This paper presents a detailed analysis of the high-resolution facies architecture of the Middle Pleistocene Porta subaqueous ice-contact fan and delta complex, deposited on the northern margin of glacial Lake Weser (Northwest Germany). A total of 10 sand and gravel pits and more than 100 wells were examined to document the complex facies architecture. The field study was supplemented with a ground-penetrating radar survey and a shear-wave seismic survey. All collected sedimentological and geophysical data were integrated into a high-resolution three-dimensional geological model for reconstructing the spatial distribution of facies associations. The Porta subaqueous fan and delta complex consist of three fan bodies deposited on a flat lake-bottom surface at the margin of a retreating ice lobe. The northernmost fan complex is up to 55 m thick, 6AE2 km wide and 6AE5 km long. The incipient fan deposition is characterized by high-energy flows of a plane-wall jet. Very coarse-grained, highly scoured jet-efflux deposits with an elongate plan shape indicate a high Froude number, probably >5. These jet-efflux sediments are deposited in front of a large 3AE2 km long, up to 1AE2 km wide, and up to 25 m deep flute-like scour, indicating the most proximal erosion and bypass area of the jet that widens and deepens with distance downstream to the region of maximum turbulence (approximately five times the conduit diameter). Evidence for subsequent flow splitting is given by the presence of two marginal gravel fan lobes, deposited in front of 1AE3 to 2AE5 km long flute-like scours, that are 0AE8 to 1 km wide and 7 to 20 m deep. In response to continued aggradation, small jets developed at the periphery of these bar-like deposits and filled in the low areas adjacent to the original superelevated regions, locally raising the depositional surface and characterized by large-scale trough cross-stratified sand and pebbly sand. The incision of an up to 1AE2 km wide and up to 35 m deep channel into the evolving fan is attributed to a catastrophic drainage event, probably related to a lake outburst and lake-level fall in the range of 40 to 60 m. At the mouth of this channel, highly scoured jet-efflux deposits formed under hydraulic-jump conditions during flow expansion. Subsequently, Gilbert-type deltas formed on the truncated fan margin, recording a second lake-level drop in the range of 30 to 40 m. These catastrophic lake-level falls were probably caused by rapid ice-lobe retreat controlled by the convex-up bottom topography of the ice valley.

BackgroundArchosaurs (birds, crocodilians and their extinct relatives including dinosaurs) dominated Mesozoic continental ecosystems from the Late Triassic onwards, and still form a major component of modern ecosystems (>10,000 species). The earliest diverse archosaur faunal assemblages are known from the Middle Triassic (c. 244 Ma), implying that the archosaur radiation began in the Early Triassic (252.3–247.2 Ma). Understanding of this radiation is currently limited by the poor early fossil record of the group in terms of skeletal remains.Methodology/Principal FindingsWe redescribe the anatomy and stratigraphic position of the type specimen of Ctenosauriscus koeneni (Huene), a sail-backed reptile from the Early Triassic (late Olenekian) Solling Formation of northern Germany that potentially represents the oldest known archosaur. We critically discuss previous biomechanical work on the ‘sail’ of Ctenosauriscus, which is formed by a series of elongated neural spines. In addition, we describe Ctenosauriscus-like postcranial material from the earliest Middle Triassic (early Anisian) Röt Formation of Waldhaus, southwestern Germany. Finally, we review the spatial and temporal distribution of the earliest archosaur fossils and their implications for understanding the dynamics of the archosaur radiation.Conclusions/SignificanceComprehensive numerical phylogenetic analyses demonstrate that both Ctenosauriscus and the Waldhaus taxon are members of a monophyletic grouping of poposauroid archosaurs, Ctenosauriscidae, characterised by greatly elongated neural spines in the posterior cervical to anterior caudal vertebrae. The earliest archosaurs, including Ctenosauriscus, appear in the body fossil record just prior to the Olenekian/Anisian boundary (c. 248 Ma), less than 5 million years after the Permian–Triassic mass extinction. These earliest archosaur assemblages are dominated by ctenosauriscids, which were broadly distributed across northern Pangea and which appear to have been the first global radiation of archosaurs.

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The collection and dissemination of vertebrate ichnological data is struggling to keep up with techniques that are becoming commonplace in the wider palaeontological field. A standard protocol is required to ensure that data is recorded, presented and archived in a manner that will be useful both to contemporary researchers, and to future generations. Primarily, our aim is to make the 3D capture of ichnological data standard practice, and to provide guidance on how such 3D data can be communicated effectively (both via the literature and other means) and archived openly and in perpetuity. We recommend capture of 3D data, and the presentation of said data in the form of photographs, false‐colour images, and interpretive drawings. Raw data (3D models of traces) should always be provided in a form usable by other researchers (i.e. in an open format). If adopted by the field as a whole, the result will be a more robust and uniform literature, supplemented by unparalleled availability of datasets for future workers.

The holotype of Brancasaurus brancai is one of the most historically famous and anatomically complete Early Cretaceous plesiosaurian fossils. It derived from the Gerdemann & Co. brickworks clay pit near Gronau (Westfalen) in North Rhine-Westphalia, northwestern Germany. Stratigraphically this locality formed part of the classic European “Wealden facies,” but is now more formally attributed to the upper-most strata of the Bückeberg Group (upper Berriasian). Since its initial description in 1914, the type skeleton of B. brancai has suffered damage both during, and after WWII. Sadly, these mishaps have resulted in the loss of substantial information, in particular many structures of the cranium and limb girdles, which are today only evidenced from published text and/or illustrations. This non-confirmable data has, however, proven crucial for determining the relationships of B. brancai within Plesiosauria: either as an early long-necked elasmosaurid, or a member of the controversial Early Cretaceous leptocleidid radiation. To evaluate these competing hypotheses and compile an updated osteological compendium, we undertook a comprehensive examination of the holotype as it is now preserved, and also assessed other Bückeberg Group plesiosaurian fossils to establish a morphological hypodigm. Phylogenetic simulations using the most species-rich datasets of Early Cretaceous plesiosaurians incorporating revised scores for B. brancai, together with a second recently named Bückeberg Group plesiosaurian Gronausaurus wegneri (Hampe, 2013), demonstrated that referral of these taxa to Leptocleididae was not unanimous, and that the topological stability of this clade is tenuous. In addition, the trait combinations manifested by B. brancai and G. wegneri were virtually identical. We therefore conclude that these monotypic individuals are ontogenetic morphs and G. wegneri is a junior synonym of B. brancai. Finally, anomalies detected in the diagnostic features for other “Wealden” plesiosaurians have prompted reconsiderations of interspecies homology versus intraspecific variability. We therefore propose that the still unresolved taxonomy of B. brancai should emphasize only those character states evident in the examinable fossil material, and specifically accommodate for growth-related modifications delimited via osteologically mature referred specimens.