Yu Liu

Yunnan University · Yunnan Key Laboratory for Palaeobiology

Artiopoda, an early arthropod group, displays post-antennal appendages resembling trilobite limbs, but relationships with other ealy arthropods remain enigmatic. Limited studies and morphological details hinder the understanding of internal relationships within Artiopoda. Recently, exceptionally well preserved arthropod fossils from the Chengjiang...

Artiopoda, an early arthropod group, displays post-antennal appendages resembling trilobite limbs, but relationships with other ealy arthropods remain enigmatic. Limited studies and morphological details hinder the understanding of internal relationships within Artiopoda. Recently, exceptionally well preserved arthropod fossils from the Chengjiang...

Artiopoda, an early arthropod group, displays post-antennal appendages resembling trilobite limbs, but relationships with other ealy arthropods remain enigmatic. Limited studies and morphological details hinder the understanding of internal relationships within Artiopoda. Recently, exceptionally well preserved arthropod fossils from the Chengjiang...

Kylinxia zhangi, Fengzhengia mamingae, and Bushizheia yangi, early branching upper stem-group euarthropods from the early Cambrian Chengjiang biota of China, each possesses a fully arthrodised body and limbs. The morphologies of their frontal appendages bear a resemblance to the raptorial appendages of radiodonts. However, we cannot be certain whet...

Bushizheia yangi O'Flynn & Liu, a euarthropod from the lower Cambrian (Series 2, Stage 3) Chengjiang Konservat-Lagerstätte, possesses both raptorial frontal appendages sharing traits with stem-group euarthropods, and deuteropodan characters shared by all extant euarthropods (e.g. dorsal arthrodization and arthropodization of all limbs). Microtomogr...

Background The early Cambrian arthropod clade Megacheira, also referred to as great appendage arthropods, comprised a group of diminutive and elongated predators during the early Palaeozoic era, around 518 million years ago. In addition to those identified in the mid-Cambrian Burgess Shale biota, numerous species are documented in the renowned 518-...

The early Cambrian Kylinxia zhangi occupies a pivotal position in arthropod evolution, branching from the euarthropod stem lineage between radiodonts (Anomalocaris and relatives) and "great-appendage" arthropods.1,2 Its combination of appendage and exoskeletal features is viewed as uniquely bridging the morphologies of so-called "lower" and "upper"...

Early euarthropod evolution involved a major transition from lobopodian-like taxa to organisms featuring a segmented, well-sclerotized trunk (arthrodization) and limbs (arthropodization). However, the precise origin of a completely arthrodized trunk and arthropodized ventral biramous appendages remain controversial, as well as the early onset of an...

Although Kachin amber harbors a remarkably diverse and abundant spider fauna, species of Mygalomorphae have been conspicuously scant. Here we report the extant family Macrothelidae (Opisthothelae: Mygalomorphae) from these deposits, representing the first fossil occurrence for the family. It is represented by a new genus and species, established as...

For social insects such as ants, the internal organs are likely important in understanding their eusocial behavior and evolution. Such organs, however, are rarely preserved on fossils. In each of the few cases reporting exceptionally fossilized soft tissues in arthropods, the nervous, muscular and cardiovascular systems have been described individu...

For social insects such as ants, the internal organs are important in understanding their eusocial behaviour and evolution. Such organs, however, are rarely preserved on fossils. In each of the few cases reporting exceptionally fossilized soft tissues in arthropods, only one of the nervous, muscular or cardiovascular systems was described. Here, we...

Megacheirans, or great-appendage euarthropods, have featured prominently in discussions regarding the early evolution of the head region in total-group Euarthropoda. However, several aspects of the ventral morphology of most representatives remain incompletely known given the loss of data associated with fossil compression, coupled with the rarity...

Dynamic mechanical analysis offers the opportunity to explore the motility and feeding strategies of extinct organisms, but the prerequisite is to have an accurate recovery engineering model. As shown with micro-computed tomography (CT) scanning, fossils of the bivalved arthropod Ercaicunia multinodosa from the Cambrian (Series 2, Stage 3) Chengjia...

The artiopodans represent a diverse group of euarthropods with a typically flattened dorsal exoskeleton that covers numerous pairs of biramous ventral appendages, and which are ubiquitous faunal components of the 518-million-year-old Chengjiang Lagerstätte in South China. Despite their abundance, several Chengjiang artiopodans remain poorly known,...

Dermaptera (earwigs) are a small order of Polyneoptera, generally with a narrow and flattened body, a pair of trademark forceps and leathery forewings, a nocturnal preference, and an omnivorous diet. Fossil earwigs are rare, but records from amber have been increasing in the last decade or so. A new genus and its type species, Tricholabidura elonga...

The trilobite Liostracina has been recognized as important in taxonomic and stratigraphic studies for more than a century. Until now, the genus Liostracina and family Liostracinidae have been known from only incomplete holaspid material, a degree 2 meraspis, and protaspides. A new locality in the Longha Formation (Cambrian: Guzhangian) of southeast...

We describe Fengzhengia mamingae gen. et sp. nov., a new euarthropod from the lower Cambrian (Series 2, Stage 3) Chengjiang Lagerstätte, Southwest China. Fengzhengia mamingae possesses prominent frontal appendages, stalked, circular eyes, a simple, sub-triangular head shield, and a trunk with 15 tergites, the anterior nine each bearing a single med...

The Cambrian Stage 3 Chengjiang biota in South China is one of the most influential Konservat-Lagerstätten worldwide thanks to the fossilization of diverse non-biomineralizing organisms through pyritization. Despite their contributions to understanding the evolution of early animals, several Chengjiang species remain poorly known owing to their sca...

Bushizheia yangi, a euarthropod from the early Cambrian Chengjiang biota of China, possesses a fully arthrodised body and limbs. The morphology of the frontal appendages of B. yangi bears a resemblance to the ’great appendage’ of radiodonts, a morphologically and ecologically diverse group of arthropods that played diverse roles in early Palaeozoic...

Background The Chengjiang biota from southwest China (518-million-years old, early Cambrian) has yielded nearly 300 species, of which more than 80 species represent early chelicerates, crustaceans and relatives. The application of µCT-techniques combined with 3D software (e.g., Drishti), has been shown to be a powerful tool in revealing and analyzi...

The iron maiden ant, which was first described as †Zigrasimecia Barden & Grimaldi, 2013, received its nickname for bearing a unique mandible and ferocious mouthparts covered by spiky, columnar-shaped denticles. Here, we describe a new species based on an alate female preserved in 99-Ma Kachin amber – †Zigrasimecia goldingot sp. nov. – which display...

The Cambrian fossil record has produced remarkable insights into the origin of euarthropods, particularly the evolution of their versatile body plan of segments bearing specialized, jointed appendages for different functions including feeding and locomotion [01, 02]. Early euarthropod evolution involved a major transition from lobopodian-like taxa...

The Cambrian Stage 3 Chengjiang biota in South China is one of the most influential Konservat-Lagerstätten worldwide thanks to the fossilization of diverse non-biomineralizing organisms through pyritization. Despite their contributions to understanding the evolution of early animals, several Chengjiang species remain poorly known due to their scarc...

The fossil record, including the record of Burgess Shale-type deposits, is biased towards late ontogenetic stages. Larval stages, juvenile and subadult specimens exist but are very rare and often preserved as phosphatic fossils, resulting in biased population structures. Here, we report a new Burgess Shale-type Lagerstätte from Haiyan, China. The H...

The last common ancestor of all living arthropods had biramous postantennal appendages, with an endopodite and exopodite branching off the limb base. Morphological evidence for homology of these rami between crustaceans and chelicerates has, however, been challenged by data from clonal composition and from knockout of leg patterning genes. Cambrian...

Although first described in 1999, the early Cambrian Pectocaris remains a poorly known euarthropod genus. Two species, Pectocaris eurypetala and P. spatiosa, have been described from the Chengjiang biota. Here, we report a third species, Pectocaris inopinata sp. nov., which bears a pair of stalked eyes attached to an anterior sclerite, a pair of sh...

Understanding the functional morphology and mobility of appendages of fossil animals is important for exploring ecological traits such as feeding and locomotion. Previous work on fossils from the 518 million‐year‐old Chengjiang biota of China was based mainly on two‐dimensional information captured from the surface of the specimens. Only recently,...

Bushizheia yangi gen. et sp. nov. is a euarthropod species from the Cambrian (Series 2, Stage 3) Chengjiang Lagerstätte, Southwest China. Sclerotised dorsal terg-ites, sclerotisation of post-frontal head limb appendages, and no isolated cephalic sclerite support the euarthropod affinities of B. yangi gen. et sp. nov. However, the frontal head limbs...

The euarthropod head is a highly versatile and functionally specialized body region composed of multiple appendage-bearing segments and whose complex evolution has been scrutinized through anatomical, developmental, and paleontological approaches [1 , 2 , 3 , 4 ]. Exceptionally preserved Cambrian fossils have allowed for the reconstruction of criti...

Background The Chengjiang biota is one of the most species-rich Cambrian Konservat-Lagerstätten, and preserves a community dominated by non-biomineralized euarthropods. However, several Chengjiang euarthropods have an unfamiliar morphology, are extremely rare, or incompletely preserved. Results We employed micro-computed tomography to restudy the...

A new exceptionally-preserved Cambrian biota, with fossils belonging to multiple phyla, has recently been found from the middle part of the Longha Formation, near Fulu Village, southeastern Yunnan, South China, and is named the Fulu biota. Groups recovered so far include polymerid trilobites, agnostoids, large bivalved arthropods, bradoriid arthrop...

Radiodonts are a diverse clade of Lower Palaeozoic stem-group euarthropods that played a key role in the emergence of complex marine trophic webs. The latest addition to the group, Cambroraster falcatus, was recently described from the Wuliuan Burgess Shale, and is characterized by a unique horseshoe-shaped central carapace element. Here we report...

The fuxianhuiid arthropod Guangweicaris spinatus, from the lower Cambrian (Series 2, Stage 4), Guanshan Biota (Wulongqing Member, Canglangpu Formation), located in the vicinity of Kunming (Yunnan Province, southwest China), is redescribed based on new specimens and a re-examination of previously described material. A more complete overview of its m...

A new exceptionally-preserved Cambrian biota, with fossils belonging to multiple phyla, has recently been found from the middle part of the Longha Formation, near Fulu Village, southeastern Yunnan, South China, and is named the Fulu biota. Groups recovered so far include polymerid trilobites, agnostoids, large bivalved arthropods, bradoriid arthrop...

Trilobitomorphs are a species-rich Palaeozoic arthropod assemblage that unites trilobites with several other lineages that share similar appendage structure. Post-embryonic development of the exoskeleton is well documented for some trilobitomorphs, especially trilobites, but little is known of the ontogeny of their soft parts, limiting understandin...

Traditionally, the origin and evolution of modern arthropod body plans has been revealed through increasing levels of appendage specialisation exhibited by Cambrian euarthropods. Here we show significant variation in limb morphologies and patterns of limb-tagmosis among three early Cambrian arthropod species conventionally assigned to the Bradoriid...

Background: Artiopodan euarthropods represent common and abundant faunal components in sites with exceptional preservation during the Cambrian. The Chengjiang biota in South China contains numerous taxa that are exclusively known from this deposit, and thus offer a unique perspective on euarthropod diversity during the early Cambrian. One such end...

Graphical Abstract Highlights d The Chengjiang euarthropod Ercaicunia multinodosa preserves appendages in 3D d Head appendages include antennulae, differentiated antennae, mandibles, and maxillae d Trunk appendages are biramous with proximal epipodites d Ercaicunia represents the first stem-group pancrustacean known from macrofossils In Brief Zhai...

The euarthropod Luohuilinella deletres sp. nov. is described from rare material from the Chengjiang biota, Cambrian Series 2, Stage 3, of Yunnan Province, China. Phylogenetic analysis recovers a xandarellid affinity for L. deletres , representing only the fifth described species of this clade. L. deletres possesses a head shield that is about one-f...

Material attributed to Liangwangshania biloba, a fuxianhuiid arthropod from the lower Cambrian (Series 2, Stage 3) of southwest China, is redescribed, with many specimens illustrated for the first time. Newly recognized features include, potential optical neuropils, a stout posterolateral carapace spine, serrated tergal pleurae, two rows of mediola...

Despite being a dominant group in both the Burgess Shale and the Chengjiang biota, diversity of the family Leanchoiliidae mostly consists of monotypic genera, with one genus, Leanchoilia, however, being represented by multiple species from several Cambrian Konservat-Lagerstätten. Here we distinguish a new species of this genus from hundreds of spec...

The central complex comprises an elaborate system of modular neuropils which mediate spatial orientation and sensory-motor integration in insects such as the grasshopper and Drosophila. The neuroarchitecture of the largest of these modules, the fan-shaped body, is characterized by its stereotypic set of decussating fiber bundles. These are generate...

The central complex represents one of the most conspicuous neuroarchitectures to be found in the insect brain and regulates a wide repertoire of behaviors including locomotion, stridulation, spatial orientation and spatial memory. In this review article, we show that in the grasshopper, a model insect system, the intricate wiring of the fan-shaped...

Significance Understanding the nature of the Cambrian radiation involves knowing not only the morphologies of adult animals but also their developmental pathways. However, fossil evidence of early larvae is rare. Here we describe a well-preserved 2-mm-long larva of the short-great-appendage arthropod Leanchoilia illecebrosa from the early Cambrian...

Significance Understanding the evolution of the CNS is fundamental for resolving the phylogenetic relationships within Panarthropoda (Euarthropoda, Tardigrada, Onychophora). The ground pattern of the panarthropod CNS remains elusive, however, as there is uncertainty on which neurological characters can be regarded as ancestral among extant phyla. H...

In the early embryonic grasshopper, two pairs of sibling cells near the apex of the antenna pioneer its dorsal and ventral nerve tracts to the brain. En route, the growth cones of these pioneers contact a so-called base pioneer associated with each tract and which acts as a guidepost cell. Both apical and basal pioneers express stereotypic molecula...

Four types of eyes serve the visual neuropils of extant arthropods: compound retinas composed of adjacent facets; a visual surface populated by spaced eyelets; a smooth transparent cuticle providing inwardly directed lens cylinders; and single-lens eyes. The first type is a characteristic of pancrustaceans, the eyes of which comprise lenses arrange...

The 520 million-year-old Chengjiang biota of China (UNESCO World Heritage) presents the earliest known evidence of the so-called Cambrian Explosion. Studies, however, have mainly been limited to the information exposed on the surface of the slabs. Thus far, structures preserved inside the slabs were accessed by careful removal of the matrix, in man...

The midbrain neuropils of Panarthropoda exhibit a wide spectrum of neuroarchitectures - from rudimentary to highly elaborated - and which at first sight defy a unifying neuroarchitectural principle. Developmental approaches have shown that in model arthropods such as insects, conserved cellular and molecular mechanisms first establish a simple axon...

The antennal nervous system of the grasshopper Schistocerca gregaria comprises two parallel pathways projecting to the brain, each pioneered early in embryogenesis by a pair of sibling cells located at the antennal tip. En route, the growth cones of pioneers from one pathway have been shown to contact a guidepost-like cell called the base pioneer....

Neuropils in the cerebral midline of Panarthropoda exhibit a wide spectrum of neuroarchitectures - from rudimentary to highly elaborated - and which at first sight defy a unifying neuroarchitectural principle. Developmental approaches have shown that in model arthropods such as insects, conserved cellular and molecular mechanisms first establish a...

An important survival strategy for animal species is the so-called niche differentiation between larva and adult. Different developmental stages of the same animal occupy different ecological niches to avoid competing for food or other essential resources. Here, we describe an exceptionally preserved larval stage of the short great appendage (SGA)...

Confirmation that acridine orange (AO) and TUNEL label the same apoptotic cells in a central complex lineage of the embryonic (80 %) grasshopper brain. a DAPI staining reveals three putative degenerated cells (white arrowheads) in the Z lineage. AO (b, green) and TUNEL (c, red) label three cells independently demonstrating that these are undergoing...

Injection of fluorochromes such as Alexa Fluor(®) 568 into single cells in brain slices reveals a network of dye-coupled cells to be associated with the central complex. Subsequent immunolabeling shows these cells to be repo positive/glutamine synthetase positive/horseradish peroxidase negative, thus identifying them as astrocyte-like glia. Dye cou...

This study employs labels for cell proliferation and cell death, as well as classical histology to examine the fates of all eight neural stem cells (neuroblasts) whose progeny generate the central complex of the grasshopper brain during embryogenesis. These neuroblasts delaminate from the neuroectoderm between 25 and 30 % of embryogenesis and form...

I investigate the pattern of gliogenesis in the brain of the grasshopper Schistocerca gregaria prior to mid-embryogenesis, with particular focus on the protocerebrum. Using the glia-specific marker Repo and the neuron-specific marker HRP, I identify three types of glia with respect to their respective positions in the brain: surface glia form the o...

We have investigated the pattern of glia associated with central complex lineages in the embryonic brain of the grasshopper Schistocerca gregaria. Using the glia-specific marker Repo, we identified glia associated externally with such lineages, termed lineage-extrinsic glia, and glia located internally within the lineages, termed lineage-intrinsic...

Dye injection into extracellular space is not taken up by neighboring somata or processes. a Photomicrograph (DIC) of a brain slice (100 % of embryogenesis) shows tip of glass microelectrode filled with dye (Alexa® Fluor 568) situated in extracellular space (outlined dashed white) associated with a small cluster of glia cells (white stars) of the p...

The central complex of the grasshopper (Schistocerca gregaria) brain comprises a modular set of neuropils, which develops after mid-embryogenesis and is functional on hatching. Early in embryogenesis, Repo-positive glia cells are found intermingled among the commissures of the midbrain, but then redistribute as central complex modules become establ...

We redescribe the morphology of Yohoia tenuis (Chelicerata sensu lato) from the Cambrian Burgess Shale Lagersta ̈tte. The morphology of the most anterior, promi- nent, so-called great appendage changes throughout ontog- eny. While its principal morphology remains unaltered, the length ratios of certain parts of the great appendage change significan...

In this study we employed the expression of the astrocyte-specific enzyme glutamine synthetase, in addition to the glia-specific marker Repo, to characterize glia cell types associated with the embryonic development of the central complex in the grasshopper Schistocerca gregaria. Double labeling experiments reveal that all glutamine synthetase-posi...

We report our investigations on the embryonic development of Gryllus assimilis, with particular attention to the head. Significant findings revealed with scanning electron microscopy (SEM) images include: (1) the pre-antennal lobes represent the anterior-most segment that does not bear any appendages; (2) each of the lobes consists of central and m...