山西闻喜早更新世地层和哺乳动物化石

山西闻喜早更新世的哺乳动物化石发现并不十分丰富,由于地层出露较好,层位清楚,虽然地层较薄,但对确定早更新世,为今后进一步深入研究汾渭盆地的第四纪下限,古气候、古地理环境可提供依据。     

A NEW GENUS OF CAPRINI (BOVIDAE, ARTIODACTYLA) FROM UPPER PLIOCENE OF YUSHE, SHANSI

<正> In the present paper a new caprine, Sinocapra minor gen. et sp. nov. is erected on the basis of several horn cores. The type specimen was collected by the Sino-American Palaeontology Expedition from the Upper Pliocene, Mazegou Formation, of Yunzhu Subbasin, Yushe Basin, Shansi province in 1988. All the other ones referred to the new genus were described and identified by Teilhard de Chardin and Trassaert (1938, p. 53, fig. 46) as Antilope gen. et sp. indet. They also came from Zhaozhuang, Yunzhu Subbasin and it is likely that they might be gathered from the same Formation as the type specimen judging by the yellow sandy clay filling into the horn cores. Magnetostratigraphic studies by Prof. N. Opdyke of the Yunzhu Subbasin indicates that this stratigraphic interval only includes the Gauss one, approximately 3.4 to 2.47 Ma. Accounts of the biostratigraphy and dating of Yunzhu Subbasin are giyen by Dr. R. H. Tedford and Dr. Z. Qiu in another paper.     

FURTHER OCCURRENCES OF SPENCERITES FROM THE MIDDLE PENNSYLVANIAN OF KANSAS AND ILLINOIS

New specimens of Spencerites moorei add knowledge of its sporophylls and method of sporangial attachment. The sporophyll consists of a slender pedicel which expands at its distal end into a fleshy, peltate, diamond-shaped head which bears a presumably fleshy lamina. The sporangium is attached through most of its length to the adaxial surface of the pedicel rather than distally as in S. insignis. It is suggested that the distal attachment shown in S. insignis may be derived through a phyletic shift from the pedicellate position. Additional specimens of Spencerites provisionally assigned to S. majusculus are also recorded. The spores are bilateral, monolete, and shaped like quadrants of a sphere. Two prominent wings extend along the two contact faces and the monolete mark is prominently raised, thus imparting a three-winged appearance to the spore. The axis consists of an exarch protostele and a cylinder of thick-walled outer cortex.     

THE ONTOGENY OF CARBONIFEROUS ARTICULATES: THE APEX OF SPHENOPHYLLUM

Twig apices of Sphenophyllum lescurianum, S. constrictum, and two new Sphenophyllum taxa are described in transverse and longitudinal section from middle and upper Pennsylvanian age specimens. In all of the species the single apical cell has the shape of a tetrahedron, with a triangular upper surface and three internal cutting faces. Segment cells are produced from each of the cutting surfaces in a dextrorse or sinistrorse direction, depending upon the species. The central portion of each segment cell contributes to the initiation of the procambium, while the remaining outer portion undergoes a vertical and subsequent horizontal division to form segment cells. Segment cells are aligned in vertical tiers beneath the respective apical cell cutting faces, with the individual leaves positioned directly beneath a tier of segment cells. Leaf primordia are first observed as a series of surface undulations below the apex, with an intercalary meristem located directly beneath each primordium. The vegetative apical organization of Sphenophyllum is demonstrated to be very similar to the type of organization found at the stem tips of Catamites and Equisetum.     

PATTERNS OF VARIATION IN THE STELLARIA LONGIPES COMPLEX: EFFECTS OF POLYPLOIDY AND NATURAL SELECTION

Patterns of morphological variation were studied in herbarium specimens of Stellaria longipes, an herbaceous perennial and subsequently in a growth chamber experiment using three cytotypes (4x, 6x, 8x) of S. longipes and diploids of its proposed progenitor S. longifolia. Despite extensive phenotypic plasticity in many traits, patterns of variation resulting from ecotypic differentiation within S. longipes could be detected in the field. A distinct form of S. longipes, which is restricted primarily to arctic and alpine tundra locations, shows genetic differentiation for the following traits: few flowers per ramet, a low proportion of flowering ramets, and ovate leaves. The three cytotypes of S. longipes could be distinguished by their mean genotypic value for leaf length and number of flowers per ramet. The extent of phenotypic plasticity in these traits makes it unlikely that the cytotypes could be distinguished in the field. The direction and extent of morphological divergence between S. longifolia and S. longipes suggest an alloploid origin for S. longipes. Variational trends (among-habitat types and cytotypes) in trait means are similar to those reported previously for the pattern of plasticity. This supports the argument that similar forces guide evolution of the mean and pattern of plasticity of a trait.     

MITOCHONDRIAL DNA SEQUENCE-BASED PHYLOGENY AND THE EVOLUTION OF VIVIPARITY IN THE SCELOPORUS SCALARIS GROUP (REPTILIA,SQUAMATA)

The lizard genus Sceloporus contains both oviparous and viviparous species. The scalaris complex is the only monophyletic group within the genus that includes both reproductive modes, thus it is particularly well suited for studies of the evolution of viviparity. Approximately 874 nucleotides of mtDNA sequence data, collected from 38 specimens, comprising 25 populations of all five recognized species within the group, were used in a phylogenetic analysis of the origin of viviparity. Viviparity appears to have evolved twice in this group: once in S. goldmani, included in a clade formed by a northern group consisting of S. scalaris, S. chaneyi, and S. goldmani, and one more time in S. bicanthalis, included in the southern group formed by S. bicanthalis and S. aeneus. An oviparous population of S. bicanthalis nested within that viviparous clade, indicates that reversal from viviparity to oviparity may be possible. Degree of sequence divergence among several S. bicanthalis individuals pertaining to a population in which both parity modes occur, was no larger between oviparous and viviparous lizards than among viviparous lizards. This suggests that this population is a single species, and it may represent a transition from oviparity to viviparity or vice-versa.     

四川江油马角坝中、晚石炭世的(竹蜓)类

中、上石炭统在四川省境内分布范围较窄,除涪陵一带可能有中石炭统沉积外,只在西北部龙门山一带及松潘区(?)有零星出露。其中以江油马角坝附近发育比较完整,产化石较丰富。1961年,我所川北地层队在江油县马角坝附近张坝沟一个采石场测得中、上石炭统剖面一个,采集了(竹蜓)类及珊瑚类化石若干。剖面的层序自上而下为:     

THE MORPHOLOGY OF STIGMARIA STELLATA

Stigmaria stellata Goeppert is a lycopod underground system occurring in Upper Mississippian and equivalent age rocks of Europe and North America. This taxon has previously been based on impressions exhibiting radiating ridges and furrows around each lateral appendage scar and numerous polyhedral projections on the remainder of the axis. Anatomically preserved specimens from the Chester Series (Upper Mississippian) of Illinois reveal that the distinctive surface pattern of this species results from polyhedral wedges of thick-walled cells in the outer cortex. Decortication produces a smooth outer surface that is indistinguishable from that of the much more abundant Stigmaria ficoides. The structure of S. stellata is quite similar to the structure of other petrified stigmarians, but the following are some of the anatomical characters that distinguish it: (1) presence of abundant polyhedral wedges of thick-walled cells in the outer cortex; (2) absence of secondary cortex; (3) very tall rays associated with appendage traces that remain confluent with the secondary xylem to its outer margin; (4) the absence of a connective in the lateral appendages. The anatomical characters of Stigmaria stellata confirm it as a taxon of at least specific rank.     

山西榆社上新世沙鼠化石

本文记述了六件短齿假沙鼠(Pseudomeriones abbreviatus abbreviatus)的上下颌骨,并对在庆阳发现的正型标本和国外有关的新材料做了补充记述和讨论。     

ON THE ORIGIN OF CULTIVATED RYE

From extensive cytological, ecological, and morphological studies, it appears that cultivated rye (Secale cereale L.) originated from weedy products derived from introgression of S. montanum into S. vavilovii. Secale vavilovii appears to have been derived from S. silvestre as a consequence of chromosomal translocations. Secale silvestre was, in turn, derived from S. montanum or a common ancestor. Secale africanum, S. dalmaticum, S. ciliatoglume, and S. kuprijanovii appear to be only slightly modified isolated populations of S. montanum. Populations of S. anatolicum are weedy forms of S. montanum, genealogically and chromosomally distinct from the weedy annual forms from which S. cereale arose.     

ON THE STRUCTURE OF CALAMOSTACHYS BINNEYANA FROM THE LOWER PENNSYLVANIAN OF NORTH AMERICA

The discovery of specimens of Calamostachys binneyana in Lower Pennsylvanan petrifaction material in North America has provided additional information about the structure of this calamitean fructification. The cones consist of regularly spaced alternating whorls of bracts and sporangiophores. Bracts are fused in a disc except at the margin where the individual units become free. Sporangiophores are inserted at right angles to the cone axis and bear four axially directed sporangia. The vascular system of the North American specimens differs from that in other reports of the taxon in the presence of twelve vascular bundles in the cone axis. Each sporangiophore is supplied by a single vascular trace that departs from one axial bundle. There appears to be no constant relationship between the number of vascular bundles and the number of bracts. Spores are spherical, thin-walled, and of the Calamospora type. Relationships with other structurally preserved members in the genus are discussed in light of the diversity in structure demonstrated by the new specimens.     

DISTRIBUTION AND SYSTEMATICS OF THE FRESHWATER GENUS SIRODOTIA(BATRACHOSPERMALES,RHODOPHYTA) IN NORTH AMERICA1

Multivariate morphometrics and image analysis were used to determine the number of well-delineated infrageneric taxa of Sirodotia in North America. Three groupings were distinguished from 25 populations examined from Newfoundland and Quebec in the north to central Mexico in the south. These groupings were statistically related to 10 type specimens, and the following species were recognized: Sirodotia huillensis (Welwitsch ex W. et G. S. West) Skuja (syn. S. ateleia Skuja), S. suecica Kylin (syn. S. acuminata Skuja ex Flint and S. fennica Skuja), and S. tenuissima (Collins) Skuja ex Flint. These species are differentiated on the basis of whorl shape and degree of separation at maturity (S. suecica, rounded and appressed; S. huillensis and S. tenuissima, truncated apex and separated), the density of spermatangia (S. huillensis, dense clusters; S. suecica and S. tenuissima, sparsely aggregated), and the mode of germination of the gonimoblast initial (S. suecica and S. tenuissima, from the nonprotuberant side of the fertilized carpogonium; S. huillensis from the protuberant side). Sirodotia huillensis was found only in the desert-chaparral, whereas S. suecica and S. tenuissima occurred from south-temperate to boreal regions in cool (temperature 8–18° C), low ion (specific conductance 10–99 μS · cm^?1), and mildly acidic to neutral (pH 5.7–7.3) waters.     

ASSOCIATION OF MUCILAGE WITH THE LIGULE OF SEVERAL SPECIES OF SELAGINELLA

Mucilage bodies of protein and some polysaccharide were closely associated with ligules of Selaginella kraussiana (Kunze) A. Braun grown in the greenhouse, and Selaginella wallacei Hieron. and Selaginella oregana D.C. Eat. from natural habitats. With S. wallacei and S. oregana, several mucilage bodies were associated with some ligules. No mucilaginous material was associated with the ligules of Selaginella douglasii Hook, et Grev., Selaginella densa Rydb. or Selaginella apoda (L.) Fernald from natural habitats. When stem tips of S. kraussiana and S. douglasii were placed in sterile culture on a medium with sucrose, massive amounts of mucilage appeared around the ligules in the tight interstices of the stem tip leaves and extended out on the surface of the leaves. The mucilage from a cultured stem tip of S. kraussiana contained 0.034 μgm of protein, 14.6 μgm of apparent glucose equivalents as polysaccharide and no significant amounts of phenolics. In stem tips with tightly appressed leaves, either ligules or young leaves could have produced the mucilage; however, in more mature regions of the stem where internodal elongation had separated the leaves, mucilage coated only the apical portions of the ligules and was not associated with leaves. No other possible source of mucilage (bacteria or fungi) was detected among the leaves. When stem tips of S. wallacei, S. densa and S. apoda were placed in culture, mucilage was not produced. Since mucilage is closely associated with the ligule of some species of Selaginella growing in nature, the greenhouse, or tissue culture, the ligule may be glandular.     

INVESTIGATIONS OF ANGIOSPERMS FROM THE EOCENE OF NORTH AMERICA: STIPULATE LEAVES OF THE RUBIACEAE INCLUDING A PROBABLE POLYPLOID POPULATION

A comparative study was made of the gross morphology, fine venation and cuticular features of Leitneria fioridana Chapman, the single living representative of the order Leitneriales and Leitneria eocenica (Berry) Brown, presumbaly a related fossil species. In addition to the type material, newly collected fossil specimens were investigated from clay pits in the Middle Eocene, Claiborne Formation, of western Tennessee and Kentucky. Foliate stipules attached to the petioles of several specimens suggest the assignment of this fossil leaf type to the genus Leitneria is incorrect. The nature of the gross morphology, fine venation and cuticular features confirms the misidentification. Previously, various specimens of this fossil leaf type have been placed in eight species of seven genera in seven families of six angiosperm orders, none of which are correct systematically. The gross morphology, venation and cuticular characters of the fossil leaf are distributed among a few extant South American genera of arborescent Rubiaceae. The fossil is an extinct rubiaceous leaf type which cannot be placed within a single modern subfamily, tribe or genus of the family. The organ genus, Paleorubiaceophyllum is proposed for these leaves. Three varieties of a single fossil species, P. eocenicum, are recognized. One variety with epidermal cells nearly twice the size of the others may represent a polyploid population.     

POLLEN ORGANS OF THE PENNSYLVANIAN CALLISTOPHYTACEAE (PTERIDOSPERMOPSIDA)

Numerous specimens of the pteridospermous pollen organs Idanothekion glandulosum and Callandrium callistophytoides are present in Middle and Upper Pennsylvanian petrifaction material, respectively. Several specimens of Idanothekion, previously known only in an isolated condition, are attached to foliage assignable to the monostelic seed fern Callistophyton. Proof of the affinities of Idanothekion allows this genus to be elevated from a form genus to an organ genus in the Callistophytaceae. The structure of the foliage and the mode of attachment of the Idanothekion specimens are like those previously described for Callandrium. Structural features of Idanothekion and Callandrium are compared, and the question of their identity is discussed. At present one basic type of pollen organ, borne on the abaxial surface of foliar pinnules, is known for members of the Callistophytaceae.     

COMPARISON OF CULTURED TRICHODESMIUM (CYANOPHYCEAE) WITH SPECIES CHARACTERIZED FROM THE FIELD1

The filamentous, colonial cyanobacterium Trichodesmium has six well‐described species, but many more names. Traditional classification was based on field samples using morphological characteristics such as cell width and length, gas vesicle distribution, and colony morphology. We used the Woods Hole Trichodesmium culture collection to identify 21 cultured strains to species using cell morphology; phycobiliprotein absorption spectra; and sequences of the 16S rRNA gene, the 16S–23S internal transcribed spacer (ITS), and the heterocyst differentiation gene hetR. We compared our results to previous studies of field specimens and found similar clades, though not all phylogenetic groups were represented in culture. Our culture collection represented two of the four major clades of Trichodesmium: clade I, made up of Trichodesmium thiebautii Gomont, Trichodesmium tenue Wille, Katagnymene spiralis Lemmerm., and Trichodesmium hildebrandtii Gomont; and clade III, consisting of Trichodesmium erythraeum Ehrenb. and Trichodesmium contortum Wille. These clades were genetically coherent with similar phycobiliprotein composition, but morphologically diverse. In the continual revision of cyanobacterial taxonomy, genetic and biochemical information is useful and informative complements to morphology for the development of a functional classification scheme.