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1.
Jurassic fossil vertebrates collected from the Falla Formation in the Central Transantarctic Mountains included a partial skull and postcranial elements of a crested theropod, Cryolophosaurus ellioti gen. nov. sp. nov. The theropod bears some resemblance to the large tetanurans of the Middle to Late Jurassic but also has primitive ceratosaurian features. Elements from a prosauropod, teeth from scavenging theropods, a pterosaur humerus, and a tritylodont molar were also recovered. The presence of this fauna suggests that a mild climate existed at high paleolatitude in this area of Gondwana during the Early Jurassic. 相似文献
2.
Zipfel B DeSilva JM Kidd RS Carlson KJ Churchill SE Berger LR 《Science (New York, N.Y.)》2011,333(6048):1417-1420
A well-preserved and articulated partial foot and ankle of Australopithecus sediba, including an associated complete adult distal tibia, talus, and calcaneus, have been discovered at the Malapa site, South Africa, and reported in direct association with the female paratype Malapa Hominin 2. These fossils reveal a mosaic of primitive and derived features that are distinct from those seen in other hominins. The ankle (talocrural) joint is mostly humanlike in form and inferred function, and there is some evidence for a humanlike arch and Achilles tendon. However, Au. sediba is apelike in possessing a more gracile calcaneal body and a more robust medial malleolus than expected. These observations suggest, if present models of foot function are correct, that Au. sediba may have practiced a unique form of bipedalism and some degree of arboreality. Given the combination of features in the Au. sediba foot, as well as comparisons between Au. sediba and older hominins, homoplasy is implied in the acquisition of bipedal adaptations in the hominin foot. 相似文献
3.
The unearthing of a complete skull and skeleton of the early dinosaur Herrerasaurus ischigualastensis sheds light on the early evolution of dinosaurs. Discovered in the Upper Triassic Ischigualasto Formation of Argentina, the fossils show that Herrerasaurus, a primitive theropod, was an agile, bipedal predator with a short forelimb specialized for grasping and raking. The fossils clarify anatomical features of the common ancestor of all dinosaurs. Herrerasaurus and younger dinosaurs from Upper Triassic beds in Argentina suggest that the dinosaurian radiation was well under way before dinosaurs dominated terrestrial vertebrate communities in taxonomic diversity and abundance. 相似文献
4.
The transition to full-time terrestrial bipedality is a hallmark of human evolution. A key correlate of human bipedalism is the development of longitudinal and transverse arches of the foot that provide a rigid propulsive lever and critical shock absorption during striding bipedal gait. Evidence for arches in the earliest well-known Australopithecus species, A. afarensis, has long been debated. A complete fourth metatarsal of A. afarensis was recently discovered at Hadar, Ethiopia. It exhibits torsion of the head relative to the base, a direct correlate of a transverse arch in humans. The orientation of the proximal and distal ends of the bone reflects a longitudinal arch. Further, the deep, flat base and tarsal facets imply that its midfoot had no ape-like midtarsal break. These features show that the A. afarensis foot was functionally like that of modern humans and support the hypothesis that this species was a committed terrestrial biped. 相似文献
5.
PC Sereno AL Beck DB Dutheil B Gado HCE Larsson GH Lyon JD Marcot OWM Rauhut RW Sadleir CA Sidor DD Varricchio GP Wilson JA Wilson 《Science (New York, N.Y.)》1998,282(5392):1298-1302
Fossils discovered in Lower Cretaceous (Aptian) rocks in the Tenere Desert of central Niger provide new information about spinosaurids, a peculiar group of piscivorous theropod dinosaurs. The remains, which represent a new genus and species, reveal the extreme elongation and transverse compression of the spinosaurid snout. The postcranial bones include blade-shaped vertebral spines that form a low sail over the hips. Phylogenetic analysis suggests that the enlarged thumb claw and robust forelimb evolved during the Jurassic, before the elongated snout and other fish-eating adaptations in the skull. The close phylogenetic relationship between the new African spinosaurid and Baryonyx from Europe provides evidence of dispersal across the Tethys seaway during the Early Cretaceous. 相似文献
6.
A nearly complete skeleton of Archaeopteryx with excellent bone preservation shows that the osteology of the urvogel is similar to that of nonavian theropod dinosaurs. The new specimen confirms the presence of a hyperextendible second toe as in dromaeosaurs and troodontids. Archaeopteryx had a plesiomorphic tetraradiate palatine bone and no fully reversed first toe. These observations provide further evidence for the theropod ancestry of birds. In addition, the presence of a hyperextendible second toe blurs the distinction of archaeopterygids from basal deinonychosaurs (troodontids and dromaeosaurs) and challenges the monophyly of Aves. 相似文献
7.
Dial KP 《Science (New York, N.Y.)》2003,299(5605):402-404
Flapping wings of galliform birds are routinely used to produce aerodynamic forces oriented toward the substrate to enhance hindlimb traction. Here, I document this behavior in natural and laboratory settings. Adult birds fully capable of aerial flight preferentially employ wing-assisted incline running (WAIR), rather than flying, to reach elevated refuges (such as cliffs, trees, and boulders). From the day of hatching and before attaining sustained aerial flight, developing ground birds use WAIR to enhance their locomotor performance through improved foot traction, ultimately permitting vertical running. WAIR provides insight from behaviors observable in living birds into the possible role of incipient wings in feathered theropod dinosaurs and offers a previously unstudied explanation for the evolution of avian flight. 相似文献
8.
Culotta E 《Science (New York, N.Y.)》2008,320(5875):433-435
At the recent American Association of Physical Anthropology meetings, a researcher described the foot bones of an 18,000-year-old Indonesian skeleton known as the "hobbit." The tiny hominin would not have walked like we do, he said, and may offer "a window into a primitive bipedal foot." 相似文献
9.
A S Romer 《Science (New York, N.Y.)》1969,166(907):881-882
A diagnostic mammalian character is jaw articulation between squamosal and dentary bones, replacing the quadrate-articular joint of reptiles. A newly discovered Argentinian Middle Triassic form shows, for the first time in an ancestral reptile, definite evidence of a squamosal-dentary articulation supplementary to the persistent primitive connection. 相似文献
10.
Some nonavian theropod dinosaurs were at least partially covered in feathers or filamentous protofeathers. However, a complete understanding of feather distribution among theropod dinosaurs is limited because feathers are typically preserved only in lagerst?tten like that of Solnhofen, Germany or Liaoning, China. Such deposits possess clear taphonomic biases toward small-bodied animals, limiting our knowledge regarding feather presence in larger members of feathered clades. We present direct evidence of feathers in Velociraptor mongoliensis based on the presence of quill knobs on the posterior forearm. This report of secondaries in a larger-bodied, derived, and clearly flightless member of a nonavian theropod clade represented by feathered relatives is a substantial contribution to our knowledge of the evolution of feathers. 相似文献
11.
White TD 《Science (New York, N.Y.)》1981,213(4505):348-349
A primitive hominid canine recovered at Laetoli by Louis Leakey in 1935 and stored at the British Museum of Natural History adds to our knowledge of dental anatomy in Australopithecus. The specimen was the first adult Australopithecus recovered and the first ancient hominid discovered in eastern Africa. 相似文献
12.
McKenzie KG 《Science (New York, N.Y.)》1967,155(3765):1005
New ostracod "living fossils" have been discovered in samples of Recent marine sediment collected from several Pacific islands. The finds include a male anatomy having several primitive features which, in conjunction with primitive features in the shell, necessitate reconsideration of current opinions on the phylogeny of freshwater ostracods. 相似文献
13.
Pollen of the primitive angiosperm family Winteraceae has been discovered in the Aptian-Albian of Israel, extending the fossil record of this phylogenetically important family of flowering plants from the uppermost Upper Cretaceous back some 40 million years to the upper Lower Cretaceous. This appears to represent the earliest known record of a magnolialean angiosperm family and is convincing evidence for the existence in the Early Cretaceous of an extant family of angiosperms. 相似文献
14.
Predatory dinosaur remains from madagascar: implications for the cretaceous biogeography of gondwana 总被引:1,自引:0,他引:1
SD Sampson LM Witmer CA Forster DW Krause PM O'Connor P Dodson F Ravoavy 《Science (New York, N.Y.)》1998,280(5366):1048-1051
Recent discoveries of fossil vertebrates from the Late Cretaceous of Madagascar include several specimens of a large theropod dinosaur. One specimen includes a nearly complete and exquisitely preserved skull with thickened pneumatic nasals, a median frontal horn, and a dorsal projection on the parietals. The new materials are assigned to the enigmatic theropod group Abelisauridae on the basis of a number of unique features. Fossil remains attributable to abelisaurids are restricted to three Gondwanan landmasses: South America, Madagascar, and the Indian subcontinent. This distribution is consistent with a revised paleogeographic reconstruction that posits prolonged links between these landmasses (via Antarctica), perhaps until late in the Late Cretaceous. 相似文献
15.
Fossils newly discovered in the Paleocene and early Eocene of western North America document some of the oldest birds known from nearly complete skeletons. These were medium-sized carinates with powers of sustained flight but which had a paleognathous palate like that of the flightless ostrich-like birds and the tinamous. The fossils provide additional evidence that the paleognathous palate is probably primitive and therefore should not be cited as a derived character state to define the ostrich-like birds as a monophyletic group. 相似文献
16.
In search of the first flower: A jurassic angiosperm, archaefructus, from northeast china 总被引:1,自引:0,他引:1
Angiosperm fruiting axes were discovered from the Upper Jurassic of China. Angiosperms are defined by carpels enclosing ovules, a character demonstrated in this fossil. This feature is lacking in other fossils reported to be earliest angiosperms. The fruits are small follicles formed from conduplicate carpels helically arranged. Adaxial elongate stigmatic crests are conspicuous on each carpel. The basal one-third of the axes bore deciduous organs of uncertain affinities. No scars of subtending floral organs are present to define the individual fertile parts as floral units, but the leaf-like structures subtending each axis define them as flowers. These fruiting axes have primitive characters and characters not considered primitive. 相似文献
17.
Stokstad E 《Science (New York, N.Y.)》2000,288(5474):2124-2125
On page 2202, researchers describe the 220-million-year-old Longisquama insignis, a squat, mouse-sized reptile with at least six vanelike appendages up to 12 centimeters long sprouting from its spine. The authors argue that the appendages are feathers much like those of modern birds; outside the paper, they have touted the fossil as "an ideal bird ancestor." That conclusion has infuriated paleontologists--not just because it challenges the prevalent theory that birds evolved from theropod dinosaurs, but because they say it does so in an unscientific way. 相似文献
18.
Olduvai hominid (O.H.) fossils 7, 8, and 35 represent the earliest species of the genus Homo dated at 1.76 million years. The O.H. 7 hand, jaw, and skull and the O.H. 8 foot come from one subadult individual, and the O.H. 35 leg are also those of Homo habilis. The skeleton represents a mosaic of primitive and derived features, indicating an early hominid which walked bipedally and could fabricate stone tools but also retained the generalized hominoid capacity to climb trees. 相似文献
19.
为明确甘薯基部腐烂病害的病原菌与发病原因,2015—2017年开展甘薯病害调查取样、病原菌鉴定与防治试验。结果表明:台州甘薯基部腐烂病主要由甘薯茎腐病菌( Dickeya dadantii)与甘薯基腐病菌(Phomopsis destruens)等复合侵染引起。简述了2种病害的分布情况、症状识别、病原菌形态、入侵途径及病害发生特点,提出了加强植物检疫、建立健康种苗制度、水旱轮作和薯田淹水、清洁田园和化学药剂预防等防控措施,以及从保障国家粮食安全的战略高度,加大经费投入,开展甘薯主要病虫抗性基因筛选、培育抗性品种和新入侵病害致病成因研究等建议。 相似文献