Ben Creisler
Some recent non-dino papers that may be of interest:
Free pdf:
Michel Laurin, David Marjanovic & Oceane Lapauze (2018)
What do ossification sequences tell us about the origin of extant amphibians?
bioarxiv preprint
The controversial origin of extant amphibians has been studied using several sources of data and methods, including phylogenetic analyses of morphological data, molecular dating, stratigraphic data, and comparisons of ossification sequences. A consensus has failed to emerge, perhaps because the diversity of methods used hampers comparisons. We have compiled a dataset of ossification sequences of 102 terminal taxa and seven cranial bones to assess the relative support for six competing hypotheses about the origin of extant amphibians: a monophyletic origin among temnospondyls, a monophyletic origin among lepospondyls, a diphyletic origin among both temnospondyls and lepospondyls, a diphyletic origin among temnospondyls alone, and two variants of a triphyletic origin, in which anurans and urodeles come from different temnospondyl taxa while caecilians come from lepospondyls and are either closer to anurans and urodeles or to amniotes. The data are analyzed through maximum likelihood, and the AICc (corrected Akaike Information Criterion) weights of the six hypotheses allow us to assess their relative support. By an unexpectedly large margin, our analyses support a monophyletic origin among lepospondyls; a monophyletic origin among temnospondyls, the current near-consensus, is a distant second. All other hypotheses are exceedingly unlikely according to our data.
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Free pdf:
Jia Jia & Gao Ke-Qin (2018)
Dataset of 3D high-resolution ÎCT scan of fossil specimens of Qinglongtriton gangouensis, a basal salamandroid (Amphibia, Urodela) from the Upper Jurassic of Hebei Province, China.
Biodiversity in China Zone II â Versions EN1 Vol 3 (1)
DOI:Â 10.11922/csdata.2017.0004.zh
Dataset DOI:Â 10.11922/sciencedb.527
It comes the digital era for paleontological research. High-resolution X-ray tomography (or ÎCT) has several advantages (high resolution, high efficiency and non-destructive detection) over traditional mechanical preparation and serial sectioning techniques when used to investigate fossil specimens. Thus, this new technique has been widely used by paleontologists in their study of fossils. This paper provides a methodological description of ÎCT scanning of fossils of a Jurassic salamander, Qinglongtriton gangouensis , and provides the ÎCT source data of the holotype (PKUP V0226) and two referred specimens (PKUP V0228, PKUP V0254) of this fossil taxon. Qinglongtriton gangouensis is a primitive salamander classified in the suborder Salamandroidea. Specimens of this taxon were discovered from the Upper Jurassic Tiaojishan Formation of Hebei Province, China, and the fossil beds have been dated at ~160 million years. A3D printable stl formatted file of the upper body skeleton of PKUP V0226, together with CT images and videos of the three specimens, was provided to display the reconstructed skeleton of the three specimens. This is the first attempt of employing ÎCT technique in the study of salamander fossils from China. Several unique osteological features were revealed via ÎCT scan of the specimens; for instance, the absence of an ossified orbitosphenoid provides deep insights in understanding character evolution in Salamandroidea. This dataset offers a methodological reference for the application of ÎCT scan technique in future research of fossil salamanders, and also opens a window to the public arena for virtual access to the results of our CT scanning of the Jurassic salamander fossils.
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Seung Choi, Seokyoung Han, Noe-Heon Kim & Yuong-Nam Lee (2018)Â
A comparative study of eggshells of Gekkota with morphological, chemical compositional and crystallographic approaches and its evolutionary implications.Â
PLoS ONE 13(6): e0199496.
The Gekkota is an important clade in the evolution of calcified eggshells in that some of its families lay rigid eggshells like archosaurs. However, the fundamental differences and similarities between the mechanism of rigid eggshell formation of the Gekkota and Archosauria have not been investigated thoroughly due to the lack of knowledge of gekkotan eggshells. Here, we report for the first time a comprehensive analysis of morphological, chemical compositional, and crystallographic features of rigid and soft gekkotan eggshells. Exhaustive morphological description provided common characters for gekkotan eggshells, as well as unique features of each species. We found that elemental distribution of rigid gekkotan eggshells is different from that of avian eggshells, especially in the case of Mg and P. In addition, the crystallographic features (size, shape, and alignment of calcite grains) of gekkotan eggshells are completely different from those of archosaur eggshells. The result of this study suggests that soft gekkotan eggshells are morphologically more similar to tuatara eggshells rather than soft eggshells of derived squamates. The chemical compositional analysis suggests that the eggshell may act as a mineral reservoir for P and F as well as Ca. More importantly, all chemical compositions and crystallographic features imply that the gekkotan eggshell formation may begin at the outer surface and growing down to the inner surface, which is opposite to the direction of the archosaur eggshell formation. This character would be crucial for identifying fossil gekkotan eggs, which are poorly known in paleontology. All these lines of evidence support that soft gekkotan and tuatara eggshells share the primitive characters of all lepidosaurid eggshells. Finally, gekkotan and archosaur rigid eggshells represent a typical example of convergent evolution in the lineage of the Sauropsida.
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Daniel Hoops, Ester Desfilis, Jeremy F. P. Ullmann, Andrew L. Janke, Timothy StaitâGardner, Gabriel A. Devenyi, William S. Price, Loreta Medina, Martin J. Whiting &Â J. Scott Keogh (2018)
A 3D MRIâbased atlas of a lizard brain.
Journal of Comparative Neurology (advance online publication)
Magnetic resonance imaging (MRI) is an established technique for neuroanatomical analysis, being particularly useful in the medical sciences. However, the application of MRI to evolutionary neuroscience is still in its infancy. Few magnetic resonance brain atlases exist outside the standard model organisms in neuroscience and no magnetic resonance atlas has been produced for any reptile brain. A detailed understanding of reptilian brain anatomy is necessary to elucidate the evolutionary origin of enigmatic brain structures such as the cerebral cortex. Here, we present a magnetic resonance atlas for the brain of a representative squamate reptile, the Australian tawny dragon (Agamidae: Ctenophorus decresii), which has been the object of numerous ecological and behavioral studies. We used a highâfield 11.74T magnet, a paramagnetic contrastingâenhancing agent and minimumâdeformation modeling of the brains of thirteen adult male individuals. From this, we created a highâresolution threeâdimensional model of a lizard brain The 3DâMRI model can be freely downloaded and allows a better comprehension of brain areas, nuclei, and fiber tracts, facilitating comparison with other species and setting the basis for future comparative evolution imaging studies. The MRI model of a tawny dragon brain (Ctenophorus decresii) can be viewed online and downloaded using the Wiley Biolucida Server at
wiley.biolucida.net.Â
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MarÃa V. Fernandez Blanco, Guillermo H. Cassini & Paula Bona (2018)
Skull ontogeny of extant caimans: a three-dimensional geometric morphometric approach.
Zoology (advance online publication)
Highlights
The TPS method is the most suitable for missing landmarks estimation with our data.
Cranial differences between caiman species and common ontogenetic trajectories were found.
Common ontogenetic morphological changes respond to ontogenetic changes in the diet.
Interspecific differences would reflect hardness food item and habitat preferences.
Some skull characters used in phylogenetic analyses vary inter- and intraspecifically in Caiman.
Abstract
Ontogenetic variation of cranial characters used in crocodylian phylogenetic systematics has never been studied. Furthermore, the relationship between diet and skull morphological transformation during ontogeny has not been properly explored yet. We quantify the inter- and intraspecific skull morphological variation in extant caiman species focusing on those areas relevant to systematics and, also investigate the relation between diet and morphological changes during ontogeny. We applied a three-dimensional approach of geometric morphometrics on post-hatching ontogenetic cranial series of Caiman latirostris and C. yacare. In order to incorporate incomplete material, we additionally tested four different methods of missing landmark estimation and apply the thin-plate spline interpolation. We detected morphological changes between species and during ontogeny (snout and pterygoid flanges increase their proportions and, orbits, temporal fenestrae, skull roof and foramen magnum decrease their relative size) that constitutes part of a general morphological change in the cranial ontogeny of crocodylians. Moreover, the negative allometry of the fenestrae and neurocranium and the positive allometry of the splanchnocranium in both caiman species are the plesiomorphic condition, at least, for tetrapods. Shape changes during growth were found to be related to ontogenetic changes in the diet. Dissimilarities between species seem to be related to different mechanical requirements and different use of the habitat. We found inter- and intraspecific variation in some morphological characters with systematic implications (the contact of nasals with naris, the contact of prefrontals in the midline, and the bones that border the suborbital fenestra and the proportion in which one of them participates) that are not currently considered in phylogenetic analyses.
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Maria Goller & Daizaburo Shizuka (2018)
Evolutionary origins of vocal mimicry in songbirds.
Evolution Letters (advance online publication)
Vocal learning is an important behavior in oscines (songbirds). Some songbird species learn heterospecific sounds as well as conspecific vocalizations. The emergence of vocal mimicry is necessarily tied to the evolution of vocal learning, as mimicry requires the ability to acquire sounds through learning. As such, tracking the evolutionary origins of vocal mimicry may provide insights into the causes of variation in song learning programs among songbirds. We compiled a database of known vocal mimics that comprised 339 species from 43 families. We then traced the evolutionary history of vocal mimicry across the avian phylogeny using ancestral trait reconstruction on a dataset of oscine passerines for which vocalizations have been described. We found that the common ancestor to oscines was unlikely to mimic sounds, suggesting that song learning evolved with mechanisms to constrain learning to conspecific models. Mimicry then evolved repeatedly within the songbird clade, either through relaxation of constraints on conspecific learning or through selection for active vocal mimicry. Vocal mimicry is likely ancestral in only a handful of clades, and we detect many instances of independent origins of mimicry. Our analysis underscores the liability of vocal mimicry in songbirds, and highlights the evolutionary flexibility of song learning mechanisms.
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Free pdf:
Martin Stevens & Graeme D. Ruxton (2018)
The key role of behaviour in animal camouflage.
Biological Reviews (advance online publication)
Animal camouflage represents one of the most important ways of preventing (or facilitating) predation. It attracted the attention of the earliest evolutionary biologists, and today remains a focus of investigation in areas ranging from evolutionary ecology, animal decisionâmaking, optimal strategies, visual psychology, computer science, to materials science. Most work focuses on the role of animal morphology per se, and its interactions with the background in affecting detection and recognition. However, the behaviour of organisms is likely to be crucial in affecting camouflage too, through background choice, body orientation and positioning; and strategies of camouflage that require movement. A wealth of potential mechanisms may affect such behaviours, from imprinting and selfâassessment to genetics, and operate at several levels (species, morph, and individual). Over many years there have been numerous studies investigating the role of behaviour in camouflage, but to date, no effort to synthesise these studies and ideas into a coherent framework. Here, we review key work on behaviour and camouflage, highlight the mechanisms involved and implications of behaviour, discuss the importance of this in a changing world, and offer suggestions for addressing the many important gaps in our understanding of this subject.
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Free pdf:
LI Xianghui, ZHANG Chaokai, WANG Yin & LIU Ling (2018)
Geochronostratigraphy and Relationship of the Late Mesozoic Terrestrial Lithostratigraphic Units in South China.
Acta Geologica Sinica 92(6): 1107-1130 (Chinese edition)
The precise age and correlation of the Late Mesozoic terrestrial lithostratigraphic units in South China have long been in dispute. Based on the summary for the zircon U Pb isotope age data of volcanic rocks published in recent years, along with complementary work in this study, this study revised and determined the ages and relationship of the lithostratigrapic units in the Late Mesozoic terrestrial volcano sedimentary basin in the Gan Hang tectonic zone, South China. Some preliminary understanding in five aspects has been made as follows. (1) In western Zhejiang, the Moshishan Gr (Group), Jiande Gr, and Yongkang Gr were probably formed in early and middle Early Cretaceous (~145~120 Ma and ~140~115 Ma), and late Early Cretaceous (~125~105 Ma), respectively, indicating they formed in a chorological order with parts co existing. Laterally superimposed relation occurs among the formations of the Jiande Group and the formations of the Yongkang Group. The age (98 Ma) of zircons from the lower Zhongdai Formation indicates that the Qujiang Group had started since the beginning of Late Cretaceous. The two typical sections, located at Shouchang of Jiande basin and Laozhu of Lishui basin respectively, all consist of two similar stratigraphical sequences. (2) The Yongâan basin in western Fujian may have the oldest stratum record in Late Mesozoic era, with the Douling Group forming in Late Jurassic to early Early Cretaceous (~162~125 Ma) and the Shimao Formation in middle to late Early Cretaceous (~135~95 Ma). The Shaxian Fm of the Chishi Gr has a time range from late Aptian to early Cenomanian (~115~93 Ma), the Baiyashan Fm has a short age duration (~100~97 Ma), and the Chongâan Fm could have not started until ~100 Ma. The study suggest that not only an up down relationship but also more coeval different lithofacies with lateral progradation occur between the Bantou Fm and Xiadu Fm, the Zhaixia Fm and Huangkeng Fm, and among the Shaxian, Junkou, Baiyashan and Chongâan formations. (3) In eastern Jiangxi, the Wuyi Gr formed in early Early Cretaceous (~145~125 Ma), the Huobashan Gr might no begin until the early Aptian (~122 Ma), the Ganzhou Gr could be deposited after early Albian (~110 Ma), and the Guifeng Gr might start in early Late Cretaceous (after~100 Ma). The study suggests that the main sequences among the Daguding, Eheling and Shixi formations, and Hekou and Tangbian formations are contemporaneous heterotopic facies in different environment, likely with lateral superimposition. While the Luotang, Lengshuiwu and Zhoujia formations, and Hekou and Lianhe formations are probably the same sequences but named differently. (4) The Late Mesozoic strata in the Gan Hang tectonic zone can be classified into three stages: stage I, the early Early Cretaceous volcanic squence; stage II, the late Early Cretaceous volcano sedimentary squence; and stage III, the Late Cretaceous sedimentary squence. Corresponding sequence record may be grouped into one supergroup, and the evolution stages of three strata to some extent reflect three tectonic evolution stages. (5) The extensive lateral superimposition and facies elationship of lithostratigraphic units of formations in the Gan Hang volocano sedimentary basin suggests that it is necessary to revise and reinterpret the successive and progradational relationships of the late Mesozoic terrestrial lithostratigraphic units in South China.