Morphology of the atlas-axis complex of the late Palaeozoic tetrapod suborders Diadectomorpha and Seymouriamorpha

1992 ◽  
Vol 336 (1277) ◽  
pp. 259-273 ◽  
Keyword(s):  
Posterior Margin ◽  
Dorsal Surface ◽  
Neural Spine ◽  
Neural Arch ◽  
Total Height ◽  
Late Palaeozoic

The atlas-axis complexes of the better-known genera of the Permo-Pennsylvanian tetrapod suborder Diadectomorpha are described and compared with those of other late Palaeozoic tetrapods. One new synapomorphy of the Diadectomorpha is identified: a large, anteriorly directed, midventral, projection of the axial intercentrum that articulates with a midventral furrow on the posterior margin of the atlantalintercentrum . Within the Diadectomorpha diadectids are apomorphic in possessing a large, anteriorly tapering axial neural spine, that accounts for approximately 40% of the total height of the axis; Limnoscelis is apomorphic in having divided parapophyseal facets of the atlantal intercentrum and anteriorly directed ventral processes of the atlantal intercentrum . Relative to the atlas-axis complex in the more primitive amphibian suborder Seymouriamorpha, that of diadectomorphs and other basal amniotes share two derived features: the atlantal pleurocentrum is fused to the dorsal surface of the axial intercentrum , except in Tseajaia where the elements are not fused but are positioned similarly; and the axial pleurocentrum and neural arch are fused in all observable stages of ontogeny. Reinterpretation of the atlantal neural arch in Seymouria indicates that it does not possess neural spines, a feature it shares with the Diadectomorpha and basal amniotes.

scholarly journals The atlas-axis complex of the Late Paleozoic Diadectomorpha and basal amniotes: defining the primitive condition of the atlas-axis complex of amniotes

1992 ◽  
Vol 6 ◽  
pp. 283-283
Author(s):  
Stuart S. Sumida ◽  
R. Eric. Lombard ◽  
David S Berman
Keyword(s):  
Phylogenetic Analyses ◽  
Dorsal Surface ◽  
Sister Group ◽  
Ventral Surface ◽  
Late Paleozoic ◽  
Neural Spine ◽  
Neural Arch ◽  
Primitive Condition ◽  
Paleozoic Tetrapods

During the past decade, phylogenetic analyses of Late Paleozoic tetrapods have consistently demonstrated that the Permo-Pennsylvanian tetrapod suborder Diadectomorpha is closely related to more traditionally defined amniotes. Recent analyses provide two competing hypotheses of relationship: 1) the Diadectomoropha is the sister group of all amniotes, or 2) the Diadectomorpha and Synapsida comprise the most primitive clade within the Amniota. Subsequently more derived groups within the Amniota are: the reptilian family Captorhinidae, and the Protorothyrididae plus the Diapsida. The availability of well preserved atlas-axis complexes for all of the better known genera of diadectomorphs now allow a determination of the primitive condition of the atlas-axis complex for the Amniota. Further, accepted hypotheses of phylogenetic relationships among Late Paleozoic tetrapods allow mapping of features of the atlas-axis complex onto predefined topologies so that the transformations of the complex may be analyzed.The diadectomorph atlas-axis complex may be characterized in the following manner: paired, well developed proatlases and atlantal neural arches; lack of proatlantal and atlantal neural spines with only posteriorly directed epipophyses present; an extremely robust atlantal intercentrum; tight articulation of the atlantal pleurocentrum with the dorsal aspect of the axial intercentrum preventing exposure of the former on the ventral surface of the vertebral column; a large, anteriorly directed midline projection of the axial intercentrum; a tall and well-developed axial neural spine, presumably for attachment of strong occipital muscles and ligaments. Except for the anterior projection of the axial intercentrum (which is an autapomorphic feature of diadectomorphs), basal amniotes share all of these features with diadectomorphs. Shared, derived features of the atlas-axis complex of diadectomorphs plus other basal amniotes include: 1) fusion of the axial centrum and neural arch, 2) small epipophyses of the atlantal neural arch and, with the exception of Tseajaia, 3) fusion of the atlantal pleurocentrum to the dorsal surface of the axial intercentrum.The morphology of the atlas-axis complex alone is not sufficient to generate hypotheses of relationship between diadectomorphs and other basal amniotes. However, the atlas-axis complexes of diadectomorphs and other basal amniotes are clearly more similar to one-another than to those of other taxa.

A new species of Pseudobunocephalus Friel, 2008 (Siluriformes: Aspredinidae) from the lower Tocantins and Mearim river drainages, North and Northeast of Brazil

Zootaxa ◽  
2019 ◽  
Vol 4586 (1) ◽  
pp. 109 ◽  
Author(s):  
MANUELA DOPAZO V. LEÃO ◽  
TIAGO P. CARVALHO ◽  
ROBERTO E. REIS ◽  
WOLMAR B. WOSIACKI
Keyword(s):  
New Species ◽  
Posterior Margin ◽  
Anterior Margin ◽  
Dorsal Surface ◽  
Proximal Portion ◽  
Disjunct Distribution ◽  
Pectoral Fin ◽  
Caudal Fin ◽  
Weberian Apparatus ◽  
River Drainages

Pseudobunocephalus timbira, new species, is described from streams of the lower Tocantins and the Mearim river drainages, in North and Northeast of Brazil. Pseudobunocephalus timbira can be distinguished from all congeners by having the second hypobranchial and the third basibranchial cartilaginous (vs. ossified). Additionally, it can be dintinguished from P. lundbergi by the following putative apomorphic features within Pseudobunocephalus: posterolateral process of premaxilla present (vs. absent); bony knobs in dorsal lamina of Weberian apparatus absent (vs. present); distal end of posterior margin of 5th parapophysis not enlarged (vs. enlarged); number of ribs three (vs. four or five) and infraorbital sensory canal entering neurocranium via frontal (vs. via sphenotic). It is distinguished from P. bifidus and P. iheringii by having a gracile body not surpassing 34 mm SL (vs. robust body, reaching up to 59 mm SL, respectively); by having the posterior margin of cranial fontanel concave (vs. posterior margin somewhat straight with parieto-supraoccipital extending anteriorly); by having a conspicuous knobby ornamentation on dorsal surface of skull (vs. skull knobs slightly pronounced); by having Weberian ventral blade of hemal canal opened (vs. closed) and by the absence of serrations on the proximal portion of the anterior margin of pectoral-fin spine (vs. serrations covering entire anterior margin of the pectoral spine). Additionally, it can be distinguished from P. amazonicus, P. rugosus and P. quadriradiatus, by having the posterolateral mental barbel with at least one fleshy lobe located proximally along the posterior margin (vs. posterolateral mental barbel simple, not having fleshy lobes). It also differs from P. amazonicus and P. rugosus by having five branchiostegal rays (vs. four). It also can be distinguished from P. amazonicus by having the contact of hyomandibula cartilage with neurocranium limited to the sphenotic (vs. extending to both sphenotic and pterotic); by having the ventral blade of Weberian apparatus open (vs. closed) and by anterior exit of hemal canal in abdominal vertebra (vs. in complex vertebra); from P. rugosus by coloration of proximal portion of caudal fin similar to rest of caudal fin (vs. clear patch) and from P. quadriradiatus by the total number of pectoral fin-rays six (vs. five). Variable characteristics within Pseudobunocephalus species are summarized and comments on the phylogenetic relationships and the disjunct distribution of the new species are made. [Species zoobank url: urn:lsid:zoobank.org:act:392F95E0-86E1-4386-8779-C4F71098DBCC] 

The atlas-axis complex in the late Paleozoic genus Diadectes and the characteristics of the atlas-axis complex across the amphibian to amniote transition

1991 ◽  
Vol 65 (6) ◽  
pp. 973-983 ◽  
Author(s):  
Stuart S. Sumida ◽  
R. Eric Lombard
Keyword(s):  
Late Paleozoic ◽  
Neural Spine ◽  
Early Permian ◽  
Neural Arch ◽  
Exposure Fusion

The atlas-axis complex in the Early Permian diadectomorph Diadectes is shown to be similar to those of a variety of primitive amniotes. Diadectes does not possess elements in addition to the standard complement seen in advanced batrachosaurs and primitive amniotes as previously thought. Characteristics of the complex include: paired, well-developed proatlases and atlantal neural arches, lack of atlantal neural spines, an extremely robust atlantal intercentrum, fusion of the atlantal pleurocentrum and axial intercentrum, a large anterior projection of the axial intercentrum, exclusion of the atlantal pleurocentrum from ventral exposure, fusion of axial neural arch and pleurocentrum, and a robustly developed axial neural spine. An analysis of the transformations of the atlas-axis complex in advanced anthracosaurs and primitive amniotes indicates that many of the characteristics of the complex previously thought to be definitive of amniotes or reptiles appear to be conditions common to Diadectes plus Amniota.

scholarly journals On Mutillidae parasitic on Glossina morsitans

1916 ◽  
Vol 7 (1) ◽  
pp. 93-95 ◽  
Author(s):  
R. E. Turner
Keyword(s):  
Fore Wing ◽  
Posterior Margin ◽  
Anterior Margin ◽  
Dorsal Surface ◽  
Apical Margin ◽  
Glossina Morsitans ◽  
The Third ◽  
Posterior Pair ◽  
Continuous Band ◽  
Radial Cell

Mutilla glossinae, Turn.Mutilla glossinae, Turner, Bull. Entom. Res., v., 1915, p. 383, ♀.♂. Niger, albo-pilosus ; pronoto, mesonoto, scutelloque rufo-ferrugineis ; calcaribus albidis ; segmentis dorsalibus 2–4 apice anguste albo-fimbriatis ; alis basi hyalinis, dimidio apicali modice infuscatis ; mandibulis apice tridentatis. Long. 6 mm.♂. Head narrower than the thorax, broader than long, rounded at the posterior angles, closely and not very finely punctured, the antennal tubercles well developed. Clypeus concave, smooth and shining. Third joint of the flagellum equal to the fourth, half as long again as the second and more than twice as long as the first. Eyes ovate, converging towards the clypeus, not emarginate ; ocelli placed in a triangle, the posterior pair a little further from each other than from the anterior ocellus and situated on the inner edge of a large but shallow depression. Thorax broad and short, closely but not coarsely punctured ; anterior margin of the pronotum straight, the posterior margin broadly arcuate ; scutellum flat, broadly truncate at the apex ; pleurae very closely punctured and sparsely clothed with long white pubescence. Median segment very coarsely reticulate, shorter than the scutellum, posterior slope very steep, not distinctly separated from the dorsal surface. Abdomen subsessile ; closely punctured, with distinct but narrow apical bands of long white hairs on segments 2–4, a less clearly defined band on the first ; apical dorsal segment broadly rounded, more coarsely punctured, the punctures more or less confluent longitudinally. Second ventral segment closely punctured and sparsely clothed with long whitish hairs, which form a continuous band on the apical margin. First dorsal segment short and broad, slightly depressed on the apical margin ; second very broad, fully twice as broad as long, the sides convex. Fore-wing with three cubital cells, radial cell very broad, not more than twice as long as broad ; first abscissa of the radius equal to the third, shorter than the second, the two recurrent nervures received near the middle of the second and third cubital cells.

scholarly journals Additional sauropod dinosaur material from the Callovian Oxford Clay Formation, Peterborough, UK: evidence for higher sauropod diversity

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6404
Author(s):  
Femke M. Holwerda ◽  
Mark Evans ◽  
Jeff J. Liston
Keyword(s):  
Transverse Process ◽  
Neural Spine ◽  
Caudal Vertebra ◽  
High Complexity ◽  
Neural Arch ◽  
Faunal Assemblage ◽  
Diagnostic Features ◽  
Nutrient Foramina ◽  
Tentative Evidence ◽  
Clay Formation

Four isolated sauropod axial elements from the Oxford Clay Formation (Callovian, Middle Jurassic) of Peterborough, UK, are described. Two associated posterior dorsal vertebrae show a dorsoventrally elongated centrum and short neural arch, and nutrient or pneumatic foramina, most likely belonging to a non-neosauropod eusauropod, but showing ambiguous non-neosauropod eusauropod and neosauropod affinities. An isolated anterior caudal vertebra displays a ventral keel, a ‘shoulder’ indicating a wing-like transverse process, along with a possible prespinal lamina. This, together with an overall high complexity of the anterior caudal transverse process (ACTP) complex, indicates that this caudal could have belonged to a neosauropod. A second isolated middle-posterior caudal vertebra also shows some diagnostic features, despite the neural spine and neural arch not being preserved and the neurocentral sutures being unfused. The positioning of the neurocentral sutures on the anterior one third of the centrum indicates a middle caudal position, and the presence of faint ventrolateral crests, as well as a rhomboid anterior articulation surface, suggest neosauropod affinities. The presence of possible nutrient foramina are only tentative evidence of a neosauropod origin, as they are also found in Late Jurassic non-neosauropod eusauropods. As the caudals from the two other known sauropods from the Peterborough Oxford Clay, Cetiosauriscus stewarti and an indeterminate non-neosauropod eusauropod, do not show the features seen on either of the new elements described, both isolated caudals indicate a higher sauropod species diversity in the faunal assemblage than previously recognised. An exploratory phylogenetic analysis using characters from all four isolated elements supports a basal neosauropod placement for the anterior caudal, and a diplodocid origin for the middle caudal. The dorsal vertebrae are an unstable OTU, and therefore remain part of an indeterminate eusauropod of uncertain affinities. Together with Cetiosauriscus, and other material assigned to different sauropod groups, this study indicates the presence of a higher sauropod biodiversity in the Oxford Clay Formation than previously recognised. This study shows that it is still beneficial to examine isolated elements, as these may be indicators for higher species richness in deposits that are otherwise poor in terrestrial fauna.

Opaepupu, a new genus and species of bivalve-associated shrimp (Decapoda: Caridea: Palaemonidae) from Hawai’i

Zootaxa ◽  
2021 ◽  
Vol 4903 (1) ◽  
pp. 55-70
Author(s):  
ARTHUR ANKER ◽  
SAMMY DE GRAVE
Keyword(s):  
New Species ◽  
Posterior Margin ◽  
New Genus ◽  
Dorsal Surface ◽  
Phylogenetic Position ◽  
New Genus And Species ◽  
The Third ◽  
Small Tooth ◽  
Female Holotype ◽  
A New Species

A new palaemonid shrimp genus, Opaepupu gen. nov., is established to accommodate a new species of bivalve-associated shrimp, Opaepupu huna sp. nov. from Hawaii. A single mated pair, the female holotype and the male allotype, were found inside the trapezid bivalve Trapezium oblongum (Linnaeus, 1758) at a depth of 14 m in Kâne’ohe Bay, Hawai’i. The new genus is characterised by the rostrum being proximally broad, distally pointed, mid-dorsally carinate, and non-dentate; the anterolateral margin of the carapace without supraorbital, hepatic or epigastric teeth, but with a strong sharp antennal tooth; the sixth pleonite posteriorly unarmed; the telson medially depressed, with the dorsal surface armed with two pairs of submarginal cuspidate setae and with the posterior margin armed with two pairs of spiniform setae; the distolateral angle of the first article of the antennular peduncle without a sharp tooth; the mandible without a palp; the maxillular palp furnished with one long stiff seta dorsal to a small tooth-like extension; the first maxilliped without a palp; the third maxilliped not being operculate; the second pereiopods moderately robust, relatively slender, subequal, subsymmetrical, with simple teeth on the cutting edges of the fingers; the ambulatory pereiopods being slender, each ending in an elongate biunguiculate dactylus; and the uropodal exopod with a faint diaeresis and greatly reduced distolateral spiniform seta. The phylogenetic position of Opaepupu gen. nov. remains unclear, although it does not appear to be closely related to other bivalve-associated palaemonid genera. 

New species of Tridentella Richardson, 1905 (Isopoda: Cymothoida: Tridentellidae), tropical marine isopod crustaceans from the Banda Sea, Indonesia

Zootaxa ◽  
2008 ◽  
Vol 1734 (1) ◽  
pp. 43 ◽  
Author(s):  
NIEL L BRUCE
Keyword(s):  
New Species ◽  
Posterior Margin ◽  
Body Shape ◽  
Dorsal Surface ◽  
First Record ◽  
Adult Males ◽  
Double Row ◽  
The Family ◽  
The Indian Ocean ◽  
Lateral Margins

Tridentella memikat sp. nov., Tridentella tanimbar sp. nov. and Tridentella brandtae sp. nov. are described and figured. T. memikat sp. nov. is the largest species in the family and can be identified by the broadly rounded pleotelson posterior margin, complete lack of dorsal ornamentation and antennule peduncle articles 2 and 3 each with the posterodistal angle produced. T. tanimbar sp. nov. is a sister species to T. recava Bowman, 1986, both species characterised by a flattened body shape, lack of dorsal ornamentation and deep excision to the pleotelson apex; T. tanimbar sp. nov. is identified by free lateral margins to pleonite 5, antennal flagellum extending to pereonite 5 or 6, pleon wider than pereon, the propodus of pereopods 1–3 lacking long slender robust setae, uropod exopod shorter (0.8) than endopod and the uropods not extending beyond the pleotelson. Tridentella brandtae sp. nov. is characterised by the posterior margin of the pleotelson being subtruncate and weakly emarginate; posterior margins of pereonites 6 and 7, pleonites 3–5 and the dorsal surface of the pleotelson weakly nodulose; inferior margins of the propodus of pereopods 2 and 3 with a double row of robust setae; the shape and setation of the uropods; adult males are further characterised by the presence of a large bluntly rounded robust seta at the inferodistal angle of the carpus. These species constitute the first record of the family from the Indian Ocean.

scholarly journals A new species of Baenothrips Crawford from China (Thysanoptera, Phlaeothripidae)

ZooKeys ◽  
2016 ◽  
Vol 636 ◽  
pp. 67-75 ◽  
Author(s):  
Chao Zhao ◽  
Xiaoli Tong
Keyword(s):  
New Species ◽  
Posterior Margin ◽  
Abdominal Tergite ◽  
Dorsal Surface ◽  
Abdominal Sternite ◽  
A New Species

A new urothripine species, Baenothripscuneatussp. n., is described from China. This is distinguished from its congeners by the following combination of characteristics: dorsal surface of head having a wedge-shaped reticulation extending from median to the posterior margin; antennal segments VII–VIII is closely joined with a complete suture; the mesoacrotergite strongly constricted in the middle; abdominal tergite I divided into 5 plates; width of membranous gap between ovispan on abdominal sternite IX approximately 1/3 of the apical width of segment IX.

A new group of species within the bee genus Ruizantheda, with a revised key to the males of the genus (Hymenoptera: Halictidae: Caenohalictini)

Zootaxa ◽  
2018 ◽  
Vol 4415 (3) ◽  
pp. 513
Author(s):  
BEATRIZ W. T. COELHO ◽  
MICHAEL S. ENGEL
Keyword(s):  
New Species ◽  
Posterior Margin ◽  
Dorsal Surface ◽  
Apical Margin ◽  
Lateral Expansion ◽  
Ventral Region ◽  
Additional Species ◽  
Ventral Area ◽  
Apical Tooth

Males of the neotropical bee genus Ruizantheda Moure sensu lato (Halictinae: Caenohalictini) differ from those of other caenohalictine genera in having the outer gonostylar plate with a large membranous region that extends to the ventral region, and the ventral gonostylar lobe retrorse. These features permit the placement of six additional species described here, four of which are new, in the genus in this broader sense. The males of these six species share the following characteristics: profemur swollen; mesofemur exceedingly swollen; mesotibia slightly swollen with flat, minutely ridged ventral area and small apical tooth; S4 shortened medially, commonly largely hidden under S3, with transverse median depression and apical margin emarginate; apicolateral lobes of S4 with tuft of branched setae and stout, simple, recurved setae on margin; S5 with U-shaped gradulus and setal patch, sometimes inconspicuous; outer lateral expansion of penis valve bilobed, and median posterior margin of volsella strongly angulate. Together, these species constitute a new group within Ruizantheda and share with the previously known Ruizantheda inca Coelho, Felizardo, & Engel, R. aerugineus Coelho, Felizardo, & Engel, and R. kallos Coelho, Felizardo, & Engel, a short outer gonostylar plate, terminating before the apex of the main gonostylar lobe as well as the presence of long setae on its dorsal surface. In other species of Ruizantheda the outer gonostylar plate extends beyond the apex of the main gonostylar lobe and lacks setae. The species comprising this distinctive subgroup of Ruizantheda, and treated herein, are: R. nigra n. sp., R. colombiana n. sp., R. venezuelana n. sp., R. baeri (Vachal) n. comb., R. pilosa n. sp., and R. gaullei (Vachal) n. comb. Two of the new species expand the distribution of the genus northward into Colombia and Venezuela. In addition to the description and illustration of the species, an updated key to the species of Ruizantheda s. l. is provided.

First occurrence of Maiasaura (Dinosauria, Hadrosauridae) from the Upper Cretaceous Oldman Formation of southern Alberta, Canada

2020 ◽  
pp. 1-11
Author(s):  
Bradley D. McFeeters ◽  
David C. Evans ◽  
Michael J. Ryan ◽  
Hillary C. Maddin
Keyword(s):  
Posterior Margin ◽  
Evolutionary History ◽  
Upper Cretaceous ◽  
Dorsal Surface ◽  
Adult Size ◽  
Southern Alberta ◽  
First Occurrence ◽  
History Of ◽  
Phylogenetic Divergence ◽  
The Relationship

We describe a new partial skull with braincase of a maiasaurin hadrosaurid from the Milk River Ridge Reservoir near Warner, southern Alberta, as the first diagnostic occurrence of Maiasaura in Canada. This material was collected in the Oldman Formation, at approximately the same stratigraphic level as a nearby bonebed of the ceratopsid Coronosaurus brinkmani. The assignment of this specimen to Maiasaura, rather than to Brachylophosaurus, is supported by the narrow and acute posterior margin of the external naris, the relationship between the postorbital and squamosal in the supratemporal bar, and the morphology of the frontals, which are greatly thickened and elevated anteriorly, with the dorsal surface not completely covered by the nasofrontal contact at adult size. The occurrence of both Maiasaura and Brachylophosaurus in approximately similar-aged deposits of the Comrey Sandstone zone in southern Alberta provides support for some cladogenesis in the evolutionary history of Maiasaurini. Geographically, the more western distribution of Maiasaura localities with respect to all Brachylophosaurus localities is consistent with the hypothesis that a preference for more inland versus seaway-adjacent habitats may have influenced the phylogenetic divergence of these taxa.

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