Fur Formation Research Articles

High-precision U–Pb geochronology of the Lundy igneous complex: implications for North Atlantic volcanism and the far-field Paleocene–Eocene ash record

The Lundy Island (Bristol Channel, UK) granite is a felsic expression of the southernmost igneous centre of the North Atlantic Igneous Province that emplaced millions of cubic kilometres of magma during the Paleogene. The granite's distinctive S-type, peraluminous, two-mica ± garnet ± tourmaline composition has led to the hypothesis that eruptions from the Lundy volcanic centre may be the source of thick felsic ash layers within the early Eocene Fur Formation (Denmark) that act as key marker horizons for the onset and duration of the Paleocene–Eocene Thermal Maximum. This paper presents high-precision zircon U–Pb emplacement ages of 57.24 ± 0.11/0.12/0.13 Ma for the granite and 55.970 ± 0.021/0.030/0.070 Ma for a felsic ‘lundyite’ dyke. Trace and rare earth element patterns indicate close similarities between late-stage Lundy activity and ash layer −33 in Denmark. This ash layer was deposited during the Paleocene–Eocene Thermal Maximum carbon isotope excursion, suggesting that the Lundy volcanic centre is likely to be the source of this key ash horizon and that magmatism at Lundy likely continued into the early Eocene.

First record of Berothidae (Neuroptera) from the early Eocene of Denmark

Danoberotha verkleijorum gen. et sp. nov. is described from the early Eocene Fur Formation, Denmark. This is the first record of Berothidae from this formation. The key distinguishing feature of the new genus is the pectinate CuP of the forewing. It differs from other genera possessing the pectinate forewing CuP by other characters (e.g., the configuration of CuA; the number of crossveins between RA and RP proximad the fusion of Sc and RA). It is assumed that the climate of the Fur Formation when layers +25 to +30 were deposited was upper microthermal.

The oldest Rhantus (Coleoptera, Dytiscidae) from the earliest Eocene Fur Formation, Denmark

†Rhantus villumi sp. nov. is described and illustrated on the basis of a single specimen from the earliest Eocene Fur Formation, Denmark. With an estimated age of ca. 55.4 Ma, it represents the oldest member of an extant genus of the family Dytiscidae. However, the presence of Rhantus in the early Eocene is only slightly older than previous estimates, and generally agrees well with phylogenetic analyses of the subfamily Colymbetinae. The presence of a predominantly temperate genus in the presumably warm Lagerstätte is briefly discussed, supporting the hypothesis of temporary cooling, as suggested by several other invertebrate records from the Fur Formation. It is suggested that the new species could feed on mosquito larvae, which are known from the Lagerstätte. Finally, a record of another Dytiscidae species from the same locality is mentioned, but, due to poor preservation and lack of diagnostic characters, this fossil remains unidentified to genus or species level.

Nothochrysinae (Neuroptera: Chrysopidae) from the early Eocene Fur Formation, Denmark, with description of a new genus

Furochrysa alisae gen et sp. nov. is described, and Stephenbrooksia multifurcata Willmann, 1993 and Danochrysa madseni Willmann, 1993 are re-described based on their holotypes and additional specimens from the early Eocene Fur Formation of Denmark. The very long crossvein 1icu between CuA and CuP in the hind wing distinguishes Furochrysa gen. nov. from all other Nothochrysinae. The hind wing venation of the holotype of S. multifurcata is strongly aberrant; in particular, its MA is deeply forked proximad the origin of RP, while it is not forked proximad the pseudocubitus in other Chrysopidae. The forewing venation of the three examined specimens of D. madseni show variability in the branching of the anterior branch of CuP and A2. The chrysopid assemblage of the early Eocene Fur Formation strongly differs from that of the late Paleogene (late Eocene/Oligocene) of Europe, while the nothochrysines of the early and late Paleogene of North America do not especially differ.

A new species of the genus Cephalallus Sharp, 1905 (Coleoptera: Cerambycidae) from the Ypresian of Denmark

A new species of longhorn beetles from the subfamily Spondylidinae, Cephalallus vitalii sp. n., is described and illustrated from the earliest Ypresian Fur Formation in Denmark. The new species differs from other species of the genus Cephalallus Sharp, 1905 in the eyes without emargination, shorter third and fourth antennomeres, and the sides of the pronotum lacking granules. This discovery marks the first record of Cerambycidae from the Fur Formation.

Stolleagrion foghnielseni (Odonata, Cephalozygoptera, Dysagrionidae) gen. et sp. nov.: a new odonatan from the PETM recovery phase of the earliest Ypresian Fur Formation, Denmark.

We describe the new genus and species Stolleagrion foghnielseni n. gen. et sp. from the Fur Formation in northwestern Denmark based on a single fossil wing. This is the first odonatan described from the earliest part of the PETM recovery phase of the early Eocene. A combination of nine wing character states are considered to be diagnostic of the Dysagrionidae Cockrell only together with the cephalozygopteran head; however, the combination of these nine plus the presence of Ax0 is also diagnostic without the head. By this, we assign Stolleagrion foghnielseni to the Dysagrionidae and reassess the position of other odonates previously treated as cf. Dysagrionidae.

New Limaiinae (Neuroptera: Chrysopidae) from the early Eocene Fur Formation, Denmark, including an unexpected finding of a Mesozoic genus.

Two species of Limaiinae (Chrysopidae) are described from the early Eocene Fur Formation of Denmark: Mesypochrysa nielseni sp. nov. and Limaiinae gen. et sp. A. All forewing character states of M. nielseni sp. nov. are similar to those of the widely distributed Mesozoic genus Mesypochrysa Martynov, 1927, which was formerly known from the Middle Jurassic to mid-Cretaceous. Limaiinae gen. et sp. A is represented by an incomplete forewing. Although it differs from other species known from the formation, we refrained to name it pending a more complete specimen. The relatively high diversity of Limaiinae in the early Eocene of Denmark, with at least by two genera and four or five species is surprising. This diversity in the Fur Formation is nearly equal to that of Nothochrysinae.

First leafhopper from the earliest Eocene Fur Formation (Denmark) representing a new genus of Cicadellinae (Hemiptera: Cicadomorpha)

The Fur Formation, located in the western Limfjord region of northern Jutland, Denmark, is famous for its numerous and often exceptionally well-preserved marine and terrestrial fossils (e.g., Bonde et al., 2008). The geological background of the Konservat-Lagerstätte was described by Pedersen & Surlyk (1983). The formation preserves a rich record of earliest Ypresian (Eocene, ca. 55 Ma) fossil insects (e.g., Madsen & Rasmussen, 2021). The fauna includes many hemipterans mostly representing Heteroptera and Sternorrhyncha but the diverse modern family Cicadellidae (leafhoppers) is represented by a single specimen among the >20,000 available insect fossils discovered so far.

EOCENE RHAMPHOSIDAE (TELEOSTEI: SYNGNATHIFORMES) FROM THE BOLCA LAGERSTÄTTE, ITALY

The Rhamphosidae is an extinct family of syngnathiform fishes from the lower Eocene deposits of Europe, primarily known from specimens derived from the Ypresian Konservat-Lagerstätte of Bolca (Verona province, Italy). A descriptive analysis of 28 specimens of Rhamphosus from Bolca revealed the existence of six species, showing a greater taxonomic diversity compared to the previous scenario of only two species (the type species Rhamphosus rastrum and Rhamphosus biserratus). Four new species are established herein: Rhamphosus bloti n. sp., characterized by a peculiar and unique rostrum with a discoid shape; Rhamphosus brevirostris n. sp., which exhibits a moderately large size associated with a relatively short rostrum; Rhamphosus longispinatus n. sp., characterized by having the longest dorsal-fin spine and rostrum of all the Rhamphosus species; Rhamphosus tubulirostris n. sp., which shows a peculiar slim rostrum, long-based dorsal and anal fins, and a unique squamation characterized by the presence of numerous bucklers. The species from Bolca are also compared to the only other known Rhamphosus species, Rhamphosus rosenkrantzi, from the Fur Formation, Denmark. A number of morphological features support the assignment of the Rhamphosidae to the syngnathiform clade Dactylopteroidei, together with the extant families Dactylopteridae and Pegasidae, representing the sister group to the Pegasidae.

Early Eocene fossils elucidate the evolutionary history of the Charadriiformes (shorebirds and allies)

AbstractWe report charadriiform and charadriiform-like birds from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). A partial skeleton of a small modern-type charadriiform is described as a new species, Charadriisimilis essexensis n. gen. n. sp., and most closely resembles taxa of the Charadrii (plovers, stilts, oystercatchers, and other “wader-like” shorebirds). Affinities to this clade were also supported by phylogenetic analyses, which placed the fossil as the sister taxon of either the Burhinidae or all crown group Charadrii. In addition, we identify specimens of the charadriiform-like taxon Scandiavis, which was before known only from the early Eocene Fur Formation in Denmark. Associated limb elements of two individuals are classified as Scandiavis cf. mikkelseni Bertelli et al., 2013, and remains of two further individuals are tentatively assigned to Scandiavis. The presence of a processus supracondylaris dorsalis on the previously unknown humerus corroborates charadriiform affinities of Scandiavis, whereas a plesiomorphic hypotarsus morphology indicates a position outside crown group Charadriiformes. Charadriisimilis essexensis is one of the earliest modern-type charadriiforms, and the holotype of the species is the most substantial early Paleogene fossil record of a charadriiform bird. Together with Scandiavis, as the best-represented taxon to be considered as a stem group charadriiform, it provides the basis for an improved understanding of the evolutionary history of charadriiform birds.UUID: http://zoobank.org/ca15ee81-09e8-4577-8beb-a362debf6636

The damselfly genus Furagrion Petrulevičius et al. (Odonata, Zygoptera) from the early Eocene Fur Formation of Denmark and the dysagrionoid grade.

The earliest Eocene odonate genus Furagrion Petrulevičius et al. from the Danish Fur Formation is revised based on eighteen specimens, two of which apparently have been lost since their publication. The holotype of Phenacolestes jutlandicus Henriksen, type species of Furagrion, is incomplete and lacks the characters currently used to differentiate species, genera and higher taxa in Odonata. We, therefore, propose that the holotype is set aside and a recently discovered nearly complete Fur Formation fossil is designated as neotype. Furagrion possesses all of the nine wing character states currently used along with head shape for diagnosing the Dysagrionidae; however, Furagrion has a characteristically zygopteran head, not the distinctive head shape of the suborder Cephalozygoptera. We, therefore, treat it as a zygopteran unassigned to family. These nine wing character states appear in different combinations not only in various Zygoptera and Cephalozygoptera, but also in the Frenguelliidae, an Eocene family of Argentina that may represent an unnamed suborder. We recognise these taxa as constituting a dysagrionoid grade, in which these character states appear either convergently or as symplesiomorphies. Furagrion morsi Zessin is synonymized with Phenacolestes jutlandicus Henriksen, syn. nov. and Morsagrion Zessin with Furagrion Petrulevičius, Wappler, Wedmann, Rust, and Nel, syn. nov.

The argentiniform Surlykus longigracilis gen. et sp. nov., the most abundant fish from the Eocene Fur Formation of Denmark.

Bony fishes are among the best represented macrofossils from the earliest Eocene Fur Formation, northern Denmark. The most abundant fish of the formation has never been formally described, in spite of its abundance throughout the formation, and only referred to as an ‘argentinoid’. This work provides a taxonomic study of this argentinoid taxon, which is described herein as Surlykus longigracilis gen. et sp. nov. The caudal skeleton shows separated first preural and first ural centra, a unique condition within the Argentiniformes. In addition, it is characterised by having a large mouth and a single supramaxilla, which suggest that Surlykus gen. nov. occupies a basal position within the Argentiniformes, representing the sister-group to all the other lineages of this clade ([Argentinidae + Opisthoproctidae] + [Bathylagidae + Microstomatidae]), and, consequently, a stem-group Argentiniformes. Mass-mortality assemblages may indicate that Surlykus longigracilis gen. et sp. nov. formed large schools in the ancient North Sea Basin, where it probably represented the trophic nucleus of the fish communities.

An ancestral hard-shelled sea turtle with a mosaic of soft skin and scutes

The transition from terrestrial to marine environments by secondarily aquatic tetrapods necessitates a suite of adaptive changes associated with life in the sea, e.g., the scaleless skin in adult individuals of the extant leatherback turtle. A partial, yet exceptionally preserved hard-shelled (Pan-Cheloniidae) sea turtle with extensive soft-tissue remains, including epidermal scutes and a virtually complete flipper outline, was recently recovered from the Eocene Fur Formation of Denmark. Examination of the fossilized limb tissue revealed an originally soft, wrinkly skin devoid of scales, together with organic residues that contain remnant eumelanin pigment and inferred epidermal transformation products. Notably, this stem cheloniid—unlike its scaly living descendants—combined scaleless limbs with a bony carapace covered in scutes. Our findings show that the adaptive transition to neritic waters by the ancestral pan-chelonioids was more complex than hitherto appreciated, and included at least one evolutionary lineage with a mosaic of integumental features not seen in any living turtle.

The second European representative of the epallagid genus Labandeiraia in the lowermost Eocene Oise amber (Odonata, Zygoptera)

Among the calopteran damselflies, the family Epallagidae was clearly dominating the diversity of the Holarctic Cenozoic (11 described species in eight extinct genera), while the Calopterygidae were extremely rare at the same time (six Cenozoic species in two extant and one fossil genera) (Fossilworks database at http://www.fossilworks.org/cgi-bin/bridge.pl?action=home, consulted 21/10/2022). They mainly belonged to the extinct subfamily Eodichrominae Cockerell, 1923, and their most diverse genus was the early Eocene genus Labandeiraia Petrulevičius et al., 2007, known from compression fossils from the lacustrine Green River Formation (USA) and the marine Fur Formation in Denmark (Petrulevičius et al., 2007; Bechly et al., 2020).

Classifying fossil Darwin wasps (Hymenoptera: Ichneumonidae) with geometric morphometrics of fore wings.

Linking fossil species to the extant diversity is often a difficult task, and the correct interpretation of character evidence is crucial for assessing their taxonomic placement. Here, we make use of geometric morphometrics of fore wings to help classify five fossil Darwin wasps from the Early Eocene Fur Formation in Denmark into subfamilies and often tribes. We compile a reference dataset with 342 fore wings of nine extant subfamilies and nine relevant fossil species. Since geometric morphometrics was mostly ignored in the past in Darwin wasp classification, the dataset is first used to examine differences and similarities in wing venation among subfamilies. In a next step, we used the reference dataset to inform the classification of the fossil species, which resulted in the description of one new genus and five new species, Crusopimpla weltii sp. nov., Ebriosa flava gen. et sp. nov., Entypoma? duergari sp. nov., Lathrolestes? zlatorog sp. nov., and Triclistus bibori sp. nov., in four different subfamilies. Carefully assessing data quality, we show that the fore wing venation of fossil Darwin wasps is surprisingly suitable to assign them to a subfamily or even lower taxonomic level, especially when used in conjunction with characters from other parts of the body to narrow down a candidate set of potential subfamilies and tribes. Our results not only demonstrate a fast and useful approach to inform fossil classification but provide a basis for future investigations into evolutionary changes in fore wings of ichneumonids. The high informativeness of wing venation for classification furthermore could be harvested for phylogenetic analyses, which are otherwise often hampered by homoplasy in this parasitoid wasp family.

Butyrumichthys henricii gen. et sp. nov.: a new stromateiform fish from the lower Eocene Fur Formation, Denmark

ABSTRACT A new genus and species of stromateiform fish, Butyrumichthys henricii gen. et sp. nov., from the Eocene Fur Formation of Denmark is described. The description is based on six well-preserved, almost complete articulated skeletons plus a well-preserved head. All the specimens originate from the carbonate concretion horizons of the Fur Formation. The fossils were investigated also through element-mapping of strontium and phosphorus using a micro-XRF spectrometer in order to expose and enhance the skeletal anatomy. Butyrumichthys gen. nov. exhibits a unique combination of characters that support its recognition as a new stromateoiform genus, including jaws with uniserially arranged, small conical teeth, preopercle with at least 15 prominent spines, 37–38 (17–18 + 20) vertebrae, dorsal fin with 5–6 weak spines and 27–28 soft rays, and anal fin with two spines and 19–20 soft rays. The new fossil stromateoid described herein shows several morphological similarities to certain species of the genus Schedophilus Cocco, 1839, especially S. pemarco (Poll, 1959) and S. medusophagus (Cocco, 1839), and is tentatively referred to the family Centrolophidae. The exceptionally preserved fossil fishes of the Fur Formation increase our knowledge of the diversity of Paleogene marine teleosts, also providing some of the earliest occurrences of modern lineages based on articulated skeletal remains, including that of the stromateiforms.

A new beardfish (Teleostei, Polymixiiformes) from the Eocene Fur Formation, Denmark

ABSTRACT The earliest Eocene (Ypresian) Fur Formation (Denmark) is globally renowned for its exceptionally well-preserved fossils, including birds, sea turtles, insects, plants, and fishes. Fishes, albeit abundant and diverse, however, are only superficially known and very few detailed, taxonomic studies have been realized to date. A new polymixiiform fish, Polyspinatus fluere gen. et sp. nov., from the Fur Formation is described based on seven well-preserved, nearly complete specimens. All the specimens were studied by traditional stereomicroscopy, and by micro-X-ray fluorescence-element mapping. Digital 2D-element images of strontium-, phosphorus-, and calcium distributions of each specimen were directly applied for the taxonomic descriptions presented herein. Polyspinatus fluere gen. et sp. nov. is the first known Eocene record of the family Polymixiidae based on articulated skeletal remains. Polyspinatus gen. nov. exhibits a unique combination of characters that support its recognition as a new genus of the Polymixiidae. Its specialized hyoid apparatus with the first and second branchiostegal rays being sinuous and parallel to each other, and the third being wide and plate-like, followed by four saber-like elements, is strikingly similar to that of Polymixia, supporting a possible sister-group relationship with extant beardfishes.

High diversity of pimpline parasitoid wasps (Hymenoptera, Ichneumonidae, Pimplinae) from the lowermost Eocene Fur Formation (Denmark)

Une grande diversité de guêpes parasitoïdes Pimplinae (Hymenoptera, Ichneumonidae) trouvée dans l'Éocène basal de la Formation de Fur (Danemark). Estimées à près de 100 000 espèces, les guêpes parasitoïdes de la famille des Ichneumonidae sont aujourd'hui plus diversifiées que l'ensemble des vertébrés. Cependant, seulement 288 espèces sont actuellement décrites dans le registre fossile. Plusieurs centaines de nouvelles espèces attendent donc dans les collections paléontologiques pour une description formelle. L'une des lacunes temporelles les plus importantes concerne les 12 millions d'années suivant la crise du Crétacé-Paléogène, jusqu'à la fin de l'Yprésien. Seulement deux espèces y sont scientifiquement décrites, dont Pimpla stigmatica Henriksen, 1922 de la Formation danoise de Fur (c. 55 Ma). Nous redécrivons ici et reclassifions cette espèce au sein du genre Epitheronia Gupta, 1962 et décrivons neuf nouvelles espèces issues de cette Formation au sein des Pimplinae: Crusopimpla collina n. sp., C. elongata n. sp., C. minuta n. sp., C. rettigi n. sp., C. violina n. sp., Theronia? furensis n. sp., T. nigriscutum n. sp., Xanthopimpla ciboisae n. sp. et X. crescendae n. sp. La diagnose du genre Crusopimpla Kopylov, Spasojevic & Klopfstein, 2018 est amendée grâce aux données des nouvelles espèces décrites. En comparant la coloration préservée au sein même d'un spécimen ou entre spécimens d'une même espèce et de différentes espèces, nous concluons sur l'intérêt des motifs de couleur observés au sein des Ichneumonidae de la Formation de Fur. Le nombre d'espèces de guêpes parasitoïdes Pimplinae de Fur est très important en comparaison aux autres données fossilifères, mais reste faible en comparaison au nombre d'espèces actuelles. Des études supplémentaires et de nouvelles fouilles permettront donc, très certainement, de révéler une diversité spécifique d'Ichneumonidae encore plus grande au sein de la Formation de Fur.

Palaeogene glendonites from Denmark

Pristinely preserved mineral pseudomorphs called glendonites, up to 1.6 m long, from the Palaeogene strata of Denmark allow detailed crystallographic characterisation and add to the understanding of the transformation of the precursor mineral, ikaite (CaCO3·6H2O), to calcite, which constitutes the glendonite. We describe Danish pseudomorphs after ikaite from two localities and formations: the Early Eocene Fur Formation and the Late Oligocene Brejning Formation. This detailed study highlights that key aspects such as morphology and mode of occurrence of these ancient glendonites are identical to those of their parent mineral ikaite, when it grows in marine sediments. Systematic distortion of the angles in glendonite and marine sedimentary ikaite relative to the ideal ikaite symmetry may arise due to the incorporation of organic matter into the crystal structure, and we demonstrate the similarity between modern and ancient ikaite formation zones in the marine sedimentary realm with respect to organic matter.

Preservation and Taphonomy of Fossil Insects from the Earliest Eocene of Denmark.

Simple SummaryInsect fossils dating 55 million-years-old from the Stolleklint Clay and Fur Formation of Denmark are known to preserve both fine morphological details and color patterns. To enhance our understanding on how such fragile animals are retained in the fossil record, we examined a pair of beetle elytra, a wasp and a damselfly using sensitive analytical techniques. In our paper, we demonstrate that all three insect fossils are composed of cuticular remains (that is, traces of the exoskeleton) that, in turn, are dominated by the natural pigment eumelanin. In addition, the beetle elytra show evidence of a delicate lamellar structure comparable to multilayered reflectors that produce metallic hues in modern insects. Our results contribute to improved knowledge on the process of fossilization of insect body fossils in marine environments.Marine sediments of the lowermost Eocene Stolleklint Clay and Fur Formation of north-western Denmark have yielded abundant well-preserved insects. However, despite a long history of research, in-depth information pertaining to preservational modes and taphonomic pathways of these exceptional animal fossils remains scarce. In this paper, we use a combination of scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to assess the ultrastructural and molecular composition of three insect fossils: a wasp (Hymenoptera), a damselfly (Odonata) and a pair of beetle elytra (Coleoptera). Our analyses show that all specimens are preserved as organic remnants that originate from the exoskeleton, with the elytra displaying a greater level of morphological fidelity than the other fossils. TEM analysis of the elytra revealed minute features, including a multilayered epicuticle comparable to those nanostructures that generate metallic colors in modern insects. Additionally, ToF-SIMS analyses provided spectral evidence for chemical residues of the pigment eumelanin as part of the cuticular remains. To the best of our knowledge, this is the first occasion where both structural colors and chemical traces of an endogenous pigment have been documented in a single fossil specimen. Overall, our results provide novel insights into the nature of insect body fossils and additionally shed light on exceptionally preserved terrestrial insect faunas found in marine paleoenvironments.