[Paleontology • 2017] Lagenanectes richterae • A New Basal Elasmosaurid (Sauropterygia: Plesiosauria) from the Lower Cretaceous of Germany ---ScRaBBlE

Lagenanectes richterae

 Sachs, Hornung & Kear, 2017

DOI:  10.1080/02724634.2017.1301945 

ABSTRACT

Here we report on a new basal elasmosaurid plesiosaurian, Lagenanectes richterae, gen. et sp. nov., from the Lower Cretaceous (probably Upper Hauterivian) of Germany. The material includes a partial skull (cranium and mandible), the atlas-axis complex, additional cervical vertebrae, caudal vertebrae, an ilium, and limb elements. The basioccipital and atlas intercentrum are pathologically deformed, probably due to an osteomyelitic infection. Two potential autapomorphies were found in the mandible: (1) the alveolar margin at the symphysis is laterally expanded with the rostral-most alveoli being markedly procumbent and situated along the lateral margins of the dentaries; and (2) the ventral midline at the symphysis is produced into a prominent wedge-shaped platform indented by numerous irregular pits. Lagenanectes richterae, gen. et sp. nov., also shows a number of typical elasmosaurid traits, including a longitudinal lateral ridge on the cervical vertebral centra (although a ventral notch is absent) and teeth with oval cross-sections. Lagenanectes richterae, gen. et sp. nov., is one of the best-preserved plesiosaurians from the Lower Cretaceous of Europe.

FIGURE 4. Lagenanectes richterae, gen. et sp. nov., BGR Ma 13328, holotype, reconstruction of the skull showing the preserved portions (shaded) in A, lateral and B, ventral views. The missing parts are reconstructed based on Libonectes spp. (partly after Carpenter 1997:figs. 2, and 5).

 Abbreviations: bo, basioccipital; den, dentary; in, internal naris; mx, maxilla; pal, palatine; pmx, premaxilla; ps, parasphenoid; pt, pterygoid; qu, quadrate; v, vomer. Scale bar equals 5 cm.

FIGURE 3. Lagenanectes richterae, gen. et sp. nov., BGR Ma 13328, holotype, cranium in ventral view. A, photograph; B, interpretive illustration. Dotting: sedimentary matrix.

 Abbreviations: dlf, dental lamina foramen; in, internal naris; pal, palatine; pmx, premaxilla; ps, parasphenoid; pt, pterygoid; rpt, replacement tooth; v, vomer. Scale bar equals 5 cm

SYSTEMATIC PALEONTOLOGY

SAUROPTERYGIA Owen, 1860

PLESIOSAURIA Blainville, 1835

ELASMOSAURIDAE Cope, 1869

LAGENANECTES, gen. nov.

Etymology:— Lagenanectes, ‘Leine swimmer,’ composed from Lagena, the medieval Old High German name of the Leine River, which passes the vicinity of Sarstedt and forms a major local hydrographic feature, and -nectes from latinized Greek: ‘o nektes’ - ‘swimmer’.

Type Species:— Lagenanectes richterae, sp. nov.

LAGENANECTES RICHTERAE, sp. nov.

Plesiosaurus elasmosaurus (Finzel, 1964:307, nomen nudum).

‘Elasmosaurus’ (Harms, 1982:2)

Elasmosaurus sp. (Zawischa, 1987:85)

Skelettrest eines Elasmosauriers (Sachs, 2000:33)

Schädelreste, Zähne und Wirbel eines Elasmosauriers (Sachs, 2011:12)

New basal elasmosaurid (Sachs et al., 2015:131)

Etymology:— The species epithet richterae is a patronym for Dr. Annette Richter, Niedersächsisches Landesmuseum, Hannover, honoring her various contributions and outstanding dedication to the vertebrate paleontology of Lower Saxony.

FIGURE 13. Life reconstruction of Lagenanectes richterae, gen. et sp. nov. Artwork by Frederik Spindler, 2015.

....

Sven Sachs, Jahn J. Hornung and Benjamin P. Kear. 2017. A New Basal Elasmosaurid (Sauropterygia: Plesiosauria) from the Lower Cretaceous of Germany. Journal of Vertebrate Paleontology. DOI:  10.1080/02724634.2017.1301945

"Lagenanectes" by Hyrotrioskjan

hyrotrioskjan.deviantart.com/art/Lagenanectes-701056165

twitter.com/pantheo27705718/status/901341256449540096

 

---------------------------------------------------------------

روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

او

من هنا

شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

[Paleontology • 2017] Vadasaurus herzogi • A New Rhynchocephalian (Reptilia: Lepidosauria) from the Late Jurassic of Solnhofen (Germany) and the Origin of the Marine Pleurosauridae ---ScRaBBlE

Vadasaurus herzogi

 Bever & Norell, 2017

DOI:  10.1098/rsos.170570  

Abstract

A new rhynchocephalian is described based on a recently discovered and well-preserved specimen from the Late Jurassic (Kimmeridgian) marine limestones of Solnhofen, Bavaria. Phylogenetic analysis recovers the new taxon as the sister group to Pleurosauridae, a small radiation of rhynchocephalians representing the oldest marine invasion of crown-clade Lepidosauria. The relatively strong evidence for this taxonomically exclusive lineage, within a generally volatile rhynchocephalian tree, places the new taxon in a position to inform the early history of the pleurosaur transition to the sea. The early steps in this transition are distributed throughout the skeleton and appear to increase hydrodynamic efficiency for both swimming and aquatic feeding. This early history may also have included a global truncation of plesiomorphic ontogenetic trajectories that left a number of skeletal features with reduced levels of ossification/fusion. The exact degree to which Vadasaurus had adopted an aquatic ecology remains unclear, but the insight it provides into the origin of the enigmatic pleurosaurs exemplifies the potential of Rhynchocephalia for generating and informing broad-based questions regarding the interplay of development, morphology, ecology and macroevolutionary patterns.

KEYWORDS: Bavaria, marine reptile, secondarily aquatic, skeletal development, sphenodon, tiatethys

Figure 1. Holotype of Vadasaurus herzogi (AMNH FARB 32768) collected from the Late Jurassic marine limestones of Solnhofen, Bavaria. The skull, forelimbs, and first 18 presacral vertebrae and ribs are exposed in the dorsal or dorsolateral view. Posteriorly, the skeleton is rotated approximately 180°, making it visible largely in the ventral view. Left hindlimb is exposed in the dorsal view.

Anatomical abbreviations: As, astragalus; Ca, calcaneum; Cdv, caudal vertebra; Co, coracoid; Cr, cervical rib; Cv, cervical vertebra; D, dentary; Dv, dorsal vertebra; F, femur; Fb, fibula; Fr, frontal; Ga, gastralia; H, humerus; I, intermedium; Is, ischium; l, left; Mc, metacarpal; Mt, metatarsal; Mx, maxilla; Ph, phalanx; Pu, pubis; R, radius; r, right; S, scapula; Sc, sternal cartilage; Ss, suprascapular cartilage; Sv, sacral vertebra; T, tibia; U, ulna.

Figure 2. The skull of Vadasaurus herzogi (AMNH FARB 32768). Photographs in the dorsolateral (a) and lateral (b) views; labelled line drawing in the dorsolateral view (c); reconstructions of lateral and dorsal views (d).

Anatomical abbreviations: An, angular; Ar, articular; cp, cultriform process; Cv, cervical vertebra; D, dentary; dd, dentary dentition; Ecp, ectopterygoid; Ept, epipterygoid; exn, external naris; Fr, frontal; Hy, hyobranchial element; if, incisiform fang; Ju, jugal; mf, mandibular foramen; Mx, maxilla; Na, nasal; Pa, parietal; Pal, palatine; paf, parietal foramen; Pf, prefrontal; Pm, premaxilla; Po, postorbital; Pof, postfrontal; Pr, prootic; Pra, prearticular; Pt, pterygoid; Q, quadrate; Qj, quadratojugal; Sa, surangular; sof, suborbital fenestra; Sq, squamosal; Vo, vomer.

Systematic palaeontology

Lepidosauria Haekel, 1866 

Rhynchocephalia Günther, 1867 

Vadasaurus herzogi gen. et sp. no.

  Etymology: Generic name from the Latin vadare ‘to go forth’, which is also the root of ‘to wade’—refers to the taxon's hypothesized phylogenetic position near the proximal end of a terrestrial-to-marine transformation series that produced the aquatic pleurosaurs—and saurus ‘lizard’. The specific epithet honours the celebrated Bavarian film-maker Werner Herzog for his continuing exploration of the relationship between life and time.

Holotype: AMNH FARB 32768, a nearly complete and largely articulated skeleton (figures 1–3). Like most specimens preserved in lithographic limestone, it exhibits compressional effects that include the flattening and shearing of composite structures and the slight displacement of certain elements. Individual bones, however, are preserved largely in three dimensions.

Gabriel S. Bever and Mark A. Norell. 2017. A New Rhynchocephalian (Reptilia: Lepidosauria) from the Late Jurassic of Solnhofen (Germany) and the Origin of the Marine Pleurosauridae.  Royal Society Open Science. 4(11):170570  DOI:  10.1098/rsos.170570 

ResearchGate.net/publication/320928771_A_new_rhynchocephalian_Reptilia_Lepidosauria_from_the_Late_Jurassic_of_Solnhofen_Germany_and_the_origin_of_the_marine_Pleurosauridae

 The fossil was recovered from Kimmeridgian-aged (a subdivision of the Late Jurrasic) marine limestones in the Solnhofen municipality of Bavaria, Germany. They belong to an up until now unknown species dubbed Vadasaurus herzogi, and belongs to the Rhynchocephalia lizard order, a close relative of a small group of ancient reptiles called pleourosaurs (genus Pleurosaurus).

Fossilized ancient lizard shows how dinos evolved to live in the oceans 

zmescience.com/science/ancient-lizard-dino-evolve-ocean-0432/ @zmescience

---------------------------------------------------------------

روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

او

من هنا

شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

[Paleontology • 2017] Ostromia crassipes [gen. nov.] • Re-evaluation of the Haarlem Archaeopteryx and the Radiation of Maniraptoran Theropod Dinosaurs ---ScRaBBlE

Ostromia crassipes (Meyer, 1857)

 “Haarlem specimen”, holotype of Ostromia crassipes (Meyer, 1857).
Counterslab, Teylers Museum TM 6929 (left) and main slab, TM 6928 (right).

Foth & Rauhut, 2017.  DOI:  10.1186/s12862-017-1076-y

Abstract

Background

Archaeopteryx is an iconic fossil that has long been pivotal for our understanding of the origin of birds. Remains of this important taxon have only been found in the Late Jurassic lithographic limestones of Bavaria, Germany. Twelve skeletal specimens are reported so far. Archaeopteryx was long the only pre-Cretaceous paravian theropod known, but recent discoveries from the Tiaojishan Formation, China, yielded a remarkable diversity of this clade, including the possibly oldest and most basal known clade of avialan, here named Anchiornithidae. However, Archaeopteryx remains the only Jurassic paravian theropod based on diagnostic material reported outside China.

Results

Re-examination of the incomplete Haarlem Archaeopteryx specimen did not find any diagnostic features of this genus. In contrast, the specimen markedly differs in proportions from other Archaeopteryx specimens and shares two distinct characters with anchiornithids. Phylogenetic analysis confirms it as the first anchiornithid recorded outside the Tiaojushan Formation of China, for which the new generic name Ostromia is proposed here.

Conclusions

In combination with a biogeographic analysis of coelurosaurian theropods and palaeogeographic and stratigraphic data, our results indicate an explosive radiation of maniraptoran coelurosaurs probably in isolation in eastern Asia in the late Middle Jurassic and a rapid, at least Laurasian dispersal of the different subclades in the Late Jurassic. Small body size and, possibly, a multiple origin of flight capabilities enhanced dispersal capabilities of paravian theropods and might thus have been crucial for their evolutionary success.

Keywords: Maniraptora, Anchiornithidae, Late Jurassic, Biogeography, Radiation

Fig. 1 Overview of the “Haarlem specimen”, holotype of Ostromia crassipes (Meyer, 1857). Counterslab, Teylers Museum TM 6929 (left) and main slab, TM 6928 (right). 

Systematic Palaeontology

Theropoda Marsh, 1881  

Maniraptora Gauthier, 1986 

Anchiornithidae tax. Nov.

Type genus. Anchiornis 

Xu, Zhao, Norell, Sullivan, Hone, Erickson, Wang, Han, and Gao, 2009  

Definition. Anchiornithidae is a stem-based taxon defined as all maniraptoran theropods that are more closely related to Anchiornis huxleyi than to Passer domesticus, Archaeopteryx lithographica, Dromaeosaurus albertensis, Troodon formosus, or Oviraptor philoceratops.

Ostromia gen. nov.

Ostromia crassipes von Meyer, 1857  

Holotype. Teylers Museum TM 6928, 6929, part and counterpart of a fragmentary skeleton.

Locality and horizon. Jachenhausen locality, near Riedenburg, Bavaria, Germany. Early Tithonian laminated limestones of the Painten Formation.

Etymology. The generic name honours the late John Ostrom, who identified the Haarlem specimen as a theropod.

Conclusions

A re-evaluation of one of the twelve skeletal specimens referred to the ‘Urvogel’ Archaeopteryx, the Haarlem specimen, revealed that this specimen represents a separate taxon, Ostromia crassipes. Phylogenetic analysis identifies Ostromia as the first representative of the basal avialian clade Anchiornithidae outside eastern Asia. In combination with a biogeographic analysis, a rapid radiation of maniraptoran theropods in eastern Asia with a subsequent dispersal of many lineages in the Late Jurassic is indicated; dispersal of maniraptorans was facilitated by small body size of basal members of all clades and, possibly, several independent acquisitions of flight capabilities. In the fragmenting world of Pangean break-up during the Late Jurassic and Cretaceous, increased dispersal potential might have been a key factor to explain the success of maniraptoran, and especially avialian theropods, with dispersal events being followed by endemic radiations of different clades.

Christian Foth and Oliver W. M. Rauhut. 2017. Re-evaluation of the Haarlem Archaeopteryx and the Radiation of Maniraptoran Theropod Dinosaurs. BMC Evolutionary Biology.   17:236. DOI:  10.1186/s12862-017-1076-y

 

Groot nieuws! De beroemde #Archaeopteryx van Teylers Museum blijkt nog ouder dan gedacht en wereldwijd uniek te zijn. Het is een fossiel van een nieuw ontdekte dinosaurussoort met veren, die de naam Ostromia heeft gekregen. #breakingnews http://bit.ly/2jdITeB  @TEYLERS

Paleontologists at LMU correct a case of misinterpretation: The first fossil “Archaeopteryx” to be discovered is actually a predatory dinosaur belonging to the anchiornithid family, which was previously known only from finds made in China: http://www.en.uni-muenchen.de/news/newsarchiv/2017/rauhut_archaeopteryx.html … @LMU_Muenchen

 xinglida.net/Museum/Archaeopteryx.htm

---------------------------------------------------------------

روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

او

من هنا

شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

[Ichthyology • 2017] The First European Cave Fish: Barbatula Cave Loach from southern Germany ---ScRaBBlE

Figure 1: Cave loaches [Barbatula sp.] adapted to life in constant darkness are of recent origin but genetically divergent from surface populations residing in the same drainage.
  (A) Two cave loaches in their natural habitat. (B) Adult male loach with typical adaptations to living in caves: reduced eyes, enlarged barbels and pale body coloration. (C) Typical epigean loach from the surface population in the Danube.

DOI: 10.1016/j.cub.2017.02.048 cell.com/current-biology  

Summary

Subterranean biodiversity in Europe is spectacularly rich, with the Western Balkans being home to about 400 cave species, representing the highest number of species per area worldwide. Nonetheless, cave fishes, which are the most commonly found vertebrates in underground habitats, have not been described from Europe so far. Here, we report the first European record of a cave fish population, a loach of the genus Barbatula, found in the Danube–Aach system, an underground karst water system in Southern Germany. The fish exhibit traits typically observed in organisms adapted to subterranean life including reduced eyes and pale body coloration. The newly discovered population also represents globally the northernmost cave fish found so far. The geological history of the region implies that the Danube–Aach system was colonized post-glacially. A recent origin of the cave fish is supported by genetic analyses, because the subterranean population shares COI gene haplotypes with adjacent surface stone loach (Barbatula barbatula) populations. Nonetheless, population genetic analyses based on microsatellites indicated that cave fish are genetically isolated from populations in surface habitats and exhibit reduced genetic variability. Hence, the newly discovered European cave loaches do not represent individuals displaced from surface populations, but they follow a unique evolutionary trajectory towards cave life.

Figure 1: Cave loaches [Barbatula sp.] adapted to life in constant darkness are of recent origin but genetically divergent from surface populations residing in the same drainage.  
 (A) Two cave loaches in their natural habitat. (B) Adult male loach with typical adaptations to living in caves: reduced eyes, enlarged barbels and pale body coloration. (C) Typical epigean loach from the surface population in the Danube.  

Figure 1 Cave loaches adapted to life in constant darkness are of recent origin but genetically divergent from surface populations residing in the same drainage.
(A) Two cave loaches in their natural habitat. (B) Adult male loach with typical adaptations to living in caves: reduced eyes, enlarged barbels and pale body coloration. (C) Typical epigean loach from the surface population in the Danube. (D) Neighbour-joining tree of Cytochrome oxidase subunit1 (COI) sequences for European stone loaches. European loaches form three clusters comprising sequences from Rhine, Danube and Elbe drainages. Loaches from the Danube–Aach cave system (AC, highlighted in orange) share haplotypes with individuals from the southern lineage sampled in the upper Rhine and Danube drainage, individuals from GenBank identified by their accession numbers. Numbers at major nodes indicate bootstrap values (>50%, 1000 replicates). (E) Graphical representation of an analysis of genetic population structure. Inferred genomic ancestry in three genetic clusters (y-axis) is depicted by red, green and blue colors for all individuals (x-axis). With prior information on the sample location of individuals, three clearly distinct genetic clusters separate cave loaches from both surface populations upstream (Danube) and downstream (Radolfzeller Aach) in the same drainage. Without prior information on the sample location of individuals, cave fish are grouped with the upstream but clearly separated from the downstream loach population.

  Jasminca Behrmann-Godel, Arne W. Nolte, Joachim Kreiselmaier, Roland Berka and Jörg Freyhof. 2017. The First European Cave Fish. Current Biology. 27(7); R257–R258. DOI: 10.1016/j.cub.2017.02.048

http://www.cell.com/current-biology/fulltext/S0960-9822(17)30219-1

First ever cavefish discovered in Europe evolved super-fast
www.newscientist.com/article/2126523-first-ever-cavefish-discovered-in-europe-evolved-super-fast

   

---------------------------------------------------------------

روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

او

من هنا

شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

[Paleontology • 2017] Rhaeticosaurus mertensi • A Triassic Plesiosaurian Skeleton and Bone Histology Inform on Evolution of A Unique Body Plan ---ScRaBBlE

Rhaeticosaurus mertensi 

Wintrich, Hayashi, Houssaye, Nakajima & Sander, 2017

DOI: 10.1126/sciadv.1701144 

Abstract
Secondary marine adaptation is a major pattern in amniote evolution, accompanied by specific bone histological adaptations. In the aftermath of the end-Permian extinction, diverse marine reptiles evolved early in the Triassic. Plesiosauria is the most diverse and one of the longest-lived clades of marine reptiles, but its bone histology is least known among the major marine amniote clades. Plesiosaurians had a unique and puzzling body plan, sporting four evenly shaped pointed flippers and (in most clades) a small head on a long, stiffened neck. The flippers were used as hydrofoils in underwater flight. A wide temporal, morphological, and morphometric gap separates plesiosaurians from their closest relatives (basal pistosaurs, Bobosaurus). For nearly two centuries, plesiosaurians were thought to appear suddenly in the earliest Jurassic after the end-Triassic extinctions. We describe the first Triassic plesiosaurian, from the Rhaetian of Germany, and compare its long bone histology to that of later plesiosaurians sampled for this study. The new taxon is recovered as a basal member of the Pliosauridae, revealing that diversification of plesiosaurians was a Triassic event and that several lineages must have crossed into the Jurassic. Plesiosaurian histology is strikingly uniform and different from stem sauropterygians. Histology suggests the concurrent evolution of fast growth and an elevated metabolic rate as an adaptation to cruising and efficient foraging in the open sea. The new specimen corroborates the hypothesis that open ocean life of plesiosaurians facilitated their survival of the end-Triassic extinctions.

Systematic paleontology

Reptilia Linnaeus, 1758

Diapsida Osborn, 1903

Plesiosauria de Blainville, 1835

Phylogenetic definition: We offer the following apomorphy-based definition of Plesiosauria: Sauropterygians with a short, wide trunk–bearing four flippers of even structure and subequal size, the flippers consisting of long, straight propodials combined with very short and dorsoventrally flattened zeugopodials.

Diagnosis: Plesiosauria is diagnosed (see Materials and Methods) by two unique and unambiguous synapomorphies: tooth enamel surface, striations present (character, 106; state, 0; see comment in table S2); orientation of cervical zygapophyses, dorsomedially facing (128, 1). An unambiguous but not unique synapomorphy is as follows: dorsal half of ilium, subequal anterior and posterior expansion (174, 0).

Rhaeticosaurus mertensi gen. et sp. nov.

Etymology: The genus name is based on rhaeticus, latinized adjective meaning “from the Rhaetian stage,” and sauros (Greek), meaning lizard or saurian. The specific epithet honors the discoverer of the holotype, Michael Mertens of Schwaney, Westphalia, Germany.

Holotype specimen: LWL-Museum für Naturkunde (Münster, Germany), LWL-MFN P 64047.

Locality and horizon: Clay pit #3 of Lücking brick company, 1 km north of the village of Bonenburg, city of Warburg, North Rhine-Westphalia, Germany (Fig. 1A). The specimen derives from Rhaetian dark marine mudstones of the Exter Formation, 21 m in the section below the Triassic-Jurassic boundary and about 3.5 m below a bonebed containing a vertebrate fauna of Rhaetian age.

Diagnosis: Small-bodied plesiosaurian with an estimated total length of 237 cm (Fig. 2, A and B). The new taxon has two autapomorphies (Fig. 2C): a modified V-shaped neurocentral suture in the anterior and middle cervical vertebrae. In Rhaeticosaurus, the sides of the “V” are ventrally concave, and the tip of the “V” almost reaches the ventral margin of the centrum. In other plesiosaurians with a V-shaped neurocentral suture, the sides of the “V” are straight, and the tip only extends to the middle of the centrum. The second autapomorphy is greatly foreshortened zeugopodials with a humerus/radius ratio of 3.8 and a femur/tibia ratio of 4.3 (Fig. 2, B, D, and E, and table S4). In addition, there are 10 unambiguous but not unique synapomorphies (tables S2 and S3).

Phylogenetic relationships: To assess the systematic position of the Triassic plesiosaurian skeleton, we coded it for a recently published phylogenetic data matrix aimed at clarifying plesiosaurian interrelationships (data file S1) (4). Rhaeticosaurus was found to be nested within Plesiosauria as a basal member of the Pliosauridae, with Anningasaura as the most basal plesiosaurian (Fig. 3A). As a consequence, six nodes in the cladogram are of Triassic age, indicating pre-Jurassic diversification of plesiosaurians into their major clades (Fig. 3A).

This is the skeleton of Rhaeticosaurus on exhibit at the LWL-Museum für Naturkunde in Münster (Germany). The disintegrated skull and neck can be seen on the left.

Photo: Georg Oleschinski

  Tanja Wintrich, Shoji Hayashi, Alexandra Houssaye, Yasuhisa Nakajima and P. Martin Sander. 2017. A Triassic Plesiosaurian Skeleton and Bone Histology Inform on Evolution of A Unique Body Plan. Science Advances. DOI: 10.1126/sciadv.1701144

The Oldest Plesiosaur Was a Strong Swimmer  eurekalert.org/e/8527 via @unibonn @EurekAlert

---------------------------------------------------------------

روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

او

من هنا

شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

[Paleontology • 2017] An 8.5 m Long Ammonite Drag Mark from the Upper Jurassic Solnhofen Lithographic Limestones, Germany ---ScRaBBlE

An artistic reconstruction of the floating ammonite leaving behind the drag mark.

Illustration: James McKay

 MCFO 0492, the drag mark created by the drifting shell of a dead ammonite (Subplanites rueppellianus)

DOI: 10.1371/journal.pone.0175426

Abstract

Trackways and tracemakers preserved together in the fossil record are rare. However, the co-occurrence of a drag mark, together with the dead animal that produced it, is exceptional. Here, we describe an 8.5 m long ammonite drag mark complete with the preserved ammonite shell (Subplanites rueppellianus) at its end. Previously recorded examples preserve ammonites with drag marks of < 1 m. The specimen was recovered from a quarry near Solnhofen, southern Germany. The drag mark consists of continuous parallel ridges and furrows produced by the ribs of the ammonite shell as it drifted just above the sediment surface, and does not reflect behaviour of the living animal.

Fig 2. Various Plattenkalk localities of the Franconian and Swabian Alb. 

Fig 1. MCFO 0492, the entire drag mark created by the drifting shell of a dead ammonite (Subplanites rueppellianus), with close-up of several portions. A. The first portion of the drag mark clearly showing two prominent ridges. B. Drag mark showing two prominent ridges with additional faint ridges. C. Drag mark showing four prominent ridges and a gentle curve. D. Drag mark showing numerous prominent ridges, along with the ammonite.

Large scale measures 1 m. Small scales measure 10 cm.DOI:  10.1371/journal.pone.0175426 

Fig 3. The ammonite Subplanites rueppellianus, the producer of the drag mark (MCFO 0492). Note the touch down mark which changes the orientation (and number) of the ridges in the substrate, anteroventral to the ammonite. Scale measures 5 cm.

DOI:  10.1371/journal.pone.0175426

Conclusions: 

This exceptionally long fossil was produced by an ammonite shell post-mortem. The shell must have been partially buoyant, firstly because only a small portion of the shell contacts the substrate over the length of the mark, and secondly to be moved by a current that was gentle enough not to disturb the surrounding sediment. It is likely that the ammonite was losing buoyancy over the length of the drag mark, which resulted in eventual loss of all buoyancy and the ammonite falling on its side.

The drag mark of the studied specimen does not represent a mortichnion because it was not created by the animal when alive. Rather, this structure should more correctly be considered a tool mark. As such, behaviour must not be inferred from the drag mark of specimens such as MCFO 0492, and they have to be interpreted as non-biogenic structures produced by physical means. MCFO 0492 represents the hitherto longest fossil drag mark created by a dead animal, complete with the animal preserved at the end.

Dean R. Lomax, Peter L. Falkingham, Günter Schweigert and Alejandro P. Jiménez. 2017. An 8.5 m Long Ammonite Drag Mark from the Upper Jurassic Solnhofen Lithographic Limestones, Germany. PLoS ONE. 12(5): e0175426.  DOI: 10.1371/journal.pone.0175426

Zombie ammonite from Jurassic Bavaria | Elsa Panciroli
theguardian.com/science/2017/may/11/zombie-ammonite-discovery-is-snapshot-of-an-unusual-moment-in-deep-time

---------------------------------------------------------------

روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

او

من هنا

شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.