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1.
Daugherty , Lyman H. (San Jose State College, San Jose, Calif.) Itopsidema, a new genus of the Osmundaceae from the Triassic of Arizona. Amer. Jour. Bot 47(9): 771–777. Illus. 1960.—Itopsidema vancleavei, a new genus and species of the family Osmundaceae, is described. The specimen consists of several segments of an arborescent stem obtained from the Upper Triassic of the Petrified Forest National Monument near Holbrook, Arizona. The surfaces on 2 of the segments are covered by adventitious roots and the remaining segments are covered by leaf bases. The fronds are spirally arranged and have an 8/21 phyllotaxy. The cortex of the stem, which contains numerous leaf traces and adventitious roots, consists of parenchyma with cell walls of medium thickness. The leaf traces are oblong to crescent-shaped in the inner cortex and horseshoe-shaped in the outer cortex. The base of the petiole contains a single, large vascular bundle and is covered by multicelled, glandular spines. The adventitious roots originate on the abaxial side of the leaf traces in the region of the inner cortex. The center of the stem is occupied by an ectophloic, mesarch siphonostele without leaf gaps. The pith is composed of firm-walled parenchyma cells which have isolated tracheids with reticulate pitting scattered among them. These tracheids are so rare the pith cannot be considered a “mixed pith.” The relationship and morphological significance of Itopsidema with respect to other members of the Osmundaceae are briefly discussed.  相似文献   

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Abstract: We document here a new taxon of sphenodontian, Whitakersaurus bermani gen. et sp. nov., that is also the most complete sphenodontian fossil from the Upper Triassic Chinle Group in the south‐western USA and the first Chinle sphenodontian represented by more than a single fragmentary dentulous element. The holotype was recovered during preparation of block C‐8‐82 from the famous Coelophysis (Whitaker) quarry at Ghost Ranch, New Mexico, and is the most complete small vertebrate recovered from the quarry. Detailed lithostratigraphy and geologic mapping demonstrate that the Whitaker quarry is in the Rock Point Formation of the Chinle Group, so Whitakersaurus is the first sphenodontian reported from this unit. Records of the phytosaur Redondasaurus at the quarry and elsewhere in the Chinle Group demonstrate that the quarry, and thus Whitakersaurus, is of Apachean (late Norian–Rhaetian) age. The sphenodontian specimen consists of incomplete left and right dentaries, a partial left? maxilla?, and impressions of a probable palatal element, all of which preserve multiple teeth. Whitakersaurus is distinct from other sphenodontians in possessing a unique combination of the following features: marginal dentition pleurodont anteriorly and posteriorly acrodont; pronounced heterodonty in dentary, with as many as 15 smaller, peg‐like teeth anteriorly and several larger, posterior teeth that are conical and striated; faint radial ornamentation of posterior tooth crowns; presence of c. 19 dentary teeth; and absence of a distinct flange on posterior teeth. Numerous other details distinguish it from both more primitive and more derived taxa. Whitakersaurus, therefore, helps to document further mosaic evolution and an extensive diversification event of sphenodontians during Triassic time. Although sphenodontian taxa are relatively easily recognized, widely distributed, and common small‐ or microvertebrate fossils, the long stratigraphic ranges of taxa known from multiple specimens hinders their utility as index fossils with which to correlate strata across Pangaea.  相似文献   

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记陕北子长晚三叠世一新的古鳕类   总被引:5,自引:0,他引:5  
记述了陕北子长晚三叠世古鳕科(Palaeoniscidae)一新属新种──子长瓦窑堡鳕(Wayaobulepis zichangensis gen. et sp. nov.)。其一般形态特征如身体长纺锤形、背鳍基长,后部对着腹鳍和臀鳍之间的空隙、鳍条粗壮、饰缘棘鳞细小、悬挂骨倾斜、鳃盖骨很高大、鳞片小及横列鳞数目多等,与澳大利亚中至晚三叠世的Myriolopis很相似,但新属具有吻较尖、背鳍鳍条数目较少、鳞片具有众多的斜嵴、后缘成梳齿状以及具有背嵴鳞等显著特征区别于Myriolopis。瓦窑堡鳕在体形、鳍的位置、鳃盖骨高大及鳞片的纹饰等方面也与欧洲中至晚三叠世的 Gyrolepis相似,但新属以背鳍基较长、臀鳍基较短、背峪鳞发达及鳍条粗壮等特征区别于Gyrolepis。根据瓦窑堡鳕的性质和化石层位的情况,将合鱼化石地层的时代定为晚三叠世。  相似文献   

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Abstract:  A lower jaw with multicusped teeth and a number of unique characteristics was discovered in an extensive exposure of the Upper Triassic Kössen Formation in the Northern Calcareous Alps. The ramus of the jaw is high and dominated by a row of large, oval foramina that lies parallel to the tooth row. In addition, the anterior portion of the dentary exhibits a large number of nutritive foramina and small pits, which might indicate an association with a soft tissue structure and/or the presence of a keratinous cover of that area during life. All elements of the jaw are thin-walled and hollow, possibly pneumatic. Two teeth are preserved within the dentary. One is tricuspid and the other bears four cuSPS. The teeth are noticeably small in comparison with the overall size of the ramus, being only one-third of the height of the ramus. The teeth show a strong similarity to those of the well-known basal pterosaur genus Eudimorphodon , whose jaw morphology, however, clearly differs from the specimen described in this study. The dentition and the pneumatic bone structure make an assignment to the Pterosauria plausible. Based on the great number of distinct morphological characters the specimen is described as Caviramus schesaplanensis gen. et sp. nov.  相似文献   

8.
The highly fossiliferous Virgilian (Upper Pennsylvanian) shales of the Kinney Brick Company quarry near Albuquerque, New Mexico, contain a diversified flora dominated by walchian conifers and neuropterid pteridosperms. Its other components include a specimen of Telangiopsis sp. and abundant material of Sphenopteridium manzanitanum, n. sp., a highly variable foliar form. Both genera are characteristically restricted to the Upper Mississippian, with the exception of one basal Pennsylvanian occurrence. Their occurrence together in the Kinney sediments and their possession in common of distinctive surficial ornamentation suggest that they represent dissociated parts of Diplopteridium, a very rare European Lower Carboniferous taxon. Other associated plants show later Paleozoic or even Early Mesozoic characteristics, which, together with the Mississippian elements, distinguish the Kinney site as paleobotanically unique.  相似文献   

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Abstract:  In the 1970s the Upper Triassic strata of the Argana Basin yielded archosaurian remains that were tentatively attributed to the rauisuchian Ticinosuchus . Restudy of this material together with new remains reveal new anatomical data and show that it in fact belongs to a new taxon, Arganasuchus dutuiti gen. et sp. nov. The systematics of the Rauisuchia are still unresolved; nevertheless, a monophyletic suprageneric group can be defined within the probable non-monophyletic rauisuchians. Arganasuchus dutuiti differs from all adequately known rauisuchians in three autapomorphies: acetabular rim on pubis runs anteroventrally parallel to pubic shift rather than being terminal and perpendicular to it; large contribution of pubis to acetabular depression; palatal process of maxillary low and confluent with interdental crest, rather than separated from it by a large area. The maxilla of Arganasuchus resembles those of Batrachotomus and Fasolasuchus in having a Y-shaped rather than a U-shaped form. As in rauisuchids, Arganasuchus dutuiti has short cervical vertebrae and a dorsal border of the proximal extremity of the pubis that is convex in lateral view. It shares one derived character state with Batrachotomus and Postosuchus (a tear-shaped and anteriorly orientated rugosity on the lateral side of the pubis, lying on a deep, longitudinal depression) and one more derived character state with Batrachotomus (narrow ante-acetabular part of the pubis; hence, the anterior border of the proximal extremity of the pubis is almost contiguous with the actabular rim).  相似文献   

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贵州关岭晚三叠世一大型鱼龙类头骨   总被引:20,自引:2,他引:20  
记述了产自贵州关岭上三叠统杯椎鱼龙属一新种——亚洲杯椎鱼龙(Cymbospondylusasiaticus sp. nov)。标本为两件几乎完整的头骨,产于法朗组瓦窑段的泥质灰岩中,这是目前已知惟一的晚三叠世(Cymbospondylus属的标本,也是该属时代最晚的一个种。亚洲杯椎鱼龙头部最明显的特征是下颌牙齿仅分布于齿骨的前半部分。此外,新种的吻部极长,超过头骨全长之半,上颌骨非常发达,并且具有已知鱼龙类中最小的眼眶。亚洲杯椎鱼龙是这一大型鱼龙类在北美和欧洲以外地区的首次记录。  相似文献   

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根据头骨和下颌建立了海龙一新属新种——短吻贫齿龙(Miodentosaurus brevis gen.et sp.nov.)。其正型标本是采自贵州三叠纪法郎组的一具骨架(台中自然科学博物馆标本编号NMNS-004727/F003960)。虽然头后骨胳还没有修理,但是几近完好的头骨和下颌显示出许多与众不同的特征,足以确定该标本代表了一新的海龙属种。短吻贫齿龙是个体较大的海龙,其全长超过4 m,头骨背部最长约为33 cm。吻直且极短是其最显著的特征之一。其他主要特征有:前颌骨沿前背中央有一隆嵴;上颌仅前颌骨有6枚圆锥形齿,无上颌骨齿;上颌骨沿前腹侧缘有一沟槽;下颌齿骨齿都集中在前端且至多不超过6枚。依据上述这些特征很易把短吻贫齿龙与其他已知海龙相区别。短吻贫齿龙头骨顶面松果孔大且很前位,头骨腭面的锄骨和翼骨均无齿,它的颈较长(至少可以辨认出13个颈椎)。这些特征显示短吻贫齿龙可能与包括中国安顺龙属(Anshunsaurus)在内的Askeptosauroidea超科有相近的系统关系。  相似文献   

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广西一种新的苏铁   总被引:3,自引:0,他引:3  
韦发南   《广西植物》1994,14(4):300-300
广西一种新的苏铁韦发南(广西植物研究所,桂林541006)关键词苏铁新种;广西ANEWCYCADFROMGUANGXI¥WeiFanan(GuangxiInstituteofBotany,Guilin541006)Keywords:Newspecie...  相似文献   

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长江源区晚三叠世伟齿蛤科(双壳类)一新属--Quemocuomegalodon   总被引:9,自引:0,他引:9  
记述青海唐古拉山北坡雀莫错附近晚三叠世甲丕拉组灰岩中的一类铰齿构造特殊的伟齿蛤类化石,建立新属Quemocuomegalodon gen.nov.及Q.orientus gen.et sp.nov.和Q.longitatus gen.et sp.nov.2新种,并简述伟齿蛤类的生活习性。  相似文献   

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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   

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The material described in this paper was collected from the Upper Triassic andMiddle Jurassic formations of Tungchuan,Liulingchuan,Yenhe-Xixingzihe and Dalihe inthe Ordos Basin of Shensi Province by the members of the Geological Expedition of theInstitute of Geology of Lanchow,Academia Sinica,in April,1961.A considerable number of ostracods have been discovered nearly from all formationsin many parts of China,yet the Triassic ostracods are comparatively rare.As far asthe writer is aware,only a few species have been known from the Lower Triassic of  相似文献   

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沈炎彬 《古生物学报》2006,45(2):175-181
报道的叶肢介新属(Kenyaestheria gen.nov.)采自肯尼亚Maji ya Chumvi地区的一钻孔,属下三叠统上马几牙楚姆维组(Upper Majiya Chumvi Formation),其特征为壳瓣后背缘最后几条生长线靠近背缘处形成一个凹缘构造,但生长线在背缘并不反转弯曲,同时具有放射线纹饰,据此将其归于凹缘叶肢介科(Ulugkemiidae)。该科是一个灭绝的类群,分布于中泥盆统至上三叠统,古生代的类型都发现于欧亚大陆,晚三叠世的Triasulugkemia见于阿根廷,新属首见于早三叠世,也是在南大陆出现的第二例凹缘叶肢介类。孢粉Lunatisporites pellucidus和叶肢介Aquilonoglypta—Cornia—Palaeolimnadia—Falsisca组合指示含化石的地层时代为早三叠世早期。  相似文献   

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Abstract:  Well-preserved cranial remains of a small sphenodontian lepidosaur from the Upper Triassic Caturrita Formation of Rio Grande do Sul, Brazil, are the first record of the genus Clevosaurus Swinton, 1939 from South America. They represent a new species, Clevosaurus brasiliensis , which is distinguished by a very short antorbital region of the skull (corresponding to about 20 per cent of skull length) and the presence of teeth in addition to two longitudinal rows on the pterygoid. C. brasiliensis most closely resembles C. bairdi from the Lower Jurassic of Nova Scotia (Canada) and C. mcgilli from the Lower Jurassic of Yunnan (China). The discovery of Clevosaurus in the Upper Triassic of southern Brazil provides a significant range extension of this widely distributed sphenodontian genus. Along with other recent finds, it also suggests that there may have been less biotic provincialism among terrestrial vertebrates during the Late Triassic than has previously been assumed.  相似文献   

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