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1.
锅底坑组是重要的二叠—三叠系过渡序列,本组在新疆吉木萨尔大龙口出露广泛,产出吉木萨尔兽以及水龙兽两类二齿兽类.本文报道了在大龙口剖面首次发现的兽头类和迟滞鳄类,这也是此二类群在锅底坑组的首次报道.新发现的兽头类被命名为付氏大龙口兽(Dalongkoua fuae).其鉴定特征包括上颌骨犬后齿齿槽外边缘向背向凹入;切齿有圆形和匙形;切齿和犬齿有微弱的锯齿;齿骨冠状突有显著的收肌窝;反折翼近三角形,有两个平滑的凹陷.锅底坑组目前有3~4属二齿兽类、1属兽头类和1属迟滞鳄类,这一发现增加了其多样性.这些类群都在二叠纪末的大灭绝中幸存下来,直到中晚三叠世才消失.  相似文献   

2.
记述了2012年在山西柳林三交二马营组上部采集的一个兽头类下颌标本,将其命名为幻阔齿兽三交种(Nothogomphodon sanjiaoensis sp.nov.)。新种以下列特征区别于属型种N.danilovi:齿骨下缘起伏,犬齿基部卵圆形,犬齿与第一犬后齿间有显著间隙,犬后齿后缘无辅助齿尖。幻阔齿兽以其特殊的犬后齿形态与具裂齿的基干犬齿兽相似,它也是已知的唯一一类具有这种复杂裂齿齿系的兽头类。将俄罗斯的引鳄动物群与中国的肯氏兽-山西鳄组合带进行比较发现,幻阔齿兽是二者唯一共有的属,而中国的二马营组与克拉玛依组却没有共享的属。  相似文献   

3.
在已知6属兽头类动物中,乌鲁木齐兽代表了进步兽头类的早期类型,哈镇兽和河套兽次之,似粗弯齿兽为最晚期进步类型.伊克昭兽的归科尚不能确定.  相似文献   

4.
掘兽类一新属——哈镇兽的头骨形态及分类位置的探讨   总被引:1,自引:0,他引:1  
在1976—1977年从内蒙古、陕西三叠纪地层里采集到的脊椎动物材料中,有两件令人注意的标本,其中之一产自和尚沟组,另一件来自二马营组底部。后者因获得在先,已由侯连海(1979)研究报道,定名为杨氏鄂尔多斯兽(Ordosia youngi),并立一新科。这两件标本均属兽齿类爬行动物中的掘兽类(Scaloposauria)。在侯连海文章里用的是包氏兽形类(Bauriamorpha)这个名称。这里为什么用掘兽类这个名称,下文将讨论到。掘兽类是从二叠纪兽头类衍生下来的一类动物,它们曾在非洲(主要是南非)二叠纪晚期至三叠纪早期繁盛一时。除非洲以外,只在苏  相似文献   

5.
本文记述内蒙古大青山地区脑包沟组中首次发现的脊椎动物化石——边缘大青山兽(Da-qingshanodon limbus)。它具有翼骨腭上枝、基蝶骨小侧架、卷曲的鳞骨等独特构造。依其颅基中轴长、翼间窝长、翼间孔窄,眶前部分短,泪骨与隔颌骨分离等特征,以及在较高层位中发现的大鼻龙类、兽头类等化石,确认大青山兽属典型的晚二叠世二齿兽类型。文中还讨论了二齿兽类鼻区、蝶筛区、翼骨区等构造的演变,“萨拉齐系”与“石千峰群”的岩性和生物的可比性。  相似文献   

6.
到目前为止,在我国陆相三叠纪地层里,完美中国颌兽是非三列齿类犬齿类的唯一代表,首次报道时曾被鉴定为犬鳄科 (Cynosuchidae). 本文记载了该头骨的牙齿、颌关节等特征,证明应归宽齿犬齿兽类的 Trirachodontinae.  相似文献   

7.
正背景:兽头类是二叠、三叠纪的一类兽孔类,与我们哺乳动物所在的犬齿兽类亲缘关系很近。它们在地球上只生存了不到三千万年,虽然躲过了二叠纪末期(大约2.5亿年前)那次大浩劫,却在三叠纪中期灭绝了。这类动物的化石早在一百多年前就在南非发现了,它们与二齿兽类、犬齿兽类等化石共同产出。目前这类化石种类、数量最丰富的也是在南非。  相似文献   

8.
重新研究了济源四足动物群的材料,表明其以锯齿龙类的复齿河南龙为主体,还包括至少三种迟滞鳄类和一种犬齿兽,可能还有一种凶脸兽。根据甲片特征推测,迟滞鳄类至少包括中国毕氏螈Bystrowiana sinica,扁平济源盖螈(新属新种)Jiyuanitectum fl atum gen.et sp.nov.以及大型脊廊盖螈(新种)Dromotectum largum sp.nov.。根据四足动物组合,济源动物群大致可以与俄罗斯Sokolki组合带的Ilinskoe亚带以及南非的小头兽组合带对比。  相似文献   

9.
近几十年,华北的二马营组上部地层以产出中国肯氏兽–山西鳄四足动物化石组合而闻名。最近在山西临县白道峪于上覆的铜川组一段发现了中国肯氏兽。本文描述了同一地点同一层位产出的主龙型类化石,包括一具山西鳄的部分骨架以及一些可以归入suchian的主龙类。它们是铜川组一段首次记述的主龙型类。最有鉴定特征的suchian材料包括一个大的髂骨以及一个小的、形状很奇特的、可能是跟骨的骨骼。髂骨可能可以归入一个奇异的波波龙类(poposauroid)。因为中国肯氏兽与山西鳄同时出现在白道峪,表明中国肯氏兽–山西鳄组合可以向上延伸到铜川组一段。髂骨与跟骨大小悬殊,可能代表两个从未在中国肯氏兽–山西鳄组合报道过的物种。白道峪发现了特化的波波龙类,支持了波波龙类在中三叠世大量分化的观点。  相似文献   

10.
近几十年,华北的二马营组上部地层以产出中国肯氏兽-山西鳄四足动物化石组合而闻名.最近在山西临县白道峪于上覆的铜川组一段发现了中国肯氏兽.本文描述了同一地点同一层位产出的主龙型类化石,包括一具山西鳄的部分骨架以及一些可以归入suchian的主龙类.它们是铜川组一段首次记述的主龙型类.最有鉴定特征的suchian材料包括一个大的髂骨以及一个小的、形状很奇特的、可能是跟骨的骨骼.髂骨可能可以归入一个奇异的波波龙类(poposauroid).因为中国肯氏兽与山西鳄同时出现在白道峪,表明中国肯氏兽-山西鳄组合可以向上延伸到铜川组一段.髂骨与跟骨大小悬殊,可能代表两个从未在中国肯氏兽-山西鳄组合报道过的物种.白道峪发现了特化的波波龙类,支持了波波龙类在中三叠世大量分化的观点.  相似文献   

11.
Entomological Review - The type and other extensive material of Coprophilus (Zonyptilus) pennifer (Motschulsky, 1845) and some of its synonyms was examined. Coprophilus (Zonyptilus) marginalis...  相似文献   

12.
Gildenkov  M. Yu. 《Entomological Review》2020,100(7):1009-1019
Entomological Review - The type material of several synonyms of Coprophilus (Zonyptilus) pennifer (Motschulsky, 1845) is revised. Both Coprophilus (Zonyptilus) striatipennis (Eppelsheim, 1894) and...  相似文献   

13.
Sarcophaga (Sarcorohdendorfia) gracilior (Chen, 1975) is documented from specimens collected in Hubei Province, China, using morphological characters and wing interference patterns (WIPs). The female of S. (S.) gracilior is described for the first time, the male is redescribed, and both sexes are photographed. The distribution of the species is updated.  相似文献   

14.
Abstract. The fruit fly genus Ceratitis (Diptera: Tephritidae) comprises several important pest species attacking a wide range of unrelated fruits. In this paper the subgenus Ceratitis ( Pardalaspis ) Bezzi is revised. Ten species are recognized of which five are described as new: C.(P.)hamata sp.n., C.(P.)munroi sp.n., C.(P.)serrata sp.n., C.(P.)semipunctata sp.n. and C.(P.)zairensis sp.n. A key to both sexes is provided. All species are restricted to the Afrotropical Region and distributional and known host plant data are given.  相似文献   

15.
The ultrastructural organization of vitellogenesis of Plagiorchis elegans (Rudolphi, 1802), experimentally obtained from the golden hamster Mesocricetus auratus (Linnaeus, 1758), is described using transmission electron microscopy. This study is the first ultrastructural study of vitellogenesis in a member of the superfamily Plagiorchioidea. The four stages usually observed during vitellogenesis are described: stage I, cytoplasm of the vitellocytes mainly filled with ribosomes and few mitochondria; stage II, beginning of the synthetic activity; stage III, active synthesis of the shell globule clusters; stage IV, vitellocytes are filled with shell globule clusters and contain several lipid droplets, and glycogen granules are grouped around clusters and droplets. Vitellogenesis in P. elegans is compared with that of other Digenea. The differences among P. elegans and previously studied digeneans include, but are not limited to the occurrence of dense coiled endoplasmic reticulum saccules and the concentration of glycogen in the mesenchyme, which may be considered as a fifth stage of maturation of the vitelline glands. This peculiarity was not observed in all trematodes, which clearly indicates differences in the vitellogenesis in various digenean lineages at different stages of maturation of their vitelline cells.  相似文献   

16.
Three genera of unstalked crinoids, Zenometra , Sarametra and Psathyrometra , formerly included in the subfamily Zenometrinae of the family Antedonidae, are removed and placed in a distinct family, the Zenometridae. Diagnostic features include a cavernous centrodorsal cavity, a complete basal circlet with a large central lumen and cirrus sockets with a concave fulcral bowl around the lumen. Sarametra nicobarica is synonymized under S. triserialis , which is redescribed in detail. Psathyrometra is redefined and includes only the species P. fragilis , P. congesta and P. bigradata , which are redescribed. P. erythrizon is synonymized under P. fragilis . The four other species formerly included in Psathyrometra are removed to Athrypsometra gen. n., retained in the Antedonidae. The other genera formerly included in the Zenometrinae are considered incertae sedis in the family Antedonidae pending detailed re-examination. Cladistic analysis using the antedonids, Poliometra prolixa (a former zenometrine) and Florometra serratissima , and the thalassometrid, Oceanometra annandalei , as outgroups produces the following tree: ( O. annandalei (( F. serratissima / P. prolixa )((( P. fragilis / P. congesta ) P. bigradata ) ( S. triserialis / Z. columnaris )))).  相似文献   

17.
Numerous individuals of the poorly known species Lecithostaphylus retroflexus (Zoogonidae) and Tergestia acanthocephala (Fellodistomidae) have been recovered from the teleost fish Belone belone gracilis from off the Scandola Nature Reserve, Western Mediterranean. They are redescribed, incorporating previously undescribed features: for L. retroflexus, a post-oral ring, a bipartite seminal vesicle, the shape of the excretory vesicle, the subterminal excretory pore and the flask-shaped gland-cells associated with the distinctly pedunculate ventral sucker; and for T. acanthocephala, the intestinal bifurcation in the forebody, necessitating its return to the genus Tergestia from Theledera. Additionally, T. acanthocephala is compared with T. laticollis from various species of Trachurus from the same geographical area.  相似文献   

18.
Peltidiidae (Copepoda, Harpacticoida) from the Weddell Sea (Antarctica)   总被引:1,自引:0,他引:1  
Alteutha polarsternae sp.n. is described and Eupelte villosa (Brady, 1910) is redescribed in detail. The distribution of both these species in the Weddell Sea is recorded.  相似文献   

19.
Genetic divergence and variability at 14 enzyme loci were examined in and between Italian populations of two edaphic Oribatid (Acarida, Oribatida) species, Steganacarus (Steganacarus) magnus (8 populations) and S. (S.) hirsutus (1 population). The seven populations belonging to S. (S.) magnus can be divided into two groups according to their phenotype, form anomala (A) (MON, ARG, AST, CDO) and form magna (M) (MAL, MAM, RIF) while another can be considered as hybrid between the two preceding groups (ZOC). Genetic identity (I) values between the S. (S.) magnus populations in spite of their morphological differences ranged from 0.977 to 1.000 showing the great genetic similarity of simple local populations while those of S. (S.) hirsutus indicated two distinct morphological species. The genetic distances between all the populations examined were very low despite the ecological differences and geographical distances between the collecting sites. Genetic variability estimates in all the populations of both species were very low when compared to those reported for most arthropods. Some explanatory considerations are suggested.  相似文献   

20.
Molecular-mechanical simulations have been carried out on “mismatched base” analogs of the DNA double-helical structure d(CGCGAATTCGCG)2, in which the base pairs CG at the 3 and 10 positions have been replaced by CA, AG, TC, and TG base pairs, as well as an insertion analog in which an extra adenine has been incorporated into one strand of the above structure between bases 3 and 4. The results of these simulations (calculated relative stabilities, structures, and nmr ring-current shifts) have been compared with calorimetric and nmr data. The calculated relative stabilities of the double-helical parent dodecamer and the various “wobble” base pairs qualitatively correlate with the experimental melting temperatures. The base-pairing structure for the GT wobble pair is in agreement with that previously determined from nmr experiments. For the GA base pair, the structure with both bases anti has a slightly more favorable energy from base pairing and stacking than a structure with non-Watson-Crick H-bonding with adenine syn, in agreement with nmr experiments. The CA wobble base is calculated to favor an adenine 6NH2 …? cytosine N3 H-bond over cytosine 4NH2 …? adenine N1, again, in agreement with nmr experiments. There is no definitive experimental data on the TC base pair, but the existence of (somewhat long and weak) H-bonds involving cytosine 4NH2 …? thymine 4CO and cytosine N3 …? thymine HN3 seems reasonable. We find a structure in which the extra adenine base of the insertion analogs sits “inside” the double helix.  相似文献   

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