Two types of bone necrosis in the Middle Triassic Pistosaurus longaevus bones: the results of integrated studies

Osteolytic Lesions in a Sub-Adult Loggerhead Sea Turtle (Caretta caretta): A Case Report

Osteolytic lesions in loggerhead sea turtles (Caretta caretta) during rehabilitation are attributed to multiple causes, including gas embolism, hypothermia, and osteomyelitis due to bacterial or fungal infection. This study reports the appearance of osteolytic lesions in a sub-adult loggerhead sea turtle with involvement of the right fore and hind flippers, visible swelling of the elbow and knee joints, and accompanied by lameness after 45 days of rehabilitation. Radiographs and computed tomography revealed multiple lytic bone lesions. This was the fourth rehabilitation admission of the turtle after being accidentally captured by trawler ships (bycatch) in 2019, 2020, 2022, and 2023. Potential causes were dysbaric osteonecrosis due to a past decompression sickness event and hypothermia with osteomyelitis from bacterial infection. Blood cultures and antibiotic susceptibility testing led to the isolation of Ewingella americana responsive to enrofloxacin. This study investigates extensive fore and hind flipper involvement in a sub-adult loggerhead turtle, aiming to determine causes and risk factors. The pathogenesis and significance of these lesions is discussed.

Bone abnormalities in the middle Anisian marine sauropsids from Winterswijk

While the occurrence of skeletal pathologies in Middle Triassic marine reptiles has been poorly documented until now, massive accumulations of bone remains from the Germanic Basin provide the opportunities for documentation. Herein, we describe skeletal abnormalities in the Middle Triassic bone material from the Vossenveld Formation of Winterswijk, the Netherlands. The aim of the study is to distinguish in the studied bones pathologies resulting from malady or trauma and taphonomic alterations. Furthermore, an attempt was made to assess on how the pathologies also represent paleoecological data. Our survey led to the identification of one broken and healed bone, one case of abnormal coossification, and one case of posttraumatic fibro-osseous dysplasia. While the latter two pathologies give little insight into the ecology and function of the affected animals, the fractured dentary is attributed to Nothosaurus marchicus, a common sauropterygian macropredator. It proves that the individual survived long enough to heal, despite the injury hampering its hunting potential. One abnormally shaped humerus is interpreted as postmortem taphonomic deformation, emphasizing the necessity of utilization of detailed diagnostics to distinguish actual paleopathologies from nonbiological distortion.

Hematological convergence between Mesozoic marine reptiles (Sauropterygia) and extant aquatic amniotes elucidates diving adaptations in plesiosaurs

Plesiosaurs are a prominent group of Mesozoic marine reptiles, belonging to the more inclusive clades Pistosauroidea and Sauropterygia. In the Middle Triassic, the early pistosauroid ancestors of plesiosaurs left their ancestral coastal habitats and increasingly adapted to a life in the open ocean. This ecological shift was accompanied by profound changes in locomotion, sensory ecology and metabolism. However, investigations of physiological adaptations on the cellular level related to the pelagic lifestyle are lacking so far. Using vascular canal diameter, derived from osteohistological thin-sections, we show that inferred red blood cell size significantly increases in pistosauroids compared to more basal sauropterygians. This change appears to have occurred in conjunction with the dispersal to open marine environments, with cell size remaining consistently large in plesiosaurs. Enlarged red blood cells likely represent an adaptation of plesiosaurs repeated deep dives in the pelagic habitat and mirror conditions found in extant marine mammals and birds. Our results emphasize physiological aspects of adaptive convergence among fossil and extant marine amniotes and add to our current understanding of plesiosaur evolution.

Tuberculosis-like respiratory infection in 245-million-year-old marine reptile suggested by bone pathologies

An absence of ancient archaeological and palaeontological evidence of pneumonia contrasts with its recognition in the more recent archaeological record. We document an apparent infection-mediated periosteal reaction affecting the dorsal ribs in a Middle Triassic eosauropterygian historically referred to as 'Proneusticosaurus' silesiacus. High-resolution X-ray microtomography and histological studies of the pathologically altered ribs revealed the presence of a continuous solid periosteal reaction with multiple superficial blebs (protrusions) on the visceral surfaces of several ribs. Increased vascularization and uneven lines of arrested growth document that the pathology was the result of a multi-seasonal disease. While visceral surface localization of this periosteal reaction represents the earliest identified evidence for pneumonia, the blebs may have an additional implication: they have only been previously recognized in humans with tuberculosis (TB). Along with this diagnosis is the presence of focal vertebral erosions, parsimoniously compared to vertebral manifestation of TB in humans.