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1.
WALKING AND JUMPING WITH PALAEOZOIC APTERYGOTE INSECTS   总被引:1,自引:0,他引:1  
Abstract: Abundant arthropod walking and jumping traces, from the Lower Permian Robledo Mountains Formation of southern New Mexico, provide direct evidence of the locomotory techniques of monurans, an extinct group of archaeognathan apterygote insects. The jumping behaviour of monurans is compared with that of the extant machilid archaeognathan Petrobius. The jumping traces are referred to Tonganoxichnus robledoensis, and demonstrate that monurans were capable of forward progression via a linear succession of jumps of several times their body length. Petrobius also employs an unusual, fast, in‐phase, jumping gait for normal directed locomotion; however, unlike the T. robledoensis traces, these jumps are only about one body length. In‐phase trackways, referred to Stiaria intermedia from the Upper Carboniferous Tonganoxie Sandstone of Kansas, are found in association with Tonganoxichnus traces, indicating that monurans were also capable of such a fast jumping gait. Petrobius employs an escape jump that is more similar in terms of magnitude to those represented by T. robledoensis; however, the escape jump is essentially random in terms of direction and rotation of the body. Out‐of‐phase trackways from the Robledo Mountains Formation, also referred to Stiaria intermedia, are found preceding or following on from several Tonganoxichnus traces, and demonstrate that monurans also used normal, out‐of‐phase, walking gaits across open ground. Analysis of these trackways demonstrates that they used a variety of gaits ranging from very slow and stable gait ratios of 1·2 : 8·8 (i.e. the propulsive backstroke phase comprises 88 per cent of the step cycle) following jumps, to fast gait ratios of 3·3 : 6·7 and 5·0 : 5·0 preceding jumps. Petrobius tends not to use such normal walking gaits unless on the undersurface of rocks, preferring to use the unusual, fast, in‐phase, jumping gait over open ground. Monurans appear to have been capable of many of the same jumping behaviours as Petrobius, apart from the random escape jump. Archaeognathans are the most primitive group of true insects, and the presence of these similar types of jumping behaviours in monurans and machilids suggests that such behaviours were a primitive method of insect locomotion.  相似文献   

2.
记述了广西横县六景那高岭组、郁江组,武宣二塘二塘组和象州大乐四排组(大乐组)的无颌类和鱼类微体化石。经过形态学和古组织学的研究,这些化石被归于13属(其中包括1新属、2未定属)11种(其中包括3新种4未定种和1比较种)。结合以往在莲花山组和那高岭组下部已报道的脊椎动物大化石资料讨论了广西中部下泥盆统的脊椎动物组合序列:莲花山组以Yunnanolepis-Qujinolepis组合,那高岭组以Asiaspis expansa-Machaeracanthus? bohemicus组合,郁江组以Turinia sp.-Cheiracanthoides comptus-Ohiolepis newberryi组合,二塘组以Nostolepis guangxinensis-Wuxuanichthys wangi-Ligulalepis cf. toombsi组合为代表。另外,据已报道的脊椎动物微体化石和大化石资料,对广西中部和云南东部下泥盆统进行了对比。  相似文献   

3.
陕西横山晚三叠世鱼类游泳遗迹化石新材料   总被引:3,自引:0,他引:3  
在多次赴化石产地陕西横山县进行大规模化石发掘后,获得一批完整精美的遗迹标本,为其中鱼类游泳遗迹化石标本建立了新种Undichna prava,并重新修订U.britannica,U.tricosta两种的特征,通过遗迹形态恢复鱼体长度为50—96cm,普遍大于以往描述的国内外据遗迹标本恢复的鱼体长度。  相似文献   

4.
本文首次报道产自鄂西宜昌大天坑茅口组中的几种软骨鱼类的鱼鳞化石和硬骨鱼类(葆青鱼和古鳕鱼)鱼牙化石,这些鱼类微体化石与牙形刺Mesogondolella aserrata,Hindeodus minutus,Ellisonia teicherli,Xaniog-nathus elongatus等共生,表明其所在地层的时代为中二叠世。  相似文献   

5.
Abstract:  The Albanerpetontidae are salamander-like, Middle Jurassic to Neogene lissamphibians from Laurasia and North Africa. Extensive series of albanerpetontid bones recently identified in collections from the Csarnóta 2 locality, south-central Hungary, extend the temporal range of the clade forward about seven million years from the middle Miocene to the early Pliocene. The Hungarian material is diagnostic for the Euramerican type genus Albanerpeton and pertains to a new species, A. pannonicus sp. nov., which differs from the seven previously reported congeners (Early Cretaceous–Miocene) in a distinctive combination of primitive and derived character states of the jaws and frontals, including a unique ventromedian keel on the azygous frontals. Some of the Hungarian specimens are articulated sets of skull bones, including ones containing the first three-dimensional examples of a nasal and jugals known for albanerpetontids, that help clarify some details of cranial osteology in these amphibians. Cladistic analysis nests A. pannonicus within the robust-snouted clade, as the sister taxon to an unnamed late Palaeocene species from Canada and A. inexpectatum from early–middle Miocene deposits in France, Austria and Germany. This phylogeny and recent reports of diagnostic Albanerpeton material from the Campanian of France and Maastrichtian of Romania suggest the evolutionary history of Albanerpeton was more complex than previously hypothesized, with Europe having played a larger role. The 25 fossiliferous layers at Csarnóta 2 record a shift from forest to grassland palaeoenvironments. Fossils of A. pannonicus are present in all layers, implying that this species was not adversely affected by the change in palaeoenvironments.  相似文献   

6.
万珊  王军 《古生物学报》2020,59(2):223-237
封印木在石炭纪–二叠纪欧美植物群的沼泽森林中占据重要地位,化石记录十分丰富,在华夏植物群中的记录则较为稀少。已知这类植物的孢子叶球都是单性的。本文基于内蒙古乌达煤田下二叠统太原组凝灰岩中的化石材料,报道了一种石松类双性孢子叶球类型,与封印木茎干及叶保存于原位埋藏的火山凝灰岩植物群中,共同构成封印木树冠。该类孢子叶球呈圆柱形,基部具柄;孢子叶紧密螺旋排列,近轴部分为水平伸出的孢子叶柄,远轴部分为上翘的远端叶片,两者转折处具明显的踵;孢子囊单生于孢子叶柄近轴面,大孢子囊位于孢子叶球的中部-基部,小孢子囊位于中部-顶部。该类双性封印木孢子叶球的发现增加了封印木繁殖器官的多样性和复杂性,为进一步探讨这类植物的系统分类与演化提供了重要信息。  相似文献   

7.
记述了四川会理下侏罗统益门组的蜥脚类化石。经研究,将化石归于马门溪龙科,建立新属新种何氏通安龙Tonganosaurus hei gen.et sp.nov.。通安龙具有进步蜥脚类的特点:颈椎细长、荐前椎发育侧凹、前肢较长,为后肢的0.80等;同时,通安龙也具有原始蜥脚类的特点:脊椎骨组织坚实不中空、肱骨和股骨骨干粗而圆。从国内外已有的资料看,原始蜥脚类主要发现于侏罗纪早期,而进步蜥脚类则主要发现于侏罗纪中晚期。由于通安龙兼具原始蜥脚类和进步蜥脚类的特点,且时代为早侏罗世,因此,通安龙化石材料的发现对中国西南地区早期蜥脚类的系统演化研究具有重要的意义。  相似文献   

8.
Evolsonia is a new gigantopterid genus (type-species: E. texana), based on leaf impressions from 3 widely separated localities in north-central Texas. The leaves are associated with terrestrial vertebrates in floodplain sediments of the Vale Formation in the Clear Fork Group, of late Leonardian (Early Permian) age. Evolsonia leaves are simple, with very large elliptic laminae reaching 27 cm in width and 80 cm, possibly more, in length. Leaf margins are sinuate to crenate, with mostly shallow concavities. Venation is pinnate, in 4 orders; all but the ultimate veins are very thick and protrude below the lamina, creating deep impressions in the matrix. The secondary and tertiary veins form a precise herringbone pattern, with the secondaries and exmedial tertiaries ending at the leaf margin between concavities. The other tertiary veins are either simple or divided into 2 nearly equal divisions; they produce simple or variously divided quaternary veins that end at a thin sutural vein, forming a dense reticulum; some of the terminally branched tertiaries delimit areolelike areas that enclose several quaternaries and meshes. One of 6 presently known American gigantopterids, Evolsonia most closely resembles the younger Delnortea in gross architecture; with its sutures and dichotomously divided veins, however, Evolsonia is architecturally intermediate between Delnortea and the older American gigantopterids with forked leaves. Sedimentary features indicate deposition under alternating periods of flooding and drought. Their huge size invites comparison of Evolsonia leaves with those of modern tropical plants, whereas their thick veins and preservational features suggest thick, coriaceous texture.  相似文献   

9.
辽西下白垩统九佛堂组尾羽龙类—新属(英文)   总被引:2,自引:0,他引:2  
记述了一件采自辽西热河群九佛堂组一新的窃蛋龙类:义县似尾羽龙(Similicaudipteryx yixianensis gen.et sp.nov.),并依据其和尾羽龙属的相似特征,及其匕首状的尾综骨,肠骨、踱骨和脚趾的形态等将其归入窃蛋龙类的尾羽龙科,但其所具有的一些特征也不同于该科已建立的尾羽龙属,如尾综骨的形态和较大的个体等。该化石具有许多典型的窃蛋龙类的特征,如短尾、较短的前肢等,有别于其他窃蛋龙类的特征还包括耻骨和肠骨的长度比为1.46,背椎上发育2个大而深的椎体下突、背椎侧部具孔等。义县似尾羽龙是又一类具有真正尾综骨的恐龙,表明尾综骨这一曾经被认为是鸟类特有的结构可能是在恐龙中独自演化的。它具有一些进步的特征如具尾综骨等,但同时也具有一些原始的特征如5个愈合的荐椎,耻骨联合长,表明在窃蛋龙类中存在着特征的镶嵌进化现象。似尾羽龙与驰龙类、其他窃蛋龙类等恐龙一样,脚趾并没有对握,已有的证据说明完全的对握目前还只是出现于鸟类中。根据其短尾、中部收缩的趾骨和灵巧的身体等都表明它是一类适于快速奔跑的动物。目前为止,已知的尾羽龙类化石均发现于北票四合屯地区的义县组下部尖山沟层(段),距今约125Ma。新标本发现于义县西二虎桥地点,属于九佛堂组,距今约120Ma,这也是迄今为止在九佛堂组发现的惟一一件尾羽龙类化石,对研究早白垩世窃蛋龙类的演化和热河生物群恐龙组合的特征具有重要的意义。  相似文献   

10.
本文详细记述了陕西府谷下三叠统和尚沟组中发现的一前棱蜥类骨架。依据头骨及头后骨骼特征订立一新属种:河套五角蜥(Pentaedrusaurus ordosianus gen.et.sp.nov.)。讨论中,对原归入前棱蜥科的袁氏三台龙(Santaisaurus yuani)的系统分类位置提出了修正意见,同时建议取消黄河保德蜥(Paoteodon huanghoensis)这一名称。  相似文献   

11.
Abstract:  Based on a well-preserved specimen from the Early Triassic Lower Qinglong Formation exposed at Qingshan Quarry, Jurong, Jiangsu Province of China, the new taxon Peia jurongensis gen. et sp. nov. is named and described with anatomical details of its dermal skull, neurocranium and postcranial skeleton. The new taxon is characterized by the following set of characters: shallow V-shaped, tuber-like rostral; anterior part of frontal widened to roughly same width as its posterior part; roughly squared parietal; supraorbital absent; wide and slightly posteriorly inclined preopercle; five small ossifications present in dorsal half of preopercle; preopercular canal shifting anteriorly in ventral half of the preopercle, and reaching the anteroventral corner of this bone; dermosphenotic joining the skull roof and with a descending lamina; numerous branchiostegal rays. Comparisons are made between the new taxon and several parasemionotids from the same locality; a discussion is carried out on the distribution and evolution of several characters in halecomorphs and other closely related neopterygians.  相似文献   

12.
Abstract:  A new fauna of Lower Cretaceous (Albian) ichthyosaurs, which includes at least one new genus and species, was recovered from deposits of the Loon River Formation at Hay River, Northwest Territories, Canada. All Cretaceous ichthyosaurs have been referred to a single genus, Platypterygius . The Loon River Formation material, however, does not satisfy the diagnosis for Platypterygius , and it is distinctive enough to warrant the erection of a new genus and species of ichthyosaur. Maiaspondylus lindoei gen. et sp. nov. is distinguished from other ichthyosaurs by an extensive overlapping contact of the jugal and the maxilla; marginal teeth with smooth crowns, fluted cementum, lingual curvature and implantation in a dental groove; and humerus with isomorphic proximal and distal ends, featuring three distal articular facets in which the medial articular facet is smaller than the lateral facets. The holotype and referred material is described here, and the relationship of Maiaspondylus to other ophthalmosaurs is discussed.  相似文献   

13.
本文详细记述了陕西府谷下三叠统上部二马营组底部的一古鳄类化石.据其骨骼形态特征拟订为古鳄亚目(Proterosuchia)、引鳄科(Erythrosuchidae)的一新属种:石拐古城鳄(Guchengosuchus shiguaiensis gen. et sp. nov.),同引鳄科内已知属的对比,表明新属古城鳄与武氏鳄 Vjushkovia 的关系最为接近.  相似文献   

14.
伊武军 《古生物学报》2004,43(4):556-570
报道福建大田崆峒山晚二叠世大隆组、长兴组及早三叠世溪口组介形类35属67种,其中描述8属9种(包括5新种)。产自长兴组的介形类化石被划分为3个组合,自下而上分别是:Polylites magnituberos-Or-thobairdia meishanensis-Pustulobairdia mailinensis组合,Baitrdia urodelofot-OS-orthobairdia exilimarginata-Bairdia subcontracta组合和Petasobairdia bicornuta-Neoamphissites costatus-Kegelites datianensis组合。大田崆峒山介形类动物群在二叠-三叠系界线上下具有明显的突变性质,这与世界其它地区一样,是遭受二叠纪末期的生物大灭绝事件重创所致。根据介形类化石组合特征,并参考共生或共存化石的内容,福建大田地区长兴组大致相当于浙江煤山长兴组的中、上部,长兴灰岩下伏的海相碎屑岩应划归长兴阶。大隆组、长兴组及溪口组的岩性和化石组合特征.显示古环境从滨海沼泽开始,经历浅海盆地→浅水碳酸盐台地→浅海近岸环境的演化过程。  相似文献   

15.
通过对产自新疆柯坪地区的阿克苏柯坪珊瑚(Kepingophyllum aksuense)的大量薄片观察,发现该类珊瑚在珊瑚体单骸形态、横板带宽度与泡沫板带宽度之比、隔壁长度、横板的形态、隔壁数目、隔壁数目与珊瑚骸直径之比等六个方面存在很大变异。此外,该类珊瑚中存在明显的周期性生长变异现象,表现在泡沫板的排列疏密相间。与模式标本的对比研究发现,此类珊瑚的群体间变异相对较小。  相似文献   

16.
本文描述了陕西镇巴下寒武统水井沱组中的小壳化石3新属5新种。样品采自镇巴小洋坝曾家坡,共生化石有三叶虫、古介形虫、海绵骨针和大量软舌螺等。化石组合面貌表明其地质时代属筇竹寺期。另外,在峡东水井沱组中发现了微网虫(Microdictyonsp.)化石骨片(图版I,图18,19),可与云南筇竹寺组及陕南水井沱组对比,说明Microdictyon广泛分布于扬子地台区。  相似文献   

17.
Studies of character evolution have frequently relied on ahistorical correlations rather than on phylogenies. However, correlations do not estimate the number of times that a trait evolved, and they are insensitive to the direction or the temporal sequence of character transformation. In contrast, cladograms can provide this information. A cladistic test of the hypothesis that the evolution of dioecy is favored in animal-dispersed plants indicates that dioecy may have originated somewhat more often in such lineages. Nevertheless, differences in rates of speciation or extinction must largely account for the observed species-level correlation between dispersal and breeding system. In considering the evolution of individual traits, cladograms help identify the context in which a feature evolved and specify which organisms should be compared in evaluating the causes of character change. Determining whether a feature and a performance advantage were strictly historically correlated or followed one another in sequence helps to distinguish whether the trait is an adaptation or an exaptation for the function. For example, cladograms of seed plants suggest that double fertilization arose incidentally prior to the origin of angiosperms and that the resulting product was later co-opted and elaborated as a nutritive tissue for the developing embryo. The order of character assembly in a lineage also bears on the evolution of functional and developmental interdependencies. In particular, it may be possible to trace the evolution of a character's “burden” from an initial period, during which change is more likely, through later stages, wherein successful modification is less likely owing to the evolution of dependent characters. The evolution of vessels and of floral phyllotaxis in angiosperms may exemplify this pattern. Recognition that the likelihood of character transformation may change during the evolution of a group warns against character weighting in phylogenetic analysis.  相似文献   

18.
依据采自广西平果早泥盆世郁江组中部的化石材料,记述了盾皮鱼纲节甲鱼目南极鱼科的一新属、新种——小眼坡塘鱼(Potangaspis parvoculatusgen.et sp.nov.)。该新属的眶孔很小,且为颅顶甲骨片所完全包围;中点线沟发育,与眶上感觉沟、中心感觉沟和后点线沟一起共同向颈片的骨化中心辏合。系统发育分析表明新属和发现于南极洲中泥盆统的南极鱼属构成姐妹群关系,支持了南极鱼科位于节甲鱼目最基干位置的假说,同时为早埃姆斯期东冈瓦纳大陆与中国南方之间的古地理密切联系提供了新的证据。  相似文献   

19.
Delnortea is a monotypic genus (type-species: D. abbottiae) of Lower Permian gymnosperms based on leaves from uppermost Leonardian deltaic sediments exposed in the Del Norte Mountains, West Texas. The leaves are simple, symmetrical, mostly oblong or elliptical, and vary in length from 1.2 to about 35 cm. The petioles are short and stout, with a basally enlarged abscission zone. The margins are crenate, with a narrow, indurated border. Venation is in 4 orders: the secondaries and tertiaries are robust, unbranched, and pinnately arranged in a precise “herringbone” pattern, with the secondaries ending in the marginal sinuses; the quaternaries divide sparingly and fuse with others to form a dense reticulum of small meshes. Permineralized petiole and midrib material reflects a bifacial cambium, shown by a semicircular vascular arc, irregularly divided into several collateral bundles with secondary xylem and phloem. Delnortea is referable to the Gigantopteridaceae, a probably artificial family of gymnosperms incertae sedis with important venation features in common, but without known diagnostic reproductive organs. With Delnortea, the North American gigantopterids now include 5 genera, but Gigantopteris itself is lacking. Delnortea holds a relatively advanced evolutionary position among the American gigantopterids; its leaf morphology and gymnospermous anatomy entail intriguing points of comparison with Gnetum. The limited geographic and stratigraphic ranges and morphological distinctiveness of the American gigantopterids and associated taxa attest to rapid evolution and dispersal from a small area of origin in the southwestern United States during Leonardian time.  相似文献   

20.
Abstract:  Remarkable new fossil taxa of Neuroptera from the laminated limestone of the Crato Formation, north-east Brazil, are described: Nuddsia longiantennata gen. et sp. nov. (Osmylidae, Gumillinae), the first fossil record of this family from South America, Parapalaeoleon magnus gen. et sp. nov. (Palaeoleontidae), and Triangulochrysopa formosa sp. nov. (Mesochrysopidae). A diagnosis of Gumillinae is provided; Epiosmylidae is considered to be a synonym of this subfamily. A revised diagnosis of Palaeoleontidae is provided, based on a new interpretation of venational characters evident on the exceptionally well-preserved specimen of P. magnus ; vein homologies are determined and the fusion of MP and CuA is discussed. The genus Triangulochrysopa has been known previously only from the Lower Cretaceous of Las Hoyas, Spain.  相似文献   

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