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Known from at least the Silurian (c. 435 Ma) up to the Late Cretaceous (c. 85 Ma), thylacocephalans are among the most intriguing fossil euarthropods. They are characterized by a prominent shield enveloping most of the body, hypertrophied compound eyes, three pairs of large, raptorial appendages and a trunk with 8–22 stout segments bearing appendages. Despite this knowledge of their anatomy, the phylogenetic affinities of Thylacocephala are controversial due to a lack of knowledge on their body organization and tagmosis. This study focuses on Mayrocaris bucculata Polz, 1994 from the Solnhofen Lagerstätte, Germany (c. 150 Ma, early Tithonian, Jurassic). We document new specimens of Mayrocaris bucculata from the Solnhofener Plattenkalke sensu lato and provide new descriptions for previously reported specimens. We demonstrate that the raptorial appendages of Thylacocephala are most probably maxillulae, maxillae and maxillipeds. Additionally, we report new details on the posterior trunk appendages, including the description of a paddle-like proximal part and of a rod-like distal part, but also of a specialized terminal trunk appendage. These new findings, in addition to the reinterpretation of a cephalic appendage of Clausocaris lithographica as a possible mandible, are essential for a better understanding of the body organization in thylacocephalans and their phylogenetic affinities within Eucrustacea. [ABSTRACT FROM AUTHOR]

Sea spiders (Pycnogonida) are strange arthropods characterized by a unique morphology, including reduced body, egg-carrying appendages and a proboscis. This peculiar body plan dates at least as early as the first undoubted occurrence of the group, 425 million years ago in the Silurian. All extant species belong to the order Pantopoda, characterized by cylindrical legs and an unsegmented abdomen. Palaeozoic fossils are much more diversified and exhibit features very different from pantopod morphology such as a segmented abdomen, limbs specialized to swim, or even a flagellum. The few Mesozoic fossils from the single Jurassic palaeoenvironment of La Voulte-sur-Rhône (south-eastern France) instead have strong affinities to Pantopoda. Here, we investigate the morphology of nine sea spider fossils using a new photographic protocol to document morphology, combining focus stacking and differential colourization. We also describe two new species of fossil pycnogonids from the Late Jurassic of Solnhofen (southern Germany): Colossopantopodus nanus sp. nov. is closely allied to a large species from La Voulte-sur-Rhône, but distinct in its smaller size; the other, ?Eurycyde golem sp. nov., is the first known fossil representative of the extant family Ascorhynchidae. Seven additional specimens, too poorly preserved for taxonomic description, are illustrated. The comparisons reveal that the shallow lagoons of Solnhofen contained a diverse assemblage of pantopods. Altogether with the fauna of La Voulte-sur-Rhône, the results suggest that Pantopoda became the dominant pycnogonid taxon of both deep and shallow marine waters after the Jurassic. [ABSTRACT FROM AUTHOR]

This second contribution on Rhamphorhynchus based on an acid-prepared specimen provides a detailed description of the braincase, concentrating on the broken skull and its hollow bones, aiming to gather data on its pneumatisation for comparative studies between crocodiles, pterosaurs and dinosaur-birds. Computed tomographic (CT) scanning was performed to further explore these cavities in the skull bones, which are easily visible especially where the bones are broken. However, it has not been possible to observe their precise origin and connections. The skull regions where the pneumatisation is most evident are the paroccipital processes and the prootics from the endoskeletal braincase, but the precise form of the cavities is not clear, and their origin as paratympanic systems cannot be seen. CT scanning with better resolution might show more details of the skull pneumatics to be used in a phylogenetic analysis. [ABSTRACT FROM AUTHOR]

A previously undescribed and near-complete specimen of the non-pterodactyloid pterosaur Rhamphorhynchus is briefly described. Although purchased in 1878 and held in a public collection in Dublin, Ireland ever since, this specimen has never been described and was not even mentioned in the literature until 2010. [ABSTRACT FROM PUBLISHER]