fossil records
Recently Published Documents

Plants and arthropods interact with each other and constitute an important part of the modern terrestrial ecosystem (Schoonhoven et al., 2005). Historically, fossil records of plant-arthropod interactions have been well documented in Paleozoic terrestrial ecosystems, which were evidenced by large coprolites containing various plant fragments (e.g., Salter et al., 2012), small larvae and coprolites remained in plant organs (e.g., Feng et al., 2017), and diverse functional feeding groups discovered on plant stems, rachises, roots, leaves and fertile organs (e.g., Liu et al., 2020).

Abstract Lichens are well known as pioneer organisms or stress-tolerant extremophiles playing a core role in the early formation of terrestrial ecosystems, of which epiphytic lichens make a distinct contribution to the water-cycle and nutrient cycling in forest ecosystem. But due to the scarcity of relevant fossil records, the evolutionary history of epiphytic lichens is poorly documented. Herein, based on the new material of Daohugouthallus ciliiferus, we demonstrated that the hitherto oldest macrolichen inhabited a gymnosperm branch, representing the first unambiguous Jurassic epiphytic lichen. Combing the fossil and extant macrolichen representatives, we performed the geometric morphometric analysis and comprehensive comparison to infer the systematic status of this rare Jurassic macrolichen. The results declared that D. ciliiferus cannot be assigned to any known macrolichen lineages for its elder age and particular habits, and therefore a new family, Daohugouthallaceae was proposed. This work updated the current knowledge to the historical evolution of epiphytic lichens, implying the macrolichens may have diversified much earlier than the generally accepted K–Pg boundary. In addition, our new finding also provided direct evidence for tracing the continuing joint development of epiphytic lichens and forest ecosystem since the Jurassic of 165 Mya.

AbstractThe temporal and spatial coarseness of megafaunal fossil records complicates attempts to to disentangle the relative impacts of climate change, ecosystem restructuring, and human activities associated with the Late Quaternary extinctions. Advances in the extraction and identification of ancient DNA that was shed into the environment and preserved for millennia in sediment now provides a way to augment discontinuous palaeontological assemblages. Here, we present a 30,000-year sedimentary ancient DNA (sedaDNA) record derived from loessal permafrost silts in the Klondike region of Yukon, Canada. We observe a substantial turnover in ecosystem composition between 13,500 and 10,000 calendar years ago with the rise of woody shrubs and the disappearance of the mammoth-steppe (steppe-tundra) ecosystem. We also identify a lingering signal of Equus sp. (North American horse) and Mammuthus primigenius (woolly mammoth) at multiple sites persisting thousands of years after their supposed extinction from the fossil record.

AbstractStudies of Triassic insects in China began in 1956, and so far, a total of 89 genera and 109 species have been found from the Triassic of China. The fossil records are from 17 provinces (or regions) in China are assigned to 11 orders except for two genera and species considered incertae sedis in Insecta. These Chinese Triassic insects including one Early Triassic, 53 Middle Triassic and 55 Late Triassic species are briefly reviewed in taxonomy and distribution, and listed here with detailed taxonomic and stratigraphic information. The Middle Triassic Tongchuan Entomofauna and Late Triassic Toksun Entomofauna are introduced much detailed from the perspectives of composition and taxonomy. Existing data indicate that the Chinese Triassic entomofauna is dominated by Hemiptera, Mecoptera and Coleoptera; the Chinese Early Triassic insects are only known from Fuyuan in Yunnan Province, Middle Triassic ones mainly known from northern China and sporadically from Guizhou Province, southern China, and Late Triassic ones widely seen in both northern and southern China; and the Middle and Late Triassic entomofaunas are similar in abundance but show a pattern of “more in northern China than in southern China”.

Abstract Background Divergence time estimation is fundamental to understanding many aspects of the evolution of organisms, such as character evolution, diversification, and biogeography. With the development of sequence technology, improved analytical methods, and knowledge of fossils for calibration, it is possible to obtain robust molecular dating results. However, while phylogenomic datasets show great promise in phylogenetic estimation, the best ways to leverage the large amounts of data for divergence time estimation has not been well explored. A potential solution is to focus on a subset of data for divergence time estimation, which can significantly reduce the computational burdens and avoid problems with data heterogeneity that may bias results. Results In this study, we obtained thousands of ultraconserved elements (UCEs) from 130 extant galliform taxa, including representatives of all genera, to determine the divergence times throughout galliform history. We tested the effects of different “gene shopping” schemes on divergence time estimation using a carefully, and previously validated, set of fossils. Our results found commonly used clock-like schemes may not be suitable for UCE dating (or other data types) where some loci have little information. We suggest use of partitioning (e.g., PartitionFinder) and selection of tree-like partitions may be good strategies to select a subset of data for divergence time estimation from UCEs. Our galliform time tree is largely consistent with other molecular clock studies of mitochondrial and nuclear loci. With our increased taxon sampling, a well-resolved topology, carefully vetted fossil calibrations, and suitable molecular dating methods, we obtained a high quality galliform time tree. Conclusions We provide a robust galliform backbone time tree that can be combined with more fossil records to further facilitate our understanding of the evolution of Galliformes and can be used as a resource for comparative and biogeographic studies in this group.

The extraordinary paleontological record from Big Bend National Park (BIBE), Texas chronicles nearly 120 million years of largely uninterrupted deposition through Late Cretaceous, Paleogene and Neogene time. Therefore, the park records one of the most complete and continuous fossil records of its kind in North America, if not the world. Paleontologists have collected and studied fossils from BIBE for over a century and nearly 1400 fossil species have been reported thus far. The BIBE paleontological record includes type specimens representing 44 scientifically valid species (five plants, nine invertebrates, and 30 vertebrates). Numerous other reported specimens are very likely new to science but have yet to be formally named. The present catalog presents the currently known assemblage of fossil plant, invertebrate, and vertebrate species from BIBE within a single, comprehensive record with significant references for each. This work is designed and written to be a research and resource management tool for scientists and non-scientists alike.

Arvicolinae is one of the most impressive placental radiations with over 150 extant and numerous extinct species that emerged since the Miocene in the Northern Hemisphere. The phylogeny of Arvicolinae has been studied intensively for several decades using morphological and genetic methods. Here, we sequenced 30 new mitochondrial genomes to better understand the evolutionary relationships among the major tribes and genera within the subfamily. The phylogenetic and molecular dating analyses based on 11,391 bp concatenated alignment of protein-coding mitochondrial genes confirmed the monophyly of the subfamily. While Bayesian analysis provided a high resolution across the entire tree, Maximum Likelihood tree reconstruction showed weak support for the ordering of divergence and interrelationships of tribal level taxa within the most ancient radiation. Both the interrelationships among tribes Lagurini, Ellobiusini and Arvicolini, comprising the largest radiation and the position of the genus Dinaromys within it also remained unresolved. For the first time complex relationships between genus level taxa within the species-rich tribe Arvicolini received full resolution. Particularly Lemmiscus was robustly placed as sister to the snow voles Chionomys in the tribe Arvicolini in contrast with a long-held belief of its affinity with Lagurini. Molecular dating of the origin of Arvicolinae and early divergences obtained from the mitogenome data were consistent with fossil records. The mtDNA estimates for putative ancestors of the most genera within Arvicolini appeared to be much older than it was previously proposed in paleontological studies.

Die Fächerflügler (Strepsiptera) sind mit nur ca. 600 beschriebenen rezenten Arten eine kleine, parasitische Gruppe der holometabolen Insekten. Fossilfunde sind selten, aber in den letzten Jahren hat sich die Kenntnis der Stammgruppe der Strepsiptera durch die Entdeckung gut erhaltener Arten aus kreidezeitlichem burmesischem Bernstein und eozänem baltischen Bernstein stark vermehrt. Bis auf ganz wenige Ausnahmen, wie eine fossile Primärlarve aus burmesischem Bernstein und ein spätes weibliches Larvenstadium der †Mengeidae aus baltischem Bernstein, sind nur Männchen bekannt. Diese Bernsteinfossilien haben wesentlich zum Verständnis der Evolution der Strepsiptera im späten Mesozoikum und Känozoikum beigetragen. Die Stammgruppenvertreter der Fächerflügler werden vorgestellt und in einen evolutiven Kontext eingeordnet. The stem-group of the twisted-winged parasites (Insecta, Strepsiptera) Abstract: With only about 600 described extant species, the twisted-winged parasites (Strepsiptera) are a small, parasitic group of holometabolous insects. Fossil records of Strepsiptera are rare, but in the last years the knowledge of the stem group has greatly increased with the discovery of well-preserved species from Cretaceous Burmese amber and Eocene Baltic amber. With very few exceptions, such as a fossil primary larva from Burmese amber and a late female larval stage of the †Mengeidae from Baltic amber, only males are known. These amber fossils have greatly contributed to the understanding of the evolution of Strepsiptera in the late Mesozoic and Cenozoic. The stem group representatives of the twisted-winged parasites are described and placed in an evolutionary context.

Today, the only living genus of coelacanth, Latimeria is represented by two species along the eastern coast of Africa and in Indonesia. This sarcopterygian fish is nicknamed a "living fossil", in particular because of its slow evolution. The large geographical distribution of Latimeria may be a reason for the great resilience to extinction of this lineage, but the lack of fossil records for this genus prevents us from testing this hypothesis. Here we describe isolated bones (right angular, incomplete basisphenoid, fragments of parasphenoid and pterygoid) found in the Cenomanian Woodbine Formation in northeast Texas that are referred to the mawsoniid coelacanth Mawsonia sp. In order to assess the impact of this discovery on the alleged characteristic of "living fossils" in general and of coelacanths in particular: 1) we compared the average time duration of genera of ray-finned fish and coelacanth in the fossil record; 2) we compared the biogeographic signal from Mawsonia with the signal from the rest of the vertebrate assemblage of the Woodbine formation; and 3) we compared these life traits with those of Latimeria. The stratigraphical range of Mawsonia is at least 50 million years. Since Mawsonia was a fresh, brackish water fish with probably a low ability to cross large sea barriers and because most of the continental components of the Woodbine Fm vertebrate assemblage exhibit Laurasian affinities, it is proposed that the Mawsonia’s occurrence in North America is more likely the result of a vicariant event linked to the break-up of Pangea rather than the result of a dispersal from Gondwana. The link between a wide geographic distribution and the resilience to extinction demonstrated here for Mawsonia is a clue that a similar situation existed for Latimeria, which allowed this genus to live for tens of millions of years.

The present paper examined the assumption of strong reproductive isolation (RI) between Homo neanderthalensis and Homo sapiens, as well as the question of what form it might have taken, using insights from the parallel case of chimpanzee–bonobo hybridization. RI from hybrid sterility or inviability was thought unlikely based on the short separation-to-introgression timeline. The forms of RI that typically develop in primates have relatively short timelines (especially for partial implementation); they generally preclude mating or influence hybrid survival and reproduction in certain contexts, and they have the potential to skew introgression directionality. These RI barriers are also consistent with some interpretations of the archaeological and fossil records, especially when behavioral, cognitive, morphological, and genetic differences between the two human species are taken into consideration. Differences potentially influencing patterns of survival and reproduction include interspecies violence, Neandertal xenophobia, provisioning behavior, and ontogenetic, morphological, and behavioral differences affecting matters such as kin and mate recognition, infanticide, and sexual selection. These factors may have skewed the occurrence of interbreeding or the survival and reproduction of hybrids in a way that might at least partially explain the pattern of introgression.