teeth,posterior postcanine expands mesiodistally,having a main large cusps and tiny anterior and posterior accessory cusps in line;neural arches of the atlas fused by the neural spine,neural spine of the axis projected posteriorly,procoracoid foramen lies between procoracoid and scapula.Features of the dentition resembles those of the small baurioid Ericiolacerta parva from South Africa and Silphedosuchus orenburgensis from Russia.The specimens provide the rare opportunity to know in detail the postcranial skeleton of baurioids.

Asymmetry in genitalia is in sync with lateralized mating behavior but not with the lateralization of other behaviors

Asymmetries in bilateral organisms attract a lot of curiosity given that they are conspicuous departures from the norm.They allow the investigation of the integration at different levels of biological organization.Here we study whether and how behavioral and asymmetrical anatomical traits coevolved and work together.We ask if asymmetry is determined locally for each trait or at a whole individual level in a species bearing conspicuous asymmetrical genitalia.Asymmetric genitalia evolved in many species;however,in most cases the direction of asymmetry is fixed.Therefore,it has been rarely determined if there is an association between the direction of asymmetry in genitalia and other traits.In onesided livebearer fish of the genus Jenynsia(Cyprinodontiformes,Anablepidae),the anal fin of males is modified into a gonopodium,an intromittent organ that serves to inseminate females.The gonopodium shows a conspicuous asymmetry,with its tip bending either to the left or the right.By surveying 13 natural populations of Jenynsia lineata,we found that both genital morphs are equally common in wild populations.In a series of experiments in a laboratory population,we discovered asymmetry and lateralization for multiple other traits;yet,the degree of integration varied highly among them.Lateralization in exploratory behavior in response to different stimuli was not associated with genital morphology.Interestingly,the direction of genital asymmetry was positively correlated with sidedness of mating preference and the number of neuromasts in the lateral line.This suggests integration of functionally linked asymmetric traits;however,there is no evidence that asymmetry is determined at the whole individual level in our study species.

The endemic Patagonian vespertilionid assemblage is a depauperate ecomorphological vicariant of species-rich neotropical assemblages

Vespertilionidae is the most diverse chiropteran family, and its diversity is concentrated in warmregions of the World; however, due to physiological and behavioral adaptations, these bats alsodominate bat faunas in temperate regions. Here we performed a comparative study of vespertili-onid assemblages from two broad regions of the New World, the cold and harsh Patagonia, versusthe remaining temperate-to-subtropical, extra-Patagonian eco-regions of the South AmericanSouthern Cone. We took an ecomorphological approach and analyzed the craniodental morpho-logical structure of these assemblages within a phylogenetic framework. We measured 17 cranio-dental linear variables from 447 specimens of 22 currently recognized vespertilionid species of thestudy regions. We performed a multivariate analysis to define the morphofunctional space, andcalculated the pattern and degree of species packing for each assemblage. We assessed the im-portance of phylogeny and biogeography, and their impact on depauperate （Patagonian） versusrich （extra-Patagonian） vespertilionid assemblages as determinants of morphospace structuring.We implemented a sensitivity analysis associated to small samples of rare species. The morpho-logical patterns were determined chiefly by the evolutionary history of the family. The Patagonianassemblage can be described as a structurally similar but comparatively depauperate ecomorpho-logical version of those assemblages from neighboring extra-Patagonian eco-regions. ThePatagonian assemblage seems to have formed by successively adding populations from Northernregions that eventually speciated in the region, leaving corresponding sisters （vicariants） in extra-Patagonian eco-regions that continued to be characteristically richer. Despite being structurallyakin, degree of species packing in Patagonia was comparatively very low, which may reflect the ef-fect of limited dispersal success into a harsh region for bat survival.

Are the number and size of scales in Liolaemus lizards driven by climate?

Ectothermic vertebrates are sensitive to thermal fluctuations in the environments where they occur.To buffer these fluctuations,ectotherms use different strategies,including the integument,which is a barrier that minimizes temperature exchange between the inner body and the surrounding air.In lizards,this barrier is constituted by keratinized scales of variable size,shape and texture,and its main function is protection,water loss avoidance and thermoregulation.The size of scales in lizards has been proposed to vary in relation to climatic gradients;however,it has also been observed that in some groups of Iguanian lizards it could be related to phylogeny.Thus,here,we studied the area and number of scales(dorsal and ventral)of 60 species of Liolaemus lizards distributed in a broad latitudinal and altitudinal gradient to determine the nature of the variation of the scales with climate,and found that the number and size of scales are related to climatic variables,such as temperature and geographical variables as altitude.The evolutionary process that best explained how these morphological variables evolved was the Ornstein–Uhlenbeck model.The number of scales seemed to be related to common ancestry,whereas dorsal and ventral scale areas seemed to vary as a consequence of ecological traits.In fact,the ventral area is less exposed to climate conditions such as ultraviolet radiation or wind and is,thus,under less pressure to change in response to alterations in external conditions.It is possible that scale ornamentation,such as keels and granulosity,may bring some more information in this regard.

When a general morphology allows many habitat uses

During the last decades the study of functional morphology received more attention incorporating more detailed data corresponding to the internal anatomy that together contribute for a better understanding of the functional basis in locomotion.Here we focus on 2 lizard families,Tropiduridae and Liolaemidae,and use information re­lated to muscle-tendinous and external morphology traits of hind legs.We investigate whether the value of the traits analyzed tend to exhibit a reduced phenotypic variation produced by stabilizing selection,and whether species showing specialization in their habitat use will also exhibit special morphological features related to it.As a result,we identified that evolution of hind limb traits is mainly explained by the Ornstein-Uhlenbeck mod­el,suggesting stabilizing selection.Liolaemids and tropidurids show clear ecomorphological trends in the vari­ables considered,with sand lizards presenting the most specialized morphological traits.Some ecomorphologi­cal trends differ between the 2 lineages,and traits of internal morphology tend to be more flexible than those of external morphology,restricting the ability to identify ecomorphs shared between these 2 lineages.Conservative traits of external morphology likely explain such restriction,as ecomorphs have been historically defined in oth­er lizard clades based on variation of external morphology.