首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 9 毫秒
1.
Two tridactyl footprints from the Chuanjie Formation (Middle Jurassic) of Yunnan Province, China are morphological characteristics of thyreophoran tracks. They show some similarities to Shenmuichnus, known from the Early Jurassic strata of both Shaanxi and Yunnan provinces, but are somewhat larger, thereby resembling the ichnogenus Stegopodus. Based on their general morphology and size being congruent with this ichnogenus, they are tentatively assigned here to cf. Stegopodus. This is the fourth report of large ornithischian (probably thyreophoran) tracks from the Lower-Middle Jurassic of China that indicates relatively large trackmakers that were likely to be taxonomically distinct from much smaller and gracile Anomoepus trackmakers, also of ornithischian affinity. The larger tracks indicate a hitherto unreported abundance, size range and diversity of track types attributed to this group. The parallel orientation of the two best preserved trackways may indicate gregariousness.  相似文献   

2.
Christian Meyer  Basil Thuring 《Ichnos》2013,20(2-4):221-228
Until now dinosaur tracks from Switzerland were only known from Triassic and Late Jurassic strata. We report here for the first time the occurrence of ornithopod tracks from the Schrattenkalk Formation (Late Aptian) from the Swiss Central Alps. The locality is situated in an abandoned quarry on the shore of Lake Lucerne close to the village of Beckenried. The steeply inclined surface has more than 50 tracks (in three trackways) of ornithopod dinosaurs that are attributed to iguanodontids. Three trackways can be followed for distances of 25 to 35 m. The lengths the footprints (mean: 30 cm) point to animals ranging in size of from 4 to 6 m, with estimated hip heights between 1.8 and 2 m (hip height 6 FL) and 1.4 to 1.7 m (hip height 5 FL). One of the trackways shows two succesive manus impressions, indicating facultative quadrupedal gait. The track bearing layer consists of shallow water micrites with traces of emersion, and it is overlain by bioclastic grainstones. Previously the Upper Schrattenkalk Member in the Helvetic realm was thought to have formed on a large shelf far away from any continents. The present discovery will shed new light on the paleogeographic position of the Helvetic nappes.  相似文献   

3.
Gerard D. Gierliński 《Ichnos》2015,22(3-4):220-226
The Late Cretaceous track assemblage of southeastern Poland includes intriguing ichnotaxa with Asian or North American affinities. New finds of the ceratopsian-like ichnite and small hadrosauroid track refer directly to this problem, whereas the re-evaluation of foraminifer taxa estimates the stratigraphic positions of the track-bearing horizon and allowed to understand paleogeographic context of the studied and adjacent areas. The results demonstrate that during the Late Cretaceous times, migration of dinosaurs was possible from Asia through the East European Land to Kukeritz Island and the islands at peri-Tethys area.  相似文献   

4.
New tracksites reported from the Zizhou area elucidate the nature of the Early-Middle Jurassic dinosaurian ichnofaunas in Shaanxi Province. The assemblage is composed of footprints and trackways of medium- to large-sized theropods that show similarities with both the ichnogenera Kayentapus and Eubrontes and of small bipedal ornithischians that are referred to AS Anomoepus isp. Additionally tracks of a quadruped are present and assigned to Deltapodus isp. that may be related to a stegosaurian. Anomoepus isp. is similar to the holotype of Shensipus tungchuanensis which is, although apparently lost, re-assigned here and considered to be a subjective junior synonym of Anomoepus. It is therefore placed in new combination as Anomoepus tungchuanensis comb. nov. Identical tracks have been reported from well-preserved trackways both in the Zizhou and Shenmu areas, where they also co-occur with theropod tracks (Kayentapus and Grallator) and tracks of quadrupedal ornithischians (Shenmuichnus and Deltapodus). Thus, it appears that the carbonaceous (coal-bearing) facies of the region reveal ichnofaunas with both relatively abundant saurischian (theropod) and ornithischian tracks. This is in contrast with many areas where the ichnofaunas are heavily or exclusively saurischian (theropod) dominated.  相似文献   

5.
A marine tidal delta siltstone from Gelmon locality in Northeast India preserved three crocodylian footprints and an elongate depression that appears to be a tail drag mark. Similar drag marks occur in nearby bedding surfaces. The discovery of crocodylian tracks from the basal part of Laisong Formation, Barail Group (Late Eocene–Early Oligocene age) of Manipur, India is noteworthy because of the age and the geographic location. Crocodylian tracks are rare in Cenozoic formations and they have not previously been reported from Asia. The footprints are herein named as a new ichnogenus and ichnospecies, Indosuchipes manipurensis.  相似文献   

6.
7.
We use microeconomic theory to frame hypotheses about the effects of income on the use of non-timber rain forest products. We hypothesize that an increase in income: (a) encourages foraging specialization, resulting in the extraction of fewer goods; (b) increases the share of household income from occupations besides foraging; (c) produces a yearly value from the extraction of nontimber forest goods of about $50 per hectare; and (d) produces depletion of forest goods entering commercial channels and sustainable extraction of goods facing cheaper industrial substitutes. To examine these hypotheses we present worldwide ethnographic information and preliminary findings from field work carried out among the Sumu Indians of Nicaragua. Field work suggests that higher income produces: (a) foraging specialization with animals rather than with plants; (b) a decline in the economic importance of forest goods in household income; (c) and a rise in the value of non-timber goods removed from the forest to about $35/ha/year. We did not have time to test hypothesis d.  相似文献   

8.
Literature concerning dinosaur footprints or trackways exhibiting abnormal gait or morphology reflecting pathology (ichnopathology) is rare. We report on a number of Jurassic and Cretaceous occurrences of theropod footprints from western North America with unusual morphologies interpreted herein as examples of inferred pathologies, or ichnopathologies. The majority of ichnopathologies are primarily manifested in the digit impressions and include examples of swelling, extreme curvature, dislocation or fracture, and amputation. A number of occurrences are single tracks on ex situ blocks with substantial deformation (inferred dislocation or fracture), or absence of a single digit impression. Two occurrences are from in situ natural mould trackways, one of which is a lengthy trackway of a presumed allosauroid with no noticeable deformation of the digits or feet but with strong inward rotation of the left footprint toward the midline and a pronounced, waddling limp. The other is a tyrannosaurid trackway consisting of three footprints (one right, two left) with the two left prints exhibiting repetitive ichnopathology of a partially missing Digit II impression.  相似文献   

9.
Human and animal footprints found in the Valsequillo Basin were formed on the upper bedding planes surfaces of a volcanic ash (Xalnene Ash) deposited by a subaqueous volcano along the shores of a Pleistocene lake. The footprints were made on lake shorelines and the exposed lake floor during low stands associated, either with water displacement during the volcanic eruption, or due to climatically-driven fluctuations in the water balance. The Xalnene Ash has been dated to at least 40 K BP and consequently the human footprints provide evidence for much earlier colonization of the Americas than is often accepted. The methodology used to record, analyze and conserve these footprints used three-dimensional laser scanning, with sub-millimeter precision. This data were used to reproduce polymer models of individual footprints using the application of rapid-prototyping technology. This technology has wide significance for the study of ichnofacies in general. The characteristics of the human footprints and some problems associated with the volcanic ash as a molding medium for the clarity of these characteristics are given. These human footprints and their dating resolve the controversy related to the age of the archaeological and associated megafaunal remains that were reported in the Valsequillo Gravels in the 1960s and 1970s.  相似文献   

10.
The upper part of the Chinle Group (Late Triassic) of the Gateway area in western Colorado is extraordinarily rich in fossil footprint assemblages. Dominant track types include small Grallator tracks, generally attributed to Coelophysis-like theropods, which often occur in high densities of 50 to 100 per m2. Other abundant ichnotaxa that are attributable to dinosaurs or dinosaur-like archosaurs include Pseudotetrasauropus and Tetrasauropus, attributed to prosauropods and sauropods, respectively. Several Pseudotetrasauropus-like tracks appear to be functionally didactyl and may indicate a new ichnotaxon that represents an animal that shows certain unusual features that are convergent with dromeosaurs and certain birds. Such convergence may reflect inherent growth programs as much as functional adaptations. Non-dinosaurian ichnotaxa include Brachychirotherium (probably of aetosaur affinity) and Rhynchosauroides, attributed to a sphenodontid/lizard-like form. Other ichnotaxa include probable therapsid (dicynodont) tracks labeled Pentasauropus sp., mammaloid (non-therian mammal and/or mammal-like reptile) tracks, and the trails of arthropods. Excellent preservation and high track densities mark the Gateway assemblages in a thin stratigraphic interval in the upper part of the Chinle Group (Rock Point Formation). The track assemblages are similar to those reported from the Chinle Group in other parts of the Colorado Plateau and Rocky Mountain region, extending over most of Colorado, Utah, northern Arizona and northern and eastern New Mexico. Some of the Chinle ichnotaxa (Grallator and Brachychirotherium) are found in the overlying Wingate Formation, indicating that it is also Late Triassic in age, at least in the lower part. However, overall the Chinle and Wingate assemblages are quite different, most notably in the rarity of mammaloid/mammal-like tracks in the Chinle Group.  相似文献   

11.
In a growing number of cases throughout Africa, communities' resource bases are being undermined or appropriated by outsiders, a process which seriously threatens the continuation of local cultures and livelihoods. In this article, we use a political ecology framework to examine how the linked processes of economic development, political power, and environmental change are transgressing the rights of fishing communities on the shores of Lake Malawi. In the cases described, these communities, or community members within them, find themselves powerless to prevent the expropriation of the resources over which they previously had either legal or customary control. Thus, it is not the economic processes of dispossession alone which lead to human rights violations but rather dispossession combined with an authoritarian political context.  相似文献   

12.
Jürgen Fichter  Reiner Kunz 《Ichnos》2013,20(3-4):183-193
Archosaur tracks are described that have been found in 1999 in a single track bed in the Dethfurth-Formation of the Middle Bunter (Lower Triassic) near Wolfhagen (Central Germany). The taxonomic evaluation of these tracks requires the erection of the new genus and species Protochirotherium wolfhagense ichnogen. n. ichosp. n. Apart from this a rearrangement of groups of chirotheroid tracks is proposed due to the digital proportions.  相似文献   

13.
The Sidi Kassem Basin is the only limnic basin of Westphalian age in Morocco. It is built up of 1,250 m of alluvio-fluvial to lacustrine deposits that have so far yielded plant fossils and invertebrate remains only. Recent exploration for fossil tetrapod footprints in floodplain-deposits of the basin revealed a moderately diverse vertebrate ichnofauna composed of tracks assigned to cf. Batrachichnus Woodworth, 1900; cf. Hylopus Dawson, 1882; Dimetropus Romer and Price, 1940; and Notalacerta Butts, 1891. The tracks can be referred to temnospondyl, anamniote reptiliomorph, non-therapsid synapsid (pelycosaur), and captorhinomorph trackmakers. The described ichnoassemblage is important in at least three aspects: (1) It suggests an Early to mid-Pennsylvanian age for the footprint-bearing strata of the study area. (2) It is the oldest association of tetrapod footprints from Africa. (3) It is the first evidence of the relatively rare ichnogenera cf. Hylopus and Notalacerta outside of North America and Europe. Judged from the variety of tetrapod tracks and previously collected floral remains, the Sidi Kassem Basin must have represented a well-established continental ecosystem during Pennsylvanian time. Further exploration for trace and body fossils of Palaeozoic vertebrates in this basin may be important for the reconstruction of early tetrapod evolution.  相似文献   

14.
The Reverend Henry Duncan (1774–1846), clergyman, philosopher, writer, politician, archeologist, poet, educator, social reformer, and the founder of savings banks, was indeed a Man for All Seasons. In 1824, while Minister of the Church of Scotland at Ruthwell, Dumfriesshire, he was presented with a slab of red sandstone from the Corncockle Muir quarry in Annandale, exhibiting a set of footprints on it. Although Duncan felt from the start that he was dealing with the tracks of an animal, he wrote to the Reverend William Buckland, Reader in Mineralogy and Geology at the University of Oxford, to solicit his opinion on the origin of these curious markings. Buckland was at first skeptical, but after receiving casts of the markings from Duncan, he became convinced that they did in fact represent footprints. Duncan and Buckland maintained a correspondence about the footprints, and on January 7, 1828, Duncan described the Corncockle Muir footprints to the Royal Society of Edinburgh and quoted Buckland's findings. Duncan's paper was not published by the Society until 1831, but it aroused considerable interest—“Footsteps before the Flood”!—and was reported in several newspapers. This was the first scientific report of a fossil track; although a schoolboy, Pliny Moody, had found fossil footprints in Connecticut in 1802, they were not scientifically described until 1836. The Scottish tracks are now considered to be not reptilian but of synapsid origin and the rocks containing them are now known to be of Permian age.  相似文献   

15.
Not only Taenia solium and Taenia saginata, but also Taenia asiatica infects humans. The last species is not included in the evaluation of the specificity of the immunodiagnostic techniques for taeniasis/cysticercosis. There is currently no specific immunodiagnostic method for T. asiatica available. Therefore, due to the fact that molecular techniques (the only tool to distinguish the 3 Taenia species) are normally not employed in routine diagnostic methods, the 2 questions concerning T. asiatica (its definite geographic distribution and its ability to cause human cysticercosis), remain open, turning T. asiatica into the most neglected agent of human taeniasis-cysticercosis.  相似文献   

16.
Abstract: New dinosaur tracksites are described from the Bajocian–Bathonian Bemaraha Formation of western Madagascar. Two track‐bearing surfaces can be followed over a distance of at least 4 km, suggesting the existence of a hitherto unrecognized megatracksite. The track assemblage is theropod dominated, but sauropod tracks also occur at one site. Qualitative and quantitative analysis of the abundant theropod track material suggests that most, if not all, theropod footprints are attributable to a single trackmaker and are referred to Kayentapus isp. Although this ichnogenus, originally described from the Lower Jurassic of North America, has never been recorded from Gondwana nor from the Middle Jurassic, track morphology strongly suggests this attribution. Palaeogeographical, sedimentological and ichnological data suggest that the dinosaur tracks formed in an intertidal to supratidal setting where the coastline influenced the preferred walking direction of the animals.  相似文献   

17.
Anatomically modern hominids were first collected from Kanjera, Kenya, by L.S.B. Leakey in the 1930s. Their apparent association with an archaic fauna was quickly challenged, throwing their age into doubt. Further unpublished hominid fragments were collected in 1974, 1975, 1981, and 1987. We review the context and morphology of the entire hominid sample. A minimum number of five individuals is represented by both cranial and postcranial elements. Several individuals have thickened cranial vaults, a characteristic originally thought to reflect their great antiquity. Vault thickening resulted from diploic expansion and may have been a response to acquired or inherited anemia. The entire hominid sample postdates the Kanjera Formation, deposited from the early into the middle Pleistocene. Most of the sample was derived from the black cotton soil capping the stratigraphic column. The morphology and context of the Kanjera hominids is consistent with human skeletal remains from nearby Holocene sites. Hominid 3 was probably an intrusive burial into an early Pleistocene bed. © 1995 Wiley-Liss, Inc.  相似文献   

18.
This study concerns the formation, taphonomy, and preservation of human footprints in microbial mats of present-day tidal-flat environments. Due to differences in water content and nature of the microbial mats and the underlying sediment, a wide range of footprint morphologies was produced by the same trackmaker. Most true tracks are subjected to modification due to taphonomic processes, leading to modified true tracks. In addition to formation of biolaminites, microbial mats play a major role in the preservation of footprints on tidal flats. A footprint may be consolidated by desiccation or lithification of the mat, or by ongoing growth of the mat. The latter process may lead to the formation of overtracks. Among consolidated or (partially) lithified footprints found on present-day tidal flats, poorly defined true tracks, modified true tracks, and overtracks were most frequently encountered while unmodified and well-defined true tracks are rather rare. We suggest that modified true tracks and overtracks make up an important percentage of fossil footprints and that they may be as common as undertracks. However, making unambiguous distinctions between poorly defined true tracks, modified true tracks, undertracks, and overtracks in the fossil record will remain a difficult task, which necessitates systematic excavation of footprints combined with careful analysis of the encasing sediment.  相似文献   

19.
Mercury is a highly toxic heavy metal that can cause adverse ecological and toxicological impacts through the mechanism of biomagnification. Hg accumulation in aquatic biota may thus also pose a serious threat to humans and other fish-eating animals. The present work observed the transfer of Hg from abiotic (water and sediments) to biotic (algae, aquatic macrophytes, and fish) components, belonging to different trophic levels in a tropical lake in India. Hg was analyzed in water, sediments, plants, and fish collected from different sampling points, receiving the discharge of chloralkali effluent. Hg concentrations increased significantly from lake water and sediments to algae and aquatic macrophytes. Statistical analysis (Pearson correlation) revealed a significant positive correlation between Hg in water and plants (r = 0.88–0.93; p < .01 and p < .05) as well as for Hg in sediment and plants (r = 0.50–0.83; p < .01 and p < .05). However, the increase in Hg concentration in fish was not significantly correlated with lake ambient water (r = 0.31–0.36), sediments (r = 0.29–0.33), and aquatic plants (r = 0.31–0.36). Results obtained encourage the use of naturally occurring wetland plants in designed systems like constructed wetlands to ameliorate Hg pollution in lakes, rivers, and ponds resulting from the discharge of industrial effluents, especially chloralkali effluent, hence reducing the human health risks associated with Hg.  相似文献   

20.
A large tridactyl track from the Franklin Series of the Eocene Puget Group has been named Ornithoformipes controversus ichnogen et ichnosp. nov. and is attributed to a large ground-dwelling Diatryma or a Diatryma-like bird. The isolated footprint clearly shows that the trackmaker had broad semi-circular unguals and feet that show several correspondences with the foot morphology inferred for Diatryma and related forms. The age of the footprint is estimated at about 45 million years, which is about 5 million years younger than known Diatryma body fossils. The sedimentary geology context of the track is consistent with an interpretation of the trackmaker as a large herbivore that lived in well-vegetated areas.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号