Abstract Traversodontids were diverse non‐mammaliaform cynodonts that occupied herbivorous and omnivorous niches during the Middle and Late Triassic. In Brazil, they are particularly well represented in the Santa Maria Supersequence, although the taxonomic status of some historically described taxa remains uncertain. Among them, “ Traversodon (?) major” von Huene, 1936 was established on the basis of isolated cranial, mandibular, and postcranial remains from the Chiniquá region of southern Brazil. Here, we reassess the anatomy and taxonomic affinities of the specimens historically assigned to this species. A left maxilla (GPIT‐PV‐61005, here designated as lectotype) is the most informative specimen. It exhibits a combination of a broad maxillary platform, a maxillary recess, and strongly shouldered postcanine alveoli, supporting traversodontid affinities but not the original assignment to the genus Traversodon. These features are typical of deeply nested gomphodontosuchines, but do not form a unique combination of diagnostic characters that would allow a confident referral to any particular genus. The remaining specimens have no association or anatomical overlap with the lectotype and are here treated independently: the mandibular fragment is referred to Traversodontidae indet., the humerus to Eucynodontia indet., and the scapulocoracoid to an indeterminate non‐cynodont amniote. Accordingly, “ Traversodon (?) major” is retained as a nomen dubium : its lectotype lacks autapomorphies, and the remaining specimens cannot be reliably referred to the same taxon.
Abstract Detailed information on the cardiac morphology of the scarlet ibis ( Eudocimus ruber ) remains limited. This study aimed to characterize the gross and microscopic anatomy of this species' heart and provide morphometric data. We examined six specimens (three males and three females) using gross anatomical analysis, morphometry, conventional radiography, three‐dimensional scanning, light microscopy, and scanning electron microscopy. The mean heart mass was 5.93 ± 1.49 g ( n = 6), corresponding to 1.10 ± 0.23% of body mass, and the mean radiographic cardiothoracic ratio was 66.90 ± 5.78% ( n = 3). Macroscopic examination identified three venae cavae: the right and left cranial venae cavae and the caudal vena cava. The left atrioventricular valve had two cusps with chordae tendineae and papillary muscles, whereas the right atrioventricular valve had a single muscular fold. Histological examination identified uninucleated and binucleated Purkinje fibers in the subendocardial region, extending into myocardial muscle bundles. The base of the aorta showed hyaline cartilage containing chondrocytes and chondroblasts, with no bone tissue identified in the examined sections. These findings provide anatomical, morphometric, and histological data on the heart of E. ruber and a basis for future comparative studies of avian cardiac morphology.
Abstract The tongue‐bite apparatus (TBA) is a secondary jaw system found in Osteoglossomorpha and, convergently, Salmonidae. It is thought to have similar prey‐processing functions as the pharyngeal jaws, possibly allowing the oral jaws to evolve separately for more efficient prey capture. The TBA is incredibly morphologically diverse, but this diversity has not been well documented across Mormyridae, the most speciose family within Osteoglossomorpha. In this study, we examined shape diversity, levels of evolutionary integration and modularity, and rates of evolution of both the TBA and other associated components of the skull in Mormyridae, both across the family and in its two subfamilies, Petrocephalinae and Mormyrinae. Petrocephalinae, the sister group to the rest of Mormyrinae, is less species rich and has evolved independently from Mormyrinae for approximately 50 million years. This has resulted in disparity across the two groups, not only morphologically but also in terms of electric organ discharges. Results of this study support different models of modularity of the skull for these two subfamilies, with Petrocephalines having two modules as compared to Mormyrine's four modules. In both groups, the TBA makes up its own module, often evolving faster than other components of the skull. We propose that this is an example of a truly decoupled two‐jaw system, making it unique compared to the pharyngeal and oral jaws of other well‐studied groups, such as cichlids and labrids.
Abstract This study presents the first detailed description of bioerosion traces produced by insects in bones from the Santa Cruz Sequence (early Carnian, Santa Maria Supersequence, Brazil). An array of traces is reported, consisting of notches, a tube, trails of grooves attributed to the ichnotaxon Osteocallis mandibulus and ornamented depressions attributed to a new ichnotaxon Osteograptus thanatobios igen. nov. et isp. nov. The traces were likely produced by insects, but a less inclusive taxonomic attribution is currently not possible. The ethological interpretation for the bioerosion structures is that they represent feeding traces. This report increases the contrast between the Middle and Late Triassic bioerosion record, since the latter is significantly more diverse and abundant. Hypotheses related to the onset of the Carnian Humid Episode as well as taphonomic biases are discussed as possible explanations for this contrast.
