Mostrando postagens com marcador Maniraptor. Mostrar todas as postagens
Mostrando postagens com marcador Maniraptor. Mostrar todas as postagens

quinta-feira, 26 de abril de 2018

150M year-old dinosaur could probably fly, new research suggests

The question as to whether the Jurassic-era Archaeopteryx was able to fly has long baffled paleontologists. Now, new research may have unveiled the answer.

It has been established as scientific fact that birds evolved from a group of dinosaurs known as maniraptoran theropods, a group that included Velociraptors and other small carnivorous dinosaurs. Now, new research suggests that the 150-million-year old Archaeopteryx, a link between dinosaurs and modern-day birds was able to fly, but drastically different than any cardinal or blue jay you've ever seen.

New research, published Tuesday in scientific journal Nature Communications, highlights new findings that the dinosaur likely flew in rapid, short bursts over small distances, unlike modern-day birds.

A questão de saber se o Archaeopteryx da era Jurássica foi capaz de voar há muito tempo desconcerta os paleontólogos. Agora, uma nova pesquisa pode ter revelado a resposta.

Estabeleceu-se como fato científico que as aves evoluíram de um grupo de dinossauros conhecidos como terópodes maniraptorianos, um grupo que incluía Velociraptors e outros pequenos dinossauros carnívoros. Agora, uma nova pesquisa sugere que o Archaeopteryx de 150 milhões de anos, um elo entre dinossauros e pássaros modernos, era capaz de voar, mas drasticamente diferente do que qualquer cardeal ou jay azul que você já viu.

 Nova pesquisa, publicada na terça-feira na revista científica Nature Communications, destaca novas descobertas de que o dinossauro provavelmente voou em rajadas rápidas e curtas por pequenas distâncias, ao contrário das aves modernas.


"Our analyses reveal that the architecture of Archaeopteryx’s wing bones consistently exhibits a combination of cross-sectional geometric properties uniquely shared with volant birds, particularly those occasionally [utilizing] short-distance flapping," the study's abstract reads. "We therefore interpret that Archaeopteryx actively employed wing flapping to take to the air through a more anterodorsally posteroventrally oriented flight stroke than used by modern birds."

"Nossas análises revelam que a arquitetura dos ossos das asas do Archaeopteryx exibe consistentemente uma combinação de propriedades geométricas transversais exclusivamente compartilhadas com aves volantes, particularmente aquelas ocasionalmente [utilizando] batidas de curta distância", diz o resumo do estudo. "Nós, portanto, interpretamos que o Archaeopteryx empregou ativamente o agitar das asas para levar para o ar através de uma trajetória de vôo mais orientada para o plano póstero-ventral do que o usado pelas aves modernas."

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The study's authors also concluded that "avian powered flight must have originated before the latest Jurassic."

“We immediately noticed that the bone walls of Archaeopteryx were much thinner than those of earthbound dinosaurs but looked a lot like conventional bird bones,” said lead author Dennis Voeten in a statement. “Data analysis furthermore demonstrated that the bones of Archaeopteryx plot closest to those of birds like pheasants that occasionally use active flight to cross barriers or dodge predators, but not to those of gliding and soaring forms such as many birds of prey and some seabirds that are optimised for enduring flight.”

Dr. Emmanuel de Margerie, who also worked on the research, said the team "focused on the middle part of the arm bones because we knew those sections contain clear flight-related signals in birds."
The study, which was received in July 2017 and accepted on Jan. 31, 2018, was authored by Voeten, Jorge Cubo, Emmanuel de Margerie, Martin Röper, Vincent Beyrand, Stanislav Bureš, Paul Tafforeau and Sophie Sanchez.

The researchers used a non-invasive technique called phase-contrast synchroron microtomography to examine the fossilized bones and get a better idea of what the Archaeopteryx could do in the air.

Os autores do estudo também concluíram que "o voo com motor deve ter se originado antes do último jurássico".

"Nós imediatamente notamos que as paredes ósseas do Archaeopteryx eram muito mais finas do que as dos dinossauros terrestres, mas se pareciam muito com os ossos das aves convencionais", disse o principal autor do estudo, Dennis Voeten, em um comunicado. A análise dos dados demonstrou ainda que os ossos do Archaeopteryx são mais próximos dos de aves como faisões que ocasionalmente usam o vôo ativo para cruzar barreiras ou desviar de predadores, mas não para planar e planar como muitas aves de rapina e algumas aves marinhas otimizado para um voo duradouro. ”

 O Dr. Emmanuel de Margerie, que também trabalhou na pesquisa, disse que a equipe "concentrou-se na parte central dos ossos do braço porque sabíamos que essas seções contêm sinais claros relacionados a vôo em pássaros".

O estudo, que foi recebido em julho de 2017 e aceito em 31 de janeiro de 2018, é de autoria de Voeten, Jorge Cubo, Emmanuel de Margerie, Martin Röper, Vincent Beyrand, Stanislav Bureš, Paul Tafforeau e Sophie Sanchez.

Os pesquisadores usaram uma técnica não-invasiva chamada microtomografia de contraste de fase para examinar os ossos fossilizados e ter uma idéia melhor do que o Archaeopteryx poderia fazer no ar.



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Twelve fossils of Archaeopteryx have been found, the first discovered in the late 19th century by famed German palaeontologist Hermann von Meyer. The most recent was discovered by an amateur collector in 2010, announced in February 2014 and described scientifically this year.

Archaeopteryx possessed feathers, like a modern-day bird. However, it also possessed a "long, stiff, frond-feathered tail" and teeth, along with bones in its hands, shoulders and pelvis that were not fused.
Other dinosaurs also took to flight, such as the Pteranodon and Pterodactyls, but the Archaeopteryx is a link between dinosaurs and birds, effectively an intermediary, giving its flight patterns added importance.
Voeten notes that because of Archaeopteryx's differences from modern-day birds, more analysis is needed to figure out exactly how it used its wings.

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"However, because Archaeopteryx lacked the pectoral adaptations to fly like modern birds, the way it achieved powered flight must also have been different," Voeten said. "We will need to return to the fossils to answer the question on exactly how this Bavarian icon of evolution used its wings."

 

quinta-feira, 17 de novembro de 2016

[Paleontology • 2016] 

Tongtianlong limosus • A Late Cretaceous Diversification of Asian Oviraptorid Dinosaurs: Evidence from A New Species preserved in An Unusual Posture


Tongtianlong limosus 
Lü, Chen, Brusatte, Zhu & Shen, 2016

 An artistic reconstruction, showing the last-ditch struggle of Tongtianlong limosus as it was mired in mud, one possible, but highly speculative, interpretation for how the specimen was killed and buried.
(Drawn by Zhao Chuang)  DOI: 10.1038/srep35780  

Abstract
Oviraptorosaurs are a bizarre group of bird-like theropod dinosaurs, the derived forms of which have shortened, toothless skulls, and which diverged from close relatives by developing peculiar feeding adaptations. Although once among the most mysterious of dinosaurs, oviraptorosaurs are becoming better understood with the discovery of many new fossils in Asia and North America. The Ganzhou area of southern China is emerging as a hotspot of oviraptorosaur discoveries, as over the past half decade five new monotypic genera have been found in the latest Cretaceous (Maastrichtian) deposits of this region. We here report a sixth diagnostic oviraptorosaur from Ganzhou, Tongtianlong limosus gen. et sp. nov., represented by a remarkably well-preserved specimen in an unusual splayed-limb and raised-head posture. Tongtianlong is a derived oviraptorid oviraptorosaur, differentiated from other species by its unique dome-like skull roof, highly convex premaxilla, and other features of the skull. The large number of oviraptorosaurs from Ganzhou, which often differ in cranial morphologies related to feeding, document an evolutionary radiation of these dinosaurs during the very latest Cretaceous of Asia, which helped establish one of the last diverse dinosaur faunas before the end-Cretaceous extinction.


Figure 2: The whole skeleton of the holotype Tongtianlong limosus gen. et sp. nov. in dorsal view (a) and lateral view (b). Scale bar = 10 cm. 

Systematic Paleontology

Dinosauria Owen, 184231.

Theropoda Marsh, 188132.
Maniraptora Gauthier, 198633.

Oviraptorosauria Barsbold, 197634.
Oviraptoridae Barsbold, 197634.

Tongtianlong limosus gen. et sp. nov. (Figs 2, 3 and 4)


Holotype: A nearly complete, three-dimensionally preserved skeleton with skull and lower jaws (DYM-2013-8). The specimen is accessioned at the Dongyang Museum, Dongyang City, Zhejiang Province.

Type locality and horizon: The building site of the No. 3 high school of Ganxian (GPS coordinates are provided on request from the first author); Nanxiong Formation (Maastrichtian, Upper Cretaceous).


Etymology: Tongtian, Chinese Pinyin, refers to Tongtianyan of Ganzhou, the first grotto south of the Yangtze River. Tongtian also means the road to heaven, a fitting epitaph for a deceased dinosaur preserved with outstretched arms. Long, Chinese Pinyin for dragonLimosus, Latin for muddy, refers to the holotype specimen being found in an unusual posture in a mudstone (Fig. 5).







Junchang Lü, Rongjun Chen, Stephen L. Brusatte, Yangxiao Zhu and Caizhi Shen. 2016. A Late Cretaceous Diversification of Asian Oviraptorid Dinosaurs: Evidence from A New Species preserved in An Unusual Posture. Scientific Reports. 6, Article number: 35780. DOI: 10.1038/srep35780

  

quarta-feira, 11 de novembro de 2015

[Paleontology • 2015]  

Dakotaraptor steini • The First Giant Raptor (Theropoda: Dromaeosauridae) from the latest Cretaceous (Hell Creek Formation, South Dakota)

Dakotaraptor steini
DePalma, Burnham, Martin, Larson & Bakker, 2015
ABSTRACT
Most dromaeosaurids were small- to medium-sized cursorial, scansorial, and arboreal, sometimes volant predators, but a comparatively small percentage grew to gigantic proportions. Only two such giant “raptors” have been described from North America. Here, we describe a new giant dromaeosaurid, Dakotaraptor steini gen. et sp. nov., from the Hell Creek Formation of South Dakota. The discovery represents the first giant dromaeosaur from the Hell Creek Formation, and the most recent in the fossil record worldwide. A row of prominent ulnar papilli or “quill knobs” on the ulna is our first clear evidence for feather quills on a large dromaeosaurid forearm and impacts evolutionary reconstructions and functional morphology of such derived, typically flight-related features. The presence of this new predator expands our record of theropod diversity in latest Cretaceous Laramidia, and radically changes paleoecological reconstructions of the Hell Creek Formation.

Keywords: Maastrichtian, maniraptoran, Laramidia, flightless, ulnar papillae, paleoecology
SYSTEMATIC PALEONTOLOGY

THEROPODA MARSH, 1881
MANIRAPTORA GAUTHIER, 1986

DROMAEOSAURIDAE MATTHEW & BROWN, 1922

DAKOTARAPTOR STEINI GEN. ET SP. NOV.
Etymology.— Dakota, referring to the geographic location of the discovery as well as the Dakota First Nations Tribe, plus raptor, Latin for “plunderer”. The specific name honors paleontologist Walter W. Stein.
Locality and horizon.— Upper Hell Creek Formation (Upper Maastrichtian), no more than 20 m below the Cretaceous-Paleogene Boundary, Harding County, South Dakota, U.S.A. The fossils were discovered in medium- to fine-grained sandstone with clay-pebble laminae that was part of a low-energy stream channel facies. While the type strata were deposited in an active fluvial system, transport energy was sufficiently low that it was not uncommon to find bones >10 cm in length from various other taxa still articulated with their adjacent elements, and plant matter that bore virtually no taphonomic alteration. In several instances, articulated or associated small vertebrate skeletons were recovered. No other theropod bones were recovered from the type substratum except for Dakotaraptor. Flora at the study locality places the site within the HC III floral zone (Johnson, 2002). 

Figure 3. Wing elements of Dakotaraptor holotype (PBMNH.P.10.113.T) compared with Deinonychus (AMNH 3015, YPM 5220, YPM 5206).
A, Deinonychus wing compared to the reconstructed left wing of Dakotaraptor (B). C, left ulna of Dakotaraptor in dorsal (top) and lateral (bottom) views, and D, patch of reactive bone on the ulna caused by physical trauma. Arrow points to the deep radial sulcus. E, Dakotaraptor right metacarpal II (1) compared with that of Deinonychus (2), in (top to bottom) distal, medial, and dorsal views.

Figure 4. Reconstructed Dakotaraptor wing and plumage, with avian and theropod comparisons.
A, enlarged view of the quill knobs on the Dakotaraptor holotype ulna (PBMNH.P.10.113.T), compared with quill knobs in Velociraptor (B) and Concavenator (C); D, conservative reconstruction of the wing plumage for Dakotaraptor based on quill knob placement and comparison with other dromaeosaurid and bird wings; E, quill knobs on a modern Masked Booby (Sula dactylatra) ulna, and (F), X-ray of a modern Barred Owl (Strix varia) wing showing attachment of the remiges on the quill knobs. The flattened dorsal surface of Dakotaraptor’s metacarpal II would have provided a stable shelf for the primary remiges that laid across it, a possible driving force for evolving the flat surface.
B modified from Turner and others, 2007; C modified from Ortega, Escaso, and Sanz, 2010; F courtesy Smalley’s Animal Hospital.  http://hdl.handle.net/1808/18764

Dakotaraptor wing reconstruction.
Photo: R. DePalma
Dakotaraptor steini
Illustration: E. Willoughby | EWilloughby.DeviantArt.com

Dakotaraptor's Ornithomimus Dinner
Illustration: E. Willoughby | EWilloughby.DeviantArt.com
CONCLUSION
A giant, feathered dromaeosaurid exhibited by gracile and robust morphotypes was unexpected and thus is an important addition to the Hell Creek fauna. It fills the gap in body size distribution between the small maniraptorans and large tyrannosaurids previously documented in the formation, while adding to the known diversity of Hell Creek maniraptorans. Dakotaraptor also records a fourth event in which dromaeosaurids achieved atypically large body size. Moreover, the presence of quill knobs, indicative of elongate, stiffened feathers on the forearms, is unprecedented in giant dromaeosaurids and requires a reexamination of trends in quill knob evolution. The functional morphology of the long feathers, possibly of modern avian aspect as implied by known Asian forms, must also be considered. Subsequent studies of Dakotaraptor and the Hell Creek fauna may aid in our understanding of the circumstances that prompted dromaeosaurids to retain ligamental architecture for feather attachment, and may also provide information critical to a more accurate understanding of the lost capacity for flight.

Robert A. DePalma, David A. Burnham, Larry D. Martin, Peter L. Larson and Robert T. Bakker. 2015. The First Giant Raptor (Theropoda: Dromaeosauridae) from the latest Cretaceous (Hell Creek Formation, South Dakota), Paleontological Contributions. 14.

quinta-feira, 30 de abril de 2015

[Paleontology • 2015]  

Yi qi • A Bizarre Jurassic Maniraptoran Theropod with preserved Evidence of Membranous Wings

Yi qi | ‘ee chee’
Xu, Zheng, Sullivan, Wang, Xing, Wang, Zhang, O’Connor, Zhang & Pan, 2015
A farmer first spotted the dinosaur fossil in the Tiaojishan Formation of Hebei Province, China, dating to the Middle–Upper Jurassic period, or about 160 million years ago. The dinosaur is a member of a group of theropods (mostly carnivorous dinosaurs) called Scansoriopterygidae.
photo: Zang Hailong
The wings of birds and their closest theropod relatives share a uniform fundamental architecture, with pinnate flight feathers as the key component. Here we report a new scansoriopterygid theropod, Yi qi gen. et sp. nov., based on a new specimen from the Middle–Upper Jurassic period Tiaojishan Formation of Hebei Province, China. Yi is nested phylogenetically among winged theropods but has large stiff filamentous feathers of an unusual type on both the forelimb and hindlimb. However, the filamentous feathers of Yi resemble pinnate feathers in bearing morphologically diverse melanosomes. Most surprisingly, Yi has a long rod-like bone extending from each wrist, and patches of membranous tissue preserved between the rod-like bones and the manual digits. Analogous features are unknown in any dinosaur but occur in various flying and gliding tetrapods, suggesting the intriguing possibility that Yi had membranous aerodynamic surfaces totally different from the archetypal feathered wings of birds and their closest relatives. Documentation of the unique forelimbs of Yi greatly increases the morphological disparity known to exist among dinosaurs, and highlights the extraordinary breadth and richness of the evolutionary experimentation that took place close to the origin of birds.
The dinosaur would have sported a robust skull with a short snout
photo: Zang Hailong
Theropoda Marsh, 1881
Maniraptora Gauthier, 1986
Scansoriopterygidae Czerkas et Yuan, 2002

Yi qi gen. et sp. nov.

Etymology. The generic and specific names are derived from Mandarin Yi (wing) and qi (strange), respectively, referring to the bizarre wings of this animal. The intended pronunciation of the name is roughly “ee chee”.

Holotype. STM 31-2 (housed at the Shandong Tianyu Museum of Nature), an articulated partial skeleton with associated soft tissue preserved on a slab and counter slab. The specimen was collected by a local farmer, but its provenance and authenticity have been confirmed by multiple lines of evidence including sedimentology, taphonomy and computed tomography (CT) data.

Locality and horizon. Mutoudeng, Qinglong County, Hebei Province, China. Tiaojishan Formation, Callovian–Oxfordian stage. On the basis of the provenance of the specimen, Yi qi is a member of the Daohugou (or Yanliao) Biota.

Preserved features of the "winged" dinosaur fossil reveal feathers over the neck (not shown), along the humerus (b) and along the humerus and ulna (c). The fossil also showed soft tissue and feathers along the right forelimb and hindlimb.
photo: Zang Hailong | doi:10.1038/nature14423



Xing Xu, Xiaoting Zheng, Corwin Sullivan, Xiaoli Wang, Lida Xing, Yan Wang, Xiaomei Zhang, Jingmai K. O’Connor, Fucheng Zhang and Yanhong Pan. 2015. A Bizarre Jurassic Maniraptoran Theropod with preserved Evidence of Membranous Wings.
Nature. doi: 10.1038/nature14423
In Photos: Bizarre 'Bat Dinosaur' Discovered in China https://shar.es/1pAfJo  @LiveScience
Chinese Dinosaur Had Bat-Like Wings and Feathers http://on.natgeo.com/1JC8rKd via