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Ammonoid anatomy is still poorly known and every new record of a specimen with soft tissue-preservation yields valuable information. In view of the impressive morphological disparity of ammonoids, we can also expect some disparity in soft tissue anatomy. Here, we present a new specimen from the Kimmeridgian of the Solnhofen region. In contrast to a recently described isolated soft body preserving the male reproductive organs, the new specimen for the first time shows a structure, which we interpret as the ovaries of the female containing immature eggs and further organs. These two specimens are of great importance for sexing ammonoids and for estimating fecundity. The high reproductive rate of Jurassic ammonites underlines their great abundance and the important role of juvenile ammonoids at the base of Devonian to Cretaceous food webs.

As actively swimming predators, cephalopods have played a key role regulating and engineering marine ecosystems for more than 500 million years and continue to do so. For the first time, we portray fluctuations of cephalopod body size including species from the Cambrian to today. For comparability, we determined the maximum body volumes of each species using various proxies, because classical measures like mantle length cannot be applied homologously to all groups. We separately examined Cephalopoda with orthoconic conchs (without ammonoids and coleoids), Nautilida, Ammonoida (without heteromorphs), and Neocoleoida (squids, octopuses and their ancestors). The long-term trajectories of these groups differ in their overall trends. Each of these groups reacted in other ways to the mass extinctions. All groups except the nautilids evolved species exceeding one meter in size, which belong to the marine megafauna. Nautilids and orthocones share a threshold volume of about 100 litres, while in ammonoids and neocoleoids, the limit lies closer to 500 litres.

Coleoid cephalopod molluscs comprise squid, cuttlefish and octopuses, and represent nearly the entire diversity of modern cephalopods. Sophisticated adaptations such as the use of colour for camouflage and communication, jet propulsion and the ink sac highlight the unique nature of the group. Despite these striking adaptations, there are clear parallels in ecology between coleoids and bony fishes. The coleoid fossil record is limited, however, hindering confident analysis of the tempo and pattern of their evolution. Here we use a molecular dataset (180 genes, approx. 36 000 amino acids) of 26 cephalopod species to explore the phylogeny and timing of cephalopod evolution. We show that crown cephalopods diverged in the Silurian–Devonian, while crown coleoids had origins in the latest Palaeozoic. While the deep-sea vampire squid and dumbo octopuses have ancient origins extending to the Early Mesozoic Era, 242 ± 38 Ma, incirrate octopuses and the decabrachian coleoids (10-armed squid) diversified in the Jurassic Period. These divergence estimates highlight the modern diversity of coleoid cephalopods emerging in the Mesozoic Marine Revolution, a period that also witnessed the radiation of most ray-finned fish groups in addition to several other marine vertebrates. This suggests that that the origin of modern cephalopod biodiversity was contingent on ecological competition with marine vertebrates.

Coleoid cephalopods exhibited two distinct reproductive strategies, resulting in small pelagic and large demersal hatchlings, both in the geologic past and recently. In ectocochleate cephalopods, the hatching event is recorded in shell structures (e.g., nepionic constrictions, ultrastructural shifts, or ornamentation differences). In contrast, well-defined hatching markers do not exist on coleoid shells. Changes in septal spacing may be evidence of hatching (e.g., some extant sepiids), but not in all fossil groups. In the present study, we subdivide the early ontogenetic shells of phragmocone-bearing coleoids (belemnoids, spirulids, and sepiids) into key architectural stages and describe their reference to the hatching event. Belemnoids exhibit three key stages, the second of which is here considered to occur shortly before or after hatching. In spirulids and sepiids, there is only one key stage. In Mesozoic belemnoids, spirulids, and sepiids, hatching accordingly occurred with a total shell length of less than 2 mm, which corresponds to mantle lengths of small planktonic hatchlings. Production of small pelagic hatchlings and thus small eggs was therefore the dominant reproductive strategy within the Coleoidea. The first evidence of enlarged hatchlings appeared during the Maastrichtian in Groenlandibelus. During the Eocene, the large-egg strategy apparently became more widespread, particularly in belosaepiids.

Many Early Jurassic marine predators were seemingly adapted to hunt soft and fast prey items such as cephalopods. However, deciphering what these animals ate and, therefore, the intensity of their competition is challenging, as fossilised gut content is biased by multiple factors. In this paper, we report a loligosepiid vampyromorph coleoid in the gut of a specimen of the ichthyosaurian Stenopterygius triscissus from the early Toarcian Bascharage Lagerstätte of Southern Luxembourg. This is the first report of octobrachian predation in ichthyosaurians. The coeval pachycormid teleosts Pachycormus macropterus and Saurostomus esocinus have recently been reported to feed on loligosepiid octobrachians as well. We use this opportunity to compare the functional anatomy of these taxa and re-evaluate the affinities of coleoids preserved as ichthyosaurian gut content.

The growing demand of society for gas sensors for energy-efficient environmental sensing stimulates studies of new electronic materials. Here, we investigated quasi-one-dimensional titanium trisulfide (TiS3) crystals for possible applications in chemiresistors and on-chip multisensor arrays. TiS3 nanoribbons were placed as a mat over a multielectrode chip to form an array of chemiresistive gas sensors. These sensors were exposed to isopropanol as a model analyte, which was mixed with air at low concentrations of 1–100 ppm that are below the Occupational Safety and Health Administration (OSHA) permissible exposure limit. The tests were performed at room temperature (RT), as well as with heating up to 110 °C, and under an ultraviolet (UV) radiation at λ = 345 nm. We found that the RT/UV conditions result in a n-type chemiresistive response to isopropanol, which seems to be governed by its redox reactions with chemisorbed oxygen species. In contrast, the RT conditions without a UV exposure produced a p-type response that is possibly caused by the enhancement of the electron transport scattering due to the analyte adsorption. By analyzing the vector signal from the entire on-chip multisensor array, we could distinguish isopropanol from benzene, both of which produced similar responses on individual sensors. We found that the heating up to 110 °C reduces both the sensitivity and selectivity of the sensor array.

Morphologic analyses of a large quantity of teudopseid coleoids from the Upper Cretaceous (Cenomanian) of Lebanon has yielded a much higher diversity than previously assumed and revealed numerous extraordinarily well-preserved soft-part characters. The Teudopseina is represented by three families (only the Muensterellidae are still unknown in the Lebanon Plattenkalks). The Teudopsidae is represented by one species (Teudopsinia haasi), the Trachyteuthididae by five species (Trachyteuthis bacchiai n. sp., Glyphiteuthis libanotica, Gl. abisaadiorum, Gl. freijii n. sp., and Glyphidopsis waagei n. gen. n. sp.), and the Palaeololiginidae by one species (Rachiteuthis donovani). Gl. freijii n. sp. represents the first record of a coleoid cephalopod from Nâmmoura. A detailed comparison with Jurassic gladii shows that the Teudopseina is a very homogenous group that can be easily differentiated from other Mesozoic, gladius-bearing groups (Prototeuthidina, Loligosepiina). Despite comparatively large gaps in the fossil record, each of the Late Cretaceous gladii can be readily associated with Jurassic precursors. Particularly, the first record of two pairs of fins in Glyphiteuthis exemplifies that in addition to gladius similarities, similarities in soft-parts exist as well. A previously undescribed specimen of Rachiteuthis exhibits unusually well-preserved gills. In general, the soft-part morphology of the Teudopseina clearly indicates octobrachiate affinities (i.e., absence of tentacles, circular suckers, cirri, two pairs of fins, octopod-like eye capsules); no existing evidence supports a decabrachiate relationship.

Although an early Cambrian origin of cephalopods has been suggested by molecular studies, no unequivocal fossil evidence has yet been presented. Septate shells collected from shallow-marine limestone of the lower Cambrian (upper Terreneuvian, c. 522 Ma) Bonavista Formation of southeastern Newfoundland, Canada, are here interpreted as straight, elongate conical cephalopod phragmocones. The material documented here may push the origin of cephalopods back in time by about 30 Ma to an unexpected early stage of the Cambrian biotic radiation of metazoans, i.e. before the first occurrence of euarthropods.Hildenbrand, Austermann et al. present new material from the early Cambrian of Newfoundland that potentially backdates the evolution of cephalopods to before euarthropods. The material is most closely aligned with the Cephalopoda, lending a tentative assignment and significant potential implications for the origin of this molluscan group.

High entropy oxides (HEOs), based on the incorporation of multiple‐principal cations into the crystal lattice, offer the possibility to explore previously inaccessible oxide compositions and unconventional properties. Here it is demonstrated that despite the chemical complexity of HEOs external stimuli, such as epitaxial strain, can selectively stabilize certain magneto‐electronic states. Epitaxial (Co 0.2 Cr 0.2 Fe 0.2 Mn 0.2 Ni 0.2 ) 3 O 4 ‐HEO thin films are grown in three different strain states: tensile, compressive, and relaxed. A unique coexistence of rocksalt and spinel‐HEO phases, which are fully coherent with no detectable chemical segregation, is revealed by transmission electron microscopy. This dual‐phase coexistence appears as a universal phenomenon in (Co 0.2 Cr 0.2 Fe 0.2 Mn 0.2 Ni 0.2 ) 3 O 4 epitaxial films. Prominent changes in the magnetic anisotropy and domain structure highlight the strain‐induced bidirectional control of magnetic properties in HEOs. When the films are relaxed, their magnetization behavior is isotropic, similar to that of bulk materials. However, under tensile strain, the hardness of the out‐of‐plane (OOP) axis increases significantly. On the other hand, compressive straining results in an easy OOP magnetization and a maze‐like magnetic domain structure, indicating the perpendicular magnetic anisotropy. Generally, this study emphasizes the adaptability of the high entropy design strategy, which, when combined with coherent strain engineering, opens additional prospects for fine‐tuning properties in oxides.