scholarly journals Reevaluation of the largest published morphological data matrix for phylogenetic analysis of Paleozoic limbed vertebrates

2015 ◽  
Author(s):  
David Marjanović ◽  
Michel Laurin
Keyword(s):  
Phylogenetic Analysis ◽  
Data Matrix ◽  
Morphological Data ◽  
Lower Jaw ◽  
12 Steps ◽  
The Matrix ◽  
One Step ◽  
The Difference ◽  
Character Complexes ◽  
The Many

The largest data matrix for phylogeny of early limbed vertebrates (Ruta M, Coates MI. 2007. J. Syst. Palaeont. 5:69–122) has supported controversial hypotheses; e.g., it has recovered Seymouriamorpha, Diadectomorpha and (in some trees) Caudata as paraphyletic and found the “temnospondyl hypothesis” on the origin of Lissamphibia (TH) to be one step more parsimonious than the “lepospondyl hypothesis” (LH). Scrutiny of the matrix reveals thousands of suboptimal scores (many clearly due to typographic and similar errors) as well as logically linked (redundant) characters, characters with only one described state, and even cases where taxa were scored after presumed relatives. Moreover, all characters – even obviously continuous ones – were unordered, effects of ontogeny were not sufficiently taken into account, and the authors mostly excluded data published after 2001, even their own. Our revised version – we document and justify all changes – yields much longer trees with a different topology, e.g. monophyletic Caudata, Diadectomorpha and (sometimes) Seymouriamorpha, Ichthyostega more rootward than Acanthostega, Anthracosauria more rootward than Temnospondyli, and the LH, which is 10 steps more parsimonious than the TH and 15 more than the “polyphyly hypothesis” (PH). Bootstrap values, though, are low, and few of the topologies are statistically distinguishable. For another set of analyses, we added 48 OTUs to the original 102. This destabilizes parts of the tree, e.g. the relationships of Anthracosauria and Temnospondyli. However, many of the added taxa have a fully resolved position or nearly so; this concerns the well-known Chroniosaurus (sister to a clade containing Solenodonsaurus, Seymouriamorpha, Diadectomorpha, Amniota and Amphibia), but also isolated lower-jaw material from the Devonian and Carboniferous. Despite the addition of Gerobatrachus, Micropholis and Tungussogyrinus and the extremely peramorphic salamander Chelotriton, the difference between LH and TH only shrinks to 9 steps, that between LH and PH to 13 steps. The “lepospondyl” Brachydectes is neither found as sister to Lissamphibia nor in the “microsaur” grade. Bootstrap values plummet, though, and all three hypotheses become statistically indistinguishable at p = 0.05. We then duplicated all analyses after coding all losses of bones as irreversible. Anthracosauria is then consistently placed more rootward than Temnospondyli; given the original taxon sample, the LH is 12 steps shorter than the “temnospondyl hypothesis” and 17 steps shorter than the PH, while the expanded taxon sample makes the LH 10 steps shorter than the TH and only 12 steps shorter than the PH. More robust results could likely be obtained by adding the many characters used in other analyses or discussed in the literature. We discuss phylogeny, approaches to coding, and certain character complexes, in particular the supposed middle ear of temnospondyls.

scholarly journals Reevaluation of the largest published morphological data matrix for phylogenetic analysis of Paleozoic limbed vertebrates

2016 ◽  
Author(s):  
David Marjanović ◽  
Michel Laurin
Keyword(s):  
Phylogenetic Analysis ◽  
Data Matrix ◽  
Morphological Data ◽  
Published Data ◽  
12 Steps ◽  
The Matrix ◽  
One Step ◽  
The Difference ◽  
Character Complexes ◽  
The Impact

The largest published data matrix for phylogenetic analysis of Paleozoic limbed vertebrates (Ruta M, Coates MI. 2007. Journal of Systematic Palaeontology 5:69–122) supported variously controversial hypotheses; e.g., it recovered Seymouriamorpha, Diadectomorpha and (in some trees) Caudata as paraphyletic and found the “temnospondyl hypothesis” on the origin of Lissamphibia (TH) to be more parsimonious than the “lepospondyl hypothesis” (LH) – though only, as we show, by one step. We report thousands of suboptimal scores due to typographic and similar errors and to questionable coding decisions: logically linked (redundant) characters, others with only one described state, even characters for which most taxa were scored after presumed relatives. Even continuous characters were unordered, the effects of ontogeny were not sufficiently taken into account, and data published after 2001 were mostly excluded. After these issues are improved – we document and justify all changes to the matrix –, but no characters are removed or added, we find (Analysis R1) much longer trees with e.g. monophyletic Caudata, Diadectomorpha and (in some trees) Seymouriamorpha; Ichthyostega rootward of Acanthostega; Anthracosauria rootward of Temnospondyli which includes Caerorhachis; the LH is 9 steps shorter than the TH (R2; constrained) and 12 steps shorter the “polyphyly hypothesis” (PH – R3; constrained). We then added 48 OTUs to the original 102. This destabilizes some parts of the tree, e.g. the positions of Anthracosauria, Temnospondyli and Caerorhachis. Yet, many added taxa have well-resolved positions, ranging from the well known Chroniosaurus (Chroniosuchia), which lies just crownward of Temnospondyli and Gephyrostegidae, to isolated lower jaws. Even though Gerobatrachus, Micropholis and Tungussogyrinus and the extremely peramorphic salamander Chelotriton are added, the difference between LH (R4) and TH (R5) rises to 12 steps, that between LH and PH (R6) to 17 steps; the TH also requires several more regains of lost bones than the LH. Brachydectes (Lysorophia) is not found next to Lissamphibia. We duplicated all analyses after coding losses of bones as irreversible. The impact on the results is modest. Anthracosauria is always rootward of Temnospondyli. With 102 OTUs, the LH (R7) is 10 steps shorter than the TH (R8) and 11 steps shorter than the PH (R9); with 150, the LH (R10) is 14 steps shorter than the TH (R12) – and 13 steps shorter than the PH (R11). Bootstrap values are mostly low, and plummet when taxa are added. Statistically, the TH (R2, R5, R8, R12) is not distinguishable from the LH or the PH, but the LH (R1, R4, R7, 53 R10) and the PH (R3, R6, R9, R11) may be distinguishable from each other under both taxon samples and both reversibility settings. A reliable test is not available. We discuss the relationships of certain taxa, approaches to coding, some character complexes, and prospects for further improvement of this matrix.

scholarly journals Reproducibility in phylogenetics: reevaluation of the largest published morphological data matrix for phylogenetic analysis of Paleozoic limbed vertebrates

2018 ◽  
Author(s):  
David Marjanović ◽  
Michel Laurin
Keyword(s):  
Phylogenetic Analysis ◽  
Bayesian Inference ◽  
Sister Group ◽  
Data Matrix ◽  
Morphological Data ◽  
P Value ◽  
The Matrix ◽  
One Step ◽  
The Difference ◽  
Character Complexes

The largest published phylogenetic analysis of early limbed vertebrates (Ruta M, Coates MI. 2007. Journal of Systematic Palaeontology 5:69–122) recovered e.g. Seymouriamorpha, Diadectomorpha and (in some trees) Caudata as paraphyletic and found the “temnospondyl hypothesis” on the origin of Lissamphibia (TH) to be more parsimonious than the “lepospondyl hypothesis” (LH) – though only, as we show, by one step. We report thousands of misscored cells, most of them due to typographic and similar accidental errors. Further, some characters are duplicated; some have only one described state; for some, most taxa were scored after presumed relatives. Even continuous characters were unordered, the effects of ontogeny were not sufficiently taken into account, and data published after 2001 were mostly excluded. After these issues are improved – we document and justify all changes to the matrix –, but no characters are added, we find (Analysis R1) much longer trees with e.g. monophyletic Caudata, Diadectomorpha and (in some trees) Seymouriamorpha; Ichthyostega either crownward or rootward of Acanthostega; Anthracosauria either crownward or rootward of Temnospondyli; the LH is 9 steps shorter than the TH (R2; constrained) and 12 steps shorter the “polyphyly hypothesis” (PH – R3; constrained). Brachydectes (Lysorophia) is not found next to Lissamphibia; instead, the sister-group of Lissamphibia is a large clade that includes adelogyrinids, urocordylid “nectrideans” and aïstopods. Adding 56 OTUs to the original 102 increases the resolution. The added taxa range in completeness from complete articulated skeletons to an incomplete lower jaw. Even though the lissamphibian-like temnospondyls Gerobatrachus, Micropholis and Tungussogyrinus and the extremely peramorphic salamander Chelotriton are added, the difference between LH (R4) and TH (R5) rises to 10 steps, that between LH and PH (R6) to 15; the TH also requires several more regains of lost bones than the LH. Most bootstrap values are low, and plummet when taxa are added. Statistically, the TH (R2, R5) is not distinguishable from the LH or the PH; the LH (R1) and the PH (R3) may be distinguishable from each other under the original taxon sample at p ≥ 0.04. A test for the upper bound of the p value is not available. Bayesian inference (Analysis EB, same settings as R4) mostly agrees with R4. High posterior probabilities are found for Lissamphibia (1.00) and for the LH (0.92); however, many branches remain weakly supported, and most are short, as expected from the small character sample. We discuss phylogeny, approaches to coding, methods of phylogenetics (Bayesian inference vs. equally weighted vs. reweighted parsimony), some character complexes, and prospects for further improvement of this matrix. In its present state, even after our changes, the matrix cannot provide a robust assessment of the phylogeny of early limbed vertebrates; sufficient improvement, however, will be laborious but not difficult.

scholarly journals Phylogeny of Paleozoic limbed vertebrates reassessed through revision and expansion of the largest published relevant data matrix

PeerJ ◽  
2019 ◽  
Vol 6 ◽  
pp. e5565 ◽  
Author(s):  
David Marjanović ◽  
Michel Laurin
Keyword(s):  
Bayesian Inference ◽  
Limb Development ◽  
Data Matrix ◽  
Lower Jaw ◽  
12 Steps ◽  
The Matrix ◽  
One Step ◽  
Systematic Palaeontology ◽  
The Difference ◽  
Character Complexes

The largest published phylogenetic analysis of early limbed vertebrates (Ruta M, Coates MI. 2007.Journal of Systematic Palaeontology5:69–122) recovered, for example, Seymouriamorpha, Diadectomorpha and (in some trees) Caudata as paraphyletic and found the “temnospondyl hypothesis” on the origin of Lissamphibia (TH) to be more parsimonious than the “lepospondyl hypothesis” (LH)—though only, as we show, by one step. We report 4,200 misscored cells, over half of them due to typographic and similar accidental errors. Further, some characters were duplicated; some had only one described state; for one, most taxa were scored after presumed relatives. Even potentially continuous characters were unordered, the effects of ontogeny were not sufficiently taken into account, and data published after 2001 were mostly excluded. After these issues are improved—we document and justify all changes to the matrix—but no characters are added, we find (Analysis R1) much longer trees with, for example, monophyletic Caudata, Diadectomorpha and (in some trees) Seymouriamorpha;Ichthyostegaeither crownward or rootward ofAcanthostega; and Anthracosauria either crownward or rootward of Temnospondyli. The LH is nine steps shorter than the TH (R2; constrained) and 12 steps shorter than the “polyphyly hypothesis” (PH—R3; constrained).Brachydectes(Lysorophia) is not found next to Lissamphibia; instead, a large clade that includes the adelogyrinids, urocordylid “nectrideans” and aïstopods occupies that position. As expected from the taxon/character ratio, most bootstrap values are low. Adding 56 terminal taxa to the original 102 increases the resolution (and decreases most bootstrap values). The added taxa range in completeness from complete articulated skeletons to an incomplete lower jaw. Even though the lissamphibian-like temnospondylsGerobatrachus,MicropholisandTungussogyrinusand the extremely peramorphic salamanderChelotritonare added, the difference between LH (R4; unconstrained) and TH (R5) rises to 10 steps, that between LH and PH (R6) to 15; the TH also requires several more regains of lost bones than the LH.Casineria, in which we tentatively identify a postbranchial lamina, emerges rather far from amniote origins in a gephyrostegid-chroniosuchian grade. Bayesian inference (Analysis EB, settings as in R4) mostly agrees with R4. High posterior probabilities are found for Lissamphibia (1.00) and the LH (0.92); however, many branches remain weakly supported, and most are short, as expected from the small character sample. We discuss phylogeny, approaches to coding, methods of phylogenetics (Bayesian inference vs. equally weighted vs. reweighted parsimony), some character complexes (e.g. preaxial/postaxial polarity in limb development), and prospects for further improvement of this matrix. Even in its revised state, the matrix cannot provide a robust assessment of the phylogeny of early limbed vertebrates. Sufficient improvement will be laborious—but not difficult.

scholarly journals Reproducibility in phylogenetics: reevaluation of the largest published morphological data matrix for phylogenetic analysis of Paleozoic limbed vertebrates

2018 ◽  
Author(s):  
David Marjanović ◽  
Michel Laurin
Keyword(s):  
Phylogenetic Analysis ◽  
Bayesian Inference ◽  
Sister Group ◽  
Data Matrix ◽  
Morphological Data ◽  
P Value ◽  
The Matrix ◽  
One Step ◽  
The Difference ◽  
Character Complexes

The largest published phylogenetic analysis of early limbed vertebrates (Ruta M, Coates MI. 2007. Journal of Systematic Palaeontology 5:69–122) recovered e.g. Seymouriamorpha, Diadectomorpha and (in some trees) Caudata as paraphyletic and found the “temnospondyl hypothesis” on the origin of Lissamphibia (TH) to be more parsimonious than the “lepospondyl hypothesis” (LH) – though only, as we show, by one step. We report thousands of misscored cells, most of them due to typographic and similar accidental errors. Further, some characters are duplicated; some have only one described state; for some, most taxa were scored after presumed relatives. Even continuous characters were unordered, the effects of ontogeny were not sufficiently taken into account, and data published after 2001 were mostly excluded. After these issues are improved – we document and justify all changes to the matrix –, but no characters are added, we find (Analysis R1) much longer trees with e.g. monophyletic Caudata, Diadectomorpha and (in some trees) Seymouriamorpha; Ichthyostega either crownward or rootward of Acanthostega; Anthracosauria either crownward or rootward of Temnospondyli; the LH is 9 steps shorter than the TH (R2; constrained) and 12 steps shorter the “polyphyly hypothesis” (PH – R3; constrained). Brachydectes (Lysorophia) is not found next to Lissamphibia; instead, the sister-group of Lissamphibia is a large clade that includes adelogyrinids, urocordylid “nectrideans” and aïstopods. Adding 56 OTUs to the original 102 increases the resolution. The added taxa range in completeness from complete articulated skeletons to an incomplete lower jaw. Even though the lissamphibian-like temnospondyls Gerobatrachus, Micropholis and Tungussogyrinus and the extremely peramorphic salamander Chelotriton are added, the difference between LH (R4) and TH (R5) rises to 10 steps, that between LH and PH (R6) to 15; the TH also requires several more regains of lost bones than the LH. Most bootstrap values are low, and plummet when taxa are added. Statistically, the TH (R2, R5) is not distinguishable from the LH or the PH; the LH (R1) and the PH (R3) may be distinguishable from each other under the original taxon sample at p ≥ 0.04. A test for the upper bound of the p value is not available. Bayesian inference (Analysis EB, same settings as R4) mostly agrees with R4. High posterior probabilities are found for Lissamphibia (1.00) and for the LH (0.92); however, many branches remain weakly supported, and most are short, as expected from the small character sample. We discuss phylogeny, approaches to coding, methods of phylogenetics (Bayesian inference vs. equally weighted vs. reweighted parsimony), some character complexes, and prospects for further improvement of this matrix. In its present state, even after our changes, the matrix cannot provide a robust assessment of the phylogeny of early limbed vertebrates; sufficient improvement, however, will be laborious but not difficult.

scholarly journals A new short-necked chelid turtle from the Loncoche Formation (Late Campanian- Early Maastrichtian) Mendoza province, Argentina: Macro, microanatomy, and preliminary phylogenetic relationships

2015 ◽  
Author(s):  
Marcelo de la Fuente ◽  
Ignacio Maniel ◽  
Juan Marcos Jannello ◽  
Juliana Sterli ◽  
Bernardo González Riga ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Cancellous Bone ◽  
Phylogenetic Relationships ◽  
Cervical Vertebrae ◽  
Data Matrix ◽  
Appendicular Skeleton ◽  
Thin Sections ◽  
Lower Jaw ◽  
A New Species ◽  
Preliminary Phylogenetic Analysis

Background. The lower section of the Loncoche Formation (Late Campanian-Early Maastrichtian) outcropping at Ranquil-Có locality (Mendoza province, Argentina) has yielded a rich assemblage of vertebrates that was studied in 1995 by Gonzalez Riga. According to this author these vertebrate remains were found in a tidal paleoenvironment, resulting from transportation, mixing and deposition of continental remains mixed with those from near costal environments. Previously to these findings Jose F. Bonaparte recovered in 1990 a large turtle from the same locality and horizon. Methods. Remains of basicranium (basioccipital and basisphenoid), fragments of both quadrates, left opisthotic, a lower jaw, cervical vertebrae, one caudal vertebra, appendicular skeleton, a partial carapace and one almost complete plastron are preserved in MACN Pv M2. In order to explore the phylogenetic relationships of MACN Pv M2, this specimen was included in a data matrix built up by 48 characters and 17 taxa. One fragmentary costal plate was sampled for histological analysis. The bone microstructure of the thin sections was studied under light microscopy using normal and polarized lights. Results. The preliminary phylogenetic analysis suggests that MACN Pv M2 is nested in a clade also including Phrynops hilarii + Mesoclemmys nasuta + long-necked chelids. The pelvic girdle attached by suture to the shell in MACN Pv M2 and the synapomorphic characters such as splenial bone in the lower jaw, ilium extending over the eight costal and anterior margin of the suprapygal bones allow us to assign this specimen to Pleurodira Chelidae. The microanatomy of MACN Pv M2 shows a diploe structure as in other turtles. The internal cortex is equal or slowly thinner than the external one, and the cancellous bone occupy the main proportion (50-60%). The external cortex is composed of structural fibre bundles that extend parallel to the external surface and orient longitudinally and transversally to the progression of the elements. The cancellous bone is mostly well developed. The internal cortex consists of parallel-fibred bone that locally can grade into lamellar bone. Discussion. The unique combination of plesiomorphies (such as lateral mesoplastra, area articularis mandibularis concave, a short midline epiplastral suture, an anterior peripherals bones shorter than posterior ones) and autapomorphies (such as both rami of the lower jaw fused, extremely wide anterior plastral lobe, and a slightly epiplastral notch) recovered in this phylogenetic analysis allow to assigned MACN Pv M2 as a new species of short-necked chelid taxa. The histology of MACN Pv M2 shows features that suggest adaptation to the aquatic lifestyle (i.e., well vascularized external cortex, the vascularization of the internal cortex composed of scattered vascular canals and primary osteons of longitudinally orientation).

A new genus of cyphophthalmid from the Iberian Peninsula with a phylogenetic analysis of the Sironidae (Arachnida : Opiliones : Cyphophthalmi) and a SEM database of external morphology

2004 ◽  
Vol 18 (1) ◽  
pp. 7 ◽  
Author(s):  
Benjamin L. de Bivort ◽  
Gonzalo Giribet
Keyword(s):  
Phylogenetic Analysis ◽  
Iberian Peninsula ◽  
New Genus ◽  
Molecular Data ◽  
Data Matrix ◽  
Morphological Data ◽  
Scanning Electron Micrographs ◽  
Single Male ◽  
Weighting Method ◽  
Male Specimen

A new species of sironid from Portugal is described based on a single male specimen collected over half a century ago. The unique combination of character states and phylogenetic comparison with representatives of all sironid genera justifies the erection of a new genus, the fourth one found in the Iberian Peninsula. Phylogenetic analysis is conducted using equal weights and the implied weighting method as a means of testing the stability of clades with respect to parameter variation, in a similar fashion to the sensitivity analysis commonly performed in molecular data analyses. Results suggest that the new genus is sister to Paramiopsalis Juberthie, 1962, although nodal support for this relationship is low. The morphological data matrix is accompanied by scanning electron micrographs of most characters for 24 species to make the morphological coding as explicit as possible. Comparison of these images fostered the discovery and proper interpretation of characters and their states.

scholarly journals New lower jaw and teeth referred toMaxakalisaurus topai(Titanosauria: Aeolosaurini) and their implications for the phylogeny of titanosaurid sauropods

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2054 ◽  
Author(s):  
Marco A.G. França ◽  
Júlio C. de A. Marsola ◽  
Douglas Riff ◽  
Annie S. Hsiou ◽  
Max C. Langer
Keyword(s):  
Phylogenetic Analysis ◽  
Minas Gerais ◽  
Body Plan ◽  
Morphological Data ◽  
Type Series ◽  
Lower Jaw

Sauropod dinosaurs compose a diversified, well known, and worldwide distributed clade, with a stereotyped body plan: deep trunk, elongated neck and tail, columnar limbs and very small skull. In Brazil, the group is represented by ten formally described Cretaceous species, mostly titanosaurs. This is the case ofMaxakalisaurus topai, known based on an incomplete and disarticulated skeleton, unearthed from deposits of the Adamantina Formation in Minas Gerais. Here, we report a partial right dentary, including five isolated teeth, collected from the same site as the type-series ofM. topaiand tentatively referred to that taxon. The bone is gently curved medially, the functional teeth are set on an anterolingual position, and two replacement teeth are seen per alveoli. New morphological data gathered from that specimen was employed to conduct a comprehensive phylogenetic analysis of Titanosauria (with 42 taxa and 253 characters), based on previous studies. The Aeolosaurini clade was recovered, withGondwanatitanandAelosaurusas sister taxa, andMaxakalisaurus,Panamericansaurus, andRinconsaurusforming a basal polytomy.

scholarly journals A new short-necked chelid turtle from the Loncoche Formation (Late Campanian- Early Maastrichtian) Mendoza province, Argentina: Macro, microanatomy, and preliminary phylogenetic relationships

2015 ◽  
Author(s):  
Marcelo de la Fuente ◽  
Ignacio Maniel ◽  
Juan Marcos Jannello ◽  
Juliana Sterli ◽  
Bernardo González Riga ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Cancellous Bone ◽  
Phylogenetic Relationships ◽  
Cervical Vertebrae ◽  
Data Matrix ◽  
Appendicular Skeleton ◽  
Thin Sections ◽  
Lower Jaw ◽  
A New Species ◽  
Preliminary Phylogenetic Analysis

Background. The lower section of the Loncoche Formation (Late Campanian-Early Maastrichtian) outcropping at Ranquil-Có locality (Mendoza province, Argentina) has yielded a rich assemblage of vertebrates that was studied in 1995 by Gonzalez Riga. According to this author these vertebrate remains were found in a tidal paleoenvironment, resulting from transportation, mixing and deposition of continental remains mixed with those from near costal environments. Previously to these findings Jose F. Bonaparte recovered in 1990 a large turtle from the same locality and horizon. Methods. Remains of basicranium (basioccipital and basisphenoid), fragments of both quadrates, left opisthotic, a lower jaw, cervical vertebrae, one caudal vertebra, appendicular skeleton, a partial carapace and one almost complete plastron are preserved in MACN Pv M2. In order to explore the phylogenetic relationships of MACN Pv M2, this specimen was included in a data matrix built up by 48 characters and 17 taxa. One fragmentary costal plate was sampled for histological analysis. The bone microstructure of the thin sections was studied under light microscopy using normal and polarized lights. Results. The preliminary phylogenetic analysis suggests that MACN Pv M2 is nested in a clade also including Phrynops hilarii + Mesoclemmys nasuta + long-necked chelids. The pelvic girdle attached by suture to the shell in MACN Pv M2 and the synapomorphic characters such as splenial bone in the lower jaw, ilium extending over the eight costal and anterior margin of the suprapygal bones allow us to assign this specimen to Pleurodira Chelidae. The microanatomy of MACN Pv M2 shows a diploe structure as in other turtles. The internal cortex is equal or slowly thinner than the external one, and the cancellous bone occupy the main proportion (50-60%). The external cortex is composed of structural fibre bundles that extend parallel to the external surface and orient longitudinally and transversally to the progression of the elements. The cancellous bone is mostly well developed. The internal cortex consists of parallel-fibred bone that locally can grade into lamellar bone. Discussion. The unique combination of plesiomorphies (such as lateral mesoplastra, area articularis mandibularis concave, a short midline epiplastral suture, an anterior peripherals bones shorter than posterior ones) and autapomorphies (such as both rami of the lower jaw fused, extremely wide anterior plastral lobe, and a slightly epiplastral notch) recovered in this phylogenetic analysis allow to assigned MACN Pv M2 as a new species of short-necked chelid taxa. The histology of MACN Pv M2 shows features that suggest adaptation to the aquatic lifestyle (i.e., well vascularized external cortex, the vascularization of the internal cortex composed of scattered vascular canals and primary osteons of longitudinally orientation).

Systematics of the Australian orb-weaving spider genus Demadiana with comments on the generic classification of the Arkyinae (Araneae:Araneidae)

2010 ◽  
Vol 24 (2) ◽  
pp. 139 ◽  
Author(s):  
Volker W. Framenau ◽  
Nikolaj Scharff ◽  
Mark S. Harvey
Keyword(s):  
Phylogenetic Analysis ◽  
Type Species ◽  
Species Level ◽  
Junior Synonym ◽  
Data Matrix ◽  
Morphological Data ◽  
Australian Species ◽  
Systematic Relationships ◽  
Australasian Region

The orb-weaving spider subfamily Arkyinae L. Koch, 1872 is exclusively found in the Australasian region and its taxonomy and the systematic relationships within and between genera of this subfamily are poorly understood. We here revise the arkyine genus Demadiana Strand, 1929 to include six Australian species, four of which are described as new: Demadiana simplex (Karsch, 1878) (type species), D. carrai, sp. nov., D. cerula (Simon, 1908), comb. nov., D. complicata, sp. nov., D. diabolus, sp. nov., and D. milledgei, sp. nov. A phylogenetic analysis based on an updated araneid morphological data matrix including 57 genera of orb-weaving spiders identified Demadiana as a member of the araneid subfamily Arkyinae. A separate phylogenetic analysis for the genus at the species level showed little resolution within Demadiana, but did identify a monophyletic Demadiana supported by three putative synapomorphies: small unique setal pits with spherical sockets covering the carapace, sternum and the bases of the paturon (chelicerae), an extreme elongation of the trumpet-like aggregate spigots of the posterior lateral spinnerets and a distinct curvature of the embolus. We detail several new generic and species synonymies within Arkyinae. Aerea Urquhart, 1891 (type species Aerea alticephala Urquhart, 1891) and Neoarchemorus Mascord, 1968 (type species N. speechleyi Mascord, 1968) are regarded as junior synonyms of Arkys Walckenaer, 1837 (type species A. lancearius Walckenaer, 1837), resulting in Arkys speechleyi (Mascord, 1968), comb. nov. Aerea magnifica Urquhart, 1893 and Archemorus simsoni Simon, 1893 are regarded as junior synonyms of Aerea alticephala Urquhart, 1891, and Arkys nitidiceps Simon, 1908 is proposed as a junior synonym of Arkys walckenaeri Simon, 1879.

Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

1987 ◽  
Vol 45 ◽  
pp. 246-247
Author(s):  
R.A. Herring
Keyword(s):  
Device Fabrication ◽  
High Concentration ◽  
Tem Analysis ◽  
Defect Clusters ◽  
High Fluences ◽  
Small Defect ◽  
Before And After ◽  
The Matrix ◽  
The Difference ◽  
Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

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