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1.
Quo vadis eohippus? The systematics and taxonomy of the early Eocene equids (Perissodactyla) 总被引:1,自引:0,他引:1
DAVID J. FROEHLICH 《Zoological Journal of the Linnean Society》2002,134(2):141-256
The systematics and taxonomy of early Eocene equids are investigated. A paraphyletic sequence of equid taxa is recovered from a phylogenetic analysis of 40 taxa and 121 characters. This analysis supports the identification of Hyracotherium as a primitive equoid and its restriction to the genotype, Hyracotherium leporinum . Sifrhippus gen. nov. is erected for the sister taxon of all other equids, Hyracotherium sandrae Gingerich. Minippus gen. nov., the next more-derived equid clade, is erected for two small equids, M. index Cope and M. jicarillai nov. species. Arenahippus gen. nov. is erected for the next three sequentially more-derived equid taxa, A. grangeri Kitts, A. aemulor Gingerich, and A. pernix Marsh. The genus Xenicohippus , which is the next more-derived equid clade, is redefined to include X. craspedotum Cope. Eohippus Marsh, the next more-derived equid taxon, is resurrected for E. angustidens Cope. Pliolophus , the only early Eocene equid from Europe, is identified as the sister taxon to Protorohippus , a sequence of successively more-derived equid taxa consisting of P. montanum Wortman and P. venticolum Cope. Protorohippus venticolum is identified as the sister taxon of Orohippus . Systemodon Cope is resurrected for S. tapirinum Cope. This taxon has historically been placed within Hyracotherium yet this analysis allies it with Cymbalophus near the base of the perissodactyl radiation. © 2002 The Linnean Society of London. Zoological Journal of the Linnean Society , 134 , 141–256. 相似文献
2.
The origin of chalicotheres (Perissodactyla, Mammalia) 总被引:1,自引:0,他引:1
3.
The beginning of the equoid radiation 总被引:1,自引:0,他引:1
J. J. HOOKER 《Zoological Journal of the Linnean Society》1994,112(1):29-63
With the benefit of newly collected material, primitive equoids are analysed cladistically to determine the detailed relationships of the families Equidae and Palaeotheriidae. The most primitive equid is shown to be Pliolophus. Cymbalophus cuniculus and 'Hyracotherium' sandrae are closely related stem equoids. The Pachynolophidae are not equoids, but most closely related to the primitive tapiromorph family Isectolophidae. Hallensia is sister to these two and therefore also not an equoid. Hyracotherium is restricted to the type species H. leporinum Owen, part of whose lower dentition is made known for the first time. It is closest to a restricted genus Propachynolophus within the family Palaeotheriidae. The original concept of Propachynolophus is polyphyletic. Using the cladogram, newly extended stratigraphic ranges and palaeogeography, an attempt is made to reconstruct the very early speciation and biogeographical history of the group. 'Cymbalophus' hookeri Godinot is recombined in the genus Pachynolophus and 'H.' pernix in Pliolophus. Hallensia louisi sp. nov. and Propachynolophus level sp. nov. are described. 相似文献
4.
The genus Pilgnmella , known from the medial Eocene of Pakistan and northwest India, is a primitive perissodactyl, not an artiodactyl as previously identified. Upper cheek teeth of Pilgrimella , when compared with those of primitive representatives of the Equoidea, Brontotherioidea, Chalicotherioidea, Tapirioidea and Rhinocerotoidea, suggest, however, that Pilgnmella cannot on present evidence be referred to any of the five accepted perissodactyl superfamilies. Pilgrimella may represent a short-lived and hitherto unknown perissodactyl lineage. 相似文献
5.
A NEW PRIMITIVE CHALICOTHERE (PERISSODACTYLA,MAMMALIA) FROM THE EARLY EOCENE OF HUBEI, CHINA 总被引:1,自引:1,他引:0
'I.DESCR1PTIoNorderPerissodactylaOwen,l848SuperfamilyCbalicotherioideacall,l872'Family?EomoropidaeVret,l958GehusDanjiangiagen.nov.TypespeciesDaniiangiapingigen.etsp-nov.DiagnoaisSma1lprimitivecha1icothere(lengthofM/l=8.3mm),skullshallowwithcranialrostrumrelatively1ong,mandibularhorizontalramusandmandibularsymphysisfairlylongandsha1low,teeth1ow-crowned,dentitionformula:3.l.4.3/3.1.4.3.Premolarnonmolariform,P2/2tIenchant,P4/withincipientmesostyle.M/widerthan1engthwithW-shapedectoIoph,… 相似文献
6.
JOHN O. CORLISS 《The Journal of eukaryotic microbiology》1974,21(2):207-220
With the realization that new data (especially ultrastructural) and new ideas are making necessary a major revision of the scheme of classification of the Ciliophora, several groups of ciliatologists are preparing treatises on the subject. The present paper is concerned with the composition of the large new class of ciliates, Kinetofragmophora de Puytorac et al., 1974, established very recently by the French group. Several new taxa, at ordinal and subordinal levels, are proposed for inclusion in that class, with special emphasis on the new order to contain the most primitive of extant species. Actions taken here are incorporated in a major review and revisory work of the author which is being published elsewhere. The class Kinetofragmophora, by far the largest of the 3 classes now recognized as comprising the whole phylum Ciliophora, is itself considered to contain 4 sizeable subclasses and to embrace a total of 13 orders and 14 suborders. Two orders and 6 suborders are named and described here as new, enumerated and briefly identified as follows: Order Primociliatida n. ord., for the most “primitive” of gymnostomes, with three new suborders— Homokaryotina n. subord., for the homokaryotic genus Stephanopogon; Karyorelictina n. subord., for a number of mostly interstitial ciliates which, though heterokaryotic, possess nondividing, diploid macronuclei (e.g. Trachelocerca, Trachelonema, and Tracheloraphis); and Prorodontina n. subord., for a group of relatively specialized formerly “rhabdophorine” gymnostomes such as Coleps, Placus, and Prorodon and order Haptorida n. ord., for rapacious carnivorous forms, formerly lumped with the preceding groups as “rhabdophorines,” many with oral toxicysts and well developed thigmotactic ciliature (e.g. Actinobolina, Didinium, Dileptus, Enchelys, Spathidium, and Trachelius). All foregoing taxa are members of the 1st kinetofragmophoran subclass, the Gymnostomata. In the taxonomic conclusions drawn, new significance is placed on ultrastructural data, on macronuclear differences of evolutionary importance, and on habitat and behavior. A brief review of the literature on psammophilous ciliates is presented. In the subclass Vestibulifera is now located the order Entodiniomorphida Reichenow, a group formerly considered to be a spirotrich taxon. A suborder, Blepharocorythina n. subord., is proposed to contain the old “trichostome” family Blepharocorythidae, species commensalistic in horses and ruminants and now—with their syncilia, etc.—considered ancestral to the ophryoscolecids and relatives. In the subclass Hypostomata, order Nassulida, the suborder Paranassulina n. subord. is established to contain nassulids which appear more highly evolved than Nassula itself (e.g. Paranassula and Enneameron) in perioral ciliature, mode of stomatogenesis, etc. In the enigmatic and still vexatious order Rhynchodida, the suborder Aneistrocomina n. subord. is erected to embrace rhynchodid genera with an anteriorly located sucking tentacle (and other unique characteristics)—for example, Ancistrocoma, Crebricoma, Holocoma, and Sphenophrya. With the banishment of the bulk of the old “thigmotrichs” to the oligohymenophoran order Scuticociliatida, the ancistrocomines are left with the family Hypocomidae (and relatives) in the order Rhynchodida. It is not yet clear, however, how closely related the 2 suborders of rhynchodids should be considered. Special nomenclatural problems are also involved. 相似文献
7.
AbstractThe deciduous premolars of early Eocene Equidae from North America, conventionally attributed to ‘Hyracotherium’, are described and compared, based primarily on a sample of >60 specimens from the early Eocene Willwood Formation of the Bighorn Basin, Wyoming. The sample represents six to nine species assigned to multiple genera by some other authors, but in the absence of diagnostic characters of the deciduous dentition, species assignments remain ambiguous for most specimens. Consequently it is not clear which generic names should be applied, and we employ the widespread name ‘Hyracotherium’ (acknowledging that the type species may not be an equid). We observed considerable variation in our sample, but most differences are minor and are largely inconsistent with respect to time or taxa, hindering attempts to characterise deciduous premolar anatomy of particular species. Comparisons were also made to Bridgerian Orohippus and Uintan Epihippus, to other early perissodactyls, and to non-perissodactyls that have been considered close to the origin of Perissodactyla (phenacodontid condylarths and Cambaytherium). Based on these comparisons, we confirm Butler’s observation that the deciduous premolars of equids show increasing molarization and lophodonty through the Eocene. However, our evidence suggests that there was little directed change through most of the Wasatchian until Wa-7. 相似文献
8.
Eria mêdogensis S. C. Chen et Tsi was recently found in southeastern Tibet, several specimens of which have been collected by various botanists since 1980. This is a “normal”
entity with its habit very similar to that of Eria coronaria, from which it differs by having a
regular perianth and longer bracts. We think it probable that this new entity is a peloric form
of Eria coronaria.
Peloria (or pelory) is a type of floral abnormality, which is found in many zygomorphicflowered taxa. It was first detected by Linnaeus (1744) in Linaria vulgaris, and then by others
in Labiatae, Orchidaceae, etc. However, it is still an open question how to explain it theoretically and how to treat it taxonomically.
In Orchidaceae, so far as our knowledge is concerned, peloria has been encountered in no
less than 21 genera. In most cases, peloric flowers are found sporadically on an occassional plant,
as seen in Cypripedium reginae and Eria oblitterata. Sometimes, however, peloric form may occur
coexisting with normal-flowered form in one and the same species, as seen in Dendrobium tetrodon and Epipogium roseum. They are both abnormally peloric forms. It would not result in
naming or renaming a plant taxonomically, whether the appearance of abnormally regular flowers on a normal-flowered inflorescence, or of abnormal-flowered individuals in normal-flowered species. In Phragmipedium lindenii, however, the case is different. It is quite “normal” and
even of wider distribution than its nonpeloric allies P. wallisii and P. caudatum, from which
it has once been considered to be derived. This is a normally peloric form. Whether it is a
reversal or not, the appearance of a “normally” peloric taxon may be taken for a leap in the
process of evolution. Taxonomically, we had better treat it as a separate species, especially when
its origin is uncertain. For example, the entity just mentioned had been treated as a peloric va riety of Phragmipedium caudatum (var. lindenii) until 1975, when Dressler & Williams recognized it as an independent species based on the fact that its nonpeloric flowers occassionally found
in a peloric population in Jungurahua of Ecuador are dissimilar in lip to those in P. caudatum. Garay (1979) considered it to be a peloric form of P. wallisii but maintained it at the
specific level. This is indeed a good example of taxonomic treatment of normally peloric form.
On the other hand, however, most of the regular-flowered entities in Orchidaceae are not
peloric but rather primitive forms, such as Neuwiedia, Apostasia and Thelymitra, of which no
less than 50 species have been reported since the eighteen century. They have never been regarded
as peloric forms. Unfortunately, this has been neglected by some botanists. For instance, a hypothetically primitive orchid flower designed by Pijl & Dodson (1966) has a distinctly specialized
lip with a short spur. In fact, in addition to the aforementioned genera we have some more examples of normally regular-flowered orchids. Among them Archineottia is the most interesting.
This is a genus of four species, two of which are regular-flowered. Of special interest is that in
this genus and its ally, Neottia, one can find all steps of column evolution from a simple form
with stamen and style not fully united to a most complicated form in which they have well fused.
Archineottia has a very primitive column, on which neither rostellum nor clinandrium is found
but a terminal and undifferentiated stigma (Fig.2: 2, 4, 6, 8). In addition, there exists on the
back of the column a thick ridge with its upper end joining the filament with which it is of
same texture. It is obviously the lower part of the filament which has been adnate to the style
(column). In Neottia, however, the column is much more advanced and very typical among the
family. It has a very large rostellum and most complicated stigma structure (Fig. 10, 12, 14, 16,
18). One of the most interesting examples is Neottia acuminata, in which the stigma even
becomes lamellate and almost backwards clasps the erect rostellum, but the perianth is more or
less regular with its lip entire and somewhat similar to, but shorter and wider than, the petals.
In these two genera there are altogether three species, namely Archineottia gaudissartii, A microglottis and Neottia acuminata, possessing regular or nearly regular perianth (Fig. 2: 1, 3, 17).
They are obviously not peloric forms. We can not imagine, indeed, that a complicated form
like Neottia acuminata or its allies would degenerate step by step into a simple form, and finally
into a peloric form. Archineottia belongs to the subtribe Listerinae, which is closely related to
Limodorinae, a rather primitivs subtribe with some genera possessing single pollen grain, relatively few and long chromosomes and monocotyledonous habit. Apparently, there is nothing surprising in the occurrence of some normally regular-flowered taxa, such as Archineottia, Diplandrorchis, Tangtsinia and Sinorchis, in these two primitive subtribes.
Another instance is Aceratorchis, a genus formerly included in Orchis, from which it is distinguished by the entire lip which is more or less similar to the petals. Strictly speaking, however, its flowers are not truly regular. Two species have been described in this genus, but they
were recently considered as conspecific. Aceratorchis tschiliensis is widely distributed from
Hebei through Qinghai and Sichuan to northwestern Yunnan. It is cross-pollinated and produces
seeds efficiently. All these indicate its normally primitive taxon, instead of peloria. It may be
noted here that Asia is rich in members of Orchidioideae, as well as its primitive representatives.
The occurrence of a normally regular-flowered form in Asia, whether representing primitive
form of Orchis or Orchidioideae, is imaginable.
In Orchidaceae, as mentioned above, regular flowers are not only found in some primitive
taxa and peloric forms, but also in a few advanced groups. For example, a close investigation
by the senior author (Chen 1979) on Satyrium ciliatum revealed that this species has hermaphrodite, staminate and pistallate forms, for which no less than nine names have been published.
The flowers of its pistallate form are almost regular, in which nothing is found but three
similar petals and an elongate style with three stigmatic lobes at its top (Fig. 2: 19).
It is interesting to note that floral reversions in Orchidaceae are not always in connection
with peloria. For example, Epidendrum triandrum of North America represents another kind
of reversion. It is a reversal to abnormal polymery of stamens and not to abnormal regularity
of perianth. Like Phragmipedium lindenii, it is also hereditary. We may give it a new name
“Polyandrism” or something else, but, in fact, there is no essential distinction of this kind of reversion from peloria.
It deserves mentioning that most of the regular-flowered entities, including primitive, advanced and peloric ones, occur in Asia and Australasia, where the Orchidaceae may have originated as pointed out by some botanists. We have good reason to verify the primitiveness and
normality of many regular-flowered entities, but there exists no sufficient evidence for the impossible existances of normally regular-flowered species in those like Dendrobium, Eria, Lecanorchis, etc. For instance, Lecanorchis javanica, Dendrobium atavus and the new species described
here are considered to be peloric forms, but it is only a conjecture, for no reason can be given
for it. It is not impossible that some so-called peloric forms may prove to be truly primitive ones
in the future. Of course, a closer investigation is needed.
Summarizing the above, we may come to the following conclusions:
1. Regular or nearly regular perianth is a normal characteristic of orchids. It is chiefly
found in some primitive taxa and sometimes also in certain peloric forms and advanced groups.
Regular-flowered entities may not necessarily be peloric forms.
2. There exist two different types of peloria in Orchidaceae. One is abnormal form, with
its peloric flowers appearing at random. The other is “normal” form, with its individuals all
possessing peloric flowers. The latter is inheritable and can produce seeds efficiently, It would
be best to treat it as an independent species taxonomically, especially when its origin is uncertain.
3. Although peloria has been considered to he a reversal as a whole, conditions vary from
plant to plant. Some peloric forms have petal-like lip, and others have labellum-like petals.
Sometimes the same plant produces different kinds of peloric flowers in different years, sometimes
peloric flowers do not reappear upon the same plant. A few species can produce both peloric
and normal individuals, but others produce peloric forms only. Peloria is in fact a term only
used to cover the phase in which lip becomes similar to the petals. It is never all-embracing.
We recognize the existance of peloria in Orchidaceae, but great care must be taken to distinguish
truly peloric form from normally primitive one. It must be admitted that what causes peloria
and even what is peloria are still problems awaiting solution.
Acknowledgments: Our heartfelt thanks are due to Dr. Leslie A. Garay, Curator of the
Orchid Herbarium of Oakes Ames, Botanical Museum of Harvard University, for his valuable
suggestions during the preparation of this paper. We are also indebted to the artists, Mrs. Chunrung Liu and Mr. Chao-zhen Ji of our department, for their preparing the fine drawings. 相似文献
9.
Lisa Noelle Cooper Erik R. Seiffert Mark Clementz Sandra I. Madar Sunil Bajpai S. Taseer Hussain J. G. M. Thewissen 《PloS one》2014,9(10)
Anthracobunidae is an Eocene family of large mammals from south Asia that is commonly considered to be part of the radiation that gave rise to elephants (proboscideans) and sea cows (sirenians). We describe a new collection of anthracobunid fossils from Middle Eocene rocks of Indo-Pakistan that more than doubles the number of known anthracobunid fossils and challenges their putative relationships, instead implying that they are stem perissodactyls. Cranial, dental, and postcranial elements allow a revision of species and the recognition of a new anthracobunid genus. Analyses of stable isotopes and long bone geometry together suggest that most anthracobunids fed on land, but spent a considerable amount of time near water. This new evidence expands our understanding of stem perissodactyl diversity and sheds new light on perissodactyl origins. 相似文献
10.
This low magnification stereomicrowear study samples a broad range of chalicotheres (Perissodactyla, Chalicotherioidea), including
basal chalicotheres and the two chalicotheriid subfamilies Schizotheriinae and Chalicotheriinae, primarily including species
from North America and Europe, but also some from Asia. The schizotheriines Moropus, Tylocephalonyx, and Metaschizotherium and the chalicotheriines Anisodon and Chalicotherium are best represented. Paleodiets are interpreted via discriminant analysis, using comparison of microwear variables from
fossil chalicothere teeth with those from a database of extant ungulates with known diets. The results suggest that all of
the chalicotheres in the study were browsers, with no evidence of significant grass consumption. Basal chalicotheres, like
basal equids, seem to have been standard fruit-dominated browsers. Stereomicrowear agrees with mesowear results by Schulz
et al. (2007) and Schulz and Fahlke (2009) for Metaschizotherium bavaricum, Metaschizotherium fraasi, Anisodon grande, and Chalicotherium goldfussi in showing a highly abrasive aspect to the diet. In these species, hard food objects such as fibrous fruits, seeds, pits,
and nuts may have abraded the teeth (based on high pit counts, the presence of large puncture pits, and many individuals with
coarse to hypercoarse scratches). Anisodon grande and C. goldfussi, despite their relatively short, brachydont teeth, show the highest degree of abrasion within the studied sample. Moropus and Tylocephalonyx from North America show somewhat different but also abrasive microwear; in these taxa the resistant foods may have been twigs
and bark (large pits common, but gouging more prevalent than puncture pits). A preliminary comparison of stereomicrowear on
DP4, the deciduous upper fourth premolar, with that on molars suggests that juveniles consumed similar foods as adults but
without the most abrasive elements. Some important methodological differences regarding the scoring of microwear features
by different low-magnification microwear methodologies are discussed. 相似文献
11.
Cypripedium subtropicum S. C. Chen et K. Y. Lang is a phytogeographycally significant new species with its habit, inflorescence and column very similar to
those of Selenipedilum of tropical America. It is found in Mêdog of southeastern Xizang, China. Its slender leafy stem bears at the summit a many-flowered raceme, amounting to 1.5 m in height. Although its ovary is unilocular—this is the reason why
we place it in Cypripedium, the column characters resemble those of Selenipedilum. For
example, the staminode is rather small and its long stalk is very similar in texture and
color to the filament of the fertile stamens. Obviously, it is a primitive new species related to Selenipedilum based on the similarities mentioned above.
In the subfamily Cypripedioideae, as generally recognized, Selenipedilum is the
most primitive genus, from which or whose allies Cypripedium is derived. Of phytogeographical significance is the fact that Selenipedilum occurs in Central America and
northern South America, while a cypripedium akin to it is discontinuously distributed
in subtropical Asia. This suggests that Selenipedilum or Selenipedilum-like form be
once continually distributed in North America and eastern Asia when the climate there
was warmer, as it is in the subtropics today. The floristic relationship between Central
America and subtropical Asia appears to be closer than expected, as shown by the distribution patterns of Tropidia, Erythrodes, etc. Based on the occurrence of all six sections and particularly the most primitive form in eastern Asia, Cypripedium seems to
be of Asian, rather than Central American, origin. Selenipedilum possesses some very
primitive characters, such as trilocular ovary, vanilla-scented fruit, seed with sclerotic
testa, simple column and more or less suffrutescent habit. The latter is considered by
Dahlgren & Clifford (1982) to be one of ancestral characters of monocotyledons, which
is now very rare not only in Orchidaceae but also in all monocotyledons. It is indeed
necessary to make further investigations on Selenipedilum and also the new species pub-lished here, as well as a detailed comparison between them. 相似文献
12.
《Ibis》1952,94(2):306-309
The Bare-throated Francolins formerly placed in the genus Ptermistis are considered to be members of the genus Francolinus (little adjustment of nomenclature is needed). Their relationship to Francolinus in environment is considered. The systematics of F. afer are discussed and attention is drawn to the genetic features of its hybrid populations. 相似文献
13.
Chen Sing-Chi 《植物分类学报:英文版》1979,17(1):1-6
Diplandrorchis is a very curious new orchid genus, containing only one species D.
sinica S. C. Chen, found in Huan-ren County of Liaoning Province in northeastern
China. It, as the genus name implies, has two fertile stamens, borne on the upper
part of the column near the terminal stigma. One of them is opposite to the dorsal
sepal, while the other to the median petal (lip). Thus, they represent two median
stamens of both inner and outer whorls. This is quite unique in the whole family,
including the diandrous group, in which the two stamens are opposite to the lateral
petals and thus represent the lateral ones of the inner whorl.
The flower is erect, with its pale greenish or whitish perianth nearly regular.
Two lateral sepals are more or less oblique, showing some difference from the dorsal
one, but the three petals, which are thinner and narrower, are very similar to each
other. Neither rostellum nor any other appendages are found in its column, but a
terminal stigma and two erect stamens. The pollinia are naked and granular, which,
in almost all flowers examined, have naturally fallen out of their cells on to the stigma.
Apparently, it is self-fertilised, as found in Tangtsinia and some other primitive
orchids.
Besides, this interesting orchid is a dwarf saprophyte, with its habit very similar
to that of Neottia, another saprophytic genus assigned to the subtribe Neottiinae. The
fact that the saprophytic orchids are largely found in the primitive subtribes, such as
the Neottiinae, Limodorinae, Vanillinae and Pogoniinae, is worthy of special attention.
Theoretically, the saprophytic plants must have developed from green-leaved plants. In
the Orchidaceae, however, what ancestor are the most primitive saprophytes derived
from ? This is indeed an interesting question closely related to the origin of the
Orchidaceae.
From the facts mentioned above, the present genus is a very primitive or relic
one and of great phylogenetic interest. It is placed here as the most primitive member
in the subtribe Neottiinae, although it is sharply distinct from the remaining generaof this subtribe. It may deserve a separate subtribe, but further study is needed. 相似文献
14.
中国蔷薇科绣线菊亚科的演化、分布——兼述世界绣线菊亚科植物的分布 总被引:15,自引:0,他引:15
绣线菊亚科是蔷薇科最原始的亚科,共有22属260余种, 包括常绿和落叶两大类群,前者是 原始类型。我国有8属100种,全都为落叶性。本文着重讨论中国各属的起源、演化和分布等 ,同时也概述全亚科植物在世界各植物区的分布等问题。绣线菊属Spiraea是该亚科落叶类群中最原始的属,它在早期发生趋异进化,衍生出形态各异而亲缘关系密切 的不同属,本文阐明了中国各属的系统位置和属间的亲缘关系。通过对我国各属地理分布的 分析对比,属的分布区可归纳为5个类型。对全球绣线菊亚科植物在世界各植物区中的属、种数统计表明,东亚区有8属105种,其中有96个特有种,是该亚科植物分布最多而又最集中 地区,具有在系统发育上处于各主要演化阶段的落叶类型,因此,东亚区是全球绣线菊亚科植 物的现代分布和分化中心,也是落叶类群发生和发展的关键地区。在北美洲,从马德雷区至落基山区一带分布着11属46种,均为特有种,显然北美洲西部也是该亚科植物的现代分布中心,但可能是第二分布中心。南美洲至今保存2个较古老的常绿属,即Quillaja和K ageneckia,基于此,南美洲可能是绣线菊亚科某些常绿属早期分化和发展的关键地区 。中国绣线菊亚科植物在东亚区占绝对优势,有8属82种,其中有62个特有种,分别占该区属 、种和 特有种数的100%、82%、和65%, 这些类群分布最密集地区是在中国喜马拉雅森林植物亚区 中的横断山脉地区和中国日本森林植物亚区的西部,这一带是中国绣线菊亚科的现代分布和多样性中心,很可能是某些属的发源地。由此看来,绣线菊亚科的落叶属可能起源于劳亚古陆。据化石记载,该亚科植物的起源时间可以追溯到白垩纪早白垩世。 相似文献
15.
Bin Bai Jin Meng Christine M. Janis Zhao‐Qun Zhang Yuan‐Qing Wang 《Ecology and evolution》2020,10(13):6333-6355
Cenozoic mammal evolution and faunal turnover are considered to have been influenced and triggered by global climate change. Teeth of large terrestrial ungulates are reliable proxies to trace long‐term climatic changes due to their morphological and physicochemical properties; however, the role of premolar molarization in ungulate evolution and related climatic change has rarely been investigated. Recently, three patterns of premolar molarization among perissodactyls have been recognized: endoprotocrista‐derived hypocone (type I); paraconule–protocone separation (type II); and metaconule‐derived pseudohypocone (type III). These three patterns of premolar molarization play an important role in perissodactyl diversity coupled with global climate change during the Cenozoic in Asia. Those groups with a relatively higher degree of premolar molarization, initiated by the formation of the hypocone, survived into Neogene, whereas those with a lesser degree of molarization, initiated by the deformation of existing ridges and cusps, went extinct by the end of the Oligocene. In addition, the hypothesis of the “Ulan Gochu Decline” is proposed here to designate the most conspicuous decrease of perissodactyl diversity that occurred in the latest middle Eocene rather than at the Eocene–Oligocene transition in Asia, as conventionally thought; this event was likely comparable to the contemporaneous post‐Uintan decline of the North American land fauna. 相似文献
16.
Lu Ling-ti 《植物分类学报:英文版》1996,34(4):361-375
The subfam. Spiraeoideae, consisting of 22 genera and more than 260 species in the world,is the most primitive subfamily of Rosaceae. It has developed into two groups,i.e. evergreen and deciduous ones, of which eight genera and 100 species in China are totally deciduous. In the present paper, the origin,evolution and distribution of the Chinese genera is discussed mainly, and the distribution of the whole subfamily in the floristic regions of the world is also mentioned. Based on evolutionary trends of morphological characters, Spiraea L. is considered as the most primitive genus in the deciduous group of subfam. Spiraeoideae, from which some genera are been derived, the systematic position and evolutionary relationships between different genera are elucidated in this paper. Through the analysis on the geographical distribution of the genera in China, the areal types may be divided as follows: (1) North Temperate Type: Spiraea, Physocarpus, Aruncus. (2) East Asian and North American Disjunct Type: Sorbaria. (3) Mediterranean, West Asian (or Central Asia) and East Asian Type: Sibiraea. (4) Temperate Asian Type: Exochorda.(5) East Asian Type: (a) Sino Himalayan Distribution: Neillia; (b) Sino Japan Distribution: Stephanandra. After analysis of the distribution of subfam. Spiraeoideae in the world, it is shown that the Eastern Asiatic Region, being the richest in genera, species and endemic species of the world,is not only the center of distribution and differentiation,but also an important region for occurrence and development of some deciduous genera of this subfamily, while in North America, the Madrean Region and Rocky Mountain Region, genera, species and endemic species are abundant, which indicates that the western part of North America is also the distribution center of this subfamily at the present, but it may be the secondary center of distribution. It can be seen that the relatively primitive and evergreen g enera, i.e. Quillaja and Kageneckia, are now confined to South America. The fact implies that the South America may be the region for early differentiation and development of the evergreen genera in Subfam. Spiraeoideae. The analysis of Chinese plants has shown that China has the most members of the subfamily in Eastern Asiatic Region, with eight genera, 82 species and 62 endemic species and that the maximum concentration is in western Sichuan, northwestern Yunnan and their adjacent areas. It is very obvious that the center of distribution and diversity of Subfam. Spiraeoideae in China lies in the Hengduan Mountain Region of Sino Himalayan Forest Subkingdom and the western part of Sino Japan Forest Subkingdom, where may be the birthplace of some genera in China. It may be considered that the deciduous genera of Subfam. Spiraeoideae might have originated in Laurasia.According to the fossil records, the time of origin of Subfam.Spiraeoideae dates back to the Lower Cretaceous. 相似文献
17.
W H Sawyer 《Federation proceedings》1977,36(6):1842-1847
Nine active neurohypophyseal principles have been isolated and identified among the vertebrates. Arginine-vasotocin is the most ubiquitous, occurring in pituitary glands from representatives of all the major vertebrate groups. There is much more variation in structure among the principles that resemble oxytocin. The manner in which these evolved remains unclear. Arginine-vasotocin stimulates smooth muscles from a wide variety of vertebrate species. It can stimulate contraction of oviducts from many jawed fishes and tetrapods. The oxytocin-like peptides are usually less active in this respect. Among adult mammals arginine-vasotocin is replaced by arginine-vasopressin which has much less oxytocin activity. Thus, although arginine-vasotocin may both stimulate oviducts and cause water retention in nonmammalian tetrapods, oxytocic and antidiuretic functions can be regulated independently by oxytocin and vasopressin in mammals. Arginine-vasotocin elicits vasoconstrictor responses in even the most primitive vertebrates. These may be systemic or regional. Their distribution may determine whether arginine-vasotocin acts as a diuretic or an antidiuretic agent. It is possible that the most primitive neurohypophyseal functions were related to cardiovascular regulation and that the neurohypophysis acquired its osmoregulatory functions later in vertebrate evolution. 相似文献
18.
Elke Willen 《Hydrobiologia》1995,302(3):241-255
Male and female of a new genus and species of the family Laophontidae, Archilaophonte maxima, are described. The specimen was found in the high Antartic (Weddell Sea) and apprears to be the most primitive genus up to now within the superfamily Laophontoidea as defined by Huys (1990). Based on its setation of legs and mouth parts, however, it can be placed unequivocally into the family Laophontidae. Archilaophonte maxima gen. n. shows close affinities to the laophontid genus Esola Edwards 1891. Both genera form a monophyletic group which is interpreted here as the first and most primitive offshot in the evolution of the Laophontidae. The synapomorphies of the former lineage are the shape of the protopodite of the P1 and shape and setation of the female P5. 相似文献
19.
B. J. MARPLES F.L.S. 《Biological journal of the Linnean Society. Linnean Society of London》1968,179(1):11-31
A group of five genera of spiders has in the past been placed in a special sub-order the Hypo-chilomorpha, lying between the Mygalomorpha and the Araneomorpha. In general they resemble the araneomorphs, but they share some primitive characters, notably the presence of two pairs of lungs. Four of them, Hypochilus, Ectatosticta, Hickmania and Austrochilus have a cribellum, while Gradungula does not. In attempting to determine their relationships, their internal anatomy is here compared with that of the members of the three main suborders, Liphis-tiomorpha, Mygalomorpha and Araneomorpha. The conclusion arrived at is that these genera belong to the Araneomorpha, and that there should not be a suborder Hypochilomorpha. Hypochilus and Ectatosticta are very similar and are placed in the family Hypochilidae, while the other three are placed in individual families. Within the Araneomorpha there seem to be two evolutionary lines. In one, the Cribellata, the anterior median spinnerets of the ancestor remained functional and became the cribellum. In the other, the Ecribellata, the anterior median spinnerets lost their function and became vestigial or absent. The most primitive cribel-late family is the Hypochilidae, while the Gradungulidae is the most primitive ecribellate one, at least with respect to its lungs and heart. 相似文献
20.
Paphiopedilum malipoense S. C. Chen et Tsi is a very interesting new species with its flower similar to that of Cypripedium, especially section Cypripedium. It belongs
to subgenus Brachypetalum, the most primitive group of Paphiopedilum, but differs from
its allied species in hgniva elliptic-lanceolate sepal with cuspidately acuminate apex, rather
narrow petals and horizontal lip, which are of common occurrence in many cypripediums, but
very rare in paphiopedilums. Apparently, this is an intermediate form, or a link, between
Paphiopedilum and Cypripedium, but it does not seem to arise from hybridization between
them, because no Cypripedium has been found wherever Paphiopedilum occurs.
The new species is distributed in southeastern Yunnan of China. In this area, as well
as in river valleys of western Yunnan or the Hengduan Mountains, there have been four
species of the same genus reported before. As we know, the Hengduan Mountains and their
adjacent areas are rich in Cypripedium. The differentiation of the genus there is remarkable. All five sections it contains occur there and three of them are quite distinctive. For
example, the general appearance of the section Bracleosa is dissimilar to that of any other
cypripediums, but closely resembles that of Listera. It appears that the difference between
sect. Bracteosa of Cypripedium and sect. Brachypetalum of Paphiopedilum is not necessarily wider than that between sect. Bracteosa and sect. Cypripedium of the same genus.
Apparently, it is reasonable to consider Paphiopedilum to be an evolutional branch of Cypripedium extending into tropical area, with its primitive group (subgenus Brachypetalum)
still remaining in its northern fringe area. This primitive subgenus has eight species, distributed from western Yunnan to the Malay Peninsula. Five of them, including the intermediate and primitive form published here, are found in the hilly land of southeastern Yunnan and the river valleys of western Yunnan. All these facts suggest its area of origin: the
river valleys of the Hengduan Mountains and the lower hilly land contiguous to the southof them. 相似文献