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Preserved skin of small dinosaurs is rare. Here, a specimen of the ceratopsian dinosaur, Psittacosaurus, presents some of the best preserved epidermal scales observed to date in a relatively small dinosaur, over wide areas extending from the head to the tail. We study the preserved epidermis of SMF R 4970, the different types of scales, color, and patterns, and their respective locations in the body. We use modern application of high-power digital imaging for close-up analysis of the tubercles and fragments of preserved color. Three types of scales are preserved, large plate-like scales, smaller polygonal scales or tubercles, and round pebble-like scales. The sizes of the plate-like scales vary in different parts of the body and vanish altogether posteriorly. Light and dark cryptic patterns are created by the associations of the tubercle and plate-like scales, and there is also evidence of countershading in the proximal caudal region, the body darker dorsally and lighter ventrally. Perhaps most impressive are the distinctive pigmented impressions of scales over most of the skeletal elements. The pigmentation follows the curvature of the bones implying that when it was deposited, the skin was still pliable and able to wrap around the visible parts of the elements. The present record of color is the first in a non-theropod dinosaur and only the second record in a non-avian dinosaur. Because of its resistance to degradation and ability to produce various color tones from yellows to blacks, we suggest that melanin was the dominant chemical involved in the coloration of Psittacosaurus. The data here enable us to reconstruct the colors of Psittacosaurus as predominantly black and amber/brown, in cryptic patterns, somewhat dull, but useful to a prey animal. Indeed, skin pigment within a partially degraded bone indicates that Psittacosaurus was scavenged shortly after death. The theropod dinosaur Sinosauropteryx has recently been reported to have naturally pigmented integumental structures, which the authors interpret as proof that they are protofeathers and not support fibers of collagen. Our findings in Psittacosaurus, on the other hand, indicate a more parsimonious and less profound alternative explanation, i.e., decomposition of the skin releases pigments that readily permeate underlying structures. 相似文献
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Heterodontosauridae is a morphologically divergent group of dinosaurs that has recently been interpreted as one of the most basal clades of Ornithischia. Heterodontosaurid remains were previously known from the Early Jurassic of southern Africa, but recent discoveries and studies have significantly increased the geographical and temporal range for this clade. Here, we report a new ornithischian dinosaur from the Middle Jurassic Ca?adón Asfalto Formation in central Patagonia, Argentina. This new taxon, Manidens condorensis gen. et sp. nov., includes well-preserved craniomandibular and postcranial remains and represents the only diagnostic ornithischian specimen yet discovered in the Jurassic of South America so far. Derived features of its anatomy indicate that Manidens belongs to Heterodontosauridae, as the sister taxon of Heterodontosaurus and other South African heterodontosaurids. The presence of posterior dentary teeth with high crowns but lacking extensive wear facets in Manidens suggests that this form represents an intermediate stage in the development of the remarkable adaptations to herbivory described for Heterodontosaurus. The dentition of Manidens condorensis also has autapomorphies, such as asymmetrically arranged denticles in posterior teeth and a mesially projected denticle in the posteriormost teeth. At an estimated total length of 60?C75?cm, Manidens furthermore confirms the small size of basal heterodontosaurids. 相似文献
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Cerda IA Paulina Carabajal A Salgado L Coria RA Reguero MA Tambussi CP Moly JJ 《Die Naturwissenschaften》2012,99(1):83-87
Sauropoda is one of the most diverse and geographically widespread clades of herbivorous dinosaurs, and until now, their remains
have now been recovered from all continental landmasses except Antarctica. We report the first record of a sauropod dinosaur
from Antarctica, represented by an incomplete caudal vertebra from the Late Cretaceous of James Ross Island. The size and
morphology of the specimen allows its identification as a lithostrotian titanosaur. Our finding indicates that advanced titanosaurs
achieved a global distribution at least by the Late Cretaceous. 相似文献
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The unusual presence of long pennaceous feathers on the feet of basal dromaeosaurid dinosaurs has recently been presented as strong evidence in support of the arboreal–gliding hypothesis for the origin of bird flight, but it could be a unique feature of dromaeosaurids and thus irrelevant to the theropod–bird transition. Here, we report a new eumaniraptoran theropod from China, with avian affinities, which also has long pennaceous feathers on its feet. This suggests that such morphology might represent a primitive adaptation close to the theropod–bird transition. The long metatarsus feathers are likely primitive for Eumaniraptora and might have played an important role in the origin of avian flight.Electronic Supplementary Material Supplementary material is available for this article at 相似文献
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Juan I. Canale Carlos A. Scanferla Federico L. Agnolin Fernando E. Novas 《Die Naturwissenschaften》2009,96(3):409-414
A nearly complete skeleton of the new abelisaurid Skorpiovenator bustingorryi is reported here. The holotype was found in Late Cenomanian–Early Turonian outcrops of NW Patagonia, Argentina. This new
taxon is deeply nested within a new clade of South American abelisaurids, named Brachyrostra. Within brachyrostrans, the skull
shortening and hyperossification of the skull roof appear to be correlated with a progressive enclosure of the orbit, a set
of features possibly related to shock-absorbing capabilities. Moreover, the development of horn-like structures and differential
cranial thickening appear to be convergently acquired within Abelisauridae. Based on the similarities between Skorpiovenator and carcharodontosaurid tooth morphology, we suggest that isolated teeth originally referred as post-Cenomanian Carcharodontosauridae
most probably belong to abelisaurids.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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Daniel Chure Brooks B. Britt John A. Whitlock Jeffrey A. Wilson 《Die Naturwissenschaften》2010,97(4):379-391
Sauropod dinosaur bones are common in Mesozoic terrestrial sediments, but sauropod skulls are exceedingly rare—cranial materials
are known for less than one third of sauropod genera and even fewer are known from complete skulls. Here we describe the first
complete sauropod skull from the Cretaceous of the Americas, Abydosaurus mcintoshi, n. gen., n. sp., known from 104.46 ± 0.95 Ma (megannum) sediments from Dinosaur National Monument, USA. Abydosaurus shares close ancestry with Brachiosaurus, which appeared in the fossil record ca. 45 million years earlier and had substantially broader teeth. A survey of tooth
shape in sauropodomorphs demonstrates that sauropods evolved broad crowns during the Early Jurassic but did not evolve narrow
crowns until the Late Jurassic, when they occupied their greatest range of crown breadths. During the Cretaceous, brachiosaurids
and other lineages independently underwent a marked diminution in tooth breadth, and before the latest Cretaceous broad-crowned
sauropods were extinct on all continental landmasses. Differential survival and diversification of narrow-crowned sauropods
in the Late Cretaceous appears to be a directed trend that was not correlated with changes in plant diversity or abundance,
but may signal a shift towards elevated tooth replacement rates and high-wear dentition. Sauropods lacked many of the complex
herbivorous adaptations present within contemporaneous ornithischian herbivores, such as beaks, cheeks, kinesis, and heterodonty.
The spartan design of sauropod skulls may be related to their remarkably small size—sauropod skulls account for only 1/200th
of total body volume compared to 1/30th body volume in ornithopod dinosaurs. 相似文献
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First nonavian dinosaur from Lebanon: a brachiosaurid sauropod from the Lower Cretaceous of the Jezzine District 总被引:1,自引:0,他引:1
Two sauropod teeth from an Early Cretaceous (Neocomian) fluviodeltaic sandstone near Jezzine (Southern Lebanon) are the first nonavian dinosaur remains to be reported from Lebanon. Their distinctive character places them within Brachiosauridae. The sauropod teeth from Lebanon are a significant addition to the very scanty dinosaur record from the Levant, which hitherto consisted mainly of very poorly preserved and not easily identifiable specimens. The Basal Cretaceous Sandstone of Lebanon, thus, appears to be a potentially important source of fossil vertebrate material. 相似文献
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Caudal autotomy is an effective antipredator strategy widespread among lizards. The shed tail thrashes vigorously for long periods to distract the predator and facilitate the lizard's escape. This movement is maintained by energy supplied by the anaerobic conversion of glycogen into lactate. It has been suggested that lactate accumulation serves as an index for the vigor of tail thrashing. We made three predictions: (1) tail loss frequency should be higher under heavier predation regime, (2) the duration of postautotomy tail movement should be extended in populations under heavy predation pressure as an adaptation to the higher risk and the increased need for defense, and (3) as result, lactate in these tail tissues should be concentrated at higher levels. To eliminate the impact of phylogeny and environmental factors on the interpretation of our result, we focused exclusively on one species, the Balearic lizard (Podarcis lilfordi). We studied three populations under different predation pressure but sharing the same climatic conditions. We found no differences among the studied populations either in postautotomy duration of tail movement or in levels of final lactate accumulation while autotomy frequency was higher where predation pressure was more intense. Tail loss effectiveness is directly influenced by the level of predation, while secondary features of the trait appear to remain independent from the impact of environment. 相似文献
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Bravoceratops polyphemus gen. et sp. nov. is a large chasmosaurine ceratopsid from the lowermost part of the Javelina Formation (early Maastrichtian) of Big Bend National Park, TX, USA. B. polyphemus has a distinctive narrow snout, a long fenestrate frill, and a fan-shaped median parietal bar with a midline epiparietal on its posterior margin, as well as a symmetrical depression on its dorsal surface at the nexus of the parietal rami. This depression is interpreted to be the attachment point for a second midline epiparietal. This parietal morphology is distinct from that exhibited by Anchiceratops or Pentaceratops. The posterior midline epiparietal in B. polyphemus and its bifurcated quadratojugal–squamosal joint are features shared with the most derived chasmosaurines, Torosaurus and Triceratops. The combination of primitive and derived traits exhibited by B. polyphemus, and its stratigraphic position, is compatible with the gradual transition from basal, to intermediate, to derived chasmosaurines observed throughout the western interior of North America, and with phylogenetic analysis, which suggests that Bravoceratops may be closely related to Coahuilaceratops. 相似文献
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房地产开发项目的地下停车场集中排放的汽车尾气对环境产生影响,分析了地下停车场有害物的种类及危害,介绍了地下停车场的设计要点,汽车污染的控制. 相似文献
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为研究电化学技术对海水养殖尾水中氨氮和亚硝酸盐的去除作用,以天津市杨家泊镇某海水养殖工厂排放的养殖尾水为研究对象,选用DSA(dimensionally stable anodes)电极、间歇流的处理方式,考察电压、电极板间距、电化学处理时间对养殖尾水中氨氮和亚硝酸盐去除率的影响,并进行了能耗分析。结果表明:在电极板间距为2 cm,电压为3 V、电化学处理时间为5 min时,氨氮去除率达96.0%,此时能耗仅为0.79 kW·h/g;电极板间距为3 cm,电压为3 V,电化学处理时间为7 min时,亚硝酸盐去除率最高,为98.9%;去除亚硝酸盐的最低能耗为0.032 kW·h/g,此时去除率为75.2%;27组试验组中有14组经电化学处理后的养殖尾水总无机氮浓度达到SC/T 9103—2007《海水养殖水排放要求》一级排放标准。电化学技术对氨氮和亚硝酸盐均有很好的去除作用,不同试验条件下氨氮和亚硝酸盐去除率均较高,且能耗较低。 相似文献
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