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The small diapsid reptile Ozimek volans is one of the most enigmatic representatives of the Late Triassic fauna of Krasiejów, Poland. Phylogenetically, Ozimek was identified as a 'protorosaurian' related to tanystropheids, but the extremely elongated limbs and presumed gliding abilities are unusual for this group. This raises the question of whether the lifestyle inferred for this taxon is reflected in its bone histology. Two long bones from a single bone association of Ozimek (humerus UOPB 1148a and femur UOPB 1148b) were sectioned at the midshaft to obtain details of the histological framework. A large medullary cavity, thin walls of lamellar bone with numerous lamellae, and only very few simple vascular canals are shared by both bones. Application of a modified 3‐front model (introducing a fourth front) of cortical growth reveals that the femur is ontogenetically younger when compared to the humerus. Ozimek limb bones, with their small diameter, compact structure, low vascularization, no remodelling, and a lack of pneumaticity, are histologically similar to those of modern small bats. The characteristic cortex of both may have been well suited to withstand high loads while limiting weight. The well‐ordered collagen fibres in successive lamellae along the bone may be a key adaptation for the better distribution of the load generated during gliding. © 2024 The Palaeontological Association. [ABSTRACT FROM AUTHOR]

Although there are problematic earliest Jurassic records, phytosaurs are thought to have become extinct during the Rhaetian. A newly-discovered left paramedian phytosaur osteoderm from a clay pit in Bonenburg, Kreis Höxter, North Rhine-Westphalia, Germany, is the youngest, well-dated phytosaur record. This osteoderm was found in a bone bed (Bone Bed 2) in the Contorta Beds of the Rhaetian Exter Formation. Palynology constrains the age of Bone Bed 2 to the late middle Rhaetian (ca. 203.5 million years ago). The Bonenburg osteoderm cannot be assigned to any named species. It most closely resembles some osteoderms from the Rhaetian of Halberstadt in Central Germany. Phytosaurs survived in Europe to at least the late middle Rhaetian, probably falling victim to the end-Triassic extinction event about two million years later. [ABSTRACT FROM AUTHOR]

Mesozoic marine reptiles and modern marine mammals are often considered ecological analogs, but the extent of their similarity is largely unknown. Particularly important is the presence/absence of deep-diving suction feeders among Mesozoic marine reptiles because this would indicate the establishment of mesopelagic cephalopod and fish communities in the Mesozoic. A recent study suggested that diverse suction feeders, resembling the extant beaked whales, evolved among ichthyosaurs in the Triassic. However, this hypothesis has not been tested quantitatively. We examined four osteological features of jawed vertebrates that are closely linked to the mechanism of suction feeding, namely hyoid corpus ossification/calcification, hyobranchial apparatus robustness, mandibular bluntness, and mandibular pressure concentration index. Measurements were taken from 18 species of Triassic and Early Jurassic ichthyosaurs, including the presumed suction feeders. Statistical comparisons with extant sharks and marine mammals of known diets suggest that ichthyosaurian hyobranchial bones are significantly more slender than in suction-feeding sharks or cetaceans but similar to those of ram-feeding sharks. Most importantly, an ossified hyoid corpus to which hyoid retractor muscles attach is unknown in all but one ichthyosaur, whereas a strong integration of the ossified corpus and cornua of the hyobranchial apparatus has been identified in the literature as an important feature of suction feeders. Also, ichthyosaurian mandibles do not narrow rapidly to allow high suction pressure concentration within the oral cavity, unlike in beaked whales or sperm whales. In conclusion, it is most likely that Triassic and Early Jurassic ichthyosaurs were 'ram-feeders', without any beaked-whale-like suction feeder among them. When combined with the inferred inability for dim-light vision in relevant Triassic ichthyosaurs, the fossil record of ichthyosaurs does not suggest the establishment of modern-style mesopelagic animal communities in the Triassic. This new interpretation matches the fossil record of coleoids, which indicates the absence of soft-bodied deepwater species in the Triassic.