Birding by Foot: A Critical Look at the Synapomorphy- and Phenetic-Based Approaches to Trackmaker Identification of Enigmatic Tridactyl Mesozoic Traces

One of the goals of vertebrate ichnology is to use trace fossils as an additional source of data to determine the palaeoecological makeup of vertebrate paleoecosystems. The features in both the synapomorphy-based and phenetic-based methods of attributing a trace to an osteologic trackmaker are those that are affected by preservational conditions, convergent due to size and/or habitat of the trackmaker, and are morphologically variable within taxa. Despite the drawbacks, the phenetic-based, or “gestalt” method, is still the most comprehensive, if not always synapomorphy-supported, means of using the largest amount of data (morphologic and behavioral) preserved for identifying tracks as avian. To date there are too few synapomorphies that are both pedes specific and are consistently preserved in footprints to be a practical method for attributing tracks to an avian trackmaker. There is still much more comparative ichnological and statistical work to be done to discern novel traits that can be used to delineate between the traces of large avian and small nonavian Mesozoic theropods.     

The Atapuerca sites and their contribution to the knowledge of human evolution in Europe

Over the last two decades, the Pleistocene sites of the Sierra de Atapuerca (Spain) have provided two extraordinary assemblages of hominin fossils that have helped refine the evolutionary story of the genus Homo in Europe. The TD6 level of the Gran Dolina site has yielded about one hundred remains belonging to a minimum of six individuals of the species Homo antecessor. These fossils, dated to the end of the Lower Pleistocene (800 kyr), provide the earliest evidence of hominin presence in Western Europe. The origin of these hominins is unknown, but they may represent a speciation event from Homo ergaster/Homo erectus. The TD6 fossils are characterized by a significant increase in cranial capacity as well as the appearance of a “sapiens” pattern of craniofacial architecture. At the Sima de los Huesos site, more than 4,000 human fossils belonging to a minimum of 28 individuals of a Middle Pleistocene population (ca. 500–400 kyr) have been recovered. These hominins document some of the oldest evidence of the European roots of Neanderthals deep in the Middle Pleistocene. Their origin would be the dispersal out of Africa of a hominin group carrying Mode 2 technologies to Europe. Comparative study of the TD6 and Sima de la Huesos hominins suggests a replacement model for the European Lower Pleistocene population of Europe or interbreeding between this population and the new African emigrants.     

东亚现代人来源的考古学思考:证据与解释

现代人的起源与扩散是当今古人类学界极具争议的问题。目前,"多地区进化"假说和非洲起源为主的"同化"假说是该争议的两大阵营。在"多地区进化"假说的基础上,立足中国的化石材料,吴新智提出了中国乃至东亚古人类"连续演化、附带杂交"的假说,认为中国的现代人主要由本地古老类型人类演化而来。本文从现代人扩散关键时段的考古材料出发,讨论氧同位素5～3阶段(大约13～3万年)考古材料在研究中国现代人形成中的作用和存在的挑战。首先,概括介绍现代人起源的主要假说和现代人扩散的假定路线——南线和北线的多重证据;其次,在此背景下,通过对中国境内考古材料的概括,分析不同石器技术可能反映的现代人来源;最后,简要探讨立足考古材料研究现代人起源与扩散的挑战。总体而言,氧同位素5～3阶段的旧石器考古材料支持中国北方南部和中国南方古人类的连续演化,同时也指示了非洲扩散而出的现代人人群自西北地区和南方地区进入中国的可能性。该模式支持中国古人类"连续演化、附带杂交"假说,然而我们也认识到中国现代人起源研究的考古基础仍十分薄弱,使用考古学材料研究现代人扩散的理论基础也需探讨。目前,细化、完善基础考古数据仍是中国旧石器时代考古学和古人类学学者努力的主要方向之一。如此,我们才能够更加有效地将人类化石与考古学证据融合,进而结合分子生物学的研究,更为全面地理解现代人的起源与演化。     

Human Footprint Variation while Performing Load Bearing Tasks

Human footprint fossils have provided essential evidence about the evolution of human bipedalism as well as the social dynamics of the footprint makers, including estimates of speed, sex and group composition. Generally such estimates are made by comparing footprint evidence with modern controls; however, previous studies have not accounted for the variation in footprint dimensions coming from load bearing activities. It is likely that a portion of the hominins who created these fossil footprints were carrying a significant load, such as offspring or foraging loads, which caused variation in the footprint which could extend to variation in any estimations concerning the footprint’s maker. To identify significant variation in footprints due to load-bearing tasks, we had participants (N = 30, 15 males and 15 females) walk at a series of speeds carrying a 20kg pack on their back, side and front. Paint was applied to the bare feet of each participant to create footprints that were compared in terms of foot length, foot width and foot area. Female foot length and width increased during multiple loaded conditions. An appreciation of footprint variability associated with carrying loads adds an additional layer to our understanding of the behavior and morphology of extinct hominin populations.     

中更新世晚期中国古人类化石的形态多样性及其演化意义

近年对许家窑、许昌、华龙洞、澎湖、夏河、哈尔滨等人类化石开展的系统研究,引发了学界对中更新世晚期人类演化及分类的不同认识。基于对相关中国人类化石形态特征的分析,作者提出这一时期中国人类化石形态特征表现为四种类型：1）以中更新世晚期人类共有特征为主;2）以原始特征为主;3）以现代特征为主;4）独特形态组合。多数化石形态特征表现为前三种类型,而许昌和许家窑这种以硕大的头骨和巨大颅容量构成的独特形态组合在其他同时期化石还没有发现。化石形态的多样性提示,不同类型的中更新世晚期中国古人类对现代人的形成贡献不同。作者认为在该时期的人类化石形态多样性规律还未阐明的情况下,将具有混合或镶嵌特征的相关人类化石归入分类地位不确定的人群较为合适。     

“许家窑人”埋藏地层与时代探讨

“许家窑人”化石发现于河北省阳原县泥河湾盆地西端的侯家窑遗址。该遗址20世纪70年代历经数次发掘,发现古人类化石20件、石制品数万件以及大量的哺乳动物化石。虽然已有大量关于遗址的研究成果发表,但人类化石和考古遗物的出土地层仍有些模糊,文化层时代也存在较大争议;年代数据在20 kaBP到500 kaBP的大范围间变化,影响学者们对“许家窑人”及其文化遗存演化位置的认识。鉴于此,河北省文物研究所（现河北省文物考古研究院）在2007~2012年对该遗址开展了持续的考古调查及发掘,重要目的之一在于廓清遗址埋藏的地貌部位和文化层的分布状况等基本信息。侯家窑遗址的地层包含上、下两个文化层;下文化层以下2~3 m（距地表约14.5 m）处确认了不整合接触面,其下为泥河湾层堆积,之上为河流阶地堆积。综合对20世纪70年代发掘的地层描述、新发掘地层以及人类化石保存状态的认识,“许家窑人”化石应出自遗址地层沉积序列的上文化层中,而非湖相的泥河湾层中。通过对目前遗址已有测年数据的重新梳理,我们认为,上文化层即“许家窑人”化石的时代为200~160 kaBP,主要对应深海氧同位素6阶段早期;下文化层的准确年代仍需验证,目前光释光年龄为198±15 kaBP, ²⁶Al/ ¹⁰Be埋藏年代为240±50 kaBP。     

Bayesian analysis of a morphological supermatrix sheds light on controversial fossil hominin relationships

The phylogenetic relationships of several hominin species remain controversial. Two methodological issues contribute to the uncertainty—use of partial, inconsistent datasets and reliance on phylogenetic methods that are ill-suited to testing competing hypotheses. Here, we report a study designed to overcome these issues. We first compiled a supermatrix of craniodental characters for all widely accepted hominin species. We then took advantage of recently developed Bayesian methods for building trees of serially sampled tips to test among hypotheses that have been put forward in three of the most important current debates in hominin phylogenetics—the relationship between Australopithecus sediba and Homo, the taxonomic status of the Dmanisi hominins, and the place of the so-called hobbit fossils from Flores, Indonesia, in the hominin tree. Based on our results, several published hypotheses can be statistically rejected. For example, the data do not support the claim that Dmanisi hominins and all other early Homo specimens represent a single species, nor that the hobbit fossils are the remains of small-bodied modern humans, one of whom had Down syndrome. More broadly, our study provides a new baseline dataset for future work on hominin phylogeny and illustrates the promise of Bayesian approaches for understanding hominin phylogenetic relationships.     

The semicircular canal system and locomotion: The case of extinct lemuroids and lorisoids

Paleontologists reconstruct the locomotor and postural behavior of extinct species by analogy with living forms and biomechanical analyses. In rare cases, behavioral evidence such as footprints can be used to confirm fossil‐based reconstructions for predominantly terrestrial orders of mammals. For instance, the chalicothere prints from Laetoli show that these perissodactyls supported their body weight on the metacarpals, as previously reconstructed. 1 Unfortunately, primates are mostly arboreal and rarely leave footprints. The cercopithecid and hominin prints at Laetoli are a rare exception. We have recently shown that the semicircular canal system can be used to test and augment locomotor reconstructions based on postcranial material or to provide first estimations of locomotor behavior for taxa not known from the postcranium. Using a sample of modern primates, we have been able to demonstrate that the radii of curvature of the semicircular canals are significantly correlated with both body mass and agility of locomotion. 2 This paper reviews those results and examines the relationship between semicircular canal morphology and other evidence in efforts to reconstruct locomotor behavior in subfossil lemurs from the Holocene of Madagascar and fossil lorisoids from the Miocene of Africa.     

Functional morphology,biomechanics and the retrodiction of early hominin diets

A fundamental axiom that underlies evolutionary biomechanics maintains that natural selection has adapted skeletal and dental morphologies to facilitate function in intelligible ways. Because selection is held to result in the improvement of functional design, it is thought possible to predict the adaptive significance of a morphological feature from a design criterion. This rationale has been widely applied to the interpretation of morphological complexes in the paleontological record for which no strict extant analogues exist. In particular, biomechanical models have been used to infer the dietary habits of extinct hominin taxa from aspects of craniodental morphology. Many of these models are hampered by missing data and loosely justified assumptions. Craniodental morphologies may indicate more about what an extinct species was capable of processing intra-orally – and probably more about its phylogenetic history – than the constitution of its diet. Even a dedicated leaf-eating hominin cannot be expected to have possessed bilophodont molars. The dietary retrodictions based on comparative anatomical that have been proffered for Plio-Pleistocene hominin species are reviewed here. We argue that the application of finite element analysis to these fossils has not revealed convincing evidence of specific feeding behaviors. Indeed, the conclusions from these biomechanical models are often incongruent with data from stable light isotopes, microwear and phytolith analysis; nor do they conform with observations on the dietary repertoires and feeding behaviors of extant primates. For example, the sooty mangabey (Cercocebus atys) is a committed hard object feeder, but suffers no deleterious consequences from the “poor design” of its facial skeleton for processing hard foods. Because primates are adept at behaviorally circumventing mechanical problems, it is perhaps useful to consider the breadth of any fossil hominin's feeding repertoire in the context of behaviors that enable mechanical problems to be dealt with prior to ingestion.     

Nadaouiyeh – A Homo erectus in Acheulean context

The Middle East is apparently the most important passage for the dispersal of early hominins. Numerous archeological sites prove the existence of hominin populations in this region, but despite these rich cultural remains, hominin fossils are very rare. In 1996, a hominin left parietal was found in an Acheulean context. In addition, the faunal remains indicate a steppe environment. What does this single cranial fragment tell us? Based on new publications and in particular on recent finds, the value of isolated elements is discussed.     

Obituary: Ron K. Pickerill (1947–2018)

Recently discovered tracks in alluvial sediments of the Late Paleocene Bullion Creek Formation of western North Dakota have been identified as belonging to the large eusuchian crocodile Borealosuchus formidabilis and an associated small arthropod. They are described as two new ichnotaxa. The first of these, Borealosuchipus hanksi igen. et isp. nov., is based on a partly complete trackway having fore- and hind-footprints as well as body marks preserved in hyporelief. These tracks are directly associated with numerous body fossils including articulated bones which provide strong implications for their probable origin. The second specimen, Koupichnium pentapodus isp. nov., is founded on a trackway of a small invertebrate in which a series of five pairs of footprints are arranged along a midline drag mark which is continuous throughout the length of its trackway. This trackway shares features with other fossils as well as living arthropod trackways in which four small feet and a larger posterior hind “pusher” foot are present. The two described new ichnotaxa represent the first recognized tracks from the Wannagan Creek local fauna.     

A history and bibliography of the study of fossil vertebrate footprints in the British isles

A comprehensive account is given of the discovery and study of the fossil footprints of vertebrates in the British Isles. Brief summaries are given of work published in journals that are generally available to the geologist at large; however, since many papers were published in obscure books and journals, the illustrations in these are reproduced and the papers themselves directly quoted wherever appropriate. A number of specimens important in the history of British vertebrate ichnology are illustrated for the first time; in particular, the holotype of Chelichnus ingens Binney (1856), the “Kegworth footprint” from Leicestershire, the supposed “monotreme footprint” of Seeley (1899), and the first Iguanodon footprint to be described from Sussex (Tagart, 1846). Illustrations are given for the first time of footprints from the Forest Marble of Wiltshire thought to be those collected by Scrope (1831), of a footprint from the Permian of Warwickshire, mentioned by Vernon (1912), and of a footprint from Caithness. The account is extensively supplemented by text-figures of principal footprint types and, so far as possible, the present whereabouts of figured or described specimens is indicated. (Many, unfortunately, are lost.) An exhaustive bibliography of fossil vertebrate footprints from the British Isles is presented.Particular attention is paid to the important discoveries in the Cheshire Basin by the amateur geologists of the Liverpool region. An account of the work of Henry C. Beasley (1836–1919), the most eminent British worker in this field, is given for the first time; his portrait, and photographs relating to his work in the Storeton quarries, are published for the first time.The stratigraphical and palaeoecological significance of the footprints is assessed wherever possible and reasons are presented why a more extensive resumption of work in this field is desirable.     

Landscapes of human evolution: models and methods of tectonic geomorphology and the reconstruction of hominin landscapes

This paper examines the relationship between complex and tectonically active landscapes and patterns of human evolution. We show how active tectonics can produce dynamic landscapes with geomorphological and topographic features that may be critical to long-term patterns of hominin land use, but which are not typically addressed in landscape reconstructions based on existing geological and paleoenvironmental principles. We describe methods of representing topography at a range of scales using measures of roughness based on digital elevation data, and combine the resulting maps with satellite imagery and ground observations to reconstruct features of the wider landscape as they existed at the time of hominin occupation and activity. We apply these methods to sites in South Africa, where relatively stable topography facilitates reconstruction. We demonstrate the presence of previously unrecognized tectonic effects and their implications for the interpretation of hominin habitats and land use. In parts of the East African Rift, reconstruction is more difficult because of dramatic changes since the time of hominin occupation, while fossils are often found in places where activity has now almost ceased. However, we show that original, dynamic landscape features can be assessed by analogy with parts of the Rift that are currently active and indicate how this approach can complement other sources of information to add new insights and pose new questions for future investigation of hominin land use and habitats.     

Mass spectrometric U-series dating of Huanglong Cave in Hubei Province,central China: Evidence for early presence of modern humans in eastern Asia

Most researchers believe that anatomically modern humans (AMH) first appeared in Africa 160-190 ka ago, and would not have reached eastern Asia until ∼50 ka ago. However, the credibility of these scenarios might have been compromised by a largely inaccurate and compressed chronological framework previously established for hominin fossils found in China. Recently there has been a growing body of evidence indicating the possible presence of AMH in eastern Asia ca. 100 ka ago or even earlier. Here we report high-precision mass spectrometric U-series dating of intercalated flowstone samples from Huanglong Cave, a recently discovered Late Pleistocene hominin site in northern Hubei Province, central China. Systematic excavations there have led to the in situ discovery of seven hominin teeth and dozens of stone and bone artifacts. The U-series dates on localized thin flowstone formations bracket the hominin specimens between 81 and 101 ka, currently the most narrow time span for all AMH beyond 45 ka in China, if the assignment of the hominin teeth to modern Homo sapiens holds. Alternatively this study provides further evidence for the early presence of an AMH morphology in China, through either independent evolution of local archaic populations or their assimilation with incoming AMH. Along with recent dating results for hominin samples from Homo erectus to AMH, a new extended and continuous timeline for Chinese hominin fossils is taking shape, which warrants a reconstruction of human evolution, especially the origins of modern humans in eastern Asia.     

Alexander von Humboldt and the hand-beast: A contribution to palaeontology from the last universal scholar

Despite a certain interest in the discipline, Alexander von Humboldt did not personally contribute much to the progress of palaeozoology. His most remarkable input derived from a communication about hand-like archosaur footprints from the Buntsandstein at the very acme of the important controversy that the discovery of these fossils generated (1835). Humboldt thought that the tracks were probably from a possum-like marsupial, but he did not discount that they could be from a primate. This study is characterized by its superficiality: both the anatomical comparisons and the considerations of the functional morphology of locomotion are very poor. Its effect on the scientific community proved about nil, in both the short and the long run, and Humboldt may himself have doubted his initial conclusions in later years. Nevertheless, in contrast with some contemporaneous renowned geognosts, he had no hesitation from the beginning that the footprints were genuine. He also did not hesitate to weaken the belief of the time on the timing of the succession of organised beings in geological ages, naturally without lapsing into “antiprogressionism”.     

Du probleme de l'origine des Dinosauriens d'apres les donneesde l'ichnologie du Trias

With the data of the osteological paleontology and these of the ichnology, the authors attempt to restore the biotopes where lived the trackmakers, biotopes which have favoured in the Triassic the evolution and the expansion of the Archosaurs, the specialized Reptiles in the easy and rapid locomotion. They pointed out that the chirotheroid footprints cannot be attributed at all events to the Pseudosuchians and they come to the conclusion that Dinosaurs and Pseudosuchians, as separated groups, are appeared as early as the lower Triassic.     

How diverse were ferns in the Baltic amber forest?

Diverse temperate forest types and a high atmospheric humidity have recently been suggested for the Eocene source area of Baltic amber. However, ferns are astonishingly rare as inclusions in this amber, which is in contrast to other seed‐free land plants, fungi, and lichens. Moreover, the identities of some of the few described putative fern taxa are dubious, and some fossils were even assigned to the Paleozoic seed fern genera Alethopteris, Pecopteris and to the form genus Sphenopteris containing Paleozoic and Mesozoic fern‐like leaf fossils. Here, we review previously described fern inclusions from Baltic amber and identify further fern‐like leaf inclusions as belonging to the extant angiosperm genus Comptonia (sweet ferns, Myricaceae). We conclude that only one taxon, Matonia striata (Matoniaceae), can with confidence be identified as a Polypodiopsida representative. Although “Pecopteris” humboldtiana is so far only known as sterile foliage, its leaf morphology strongly suggests that also this taxon belongs to the Polypodiopsida rather than to any other tracheophyte lineage. We propose accommodating “Pecopteris” humboldtiana in the new genus Berendtiopteris. “Alethopteris” serrata and “Sphenopteris” phyllocladoides are not to be regarded as evidence of ferns from Baltic amber. Reinvestigation of the holotypes of these two taxa did not reveal to which tracheophyte lineages these fossils belong. We suggest that the scarcity of fern remains from Baltic amber may reflect both a relatively low fern diversity in the source area of the fossil resin, and an absence or rarity of epiphytic and climbing ferns as observed in modern temperate forest ecosystems.     

The Employment Footprints of Nations

In this study, we present an analysis of the average wages paid for producing direct and indirect imports of nations using employment and income footprints. An employment footprint includes a country's domestic employment and that occurring along the supply chains of, and hence embodied in, its imported goods and services. Our results allow us to group the world's nations into “masters” that enjoy a lifestyle supported by workers in other countries and “servants” that support the lifestyle of master countries. We show that, in 2010, employment footprints of countries differed substantially from their own workforce footprints. Hong Kong, Singapore, the United Arab Emirates, and Switzerland occupy the top‐ranking positions of master countries, whereas many African and Asian countries are servants. Our findings show that the commodities that are “servant intensive,” such as electronics, agricultural products, and chemicals, tend to have complex supply chains often originating in third‐world countries. The quantification of these master‐servant relationships and the exposing of implicated supply chains could be of benefit to those concerned with their corporate social responsibility and committed to fairer trading or those developing policy around fair globalization.     

The rise of bilaterians: a few closing comments

Freeman (2009, 2010) argue that Ediacara “faunas” should be analysed using “promorphologies” of extant animals, that rangeomorphs and erniettomorphs are colonial animals, and that Vernanimalcula is a bilaterian animal. Recent studies of Ediacara fossils have provided multiple lines of evidence that these fossils represent a sample of phylogenetically diverse marine organisms that included crown-group animals as well as stem-group animals and non-animals. Thus, it is inappropriate to analyse Ediacara fossils using “promorphologies” of extant animals. The interpretation of rangeomorphs and erniettomorphs as colonial animals is inconsistent with the functional morphologies of these Ediacara fossils. Although Vernanimalcula is a fossil, the purported germ layers of Vernanimalcula are of diagenetic origin and there is no morphological evidence in support of its bilaterian affinity.