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 31 毫秒
1.
Iguanodon galvensis is the second valid species in the European and Barremian large-ornithopod genus Iguanodon. In the present work, the I. galvensis holotype and referred material from the lower Barremian of Spain are described and discussed in detail. As a result, emended diagnoses of Iguanodon, I. galvensis and I. bernissartensis are proposed; I. galvensis can now be identified by three autapomorphies in the dentary, ischium and femur as well as a unique combination of characters. Moreover, I. galvensis is compared with other European Early Cretaceous large styracosternans. Finally, a new phylogenetic hypothesis is proposed that resolves Iguanodon (I. bernissartensis, I. galvensis) with the Valanginian Barilium dawsoni into a monophyletic clade (Iguanodontoidea).  相似文献   

2.
We describe the tadpole of Scinax aromothyella from the surroundings of Quebrada de los Cuervos, Departamento de Treinta y Tres, Uruguay. It shares with other larvae of the Scinax catharinae clade the slightly depressed body, a dextral vent tube that reaches the free margin of the ventral fin, and the oral disc with a dorsal gap in the marginal row of papillae and with a concave posterior edge. It is most similar to the tadpole of Scinax berthae, from which it differs in the larger total length of S. aromothyella.

Describimos la larva de Scinax aromothyella de los alrededores de la Quebrada de los Cuervos, Departamento de Treinta y Tres, Uruguay. Comparte con las larvas de otras especies del clado de Scinax catharinae el tener el cuerpo levemente deprimido, el tubo proctodeal dextro que alcanza el borde libre de la aleta ventral, y el disco oral con un claro rostral en la hilera de papilas marginales y con su borde posterior cóncavo. Es muy parecida a la larva de Scinax berthae, de la que difiere en la mayor longitud total de S. aromothyella.  相似文献   

3.
4.
5.
The egg and the five instars of Ectemnostega are described based on examined material and published information. The characters most useful in identifying nymphs of Ectemnostega are body and head lengths and widths; number of transverse sulcations of the rostrum; chaetotaxy of mesofemur, meso- and metatibiae, metatarsus, and pterothorax; and grade of development of wing pads. A key to the five nymphal instars of Ectemnostega is provided. The egg of E. quadrata is figured and described for the first time; and the five instars are redescribed in detail and illustrated, with emphasis on the morphometry and chaetotaxy of selected structures.

Se describe el huevo y los cinco estadios de Ectemnostega a partir de material examinado e información publicada. Los caracteres mas útiles para identificar las ninfas de Ectemnostega son: longitudes y anchos de cuerpo y cabeza; número de: crestas transversales del rostro, quetotaxia del mesofemur, meso- y metatibias, metatarso, y pterotórax; y grado de desarrollo de pterotecas. Se provee una clave para identificar los cinco estadios de Ectemnostega. Por primera vez se ilustra y describe el huevo de E. quadrata; y se redescriben en detalle e ilustran los cinco estadios, con énfasis en la morfometría y quetotaxia de ciertas estructuras.  相似文献   

6.
Abstract

The two endemic species of New Zealand Limnichthys differ in several osteological characters. L. polyactis differs from L. rendahli in having a rayed dorsal margin of the opercle (cf. entire), little or no gap between the lower limb of the coracoid and the pelvis (cf. wide gap), one epural (cf. two), and narrow posterior neural and haemal spines (cf. wide spines). Comments are given on some characters in the other 10 recognised named species of Creediidae. Squamicreedia obtusa is removed from the Creediidae, and is provisionally placed in the Percophididae.  相似文献   

7.
8.
9.
Mature male Pacific salmon (Genus Oncorhynchus) develop a dorsal hump, as a secondary male sexual characteristic, during the spawning period. Previous gross anatomical studies have indicated that the dorsal humps of salmon are mainly composed of cartilaginous tissue (Davidson [1935] J Morphol 57:169–183.) However, the histological and biochemical characteristics of such humps are poorly understood. In this study, the detailed microstructures and components of the dorsal humps of pink salmon were analyzed using histochemical techniques and electrophoresis. In mature males, free interneural spines and neural spines were located in a line near to the median septum of the dorsal hump. No cartilaginous tissue was detected within the dorsal hump. Fibrous and mucous connective tissues were mainly found in three regions of the dorsal hump: i) the median septum, ii) the distal region, and iii) the crescent‐shaped region. Both the median septum and distal region consisted of connective tissue with a high water content, which contained elastic fibers and hyaluronic acid. It was also demonstrated that the lipid content of the dorsal hump connective tissue was markedly decreased in the mature males compared with the immature and maturing males. Although, the crescent‐shaped region of the hump consisted of connective tissue, it did not contain elastic fibers, hyaluronic acid, or lipids. In an ultrastructural examination, it was found that all of the connective tissues in the dorsal hump were composed of collagen fibers. Gel electrophoresis of collagen extracts from these tissues found that the collagen in the dorsal hump is composed of Type I collagen, as is the case in salmon skin. These results indicate that in male pink salmon the dorsal hump is formed as a result of an increase in the amount of connective tissue, rather than cartilage, and the growth of free interneural spines and neural spines. J. Morphol. 275:514–527, 2014. © 2013 Wiley Periodicals, Inc.  相似文献   

10.
One of the diagnostic characters of dicraeosaurid sauropods is a reduction of pneumatization of dorsal and caudal vertebrae relative to their Flagellicaudata sister taxon, Diplodocidae. Here, we analyse pneumatic structures in the dicraeosaurid sauropod Pilmatueia faundezi, compare them to those of diplodocoids and report the first record of camerate chambers in a dicraeosaurid. The pneumatic structures are in a posterior cervical centrum (MLL-Pv-002) and consist of lateral pneumatic fossae on the centrum that communicate internally with large camerae. By contrast, Pilmatueia's dorsal and caudal vertebrae (MLL-Pv-005-016) lack pneumatic fossae on the centra, which is consistent with the previously reported reduced pneumaticity in dicraeosaurids. Nevertheless, the base of the neural arch and possibly the base of the bifid neural spines of a posterior dorsal vertebra (MLL-Pv-005) show pneumatic internal chambers. The pneumatic features of the Pilmatueia cervical centrum and dorsal neural arch we describe indicate that the degree of pneumatization is variable within dicraeosaurids.  相似文献   

11.
12.
13.
Abstract: The sauropod dinosaur, Barapasaurus tagorei, is known from the Early Jurassic Kota Formation (Sinemurian to Pliensbachian) of India. The taxon is represented by c. 300 bones that were found associated with large fossilized tree trunks and were collected from the interface of sandstone and mudstone units covering an area of c. 276 m2. The collection includes one partial skeleton; most of the remainder of the bones were disarticulated, disassociated and dispersed, but taphonomic analysis permits recognition of associated elements comprising several individuals. Skeletal anatomy of Barapasaurus includes several teeth, vertebrae from the caudal cervicals rearward to the terminal caudals, and most elements of the appendicular skeleton. Barapasaurus is characterized by spoon‐shaped teeth with bulbous bases and grooves on the anterolabial and posterolingual sides of the crown, coarse tubercles on the carina, acamerate cranial and dorsal vertebrae, lateral laminae of the middle and caudal dorsal neural spines composed of spinodiapophyseal and spinopostzygapophyseal laminae, neural canal of the mid‐dorsal vertebrae opens dorsally through a narrow slit into a large cavity and sacrum with four co‐ossified vertebrae. Phylogenetic analysis reveals that Barapasaurus is basal in comparison with Vulcanodon and is removed from Eusauropoda.  相似文献   

14.
 Larvae of two paralichthyids, Pseudorhombus oculocirris and P. arsius, are described and illustrated from specimens collected off Tosa Bay, southern Japan. Peudorhombus oculocirris larvae (5 specimens, 4.5–7.8 mm BL) are characteristic in having 6 or 7 elongated anterior dorsal fin rays and poorly developed head spines and melanophores on the tail. Pseudorhombus arsius larvae (3 specimens, 5.3–8.4 mm BL) are distinctive in having 11 or 12 elongated anterior dorsal fin rays and well-developed head spines, including a row of spines on the sphenotic. Received: June 28, 2001 / Revised: November 2, 2001 / Accepted: November 22, 2001  相似文献   

15.
The ontogenetic development of caudal vertebrae and associated skeletal elements of salmonids provides information about sequence of ossification and origin of bones that can be considered as a model for other teleosts. The ossification of elements forming the caudal skeleton follows the same sequence, independent of size and age at first appearance. Dermal bones like principal caudal rays ossify earlier than chondral bones; among dermal bones, the middle principal caudal rays ossify before the ventral and dorsal ones. Among chondral bones, the ventral hypural 1 and parhypural ossify first, followed by hypural 2 and by the ventral spine of preural centrum 2. The ossification of the dorsal chondral elements starts later than that of ventral ones. Three elements participate in the formation of a caudal vertebra: paired basidorsal and basiventral arcocentra, chordacentrum, and autocentrum; appearance of cartilaginous arcocentra precedes that of the mineralized basiventral chordacentrum, and that of the perichordal ossification of the autocentrum. Each ural centrum is mainly formed by arcocentral and chordacentrum. The autocentrum is irregularly present or absent. Some ural centra are formed only by a chordacentrum. This pattern of vertebral formation characterizes basal teleosts and primitive extant teleosts such as elopomorphs, osteoglossomorphs, and salmonids. The diural caudal skeleton is redefined as having two independent ural chordacentra plus their arcocentra, or two ural chordacentra plus their autocentra and arococentra, or only two ural chordacentra. A polyural caudal skeleton is identified by more than two ural centra, variably formed as given for the diural condition. The two ural centra of primitive teleosts may result from early fusion of ural centra 1 and 2 and of ural centra 3 and 4, or 3, 4, and 5 (e.g., elopomorphs), respectively. The two centra may corespond to ural centrum 2 and 4 only (e.g., salmonids). Additionally, ural centra 1 and 3 may be lost during the evolution of teleosts. Additional ural centra form late in ontogeny in advanced salmonids, resulting in a secondary polyural caudal skeleton. The hypural, which is a haemal spine of a ural centrum, results by growth and ossification of a single basiventral ural arococentrum and its haemal spine. The proximal part of the hypural always includes part of the ventral ural arcocentrum. The uroneural is a modification of a ural neural arch, which is demonstrated by a cartilaginous precursor. The stegural of salmonids and esocids originates from only one paired cartilaginous dorsal arcocentrum that grows anteriorly by a perichondral basal ossification and an anterodorsal membranous ossification. The true epurals of teleosts are detached neural spines of preural and ural neural arches as shown by developmental series; they are homologous to the neural spines of anterior vertebrae. Free epurals without any indication of connection with the dorsal arococentra are considered herein as an advanced state of the epural. Caudal distal radials originate from the cartilaginous distal portion of neural and haemal spines of preural and ural (epurals and hypurals) vertebrae. Therefore, they result from distal growth of the cartilaginous spines and hypurals. Cartilaginous plates that support rays are the result of modifications of the plates of connective tissue at the posterior end of hypurals (e.g., between hypurals 2 and 3 in salmonids) and first preural haemal spines, or from the distal growth of cartilaginous spines (e.g., epural plates in Thymallus). Among salmonids, conditions of the caudal skeleton such as the progressive loss of cartilaginous portions of the arcocentra, the progressive fusion between the perichondral ossification of arcocentra and autocentra, the broadening of the neural spines, the enlargement and interdigitation of the stegural, and other features provide evidence that Prosopium and Thymallus are the most primitive, and that Oncorhynchus and Salmo are the most advanced salmonids respectively. This interpretation supports the current hypothesis of phylogenetic relationships of salmonids. © 1992 Wiley-Liss, Inc.  相似文献   

16.
Larval development of Leiognathus equulus is described from reared postflexion specimens (4.6–15.8 mm Standard Length, SL) from Taiwan. Larvae have strong head spination, particularly a supraoccipital crest, strong supraocular ridge and very long, serrate preopercular spines, with the spine at the preopercular angle initially heavily pigmented. Fin spines are robust, and the anterior spines of dorsal, anal and pelvic fins are long and serrate. Structures characteristic of the family Leiognathidae form early in development (ca. 5 mm SL), including the very protrusible mouth, the fin-locking mechanism and the bacterial light organ. Pigment is initially largely confined to the ventral midline, but as development proceeds, extensive lateral and dorsal pigment patches appear. Larvae of L. equulus have the Trnski and Leis Morph 1 morphology.  相似文献   

17.
Feeding experiments with two species of carnivorous copepod, Mesocyclops longisetus (Thiebaud) and Mesocyclops kieferi Van de Velde from Barra Bonita, a eutrophic reservoir in São Paulo, Brasil, were performed using two common types of prey: Ceriodaphnia cornuta, a cladoceran, with a mean body length of 464 µm (including spines) or 393 µm (without spines), and Brachionus calyciflorus, a rotifer with a mean body length of 350 µm (including spines) or 279 µm (without spines).Both species showed higher consumption rates on Brachionus than on Ceriodaphnia. For Mesocyclops longisetus, the average rates were: 2.19 prey ind–1 h–1 (Brachionus), and 1.30 prey ind–1 h–1 (Ceriodaphnia). For Mesocyclops kieferi, the rates were 1.85 prey ind–1 h–1 (Brachionus) and 0.60 prey ind–1 h–1 (Ceriodaphnia). These experimental data are discussed with reference to the dynamics of the predator and prey populations in the reservoir.Laboratorio de Limnologia, Departamento de Ciencias Biologicas, Universidade Federal de São CarlosCentro de Recursos Hidricos e Ecologia Aplicada Lab. de Limnologia, Departamento de Hidraulica e Saneamento, Escola de Engenharia de São Carlos, Universidade de São Paulo  相似文献   

18.
The South American fur seal (SAFS), Arctocephalus australis, was severely depleted during the 18th century. This work updates information on distribution, abundance, seasonal movements, and genetic structure along the southwestern South Atlantic. Its distribution in Argentine waters includes nineteen rookeries on the Patagonian coast, Isla de los Estados, and islets of the Beagle Channel. Censuses were carried out in rookeries from Isla Escondida to Isla de los Estados from 1996 to 2014. The largest concentrations are found in Chubut, (4,500–15,500 seals) and Isla de los Estados (4,500). Pups were recorded on Isla Escondida, Rasa, and Isla de los Estados. An increasing number of SAFS were recorded in northern Patagonia, including seals marked in Uruguay. Skin samples were taken from southern Brazil to Tierra del Fuego in order to evaluate population structure and demographic trends. Genetic results indicated no population subdivisions (Φst = ?0.0292, Fst = ?0.00716, P > 0.05). Bayesian skyline plots constructed for the entire data set indicated evidence of rapid population expansion discernible in Nef between the last 20,000 and 17,000 yr. Genetics results and observation data from marked fur seals support the hypothesis of ancient gene flow and a single Atlantic population. Therefore, SAFS should be managed under international and integrated conservation policies.  相似文献   

19.
The Collection and Sale of Wild Mushrooms in a Community of Tlaxcala, Mexico. In this paper, we characterize the harvest and sale of wild mushrooms in Javier Mina (Tlaxcala state, Mexico) based on observations made during visits to that community during the rainy seasons of 1995 and 2001. While there, we visited the forests with various families of mushroom gatherers and also carried out 16 visits to a local mushroom broker to obtain information on the buying and selling of the mushrooms, including a list of the prices per kilo of the species that are sold commercially. Boletus cf. pinophilus, Lyophyllum cf. decastes, Hebeloma aff. mesophaeum and the Amanita caesarea complex were the highest–priced species, and were those collected in the greatest amounts. Our observations indicate that the gathering of mushrooms, a traditional activity among the people of Javier Mina, contributes, through the sale of the mushrooms, to the income of the community during the rainy season.
Recolección y venta de hongos silvestres en una comunidad de Tlaxcala, México. Recolección y venta de hongos silvestres en una comunidad de Tlaxcala, México. El objetivo de este trabajo es describir el proceso de recolección y venta de hongos silvestres en Javier Mina, Tlaxcala. Para describir estas actividades se realizaron visitas a los bosques con varias familias recolectoras de hongos durante las épocas de lluvias de 1995 y 2001. Además, se realizaron 16 visitas a un distribuidor local para registrar información con respecto a la compra y venta de los hongos. Se obtuvo un listado de los precios por kilo de los hongos que se comercializan. Boletus cf. pinophilus, Lyophyllum cf. decastes, Hebeloma aff. mesophaeum y Amanita caesarea complex fueron los hongos recolectados en mayor cantidad durante este estudio, mismos que tuvieron los precios más altos de compra–venta. Se concluye que la recolección de hongos es una actividad tradicional para la gente de Javier Mina; sin embargo, la venta de éstos, contribuye a la obtención de ingresos durante la temporada de lluvias.
  相似文献   

20.
The Bayesian statistical approach considers teeth as forming a developmental module, as opposed to a tooth-by-tooth analysis. This approach has been employed to analyze Upper Pleistocene hominins, including Neandertals and some anatomically modern humans, but never earlier populations. Here, we show its application on five hominins from the TD6.2 level of the Gran Dolina site (Homo antecessor, Early Pleistocene) and the Sima de los Huesos site (Middle Pleistocene) of the Sierra de Atapuerca (Burgos, northern Spain). Our results show an advanced development of the third molars in both populations with respect to modern Homo sapiens. In addition, the Sima de los Huesos hominins differ from H. sapiens and H. antecessor in the relatively advanced development of their second molar. The relative mineralization of I1/M1 in H. antecessor appears to be similar to that of modern humans, as opposed to that of Neandertals, which appear to be unique. These observations, combined with reduced enamel formation times and the advanced development of the third molars, appear to indicate a shorter ontogenetic period in the hominins from Gran Dolina and Sima de los Huesos in comparison to modern human average.  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