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1.
McKellar et al. (Reports, 16 September 2011, p. 1619) analyzed Late Cretaceous amber specimens from Canada and identified some filaments as dinosaurian protofeathers. We argue that their analysis and data do not provide sufficient evidence to conclude that such filaments are feather-like structures. Further investigation, including destructive sampling, must be carried out for more convincing conclusions. 相似文献
2.
Carnivorous fungi dating back to the age of the dinosaurs have been found fossilized in circa-100-million-year-old amber. The fossil fungi used hyphal rings as trapping devices and are preserved together with their prey, small nematodes. The excellent preservation in amber allowed comparison with extant groups: On the basis of the mode of ring formation and the dimorphic mode of life, the fossils cannot be assigned to any recent carnivorous fungus, providing evidence that different groups occupied this ecological niche in the Cretaceous and that trapping devices were developed independently multiple times in the course of Earth history. 相似文献
3.
PC Sereno DB Dutheil M Iarochene HCE Larsson GH Lyon PM Magwene CA Sidor DJ Varricchio JA Wilson 《Science (New York, N.Y.)》1996,272(5264):986-991
Late Cretaceous (Cenomanian) fossils discovered in the Kem Kem region of Morocco include large predatory dinosaurs that inhabited Africa as it drifted into geographic isolation. One, represented by a skull approximately 1.6 meters in length, is an advanced allosauroid referable to the African genus Carcharodontosaurus. Another, represented by a partial skeleton with slender proportions, is a new basal coelurosaur closely resembling the Egyptian genus Bahariasaurus. Comparisons with Cretaceous theropods from other continents reveal a previously unrecognized global radiation of carcharodontosaurid predators. Substantial geographic differentiation of dinosaurian faunas in response to continental drift appears to have arisen abruptly at the beginning of the Late Cretaceous. 相似文献
4.
Wilf P Labandeira CC Kress WJ Staines CL Windsor DM Allen AL Johnson KR 《Science (New York, N.Y.)》2000,289(5477):291-294
Stereotyped feeding damage attributable solely to rolled-leaf hispine beetles is documented on latest Cretaceous and early Eocene ginger leaves from North Dakota and Wyoming. Hispine beetles (6000 extant species) therefore evolved at least 20 million years earlier than suggested by insect body fossils, and their specialized associations with gingers and ginger relatives are ancient and phylogenetically conservative. The latest Cretaceous presence of these relatively derived members of the hyperdiverse leaf-beetle clade (Chrysomelidae, more than 38,000 species) implies that many of the adaptive radiations that account for the present diversity of leaf beetles occurred during the Late Cretaceous, contemporaneously with the ongoing rapid evolution of their angiosperm hosts. 相似文献
5.
Two worker ants preserved in amber of Upper Cretaceous age have been found in New Jersey. They are the first undisputed remains of social insects of Mesozoic age, extending the existence of social life in insects back to approximately 100 million years. They are also the earliest known fossils that can be assigned with certainty to aculeate Hymenoptera. The species, Sphecomyrma freyi, is considered to represent a new subfamily (Sphecomyrminae), more primitive than any previously known ant group. It forms a near-perfect link between certain nonsocial tiphiid wasps and the most primitive myrmecioid ants. 相似文献
6.
Gases trapped in Miocene to Upper Cretaceous amber were released by gently crushing the amber under vacuum and were analyzed by quadrupole mass spectrometry. After discounting the possibility that the major gases N(2), O(2), and CO(2) underwent appreciable diffusion and diagenetic exchange with their surroundings or reaction with the amber, it has been concluded that in primary bubbles (gas released during initial breakage) these gases represent mainly original ancient air modified by the aerobic respiration of microorganisms. Values of N(2)/(CO(2) + O(2)) for each time period give consistent results despite varying O(2)/CO(2) ratios that presumably were due to varying degrees of respiration. This allows calculation of original oxygen concentrations, which, on the basis of these preliminary results, appear to have changed from greater than 30 percent O(2) during one part of the Late Cretaceous (between 75 and 95 million years ago) to 21 percent during the Eocene-Oligocene and for present-day samples, with possibly lower values during the Oligocene-Early Miocene. Variable O(2) levels over time in general confirm theoretical isotope-mass balance calculations and suggest that the atmosphere has evolved over Phanerozoic time. 相似文献
7.
The bee fossil record is fragmentary, making it difficult to accurately estimate the antiquity of bee-mediated pollination. Here, we describe a bee fossil [Melittosphex burmensis (new species), Melittosphecidae (new family)] from Early Cretaceous Burmese amber (approximately 100 million years before the present). The fossil provides insights into the morphology of the earliest bees and provides a new minimum date for the antiquity of bees and bee-mediated pollination. 相似文献
8.
A frog of the leptodactylid genus Eleutherodactylus is reported from Eocene amber found in the Dominican Republic. It is the first described amphibian fossil in amber, and the oldest complete lissamphibian fossil from Mesoamerica (Central America and Mexico). Dating of the amber matrix indicates that by the end of the Eocene a diverse fauna was present in the Antilles, much earlier than has generally been proposed. The presence of this and other amber fossils from this same age suggests that Tertiary patterns of landmass movements were significant in determining the present distribution of species. 相似文献
9.
We present a large-scale molecular phylogeny of the ants (Hymenoptera: Formicidae), based on 4.5 kilobases of sequence data from six gene regions extracted from 139 of the 288 described extant genera, representing 19 of the 20 subfamilies. All but two subfamilies are recovered as monophyletic. Divergence time estimates calibrated by minimum age constraints from 43 fossils indicate that most of the subfamilies representing extant ants arose much earlier than previously proposed but only began to diversify during the Late Cretaceous to Early Eocene. This period also witnessed the rise of angiosperms and most herbivorous insects. 相似文献
10.
Late Jurassic and Early Cretaceous birds from northeastern China, including many complete skeletons of Confuciusornis, provide evidence for a fundamental dichotomy in the class Aves that may antedate the temporal occurrence of the Late Jurassic Archaeopteryx. The abundance of Confuciusornis may provide evidence of avian social behavior. Jurassic skeletal remains of an ornithurine bird lend further support to the idea of an early separation of the line that gave rise to modern birds. Chaoyangia, an ornithurine bird from the Early Cretaceous of China, has premaxillary teeth. 相似文献
11.
Well-preserved Lower Cretaceous fossil copepods related to the super-family Dichelesthioidea have been collected from the gill chamber of the ichthyodectid fish Cladocyclus gardneri. The fossils provide conclusive evidence suporting recent theories that link caligid copepods, which are parasitic on fish, to the invertebrate-associated siphonostomes. This is the first discovery of fossil parasitic copepods, and they are by far the oldest copepods of any sort known. 相似文献
12.
An embryo of an enantiornithine bird has been recovered from the Lower Cretaceous rocks of Liaoning, in northeast China. The bird has a nearly complete articulated skeleton with feather sheet impressions and is enclosed in egg-shaped confines. The tucking posture of the skeleton suggests that the embryo had attained the final stage of development. The presence of well-developed wing and tail feather sheets indicates a precocial developmental mode, supporting the hypothesis that precocial birds appeared before altricial birds. 相似文献
13.
Fossil worm tubes of Cretaceous age preserved in the Bayda massive sulfide deposit of the Samail ophiolite, Oman, are apparently the first documented examples of fossils embedded in massive sulfide deposits from the geologic record. The geologic setting of the Bayda deposit and the distinctive mineralogic and textural features of the fossiliferous samples suggest that the Bayda sulfide deposit and fossil fauna are remnants of a Cretaceous sea-floor hydrothermal vent similar to modern hot springs on the East Pacific Rise and the Juan de Fuca Ridge. 相似文献
14.
Clarke JA Ksepka DT Salas-Gismondi R Altamirano AJ Shawkey MD D'Alba L Vinther J DeVries TJ Baby P 《Science (New York, N.Y.)》2010,330(6006):954-957
Penguin feathers are highly modified in form and function, but there have been no fossils to inform their evolution. A giant penguin with feathers was recovered from the late Eocene (~36 million years ago) of Peru. The fossil reveals that key feathering features, including undifferentiated primary wing feathers and broad body contour feather shafts, evolved early in the penguin lineage. Analyses of fossilized color-imparting melanosomes reveal that their dimensions were similar to those of non-penguin avian taxa and that the feathering may have been predominantly gray and reddish-brown. In contrast, the dark black-brown color of extant penguin feathers is generated by large, ellipsoidal melanosomes previously unknown for birds. The nanostructure of penguin feathers was thus modified after earlier macrostructural modifications of feather shape linked to aquatic flight. 相似文献
15.
Li Q Gao KQ Meng Q Clarke JA Shawkey MD D'Alba L Pei R Ellison M Norell MA Vinther J 《Science (New York, N.Y.)》2012,335(6073):1215-1219
Iridescent feather colors involved in displays of many extant birds are produced by nanoscale arrays of melanin-containing organelles (melanosomes). Data relevant to the evolution of these colors and the properties of melanosomes involved in their generation have been limited. A data set sampling variables of extant avian melanosomes reveals that those forming most iridescent arrays are distinctly narrow. Quantitative comparison of these data with melanosome imprints densely sampled from a previously unknown specimen of the Early Cretaceous feathered Microraptor predicts that its plumage was predominantly iridescent. The capacity for simple iridescent arrays is thus minimally inferred in paravian dinosaurs. This finding and estimation of Microraptor feathering consistent with an ornamental function for the tail suggest a centrality for signaling in early evolution of plumage and feather color. 相似文献
16.
Cycads: fossil evidence of late paleozoic origin 总被引：1，自引：0，他引：1
Mamay SH 《Science (New York, N.Y.)》1969,164(3877):295-296
Plant fossils from Lower Permian strata of the southwestern United States have been interpreted as cycadalean megasporophylls. They are evidently descended from spermopterid elements of the Pennsylvanian Taeniopteris complex; thus the known fossil history of the cycads is extended from the Late Triassic into the late Paleozoic. Possible implications of the Permian fossils toward evolution of the angiosperm carpel are considered. 相似文献
17.
Mackay MR 《Science (New York, N.Y.)》1970,167(3917):379-380
The discovery of the head capsule of a lepidopterous larva in Canadian amber of the Cretaceous period is the first fossil evidence of Lepidoptera before the Tertiary period. 相似文献
18.
Hsü KJ He Q McKenzie JA Weissert H Perch-Nielsen K Oberhänsli H Kelts K Labrecque J Tauxe L Krähenbühl U Percival SF Wright R Karpoff AM Petersen N Tucker P Poore RZ Gombos AM Pisciotto K Carman MF Schreiber E 《Science (New York, N.Y.)》1982,216(4543):249-256
The latest Mesozoic and earliest Tertiary sediments at Deep Sea Drilling Project site 524 provide an amplified record of environmental and biostratographic changes at the end of Cretaceous. Closely spaced samples, representing time intervals as short as 10(2) or 10(3) years, were analyzed for their bulk carbonate and trace-metal compositions, and for oxygen and carbon isotopic compositions. The data indicate that at the end of Cretaceous, when a high proportion of the ocean's planktic organisms were eliminated, an associated reduction in productivity led to a partial transfer of dissolved carbon dioxide from the oceans to the atmosphere. This resulted in a large increase of the atmospheric carbon dioxide during the next 50,000 years, which is believed to have caused a temperature rise revealed by the oxygen-isotope data. The lowermost Tertiary sediments at site 524 include fossils with Cretaceous affinities, which may include both reworked individuals and some forms that survived for a while after the catastrophe. Our data indicate that many of the Cretaceous pelagic organisms became extinct over a period of a few tens of thousands of years, and do not contradict the scenario of cometary impact as a cause of mass mortality in the oceans, as suggested by an iridium anomaly at the Cretaceous-Tertiary boundary. 相似文献
19.
Beauchamp B Harrison JC Nassichuk WW Krouse HR Eliuk LS 《Science (New York, N.Y.)》1989,244(4900):53-56
Lower Cretaceous cold-seep fossil assemblages have been found in the Canadian Arctic Archipelago. Serpulid worm tubes and bivalves are most abundant in these communities; in contrast, fossils are scarce in the surrounding strata. The fossils are contained in an isotopically light (delta(13)C = -25 to -50 per mil) carbonate rock groundmass that is interpreted to have formed from bacterial oxidation of methane. The rocks were deposited at intermediate depth (相似文献
20.
Cores recovered from horizon A are Late Cretaceous (Maestrichtian) in age and consist o alternating layers of calcareous turbidites and "red clay." The presence of red clay suggests that the water depth in this area during Cretaceous time was at least as great as at present-more than 5100 meters. A middle Cretaceous (Cenomanian) core consisting of interbedded sand and gravel and light-to-dark-gray lutite was taken in the same area from a layer stratigraphically below the horizon; the presence of hydrogen sulfide and iron sulfide may indicate anaerobic conditions that may be attributable to local ponding of sediment in Cenomanian time. 相似文献