Soft-bodied Fossils Research Articles

A burrowing annelid from the early Cambrian.

Soft-bodied fossils of annelids from the Cambrian are relatively rare but provide vital insights into the early evolution and diversification of annelids. Here we describe a new annelid, Xiaoshibachaeta biodiversa gen. et sp. nov., from the early Cambrian (Stage 3) Xiaoshiba biota of Kunming, Yunnan Provence, China. This worm is obliquely oriented in the sediment, and is characteristic of a cephalic cage-like structure formed by the anteriorly directed parapodia and long chaetae of chaetiger 1, strongly suggesting an endobenthic lifestyle. This first report of an annelid worm from the Xiaoshiba biota provides the earliest known plausible evidence of burrowing behaviour in Annelida. Phylogenetic analyses recover X. biodiversa in the polytomy with other crown-group Annelida, indicating that the evolution of cephalic cage in Annelida is most likely convergent.

Unveiling an ignored taphonomic window in the early Cambrian Chengjiang Biota

Abstract The exceptionally preserved soft-bodied fossils from the Chengjiang Biota of southwest China have proved to be critical for our understanding of the biodiversity and ecology of the Cambrian explosion of animals. Almost all previously reported soft-bodied Chengjiang fossils are from the event mudstone beds (EB) of the Yu’anshan Formation. Here, we present the first comprehensive investigation of the soft-bodied fossils from the interbedded background mudstone beds (BGB), based on collections made across the past decade, and characterize their preservation. Soft internal cellular organs/tissues, such as digestive tracts and glands, cardiovascular systems, nervous systems, and musculature, are predominantly preserved as carbonaceous compressions, in contrast to their iron oxide–rich preservation in the EB. Our work highlights two distinct preservation modes within a single Burgess Shale–type Lagerstätte, possibly due to the complex interplay of decay, kerogenization, and pyritization.

The lower Cambrian Cranbrook Lagerstätte of British Columbia

Discovered over a century ago, the lower Cambrian (Series 2, Stage 4) Cranbrook Lagerstätte of southeastern British Columbia's Eager Formation is one of the oldest Burgess Shale-type deposits in North America. This Konservat-Lagerstätte is rich in olenelloid trilobites, but also yields a very low-diversity soft-bodied fossil assemblage including Tuzoia and Anomalocaris , and a low-diversity ichnofauna. Its scientific study, however, remains limited. A 2015 field-based investigation by the Royal Ontario Museum has revealed new information about the site's biota, depositional environment and taphonomic conditions. Not only is the Cranbrook Lagerstätte significant for early Cambrian biostratigraphy and comparisons with other Burgess Shale-type deposits, it also reveals some of the little-known diversity of life in a distal outer shelf environment during the Cambrian period. Supplementary material: Three supplementary figures (historical map, Tuzoia outlines, Anomalocaris specimens), supplementary material and methods, and a supplementary data file (generic presence/absence matrix) are available at https://doi.org/10.6084/m9.figshare.c.6850810

Shadows of the past: An Ediacara-style taphonomic window in advent of Cambrian bioturbators

One of the hypotheses, explaining a sudden vanishing of the Ediacaran biota at the Ediacaran-Cambrian transition, correlates this phenomenon with a disappearance of specific taphonomical factors providing fossilization of soft-bodied organisms (‘Cheshire Cat’ hypothesis). The terminal Ediacaran-Lower Cambrian fossil record does reveal a progressive development of bioturbation and associated decrease of microbial mats, which played a crucial role in the late Precambrian ecosystems. But the tempo of the evolution of organism-sediment interactions significantly varied between different zones of marine basins. Hence, if the ‘Cheshire Cat’ hypothesis is correct, the sedimentary environments barely (if any) colonized by the burrowing eumetazoans might provide the unique interplay of conditions for habitat and Ediacara-style preservation of soft-bodied organisms even in the early Cambrian. Herein we present the new carbon isotope data calibrating the Terreneuvian record in the Ura Uplift of South Siberia and also report fossilized soft-bodied organisms morphologically-close to the Ediacaran holdfasts preserved in association with microbially-induced sedimentary structures in the Cambrian Stage 2 carbonate-siliciclastic Nokhtuisk Formation. Although the late Terreneuvian age, this marginal marine succession is poorly bioturbated and hosts the soft-bodied fossils in the intervals undisturbed by the burrowing organisms. Our study demonstrates the possibility of Ediacara-style preservation of soft-bodied organisms in specific habitat and taphonomic conditions until being replaced by the Cambrian endobenthos.

New soft-bodied panarthropods from diverse Spence Shale (Cambrian; Miaolingian; Wuliuan) depositional environments

AbstractThe Cambrian (Miaolingian; Wuliuan) Spence Shale Lagerstätte of northern Utah and southern Idaho is one of the most diverse Burgess Shale-type deposits of Laurentia. It yields a diverse fauna consisting of abundant biomineralized and locally abundant soft-bodied fossils, along a range of environments from shallow-water carbonates to deep-shelf dark shales. Panarthropods are the dominant component throughout the deposit, both in time and space, but whereas the trilobites and agnostoids are abundant, most of the soft-bodied taxa are only known from very few specimens. Additionally, the knowledge of soft-bodied panarthropods is currently largely limited to locations in the Wellsville Mountains of northeastern Utah. This contribution describes 21 new soft-bodied panarthropods from six locations, including the first occurrences of soft-bodied panarthropods in the High-Creek, Smithfield Creek, Spence Gulch, and Two-Mile Canyon localities. Additionally, we report the presence of bradoriids— i.e., Branchiocaris pretiosa Resser, 1929, Perspicaris? dilatus Robison and Richards, 1981, Naraoia? sp. indet., Thelxiope cf. T. palaeothalassia Simonetta and Delle Cave, 1975, and Tuzoia guntheri Robison and Richards, 1981—for the first time from the Spence Shale Lagerstätte; the first reported occurrence outside of the Burgess Shale for Thelxiope cf. T. palaeothalassia; and the first Wuliuan occurrence of Tuzoia guntheri. We also report on a new hurdiid carapace element and additional specimens of Buccaspinea cooperi? Pates et al., 2021, Dioxycaris argenta Walcott, 1886, Hurdia sp. indet., and Tuzoia retifera Walcott, 1912. This new material improves our understanding of the panarthropod fauna of the Spence Shale Lagerstätte and substantially increases our understanding of the distribution of the described taxa in time and space.

The role of iron in the formation of Ediacaran 'death masks'.

The Ediacara biota are an enigmatic group of Neoproterozoic soft-bodied fossils that mark the first major radiation of complex eukaryotic and macroscopic life. These fossils are thought to have been preserved via pyritic "death masks" mediated by seafloor microbial mats, though little about the chemical constraints of this preservational pathway is known, in particular surrounding the role of bioavailable iron in death mask formation and preservational fidelity. In this study, we perform decay experiments on both diploblastic and triploblastic animals under a range of simulated sedimentary iron concentrations, in order to characterize the role of iron in the preservation of Ediacaran organisms. After 28 days of decay, we demonstrate the first convincing "death masks" produced under experimental laboratory conditions composed of iron sulfide and probable oxide veneers. Moreover, our results demonstrate that the abundance of iron in experiments is not the sole control on death mask formation, but also tissue histology and the availability of nucleation sites. This illustrates that Ediacaran preservation via microbial death masks need not be a "perfect storm" of paleoenvironmental porewater and sediment chemistry, but instead can occur under a range of conditions.

Steinkern spiders: A microbial mat-controlled taphonomic pathway in the Oligocene Aix-en-Provence Lagerstätte, France

The Aix-en-Provence Formation is an Oligocene (22.5 Ma) Lagerstätte in southern France that contains an abundance of soft-bodied fossils preserved in exceptional detail. Many taxa have been described from this formation, including insects, spiders, fishes, and plants, suggesting a diverse ecosystem in a subtropical, brackish, lacustrine paleoenvironment. Fossil spiders from this deposit are preserved as compression fossils and internal and external molds. Recently, compression fossils of spiders from Aix-en-Provence were hypothesized to be a product of a taphonomic pathway based on diatoms and sulfurization. Here, we examine fossil spiders preserved as molds to uncover a second taphonomic pathway based on microbial mats. Evidence of microbial mats include wrinkles, pustular textures, and possible microbial mat chips on the bedding surfaces as well as a matrix fabric that contains possible microbial sheaths and bacterial spherules. The evidence presented here supports prolific microbial mat communities during deposition of the Aix-en-Provence Formation, and suggests that they are likely responsible for the moldic preservation of the spiders. Our work shows that the paleoenvironment of the Aix-en-Provence Formation promoted at least two possible taphonomic pathways that resulted in the differing modes of preservation observed.

The Liexi fauna: a new Lagerstätte from the Lower Ordovician of South China.

The Ordovician Lagerstätten record substantial amounts of excellent preservation and soft-bodied fossils during the Great Ordovician Biodiversification Event (GOBE). However, few Lagerstätten are known from the Lower Ordovician, most of which are preserved in restricted environments and high-latitude regions. Here, we report on a new tropical Lagerstätte, Liexi fauna, which has been recently discovered from a carbonate succession within the Lower Ordovician Madaoyu Formation in western Hunan, South China. It contains a variety of soft tissues, as well as rich shelly fossils, including palaeoscolecidan worms, possible Ottoia, trilobites, echinoderms, sponges, graptolites, polychaetes, bryozoans, conodonts and other fossils. The fauna includes taxa that are not only Cambrian relics, but also taxa originated during the Ordovician, constituting a complex and complete marine ecosystem. The coexistence of the Cambrian relics and Ordovician taxa reveals the critical transition between the Cambrian and Palaeozoic Evolutionary faunas. The unusual Liexi fauna provides new evidence for understanding Ordovician macroevolution and the onset of the GOBE.

The middle Cambrian Linyi Lagerstätte from the North China Craton: a new window on Cambrian evolutionary fauna.

The rapid appearance of major animal groups and complex marine communities during the Cambrian explosion is recorded in large part in Burgess Shale-type lagerstätten. However, the restricted temporal and spatial distribution of known lagerstätten continues to hinder the formation of a comprehensive perspective on Cambrian evolutionary faunas. Here we describe the Linyi Lagerstätte (ca. 504 mya), a new Cambrian Miaolingian lagerstätte from the Zhangxia Formation in Shandong Province, North China. The Linyi Lagerstätte contains a variety of well-preserved soft-bodied fossils, among which the non-trilobite arthropods, particularly the mollisoniids and radiodonts, are the most important groups. The new assemblage is remarkable for its excellent preservation of arthropod limbs, eyes and guts, as well as for its close similarity in taxonomic composition to Laurentian lagerstätten. The distinctive Linyi Lagerstätte holds great promise for providing additional insights into the morphological disparity, community structure and paleogeographic range of marine faunas during the middle Cambrian (Miaolingian).

Deep-water fossil assemblages from the Ediacaran-Cambrian transition of western Hunan, South China and their biostratigraphic and evolutionary implications

The Ediacaran-Cambrian (E-C) transition was a critical stage for the origin and evolution of early complex life on Earth. Because studies of E-C biotas and environments are relatively fewer for deep-water than for shallow-water facies, we undertook a systematic paleontological analysis of the E-C transition in the deep-water Liuchapo Formation at Longbizui, South China. Two sequential but distinct assemblages were recovered, namely the Lower Liuchapo Assemblage (LLA) and the Upper Liuchapo Assemblage (ULA). The LLA consists mainly of soft-bodied fossils, including Longbizuiella hunanensis gen. et sp. nov., Nenoxites jishouensis sp. nov., Nenoxites irregularis sp. nov., Nenoxites sp., Helanoichnus sp., Shaanxilithes ? sp. and tiny-sized spherical fossils. The ULA is dominated by skeletal organisms comprising the small shelly faunas (SSFs, mainly protoconodonts, hyoliths and Cambroscleritida), sponge spicules, and the first reported Poratusiramus xiangxiensis gen. et sp. nov. Biostratigraphic correlation support a latest Ediacaran age for the LLA, whereas the majority of the ULA belongs to the early Cambrian—thus the change from the LLA to the ULA coincided with the E-C transition. Our results suggest that, during the E-C transition, a biological revolution may have occurred in deep-water settings synchronously with the well-studied faunal turnover in shallow-water environments. At Longbizui, fossil abundance and diversity decreased gradually during the latest Ediacaran and recovered stepwise after the E-C transition. The deep-water fauna, including both benthic and pelagic members, developed a biomineralization ability during the E-C transition. As calcareous and possibly phosphatic skeletal organisms began to flourish in shallow-water environments, siliceous skeleton-forming organisms, represented by the spicule-bearing sponges, colonized the deep seafloor in great abundance. In addition, the siliceous spicules documented in this study record fast evolutionary development during the early history of sponges, one of the earliest-branching metazoan phyla. The evolution of spicules from monaxon to diaxon-triaxon and then to tetraxon and polyactinal forms, as well as their considerable increase in diameter and length, was achieved during the first SSF biozone. • First detailed study of deep-water fossil assemblages of Ediacaran-Cambrian age. • Deep-water fauna may have experienced a turnover during the E -C transition. • Patterns of biodiversity and abundance paralleled those of shallow-marine habitats. • Record of diversification of earliest sponges and other siliceous biomineralizers. • Utility of evolutionary sequence of sponge spicule types as biostratigraphic index.

Preservation and diagenesis of soft-bodied fossils and the occurrence of phosphate-associated rare earth elements in the Cambrian (Wuliuan) Spence Shale Lagerstätte

The Spence Shale Lagerstätte is a middle Cambrian (Miaolingian Series; Wuliuan Stage) fossil deposit in northern Utah and southern Idaho, USA. At present, it is known to preserve 89 species, from at least 10 phyla, of biomineralizing and soft-bodied taxa, and represents the only major Lagerstätte of Wuliuan age in Laurentia outside the Canadian Rockies. In addition to taxonomic diversity, the Spence Shale exposures represent a variety of depositional environments along a continental shelf, which have been affected by several diagenetic events, making it a compelling setting to improve our understanding of taphonomic and diagenetic pathways as they affect the broader Burgess Shale-type (BST) preservation. We present analyses of 28 specimens from six localities using scanning electron microscopy (SEM) and integrated energy dispersive X-ray spectrometry (EDS), together with comparisons of published data. Taxa are predominantly preserved as a combination of carbonaceous compressions, iron oxide and pyrite replacement, but eldoniids of the genus Eldonia consistently show enrichment in rare earth elements (REE). The REE, predominantly lanthanum and cerium, are enriched in the phosphate mineral monazite, which occurs in the inner coil of Eldonia ludwigi . This pattern, seen in all sampled Eldonia , differs from previous reports of REE association in BST preservation in being limited to one tissue type within a specific identifiable taxon. REE enrichment of tissues can occur during the lifetime of an individual or during fossilization, and we present both possible pathways along with an outline of taphonomic processes leading to the preservation of soft-bodied fossils from the Spence Shale. • Main preservation modes are carbonaceous compressions and iron oxides/pyrite. • Phosphatized Eldonia ludwigi have unique REE associations. • Preservation of tissue types is biased, as is found in other Paleozoic Lagerstätten.

The Late Ordovician Tafilalt Biota, Anti-Atlas, Morocco: a high-latitude perspective on the GOBE

Abstract The extensive, predominantly siliciclastic deposits of the Upper Ordovician of the Tafilalt have long been the subject of scientific investigation. In the past 25 years, intensified collecting for commercial purposes has resulted in the discovery of several exceptionally-preserved faunas (Konservat-Lagerstätten) in the Tafilalt region, preserving a range of non-biomineralized and soft-bodied organisms. The preservation of these fossils in the coarse clastic sediments of the Tafilalt is surprising, and in the case of soft-bodied organisms, remarkably similar to the preservational mode of typical Ediacaran biotas. These relatively recent discoveries have increased the scientific significance of the Tafilalt Biota, providing an unparalleled insight into the composition and temporal evolution of the shallow, open-marine ecosystems and their denizens during the later stages of the Great Ordovician Biodiversification Event. At least nine different phyla, in addition to several soft-bodied problematica are represented in the Tafilalt. While the highly diverse and remarkably well-preserved echinoderm and euarthropod faunas are most emblematic for the Tafilalt Biota, further studies have revealed a relatively high diversity of molluscs and brachiopods. Among soft-bodied fossils, the problematic paropsonemid eldonids are iconic for the Tafilalt and stand out both through their abundance, and their wide temporal and geographical range throughout the area.

A new marrellomorph arthropod from southern Ontario: a rare case of soft-tissue preservation on a Late Ordovician open marine shelf

AbstractOrdovician open marine Lagerstätten are relatively rare and widely dispersed, producing a patchy picture of the diversity and biogeography of nonmineralized marine organisms and challenging our understanding of the fate of Cambrian groups. Here, for the first time, we report soft-bodied fossils, including a well-preserved marrellomorph arthropod, fragmentary carapaces, and macroalgae, from the Late Ordovician (Katian) Upper Member of the Kirkfield Formation near Brechin, Ontario. The unmineralized elements and associated exceptionally preserved shelly biota were entombed rapidly in storm deposits that smothered the shallow, carbonate-dominated shelf. The marrellomorph, Tomlinsonus dimitrii n. gen. n. sp., is remarkable for its ornate, curving cephalic spines and pair of hypertrophied appendages, suggesting a slow-moving, benthic lifestyle. Reevaluation of marrellomorph phylogeny using new data favors an arachnomorph affinity, although internal relationships are robust to differing outgroup selection. Clades Marrellida and Acercostraca are recovered, but the monophyly of Marrellomorpha is uncertain. The new taxon is recovered as sister to the Devonian Mimetaster and, as the second-youngest known marrellid, bridges an important gap in the evolution of this clade. More generally, the Brechin biota represents a rare window into Ordovician open marine shelf environments in Laurentia, representing an important point of comparison with contemporaneous Lagerstätten from other paleocontinents, with great potential for further discoveries.UUID: http://zoobank.org/884589d0-08f7-4398-ab42-1f5d459be9e9

The Chengjiang Biota inhabited a deltaic environment

The Chengjiang Biota is the earliest Phanerozoic soft-bodied fossil assemblage offering the most complete snapshot of Earth’s initial diversification, the Cambrian Explosion. Although palaeobiologic aspects of this biota are well understood, the precise sedimentary environment inhabited by this biota remains debated. Herein, we examine a non-weathered core from the Yu’anshan Formation including the interval preserving the Chengjiang Biota. Our data indicate that the succession was deposited as part of a delta influenced by storm floods (i.e., produced by upstream river floods resulting from ocean storms). Most Chengjiang animals lived in an oxygen and nutrient-rich delta front environment in which unstable salinity and high sedimentation rates were the main stressors. This unexpected finding allows for sophisticated ecological comparisons with other Burgess Shale-type deposits and emphasizes that the long-held view of Burgess Shale-type faunas as snapshots of stable distal shelf and slope communities needs to be revised based on recent sedimentologic advances.

An atypical Burgess Shale-type fossil assemblage from Cambrian Stage 4 of the Jingshan area, South China: Taphonomy, palaeoecology, and global correlations

Burgess Shale-type biotas have been widely reported from the Cambrian in North America, Siberia, Greenland, China, and Australia; they are crucial in reconstructing the biotic evolution and ecological interactions of early metazoans. Here, we report an atypical Burgess Shale-type fossil assemblage from the Shilongdong Formation (Cambrian Stage 4) in the Jingshan area, central Hubei Province, South China. The newly recovered fauna is preserved in a nearly two-meter-thick yellowish-green shale unit intercalated within the massive dolomite and dolomitic limestone succession of the upper Shilongdong Formation. The fossil-bearing shale unit is likely deposited in the deep subtidal zone below storm wave base with occasional influence of weak storm flows, which was likely situated in the relatively low location with the interior of the restricted carbonate platform. The presence of the trilobite Redlichia guizhouensis assigns the Jingshan fossil assemblage to the Longwangmiaoan Stage (Cambrian Series 2, Stage 4), which is of similar age to the Jianhe biota, but younger than the Guanshan, Balang, and Shipai biotas, and slightly older than the Kaili biota, South China. The Jingshan assemblage is fossiliferous, containing common shelly and some soft-bodied fossils. It comprises algae, brachiopods, arthropods, hyoliths, priapulid worms, echinoderms, possible cnidarians, molluscs, and some enigmatic organisms. The fossils retain soft parts, including brachiopods with pedicles and delicate setae, a naraoiid with the antenna preserved and digestive tracts. The diversity of the assemblage is limited compared with better-known biotas of similar age, but investigation is at a preliminary stage. It is an important geographical extension of the Burgess Shale-type biotas in China and provides more information about the Cambrian Explosion of life and biodiversity by comparing fossiliferous horizons in a chronological framework.

Metamorphism obscures primary taphonomic pathways in the early Cambrian Sirius Passet Lagerstätte, North Greenland

Abstract Correct interpretation of soft-bodied fossils relies on a thorough understanding of their taphonomy. While the focus has often been on the primary roles of decay and early diagenesis, the impacts of deeper burial and metamorphism on fossil preservation are less well understood. We document a sequence of late-stage mineral replacements in panarthropod fossils from the Sirius Passet Lagerstätte (North Greenland), an important early Cambrian Burgess Shale–type (BST) biota. Muscle and gut diverticula were initially stabilized by early diagenetic apatite, prior to being pervasively replaced by quartz and then subordinate chlorite, muscovite, and chloritoid during very low- to low-grade metamorphism. Each new mineral replicates the soft tissues with different precision and occurs in particular anatomical regions, imposing strong biases on the biological information retained. Muscovite and chloritoid largely obliterate the tissues’ original detail, suggesting that aluminum-rich protoliths may have least potential for conserving mineralized soft tissues in metamorphism. Overall, the fossils exhibit a marked shift toward mineralogical equilibration with the matrix, obscuring primary taphonomic modes. Sequential replacement of the phosphatized soft tissues released phosphorus to form new accessory monazite (and apatite and xenotime), whose presence in other BST biotas might signal the prior, more widespread, occurrence of this primary mode of preservation. Our results provide critical context for interpreting the Sirius Passet biota and for identifying late-stage overprints in other biotas.

Evidence for microbially mediated silver enrichment in a middle Cambrian Burgess Shale-type deposit, Mackenzie Mountains, northwestern Canada

The Selwyn basin and Mackenzie platform of northwestern Canada house an array of mineral deposits and prospects that are rich in silver, including Neoproterozoic red-bed or Kupferschiefer-type Cu and lower Paleozoic sedimentary exhalative (SEDEX) and Zn–Pb deposits. Within this overall metallogenic setting, the middle Cambrian (Drumian) Rockslide Formation was deposited under a largely oxic water column on the platform-to-basin slope along the eastern side of the Selwyn basin. The formation includes an interval termed the Ravens Throat River Lagerstätte, which is a localized Burgess Shale-type calcareous mudstone about 2 m thick that preserves soft-bodied fossils. The mudstone contains comparatively large amounts of organic carbon preserved as thin carbonaceous laminae and discontinuous seams, representing benthic microbial mats, the remains of cyanobacteria and algae that were living in the water column, fecal pellets, large coprolites, and degraded animal tissues. The upper part of the Rockslide Formation, including the fossiliferous interval, contains elevated concentrations of Ag, up to 0.47 ppm. Some of the Ag in the mudstone occurs as aggregates of elemental particles ∼10 µm in size, preferentially on the carbonaceous material comprising the coprolites. This localized enrichment suggests bioaccumulation of Ag nanoparticles or Ag+ from the water column by microorganisms on the coprolites or degrading organic matter in them. The source of the Ag may have been from penecontemporaneous SEDEX metallogeny or from broadly related subsurface fluids in the Selwyn Basin that enriched the overlying seawater.

Furongian (Jiangshanian) occurrences of radiodonts in Poland and South China and the fossil record of the Hurdiidae.

The Furongian period represents an important gap in the fossil record of most groups of non-biomineralizing organisms, owing to a scarcity of Konservat-Lagerstätten of that age. The most significant of these deposits, the Jiangshanian strata of the Sandu Formation near Guole Township (Guangxi, South China), have yielded a moderately abundant, but taxonomically diverse soft-bodied fossil assemblage, which provides rare insights into the evolution of marine life at that time. In this contribution, we report the first discovery of a radiodont fossil from the Guole Konservat-Lagerstätte. The specimen is an incomplete frontal appendage of a possibly new representative of the family Hurdiidae. It is tentatively interpreted as composed of seven podomeres, six of which bearing laminiform endites. The best preserved of these endites is especially long, and it bears short auxiliary spines that greatly vary in size. This is the second occurrence of hurdiids and more generally radiodonts in the Furongian, the first being the external mould of an oral cone from Jiangshanian strata of the Wiśniówka Sandstone Formation in Poland. Restudy of this Polish specimen confirms that it belongs to a hurdiid radiodont and best compares to Peytoia. The family Hurdiidae includes the oldest (basal Cambrian Epoch 2) and youngest (Early Ordovician, possibly Early Devonian) representatives of the Radiodonta and as such, has the longest stratigraphical range of the group. Yet, hurdiids only became prominent components of marine ecosystems during the middle Cambrian (Miaolingian), and their fossil record in younger strata remains limited.

Distraction sinking and fossilized coleoid predatory behaviour from the German Early Jurassic

Exceptional fossil preservation is required to conserve soft-bodied fossils and even more so to conserve their behaviour. Here, we describe a fossil of a co-occurrence of representatives of two different octobrachian coleoid species. The fossils are from the Toarcian Posidonienschiefer of Ohmden near Holzmaden, Germany. The two animals died in the act of predation, i.e. one had caught the other and had begun to nibble on it, when they possibly sank into hypoxic waters and suffocated (distraction sinking). This supports the idea that primitive vampyromorphs pursued diverse feeding strategies and were not yet adapted to being opportunistic feeders in oxygen minimum zones like their modern relative Vampyroteuthis.

A new middle Cambrian radiodont from North China: Implications for morphological disparity and spatial distribution of hurdiids

Hurdiidae, a clade of Radiodonta that has attracted widespread attention in recent years, is notable for their massive tripartite cephalic carapace and a wide variety of feeding habits. Although the Hurdiidae has a cosmopolitan distribution in the Cambrian, their Miaolingian occurrences are restricted to Laurentia. Here we describe a new hurdiid radiodont, Cordaticaris striatus gen. et sp. nov., based on well-preserved specimens from the middle Cambrian (Miaolingian, Drumian) Zhangxia Formation in Shandong Province, North China. This new taxon is characterized by a heart-shaped central element with linear ornament, frontal appendages equipped with nine blade-like endites including seven subequal elongate endites, a node-bearing ‘peytoia’-type oral cone, and a trunk covered with rows of setal structures. Cordaticaris not only enriches the taxonomic diversity of Hurdiidae, but also further documents the great morphological disparity of hurdiid sclerotized body elements. The discovery of soft-bodied fossils in the Zhangxia Formation also stresses the great potential of the Miaolingian strata of North China for the preservation of non-biomineralized organisms.