Faunal assemblage seriation of southern African Pliocene and Pleistocene fossil deposits

Fossil assemblages from the Pliocene and Pleistocene of southern Africa were seriated in order to give a better idea of their relative chronology. Time-sensitive mammals were selected for calculation of the Faunal Resemblance Index among 17 site units. On the basis of a logistical seriation and subsequent site analysis, the following sequence of sites was deemed most probable: Makapansgat Member 3, Makapansgat Member 4, Taung Dart deposits, Sterkfontein Member 4 and Taung Hrdli?ka deposits, Sterkfontein Member 5 (in part) and Kromdraai B, Kromdraai A and Swartkrans Member 1, Swartkrans Member 2, Swartkrans Member 3, Plovers Lake, Cornelia, Elandsfontein Main Site, Cave of Hearths Acheulian levels, Florisbad and Equus Cave and Klasies River Mouth. © 1995 Wiley-Liss, Inc.     

Tetrapod Footprint Biostratigraphy and Biochronology

Tetrapod footprints have a fossil record in rocks of Devonian-Neogene age. Three principal factors limit their use in biostratigraphy and biochronology (palichnostratigraphy): invalid ichnotaxa based on extramorphological variants, slow apparent evolutionary turnover rates and facies restrictions. The ichnotaxonomy of tetrapod footprints has generally been oversplit, largely due to a failure to appreciate extramorphological variation. Thus, many tetrapod footprint ichnogenera and most ichnospecies are useless phantom taxa that confound biostratigraphic correlation and biochronological subdivision. Tracks rarely allow identification of a genus or species known from the body fossil record. Indeed, almost all tetrapod footprint ichnogenera are equivalent to a family or a higher taxon (order, superorder, etc.) based on body fossils. This means that ichnogenera necessarily have much longer temporal ranges and therefore slower apparent evolutionary turnover rates than do body fossil genera. Because of this, footprints cannot provide as refined a subdivision of geological time as do body fossils. The tetrapod footprint record is much more facies controlled than the tetrapod body fossil record. The relatively narrow facies window for track preservation, and the fact that tracks are almost never transported, redeposited or reworked, limits the facies that can be correlated with any track-based biostratigraphy.

A Devonian-Neogene global biochronology based on tetrapod footprints generally resolves geologic time about 20 to 50 percent as well as does the tetrapod body fossil record. The following globally recognizable time intervals can be based on the track record: (1) Late Devonian; (2) Mississippian; (3) Early-Middle Pennsylvanian; (4) Late Pennsylvanian; (5) Early Permian; (6) Late Permian; (7) Early-Middle Triassic; (8) late Middle Triassic; (9) Late Triassic; (10) Early Jurassic; (11) Middle-Late Jurassic; (12) Early Cretaceous; (13) Late Cretaceous; (14) Paleogene; (15) Neogene. Tetrapod footprints are most valuable in establishing biostratigraphic datum points, and this is their primary value to understanding the stratigraphic (temporal) dimension of tetrapod evolution.     

A NEW SPECIES OF BANDICOOT FROM THE OLIGOCENE OF NORTHERN AUSTRALIA AND IMPLICATIONS OF BANDICOOTS FOR CORRELATING AUSTRALIAN TERTIARY MAMMAL FAUNAS

Abstract:  A new species of primitive bandicoot, Yarala kida sp. nov., is described from Kangaroo Well, a site in the Northern Territory of Australia. This species is possibly ancestral to Yarala burchfieldi , the type species of the Yaraloidea, and supports a late Oligocene age for the Kangaroo Well Local Fauna. The yaraloid bandicoots are likely to become important biochronological tools for Australian faunas of late Oligocene to early Miocene age, as they are widespread and diverse. Developing morphoclines for this group is therefore essential, as is publication of the mostly undescribed bandicoot material known from other sites of similar age.     

BIOCHRONOLOGICAL RELATIONSHIPS OF THE EARLIEST SOUTH AMERICAN PALEOGENE MAMMALIAN FAUNAS

Abstract:  The oldest Cenozoic mammalian assemblages in South America have been recovered from levels of the Hansen Member of the Salamanca Formation, Punta Peligro locality in Argentina, and from the Santa Lucía Formation in Tiupampa, Bolivia. These faunas led to the recognition of the Peligran and Tiupampan South American Land Mammal Ages (SALMAs), each alternatively regarded as the oldest Paleocene SALMA. Due to the lack of radioisotopic dates for mammals bearing levels at these localities, no agreement has been reached yet about their relative ages. In this paper, the role of mammal faunas in age inference is discussed. Analysis of the SALMAs shows that the presence of non-therian mammals in the Peligran is of little consequence to the biochronological evaluation, reflecting instead a relict Mesozoic distribution. In contrast, therian mammals are particularly important in that (1) they were Lauraisan immigrants and (2) they support direct comparisons between the Tiupampa and Punta Peligro faunas. Parsimony and cluster analysis were used to quantitatively test hypotheses concerning the relative age of the Peligran and Tiupampan SALMAs. Our results support the hypothesis that the Tiupampan SALMA (early Danian) is older than the Peligran SALMA (early Selandian). This alignment results in an interpretation of the evolutionary history of South American land mammals that is more straightforward than the alternative.     

Biochronology of the first hominid remains in Europe using the vole Mimomys savini: Fuente Nueva 3 and Barranco León D,Guadix-Baza Basin,south-eastern Spain

The sites of Barranco León D (BL-D) and Fuente Nueva 3 (FN-3) in the Guadix-Baza Basin (Granada, Spain), together with the site of Sima del Elefante in the Sierra de Atapuerca (Burgos, Spain), constitute one of the oldest records of the earliest hominid population in the European continent west of Dmanisi (Georgia, Lesser Caucasus). In the Guadix-Baza Basin, evidence of human occupation has been found to date in the form of lithic industry (Mode 1) and cut marks in large-mammal fossil remains (mainly of hippopotamuses and elephants), and recently a human tooth considered as the oldest in Europe has been discovered. Although in the case of Sima del Elefante there is unanimity among the scientific community regarding the chronology of the unit in which the hominid remains were found (Unit TE9c, 1.22 Ma), there is continuing debate on the chronology of the sites of the Guadix-Baza Basin (FN-3 and BL-D). This applies especially to BL-D, as the numerical datings published for this site have a very high error range (1.4 ± 0.38 Ma). In this paper, the chronology of these two sites is determined using as a marker the morphological and morphometric changes undergone by Mimomys savini in its first lower molar (m1) over the course of its evolutionary history. It has been possible to confirm that the oldest human presence in the Guadix-Baza Basin and at Sima del Elefante (Atapuerca) share a similar chronology, dated to between 1.1 and 1.4 Ma. Apparently, the oldest site with human remains in Europe is seen to be BL-D, dated to 1.26 ± 0.13 Ma, followed by Level TE9c, dated to 1.22 ± 0.16 Ma, and FN-3, dated to 1.20 ± 0.12 Ma.     

Environmental change drives long‐term recruitment and growth variation in an estuarine fish

How individuals respond to environmental change determines the strength and direction of biological processes like recruitment and growth that underpin population productivity. Ascertaining the relative importance of environmental factors can, however, be difficult given the numerous mechanisms through which they affect individuals. This is especially true in dynamic and complex estuarine environments. Here, we develop long‐term otolith‐based indices of recruitment and growth for estuary perch Percalates colonorum (Bemm River, Australia), to explore the importance of intrinsic (individual, demographic) and extrinsic (hydrologic, climatic, density‐dependent) factors in driving estuarine fish productivity. Analyses involved a novel zero‐inflated specification of catch curve regression and mixed effects modelling. The 39 years of recruitment and 46 years of growth data, spanning a period of environmental change including severe drought, displayed considerable inter‐annual variation. Recruitment success was strongly related to high freshwater inflows during the spawning season, suggesting that these conditions act as spawning cues for adults and potentially provide favourable conditions for larvae. Individuals displayed age‐dependent growth, with highest rates observed at younger ages in years characterized by warm temperatures, and to a lesser degree, greater magnitude base inflow conditions. We detected systematic among‐year‐class growth differences, but these were not attributable to year class strength, suggesting that environmental conditions experienced by individuals as juveniles can have long‐lasting effects of greater importance to population productivity than density‐dependent growth responses. The primacy of temperature in driving growth variation highlights that under‐appreciated climatic variation can affect estuarine fish productivity through direct physiological and indirect food web mechanisms. We predict that climatic warming will promote individual growth in southerly populations of P. colonorum but concurrently limit recruitment due to forecast reductions in spawning season river discharge. Disparate trait responses are likely in other fishes as they respond to multiple and changing environmental drivers, making predictions of future population productivity challenging.     

内蒙古中部新近纪动物群的演替与生物年代

内蒙古中部地区陆相新近系出露广、含化石丰富。对这一地区新近纪的研究,可以追溯到20世纪初期瑞典地质学者安特生(J．G．Andersson)、法国古生物学者德日进(P．Teilhar de Chardin)和以美国探险家安德鲁斯(R．C．Andrews)为首的美国自然博物馆中亚考察团分别对二登图、高特格和通古尔的考察与化石采集。他们的开拓性工作使这些地方成为中国十分重要的新近纪经典地点。特别是通古尔,由于其产出的化石丰富、具有中中新世动物群的特征, 已引入中国地质年表,作为新生代中一个“阶”的名称。最近20多年对这一地区新近纪生物地层学的研究又取得了很大的进展,新发现了数个不同时代的化石地点和层位,同时采集到大批哺乳动物化石标本。内蒙古中部各地点化石层的厚度一般不大,但所含的哺乳动物化石种类多、材料丰富。由于具有这一特点,使其化石组合能比较接近地反映短期内动物群体的结构面貌,较客观地指示沉积时期的生态环境。利用这些组合进行动物群相对时代的确定,以及对其生态环境的恢复无疑都会很有意义。但是,这里的地层缺乏测试绝对年龄的材料,化石组合间少见有直接的叠置关系,使得在这一地区建立独立的动物群时间顺序,确定动物群的演替序列和生物年代只能更多地依赖于对动物系统发育和动物群体变化的研究。本文对这一地区各地点发现的哺乳动物化石组合进行了审定,提供了最新的动物群名单;根据默尔根地点上部层位产出的化石组合特征,提议把该组合命名为铁木钦动物群;通过对哺乳动物系统发育关系的分析,将动物群进行先后排序,并阐述了这些动物群在各生物年代的演替特征;同时展示了各动物群与有关岩石地层和磁性地层的关系。文中进一步认定了苏尼特左旗的嘎顺音阿德格动物群为内蒙古中部地区现知新近纪动物群中的最早代表,其后依次为推饶木动物群、默尔根动物群、铁木钦动物群、阿木乌苏动物群、沙拉动物群、宝格达乌拉动物群、二登图动物群、哈尔鄂博动物群、比例克动物群、高特格动物群。内蒙古中部被认为是新近纪生物年代学研究的重要地点,在地质时代上这一哺乳动物群系列跨越了新近纪中新世至上新世的大部分时段。其中的嘎顺音阿德格动物群具有中国陆生哺乳动物年代山旺期的典型持征;推饶木动物群、默尔根动物群、铁木钦动物群构成的广义通古尔动物群,正是定义东亚中中新世陆生哺乳动物年代的依据;阿木乌苏动物群、沙拉动物群、宝格达乌拉动物群和二登图动物群符合保德期动物群的含义;比例克动物群和高特格动物群具有榆社期动物群的性质。虽然目前还无法根据这些动物群对我国陆生哺乳动物年代的时限进行精确界定, 但依某些动物阶元(主要为科和属一级)的最早迁入或在该区的最早出现,以及在该区地层中的最后出席,概述了内蒙古中部地区新近纪动物群所指示的哺乳动物年代特征,并分别把通古尔期和保德期细分为3个和4个非正规亚期。深入的研究,包括在这一地区发现新的化石层位和材料,不仅会为内蒙古中部地区生物年代的厘定提供更多的资料,而且有助于完善中国新近纪地质年代的内涵。     

The implications of the numerical dating of the Messel fossil deposit (Eocene, Germany) for mammalian biochronology

Radiometric dating of volcaniclastic material from a borehole below the Middle Eocene Messel Formation leads to a revised numerical age of the Messel fossil deposit. Accordingly, the Grauvian/Geiseltalian boundary moves up from about 49 to 47.5 ma. The consequences of this change as well as the necessity of the Geiseltalian European Land Mammal Mega-Zone (ELMMZ)¹ for mammalian biochronology are discussed.     

美国怀俄明州大角盆地北部Polecat台地古新世动物群演化（英文）

怀俄明州大角盆地北部的Polecat台地和麦卡洛峰的重要发现对了解北美古新世哺乳动物生物地层以及古新世-始新世极热事件中陆生动物群更替模式和原因具有重要意义。1910年,普林斯顿大学和美国自然历史博物馆的古生物学者指出,古新世的哺乳动物与始新世的明显不同,这使得古新世是一个不同于始新世的时期的观点很快被接受。80年之后,密歇根大学和卡耐基研究院的古生物学者指出,陆相古新统-始新统界线可以用动物群的快速更替和小型化作为标志,并伴随着一次重要的碳同位素漂移,这使得古新世-始新世极热事件(PETM)作为真正的全球性温室升温事件得到了公认。1950年,投身古生物事业的年轻学者周明镇被介绍到怀俄明参加古新世哺乳动物野外工作。在那里,他积累了专业知识和经验,并促成了对中国古新统进行的类似考察。现在的挑战是如何将北美和亚洲大陆相似的古新世历史拼合在一起。