甘肃临夏盆地晚中新世鬣狗类群头骨的几何形态测量学及生态形态学分析(英文)

在晚新生代大型食肉目动物中,鬣狗科动物地史分布广、种类和数量多,在中国出现于中中新世至更新世晚期的地层中。形态功能学家将鬣狗科的60多个化石种分为似豺、似狼和似灵猫等生态类群,这些生态类群和现生仅存的3个食骨和1个食虫类群形成鲜明的对比。生态形态学是基于生物形态与生态环境的密切关系研究不同物种形态所代表的生态位的一种方法;研究者依靠化石鬣狗类与现生种类牙齿和头骨整体形态的相似度进行了生态形态(ecomorphology)的分类,但尚未对这些已定的生态形态进行过多变量的头骨形状分析。本文拟采用平面几何形态测量学的方法对晚中新世临夏盆地的鬣狗类进行研究,并探讨以头骨形状划分其生态形态类型的可行性。几何形态测量法是以生物形态的轮廓作为数据的计算方法,虽然目前尚未被国内古生物研究者广泛采用,但自20世纪30年代多变量统计学的理论成熟以来,这一方法的理论基础和软件算法在国外得到迅速发展,至今已成为近代生物学(neontology)和古生物学形态研究领域的一个常用工具。三维几何形态测量分析也因为三维激光扫描仪的普及而变得更简单和直观。然而,化石标本由于埋藏和保存的关系通常会出现变形或残缺不全,使目前几何形态测量方法在古生物学的应用仍主要以平面数据分析为主。平面数据采集的第一步是从与标本某一平面相垂直的角度拍摄数码照片;虽然拍摄平面的选择通常由研究者自定,但一般会选择待研究类群形状变异最具代表性的一面(如,鱼类一般选取侧视)。第二步是形态的数字化,即使用某一种形态测量软件来标出地标点(landmarks;或称界标点、标志点、标点)。地标点的选择对于分析的结果有直接而且重要的影响,一般会选择Bookstein分类中的I型或II型作为地标点的标准。这两种地标点的共同点是可以从解剖学特征上准确地在每一个标本上找到,而无不明确或复现困难的可能性。数字化后的数据在软件中用数学算法叠加起来(superimposition,或称叠合,重叠),以去除原始图片数据中标本位置、角度及其他与几何形态无关的冗余信息。所有的数字化数据叠加起来后,利用软件计算所有标本之间的几何距离。现在常用的软件中都会以平均几何形状作为中心,而且利用类似主成分分析(principal components analysis)的多变量计算来呈现相对扭曲(或称相对反卷)轴(relative warp axis),后者即是可以用来把形态差异视觉化的多变量数据。这些数据可以用平面坐标图来看不同形态的空间分布,也可以用所谓的薄板样条曲线图(thin-plate spline grid)来表示相对形态上的变化。相对扭曲轴所代表的形状数据还经常被拿来与代表几何物体大小的距心值(或称重心距离,centroid size)做回归曲线分析,以便发现种群中某些形态的异速生长模式(allometry)。本文采用几何形态测量的方法对产自和政地区的鬣狗科Hyaenictitherium,Ictitherium,Adcrocuta和旁鬣狗科Dinocrocuta的材料进行研究,分析了这4个属保存完好的头骨标本的侧面形态。与东非大草原现生食肉动物的头骨整体形态分布的比较和分析表明,和政的鼬鬣狗(Ictitherium)和鬣型鼬鬣狗(Hyaenictitherium)的头骨形状分布介于现生斑鬣狗(Crocuta crocuta)、犬科猎狗(Lycaon pictus)和金豺(Canis aureus)之间,为二者似豺生态形态的解释提供了几何形态测量证据。再者,上述两属化石鬣狗的形状分布与现生斑鬣狗的幼年个体形状重叠,表明现生斑鬣狗头骨的发育机制可能是在鼬鬣狗祖先类型的异速生长规律基础上的持续发育,进而演化出现有的粗壮形态。此外,巨鬣狗(Dinocrocuta)和副鬣狗(Adcrocuta)的头骨形状与现生的斑鬣狗在几何形态测量空间内有普遍重叠的现象,指示了这些异时出现的种类具有相似的生态形态,因而可能占据相近的生态位。结果还显示巨鬣狗和斑鬣狗的幼年个体形状相近,以及两者从幼年到成年发育的形状变化过程也具有相似的规律。因而,巨鬣狗和斑鬣狗之间的趋同演化不仅表现在成年头骨的粗壮程度上,而且在幼年发育模式中也存在平行演化现象。现生发育学与行为生态学已经证实,相对其他大型食肉动物,现生斑鬣狗发育粗壮头骨形态的机制不是以增速生长,而是以延长发育期来实现的。由此推断,巨鬣狗的发育期有可能和现生鬣狗相当(35个月),也可能由于具有相对粗壮和巨大的头骨形态,其发育期会延长些。当然,这个新解释仍需要更多的化石数据和发育研究来证实。     

华北京津冀地区兽类新纪录——香鼬

香鼬(Mustela altaica Pallas,1811)属食肉目(Carnivora)鼬科(Mustelidae)鼬属(Mustela),是分布于东亚和中亚的一种小型食肉动物,主要以小型啮齿动物为食,其典型栖息地为海拔1 500～4 000 m的森林、森林草原、高山草甸及灌丛或多岩石的山地等环境(高耀亭等,198...     

内蒙古三盛公渐新世古鼬(食肉目,古鼬科)新材料及系统发育关系分析

古鼬属(palaeogale)由H.von Meyer于1846年建立,欧亚大陆以及北美的晚始新世一中新世地层中均有报道。但受化石标本以及研究程度的限制,古鼬的分类位置问题一直存在争议,曾被分别归入鼬科(Mustelidae)、古灵猫科(Viverravidae)、猫科(Felidae)、古鼬科(Palaeogalidae)和猫型亚目(Feliformia)科未定等。内蒙古三盛公地区新发现了5件古鼬标本,其中IVPP V 19325(包括属于同一个体的一件残破头骨、一对近乎完整的下颌以及一些椎体和肋骨)是目前为止亚洲发现的保存最完好的标本。本文详细描述了这些新材料,并基于新材料,结合前人的图版描述,提取了古鼬的形态学性状特征用于系统发育关系分析。参考Wesley-Hunt and Flynn(2005)的系统发育关系分析,选用了共计42个类群的100个性状特征进行了分析。此外,对12个现生类群的6个基因(细胞核基因TR-i-I,TBG和IRBP;线粒体基因ND2,CYTB和12S rRNA),共计5893个碱基对进行的分子系统发育关系分析,帮助完善了古鼬的形态学系统发育关系分析结果。50%多数合意树的结果显示古鼬与鼬科及古灵猫科均无明显的亲缘关系,而是位于猫型亚目基干位置,代表了猫型亚目下一个原始的支系,可被归入古鼬科(Palaeogalidae)。同时,还厘定了古鼬科的鉴定特征。未来还需要更完整的性状数据,尤其是耳区的性状特征,来完善古鼬的系统发育关系分析。     

准噶尔盆地北缘中中新世偶蹄类

本文记述了新疆准噶尔盆地北缘哈拉玛盖组中的偶蹄类七属七种(包括一个新种Eot-ragus halamagaiensis sp.nov.),奇蹄类三属三种。其中始羚在在国内尚属首次报道。该化石集群与内蒙东部的通古尔动物群比较两者成分相接近,但其中一些分子具有更原始的特征。显然哈拉玛盖组比通古尔组的沉积时期早,但仍属中中新世通古尔期。     

大熊猫巴氏亚种齿列变异一例的分析

一、材料来源柳州博物馆保存了来自柳州市东南郊东方红公社新风大队楼梯山水边洞(野外号:74099)的大熊猫下颌骨和花面狸(Paguma larvata)头骨各一个。根据这一线索,1974年12月,我们与广西博物馆、柳州博物馆共同在这一地点作了发掘,又获得一具大熊猫头骨(V4715),和前一件标本属同一个体。根据尺寸大小和形态特点,它属巴氏亚种(我们同意王将克的意见,采用如下学名:Ailuropoda melanoleuca baconi)。同时获得的其它哺乳动物化石有:     

Dinocrocuta gigantea头骨的发现

本文记述了甘肃和政县晚中新世地层中发现的一个完整的巨鬣狗头骨;讨论了它的分类地位,修正了 Schlosser 1903年建种时的一些鉴定错误.巨鬣狗是鬣狗科中一个十分特化的成员,应代表一个独立的属.根据命名规则,我们采用 N. schmidt-Kittler 1976年所创的 Dinocrocuta. 因此,这个种应订正为 Dinocrocuta gigantea (schlosser, 1903).     

记裂头鳄属(Dibothrosuchus)一新种

本文记述的裂头鳄属-新种 (Dibothrosuchus xingsuensis sp. nov.)的标本采自云南禄丰盆地下禄丰组深红层.通过描述,对裂头鳄属属级特征作了补充.新种的头骨中鳞骨缺失降突;方骨极度向前背方伸展,形成大的耳凹,乌喙骨具后腹突,以及具有鳄类式的腕骨等,表明裂头鳄属应改属为楔形鳄科 (Sphenosuchidae).根据该科各属的头骨中方骨与脑颅侧壁的连接关系,可以清楚地看到楔形鳄科在这局部解剖学上存在一连续的发展过程.在形态上,裂头鳄属和南非的 Sphenosuehus (典型属)最为相近.     

肯尼亚新发现的头骨化石改变了人类进化系统树的模式

1986年8月,肯尼亚国家博物馆的理查德·利基(Richard Leakey)宣布,他们在肯尼亚北部特卡纳湖两岸发现了一个非常完整的人科成员的头骨(缺下颌骨),年代为距今250万年。这个发现使原先的二分叉模式的人类进化系统树改变成了三分叉的模式。 这个头骨是1985年夏季由美国约翰·霍普金斯大学的沃克(Alan Walker)从特卡纳湖西岸富含化石的堆积中发现的,头骨标本编号为KNM-WT17000,这个地点就在1984年发现著名的直立人男孩的完整骨架以南32公里处,但其层位较     

宁夏同心发现的一颗上猿牙齿

本文记述了采自宁夏同心地区中中新世(相当于通古尔早期)地层中一颗上猿的左下第二臼齿。它的齿冠形态和Hurzeler(1954)以Goriach地点为基础所总结出的上猿下臼齿的“模式”形态基本一致,而和其它几个在形态上比较接近的属,如湖猿、树猿、宽齿猿和池猿等有较明显的区别。这是我国第一颗比较可靠的上猿牙齿化石。     

通古尔河狸化石的新材料

本文內記述的內蒙二連通古尔的河狸化石是属于单沟河狸(Monosaulax)的一下頜骨。标本是由中苏古生物工作者在1959年采集的。它是继河北张北的张北单沟河狸(M.changpeiensis Li)之后該属化石在我国的又一次发現;但无論从它的地貭时代或牙齿型式来看与张北种都有不同。通古尔的标本是中新世晚期的一种較为进步的单沟河狸,     

Studies of fossil hyaenids: the genus Adcrocuta Kretzoi and the interrelationships of some hyaenid taxa

Material of the Miocene hyaenid Adcrocuta eximia from China is analysed statistically. No heterogeneities were found within this material. Comparisons with material from Samos and Pikermi, Greece, show that no taxonomic differentiation between these three samples is warranted. Adcrocuta eximia latro from the Sivalik deposits is provisionally considered a valid subspecies. The species A. australis from Langebaanweg, South Africa is removed from Adcrocuta to the genus Chasmaporthetes . The phylogenetic position of Adcrocuta has been subject to dispute, and for this reason we present a study of the interrelationships of selected hyaenid taxa using numerical cladistic methods. Two equally parsimonious trees of length 47 and consistency index 0.766 were found. Adcrocuta is placed as a sister-group to the Recent Crocuta crocuta , and not as a separate clade as suggested by other workers. Recent hyaenids form a crown-group which does not extend deep into the cladogram. Hyaena hyaena and H. brunnea are not sister-groups, and we resurrect the genus Parahyaena for the latter species.     

A New Skull of <Emphasis Type="Italic">Hyaenictis</Emphasis> Gaudry, 1861 (Carnivora,Hyaenidae) Shows Incipient Adaptations to Durophagy

The European Miocene records a wide diversity of hyaenid ecomorphotypes represented by multiple genera. Among these, Hyaenictis Gaudry, 1861, is one of the least known. This genus includes four species from the late Miocene and Pliocene of the Old World, but in Europe Hyaenictis is only represented by two species, recorded by scarce and fragmentary remains: Hyaenictis graeca Gaudry, 1861, from Pikermi (MN12; Greece) and Hyaenictis almerai Villalta Comella and Crusafont Pairó, 1948, from Sant Miquel de Toudell (MN10; Vallès-Penedès Basin, NE Iberia). Here, we describe a new skull of Hyaenictis aff. almerai from the Vallès-Penedès site of Ronda Oest Sabadell Sector D (MN10), representing the most complete European specimen of the genus. In the presence of m2 and virtual lack of m1 metaconid, the described cranium more closely resembles Hyaenictis rather than any other medium- to large-sized European hyaenid. However, the new skull does not fit well with previously known Hyaenictis species, more closely resembling the bone-cracking Adcrocuta Kretzoi, 1938, in the development of premolar accessory cuspids and the possession of relatively broad cheek teeth. These and other features (strong mandibular muscular insertions and enamel microstructure) denote more durophagous adaptations than previously documented in Hyaenictis (considered a cursorial/dog-like hyaena), and favor the inclusion of H. aff. almerai in the transitional bone-cracking hyaenid ecomorphotype.     

Miocene hyaenids (Hyaenidae; Carnivora) from Siwaliks of Pakistan

Newly discovered Miocene hyaenid specimens, recently collected from the Siwalik Group, are described and discussed. A careful comparison with the known material reveals that these specimens belong to the early hyaenid species Thalassictis cf. T. proava, Ictitherine indet. and Lepthyaena sivalensis. The stratigraphic range of T. proava extended up to the Dhok Pathan Formation (Middle Miocene to Early Pliocene). The stratigraphic range of T. proava comprises the Middle to Late Miocene, with the youngest record in Hasnot, Potwar Plateau in the Siwalik Group. The material is of great interest because Siwalik carnivoran material is rare.     

Mosaic functionality in a transitional ecomorphology: skull biomechanics in stem Hyaeninae compared to modern South African carnivorans

Ecomorphologies are categories of ecological adaptation and function, although intermediates are not always available to shed light on functionality at the transitional stages between them. We examined an intermediate bone‐cracking carnivoran ecomorphology, the stem hyaenine Ikelohyaena abronia, using finite element analysis. Skull models of Ikelohyaena, crown hyaenine Crocuta crocuta, and two other hypercarnivores were simulated with mastication and prey apprehension forces. The results obtained show that Ikelohyaena already possessed derived features in skull stress distribution and levels of strain energy, characteristic of the extant bone‐cracking Crocuta; however, the estimated bite forces in Ikelohyaena were significantly lower. Prey apprehension simulations showed similar patterns; the low skull strain energy and low bite force of the Ikelohyaena mandible indicate a poor individual ability to take down large prey. The mosaic features of craniodental function in Ikelohyaena suggest that initial evolution of the hyaenid bone‐cracking ecomorphology involved skull shape changes that increased stress dissipation, permitting incorporation of more hard food into the diet. Subsequent evolution of larger bite forces was then required to increase the size limit of bones that can be cracked and consumed. This mode of evolution would have allowed transitional hyaenid ecomorphologies to continuously increase the carcass processing ability both during competitive feeding and scavenging throughout their evolution. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 540–559.     

Taxonomical reappraisal of “ictitheres” (Mammalia,Carnivora) from the Late Miocene of Kenya

In 2003, Werdelin has identified three hyaenid species from the Late Miocene of Kenya (Lothagam Formation), including two “ictitheres” – a newly erected Ictitherium ebu Werdelin, 2003, and Hyaenictitherium cf. parvum. The present article discusses the published evidence on the Kenyan hyaenids and explores additional cranial and postcranial characters useful for differentiation between the true ictitheres (i.e., the genera of the subfamily Ictitheriinae Trouessart, 1897) and some small members of the subfamily Hyaeninae Gray, 1869.     

The deciduous dentition ofPercrocuta Kretzoi and the diphyletic origin of the hyaenas (Carnivora,Mammalia)

A juvenile mandible with complete deciduous dentition from the Middle Miocene locality Jianshan near Shilee (Xinan County, Honan Prov., China) belonging toPercrocuta hobeiensis Chen Guanfang & Wu Wenyu is described. The lower deciduous carnassial, which is by far the most informative element of the juvenile dentition, is distinguished from the D₄ of all other hyaenas by fundamental differences and exhibits principal similarities to that of the felids. Although these resemblances are very likely a result of parallel evolution, they can be taken as evidence of a considerable phylogentic distance betweenPercrocuta on one side and the Recent hyaenas with their forerunners on the other side. Judging from the special features of the deciduous carnassial and the high degree of hyaenid adaptation already attained in the Middle Miocene,Percrocuta probably derived from the neighbourhood of the Upper Oligocene and Lower Miocene generaStenoplesictis, Palaeoprionodon andProailurus, which in their turn take up a phylogenetically transitional position between felids and viverrids.     

Studies of fossil hyaenids: the genus Adcrocuta Kretzoi and the interrelationships of some hyaenid taxa

Material of the Miocene hyaenid Adcrocuta eximia from China is analysed statistically. No heterogeneities were found within this material. Comparisons with material from Samos and Pikermi, Greece, show that no taxonomic differentiation between these three samples is warranted. Adcrocuta eximia latro from the Sivalik deposits is provisionally considered a valid subspecies. The species A. australis from Langebaanweg, South Africa is removed from Adcrocuta to the genus Chasmaporthetes. The phylogenetic position of Adcrocuta has been subject to dispute, and for this reason we present a study of the interrelationships of selected hyaenid taxa using numerical cladistic methods. Two equally parsimonious trees of length 47 and consistency index 0.766 were found. Adcrocuta is placed as a sister-group to the Recent Crocuta crocuta, and not as a separate clade as suggested by other workers. Recent hyaenids form a crown-group which does not extend deep into the cladogram. Hyaena hyaena and H. brunnea are not sister-groups, and we resurrect the genus Parahyaena for the latter species.     

Allohyaena (Mammalia: Carnivora): giant hyaenid from the Late Miocene of Hungary

The topotypic material of the giant Late Miocene hyaenid Allohyaena kadici Kretzoi is described. New data on the deciduous dentition shows unambiguously that A. kadici is a hyaenid and not a percrocutid as reported by some previous authors. A. kadici is compared to the large hyaenids Adcrocuta eximia and Crocuta crocuta. These comparisons show that A. kadici has a mixture of primitive characters such as dp4 morphology, retention of m2, long and slender premolars and a large protocone on P4, and derived characters such as a preparastyle on P4, an internal root on P3 and a uniquely derived talonid structure of ml. This combination of features makes A. kadici difficult to classify, but it is considered to probably be most closely related to derived, bone-cracking hyaenids such as Pachycrocuta and Crocuta. A. kadici is rare in the fossil record, being found at only two sites. We suggest that the reason for this rarity is that it had a geographic and stratigraphic range which is poorly sampled in the Miocene fossil record of Europe.     

Evolution and systematics of the feliform Carnivora

Recent studies have improved our knowledge about the evolution and phylogeny of feliform taxa. Detailed study on new fossil remains of extinct feliform nimravides allows a new hypothesis concerning interrelationships within this family. Many factors indicate lack of sister relationships of Nimravinae and Barbourofelinae. However, only further investigations may bring full acceptance of this hypothesis. The paraphyly of Viverridae has been resolved by excluding the taxa Nandinia, Prionodon and Cryptoprocta and Fossa, which today are placed basally to all remaining Feliformia (family Nandiniidae), as sister taxon of Felidae (family Prionodontidae) and as Malagasy Carnivora lineage basal to hyaenid–herpestid clade, respectively. Still, incongruence among results concerning the systematic position of these taxa exhibits the necessity of further investigation. Detailed study revealed inconsistencies within genet and genet-like taxa phylogeny, which have still to be resolved. Malagasy Carnivora belong to a separate lineage, which originated from herpestid–hyaenid ancestors and colonised Madagascar during a single colonisation event. However, interrelationships among Malagasy Carnivora are poorly resolved. The situation of the social mongooses clade was resolved by including ethologic data to phylogenetic analyses; however, there is little information on solitary mongooses, which have a paraphyletic status today. Felid morphology and taxonomic revision attained during recent years show greater evolutionary differentiation. Nevertheless, no clear taxonomy has been achieved. New investigating methods are required. In the hyaenid family, which includes only four living species, some investigations related to the ecomorphological evolutionary path have been performed. The comparisons of fossil and subfossil remains with modern feliforms, combined with recent molecular methods, may improve our knowledge.