The Early Devonian Rhynie chert Konservat Lagerstätte in Aberdeenshire, Scotland, contains an abundance of structurally preserved fossils of organisms that lived together in an early terrestrial geothermal-wetland ecosystem, including cyanobacteria, fungi and fungus-like organisms, algae, land plants, and animals ranging from testate amoebae to nematodes and aquatic crustaceans to the earliest harvestmen, which were fully adapted to life on land. The chert also provides ample direct evidence of interactions between different organisms. Many of the fossils are preserved in situ and reveal astonishing details at the (sub-)cellular level, suggesting that entombment in silca has occurred rapidly to virtually instantaneously. However, not all fossils from the Rhynie chert are excellent; there are also signs of desiccation and shrinkage, as well as biological decay and mechanical destruction. Understandably, most attention has been directed at the well-preserved fossils, while the tattered, fragmented, (partially) decayed, and otherwise inferior ones have received little attention. In this article, we present examples of the varying quality of preservation of organic remains in the Rhynie chert and discuss the taphonomic processes that have led to this. We focus on land plant reproductive biology, microbial fossils, and different levels of fungal interaction, three aspects that stand out in the fossil content of the Rhynie chert Lagerstätte.
Pujatopouli soberana is a small Cretaceous bird collected from Maastrichtian rocks of the López de Bertodano Formation, Marambio (Seymour) Island, Antarctica. The exquisite preservation of the skull, including the braincase and beak, and the synsacrum enabled the most complete examination of the central nervous system for an extinct Neornithes. The soft tissue reconstructions based on CT scan data include the brain, inner ear, craniofacial nervovasculature (peripheral trigeminal nerve), and spinal medulla (synsacrum organ). The innervation of the mandible and upper beak, and the morphology of the lumbosacral canal (which encloses the second-largest nervous structure by volume) are also described for the first time in a Cretaceous bird. The implications of inner ear morphology, the presence of a glycogen organ, and the innervation of mandible and bill for the sensory biology of Pujatopouli are analyzed to shed light on its lifestyle.
The Piesberg north of the city of Osnabrück, NW Germany, has been known as a locality for plant fossils of Pennsylvanian age since at least 1799. Still, even in modern times palaeontological progress can be made, from the insight that faunal elements are far more common than previously thought throughout the succession, gained in the late 1980’s, to the recent discovery of lacustrine freshwater deposits in 2018, a palaeoenvironment rarely recorded in the Moscovian of equatorial Pangaea. The present paper highlights recent palaeontological finds from the Piesberg Fossil-Lagerstätte and their significance for our understanding of systematics, phylogeny and palaeoecology of various taxa ranging from arthropods to sphenophytes. A sedimentological overview of the shale beds representing the palaeo-lake illustrates a deepening-shallowing-trend with the highstand sedimentation exhibiting rhythmic, varve-like stratification, probably representing a seasonal to subseasonal signal in an otherwise calm and inhospitable depositional environment. Fossil preservation is often exceptional in these black shales, due to the small grain sizes, anoxic depositional environment and subsequent lack of bioturbation, and thus records fine anatomical details of specimens. The biotic inventory of the palaeo-lake exhibits significant differences to other fossil-bearing beds of the Piesberg succession, with e.g. occurrences of “dryland” flora such as Dichophyllum moorei and Taeniopteris, as well as a higher abundance of scorpions and representatives of the xiphosuran genus Liomesaspis. In the light of these recent discoveries, the Piesberg locality will very likely continue to provide significant palaeontological insights in the future.
Laminated limestones from quarries in the vicinity of Solnhofen preserved remains of a diverse and complex shallow marine ecosystem. The so-called Solnhofen[-er] Plattenkalke are famous for their exceptionally well-preserved fossils of more than 1600 described species of extinct plants and animals. They have yielded an important pancrustacean palaeodiversity, including four species of Thylacocephala, a peculiar ingroup of fossil marine pancrustaceans. Two of these species, Mayrocaris bucculata and Clausocaris lithographica, have been the subject of several studies, in contrary to Dollocaris michelorum, which, after its original publication, has received little attention in the published literature. In this study, we describe a new species, Ovalicaris wulforum sp. nov., based on a newly discovered specimen. In addition, we re-examine D. michelorum based on new material. Additional morphological features of its shield are reported, including ornamentation on its margins (serrations, crenations) and surface (punctuations). The re-examination of D. michelorum leads to important insights into the impact of taphonomy on intra-specific morphological variability of thylacocephalans. Finally, we discuss the taxonomic diversity of Thylacocephala in the Solnhofen Lagerstätten and compare it with other important thylacocephalan faunae.
A new specimen of the fossil spider Parvithele muelleri Wunderlich, 2017 (Araneae: Mesothelae) is described from the mid-Cretaceous (ca. 99 Ma) Burmese amber of Myanmar. Like the original holotype, the new specimen is a mature male, which clearly preserves a series of tibial macrospines, similar to the condition in the extant genus Liphistius Schiødte, 1849. Given that the single extant mesothele family, Liphistiidae, is predicted to have radiated ca. 39–58 million years ago, the occurrence of somewhat modern-looking male pedipalp spination in older fossil mesotheles is of considerable interest. The new specimen also shows spinnerets in a relatively posterior position, although variability observed in extant species suggests that this trait may be of limited systematic value. Of particular note is the presence of a large and well-developed anal tubercle, a feature seen in other Burmese amber mesotheles, but absent or much reduced in modern taxa. This structure may represent a vestige of the ancestral pygidium and could provide evidence for an intermediate stage following the loss of a segmented pygidium plus a flagellum as seen in the tailed spiders belonging to the chimerarachnid group. The combination of characters in P. muelleri—especially the prominent anal tubercle—supports Wunderlich’s resurrection of the family Parvithelidae from its synonymy with the otherwise Carboniferous family Arthromygalidae.
