Royal Belgian Institute of Natural Sciences

Abstract The quality of ground-based radiometric data for satellite calibration and validation may be significantly affected by contamination of optical surfaces exposed over long deployment periods. In this study, the spectral transmittance of optical surfaces is measured over two years in field conditions. Results show that fore-optics contamination depends strongly on zenith-pointing angle and varies non-monotonically in time since environmental conditions may either dirty (dust, pollen, birds, spiders) or clean (rain, perhaps wind) an optical surface. It is recommended to: point sensors sideways or downwards when not measuring, monitor rain conditions, and monitor radiometer sensitivity continuously during long deployments.

Investigations of bone microanatomy are commonly used to explore lifestyle strategies in vertebrates. While distinct microanatomical limb bone features have been established for exclusively aquatic and terrestrial lifestyles, identifying clear patterns for the semiaquatic lifestyle remains more challenging. Pinnipeds and mustelids provide an ideal framework for studying the diversity of semiaquatic adaptations. Here, we tested whether their humerus and femur showed significant differences in microanatomical and biomechanical parameters along the diaphysis relative to locomotor strategies. We μCT-scanned extant pinnipeds and included semiaquatic and generalist mustelids to build a reference for the amphibious lifestyle. Statistical analyses showed that comparisons away from the growth center distinguished species with non-weight-bearing hind limbs from those with all-limb weight-bearing. Among the latter, otariids and semiaquatic mustelids shared highly compact bones and a reduced medullary cavity, though otariids exhibited a more gradual medullocortical transition with more trabeculae. Contrary to the prevailing assumption, our findings indicate bone mass increase can also be associated with fast-swimming predators diving beyond shallow depths. Phocids, which cannot bear weight on their hind limbs, include species that spend 70%-80% of their lives at sea. These species exhibited extremely spongious bones: low compactness, thin cortex, and a trabeculae-filled medullary region-reminiscent of the osteoporotic-like condition seen in some extant cetaceans. Additionally, the shared humerus-femur pattern, regardless of locomotor type, suggests that skeletal adaptations can be systemic in carnivorans. This new comparative dataset broadens the spectrum of microanatomical patterns associated with an amphibious lifestyle and provides a foundation for better deciphering extinct species' locomotion.

In Portugal, iguanodontian dinosaurs are mostly known from the Late Jurassic of the Lourinhã Formation and are represented by dryosaurids and basal styracosternans. The Early Cretaceous record of iguanodontians in Portugal is scarce in comparison, with scattered and uninformative remains referred to Styracosterna indet. Here, we describe SHN.832, the first iguanodontian skull from Portugal, named Cariocecus bocagei gen. nov. sp. nov. The specimen was found in Praia do Areia do Mastro (Cabo Espichel, Sesimbra) in the Papo Seco Formation (lower Barremian), and comprises the right side of the skull, part of the skull vault and a nearly complete basicranium. Cariocecus bocagei is diagnosed based on autapomorphies such as the co-ossified maxillo-jugal complex and the trilobated shape of the supraoccipital. The phylogenetic analysis retrieves C. bocagei as a basal hadrosauroid in a clade with Comptonatus chasei and Brighstoneus simmondsi. Our biogeographical analysis emphasizes the effects of insular endemism during the Hauterivian–Aptian range in the European regions. We show that Iguanodontia originated in South America, and through a dispersal event towards North America during the Upper Jurassic, expanded their latitudinal range. Cariocecus and other early-diverging iguanodontians emerged during an eastward dispersal event in the Lower Cretaceous. We reconstructed the endocast, cranial nerves and inner ear of Cariocecus via segmentation of micro-computed tomography scanning, showing similarities with other Hadrosauriformes such as Iguanodon and Proa. We propose the most detailed inner ear soft-tissue reconstruction for a dinosaur so far, including the macula and sub-branches of the vestibulocochlear nerve, supported by the extant phylogenetic bracket. Based on the unossified suture of the cranial elements, we hypothesize that SHN.832 had not yet reached full skeletal maturity, and our restoration suggests a total skull length of about 45 cm. The supraorbital membrane was reconstructed based on the well-preserved supraorbital bone and comparison with modern taxa. https://zoobank.org/urn:lsid:zoobank.org:pub:C02A3840-F7A5-44FA-882D-4403933EAB4C

Bone collagen of terrestrial and marine animals (n = 218) recovered from Ottoman period contexts at Aqaba Castle, Jordan (16th–19th centuries CE), were analyzed for δ13C, δ15N, and δ2H isotope ratios. While δ13C and δ15N values showed considerable overlap among species in the hyperarid environment, δ2H values exhibited less overlap, enhancing stable isotopic niche differentiation. In domesticates, δ2H values show trophic enrichments of +18.4‰ from herbivores to omnivores (dogs), and +26‰ to cats which had the highest δ2H values. Fish δ2H values show a positive relationship with increasing trophic level but also moderately correlate with body size (r = 0.61, R2 = 0.37). The offset between collagen δ2H and rainfall (δ2Hmw) values is smaller for camels (−1.4‰), sheep (−4.5‰), and goats (+6.8%), than for chickens (−18.5‰) and cattle (−27.0‰) due to more frequent consumption of 2H-depleted groundwater by the latter species, because of their higher water requirements. Similarities between local precipitation and bone collagen δ2H values for most terrestrial herbivores suggest the utility of δ2H values for geographic provenancing. This is explored by overlapping gazelle and chukar collagen δ2H values over a regional δ2Hmw isoscape, tentatively suggesting these species inhabited the water-stressed highland environments surrounding Aqaba Castle. This study demonstrates the advantages of incorporating bone collagen δ2H values alongside δ13C and δ15N values as a useful environmental proxy, enhancing interpretations of animal dietary behaviour, trophic levels, water sources, and wild animal home ranges.

ABSTRACT Dromaeosauridae is a clade of bird-like theropod dinosaurs including, among others, the genera Deinonychus and Velociraptor, and characterised by a specialised second toe bearing an enlarged and falciform ungual. Here, we describe an exquisitely-preserved velociraptorine dromaeosaurid from the Upper Cretaceous Djadokhta Formation of Mongolia, and refer it to the new species Shri rapax. This dromaeosaurid is diagnosed by a peculiar combination of vertebral and pelvic features and by an exceptionally robust hand with a very stout pollex bearing the ungual proportionally larger than in any other dromaeosaurid. Combined with cranial adaptations which could support a bite more powerful than in other velociraptorines, the enlarged unguals in both Shri species suggest ecological partitioning in prey preference among the sympatric Djadokhtan dromaeosaurids.

Abstract. In this work we present a super-resolution approach for deriving high-spatial-resolution and high-temporal-resolution ocean colour satellite datasets. The technique is based on DINEOF (data-interpolating empirical orthogonal functions), a data-driven method that uses the spatio-temporal coherence of analysed datasets to infer missing information. DINEOF is used here to effectively increase the spatial resolution of satellite data and is applied to a combination of Sentinel-2 and Sentinel-3 datasets. The results show that DINEOF is able to infer the spatial variability observed in the Sentinel-2 data to the Sentinel-3 data while reconstructing missing information due to clouds and reducing the amount of noise in the initial dataset. In order to achieve this, the Sentinel-2 and Sentinel-3 datasets have undergone the same pre-processing, including a comprehensive, region-independent, and pixel-based automatic switching scheme for choosing the most appropriate atmospheric correction and ocean colour algorithm to derive in-water products. The super-resolution DINEOF has been applied to two different variables (turbidity and chlorophyll) and two different domains (Belgian coastal zone and the whole of the North Sea), and the sub-mesoscale variability of the turbidity along the Belgian coastal zone has been studied.

The evolution of baleen whales (Mysticeti) comprises two main phases, namely, (i) a Paleogene phase, which saw the diversification of stem lineages, and (ii) a Neogene phase, dominated by modern-looking, toothless, baleen-bearing forms in the monophyletic group Chaeomysticeti. These two phases are separated by a global turnover event coinciding with a gap-or "dark age"-in the mysticete fossil record. This dark age occurred between 23 and ~18 Ma and is apparently detected worldwide, except in Zealandia. Here, we report on a new mysticete fossil from the Lower Miocene (Burdigalian: ~19.2 Ma) strata of the Chilcatay Formation cropping out at the newly discovered locality of Cerro Tiza (East Pisco Basin, Peru), which represents a limited but precious testament from the last phase of the baleen whale dark age. Two previously mentioned, slightly geologically younger fossils from the same formation are also reappraised herein, revealing the occurrence of at least another baleen whale taxon in the upper Chilcatay strata-one that belongs in the mysticete crown group. Although the Early Miocene remains a problematic time interval for the fossil record of baleen whales, our new results encourage the search for mysticete fossils in the Lower Miocene strata of the East Pisco Basin, whose basin fill preserves a cornucopia of extraordinarily informative marine vertebrate fossils of the Cenozoic age, as well as in coeval deposits worldwide.

ABSTRACTThe Last Glacial maximum (LGM), spanning from 26.5 to 19 thousand years before present (ka bp), is a period of extreme climatic degradation associated with reduced biomass production and resource stress throughout Eurasia. Arguably, one of the most fundamental tools for human survival during this cold and arid period was the ability to create, maintain and use fire. While fire is widely considered a ubiquitous tool in modern human behaviour, there are surprisingly few well‐described combustion features during the LGM in Europe. In this paper, we provide high‐resolution geoarchaeological research into three combustion features associated with Epigravettian occupations at the site of Korman' 9 (Ukraine) with ages falling in the LGM. Our results show distinct variations in the size and structure of the combustion features, potentially indicating multiple occupations within the same layer or reflect differences in site organization or function during a single occupation. Additionally, our analysis shows clear evidence of the effect of solifluction and the lack of preservation of the ash layer(s) of the combustion features, as well as the development of bioturbation features enhanced by anthropogenic input. To better estimate heating temperatures of the combustion events, we employed a novel approach using colour analysis showing temperatures reaching 600°C in the substrate underlying the combustion features. In all, the combustion features at Korman' 9 provide invaluable new insights as well as high resolution description of pyrotechnological behaviours during the LGM, which has been lacking during this critical period in our evolutionary history.

A ParasiteBlitz event offers a brief, intense opportunity to discover diverse parasite species and to reveal life cycles of heteroxenous parasite taxa. In this study, we describe Monomyxum ligophori n. sp., a hyperparasitic myxozoan (Monomyxidae) proliferating in two dactylogyrid monopisthocotylan flatworms (Ligophorus saladensis, Ligophorus mugilinus) infecting mugilid fishes (Mugil cephalus, Mugil curema) on the Atlantic coast of North America. Furthermore, we used DNA barcoding to infer the parasite's complex life cycle, matching its hyperparasitic myxospore stages with actinospore stages infecting the polychaete Streblospio benedicti found in the same locality during the ParasiteBlitz and also reported previously from the same region. Thus we report the first life cycle of a myxozoan that most likely does not require a vertebrate host. Hyperparasitic myxozoans are rare with only five species reported worldwide to infect flatworms. This study provides more information on the previously discussed host specificity towards monopisthocotylan hosts of these monomyxid myxozoan hyperparasites. Notably, Monomyxum ligophori n. sp. was detected in two out of four gill-infecting parasitic flatworms (being absent in Ligophorus uruguayensis and Metamicrocotyla macracantha) found infecting the same fish individuals during the ParasiteBlitz. Our molecular data and phylogenetic analysis support the previously suggested common origin of Monomyxum species infecting monopisthocotylan flatworms, and contribute to understanding the life cycle and host interactions of this unique hyperparasitic myxozoan lineage.

Parrots produce stunning plumage colors through unique pigments called psittacofulvins. However, the mechanism underlying their ability to generate a spectrum of vibrant yellows, reds, and greens remains enigmatic. We uncover a unifying chemical basis for a wide range of parrot plumage colors, which result from the selective deposition of red aldehyde- and yellow carboxyl-containing psittacofulvin molecules in developing feathers. Through genetic mapping, biochemical assays, and single-cell genomics, we identified a critical player in this process, the aldehyde dehydrogenase ALDH3A2, which oxidizes aldehyde psittacofulvins into carboxyl forms in late-differentiating keratinocytes during feather development. The simplicity of the underlying molecular mechanism, in which a single enzyme influences the balance of red and yellow pigments, offers an explanation for the exceptional evolutionary lability of parrot coloration.