MUSCULAR ANATOMY OF THE PECTORAL AND FORELIMB OF Caiman crocodilus crocodilus (LINNAEUS, 1758) (CROCODYLIA: ALLIGATORIDAE)

Hindlimb and pelvic anatomy of Caiman yacare (Archosauria, Pseudosuchia): Myology and osteological correlates with emphasis on lower leg and autopodial musculature

The anatomy of the archosaurian pelvis and hindlimb has adopted a diversity of successful configurations allowing a wide range of postures during the evolution of the group (e.g., erect, sprawling). For this reason, thorough studies of the structure and function of the pelvic and hindlimb musculature of crocodylians are required and provide the possibility to expand their implications for the evolution of archosaurian locomotion, as well as to identify potential new characters based on muscles and their bony correlates. In this study, we give a detailed description of the pelvic and hindlimb musculature of the South American alligator Caiman yacare, providing comprehensive novel information regarding lower limb and autopodial muscles. Particularly for the pedal muscles, we propose a new classification for the dorsal and ventral muscles of the autopodium based on the organisation of these muscles in successive layers. We have studied the myology in a global background in which we have compared the Caiman yacare musculature with other crocodylians. In this sense, differences in the arrangement of m. flexor tibialis internus 1, m. flexor tibialis externus, m. iliofibularis, mm. puboischiofemorales internii 1 and 2, between Ca. yacare and other crocodylians were found. We also discuss the muscle attachments that have different bony correlates among the crocodylian species and their morphological variation. Most of the correlates did not exhibit great variation among the species compared. The majority of the recognised correlates were identified in the pelvic girdle; additionally, some bony correlates associated with the pedal muscles are highlighted here for the first time. This research provides a wide framework for future studies on comparative anatomy and functional morphology, which could contribute to improving the character definition used in phylogenetic analyses and to understand the patterns of musculoskeletal hindlimb evolution.

Functional Anatomy of the Thoracic Limb of the Komodo Dragon (Varanus komodoensis)

Since the Komodo dragon has been included on The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, it is crucial to know in detail its biology as there is a limited availability of research material on these animals-mainly those who died in zoos or whose remains were found in the wild. Anatomy is essential for understanding physiology, identification of diseases, adaptations in the environment, and behavior. In this dissection study, the relationship of individual anatomical structures was analyzed, the anatomy of the active and passive movement system of the thoracic limb was described, photographs were taken, and a radiographic examination was conducted. This species has its own differences, even within closely related lizard species. Varanus komodoensis possesses triceps muscles with three heads, and the wrist is extended with additional bones for greater flexibility of the hand. The muscles of the forelimb are analogous to the hind limb; however, they differ in the mass of individual muscles, especially those predisposed to perform the most important antigravity and locomotive functions.

The postcranial anatomy of Brasilodon quadrangularis and the acquisition of mammaliaform traits among non-mammaliaform cynodonts

Brasilodon quadrangularis (Cynodontia, Probainognathia) is an iconic non-mammaliaform cynodont from the Late Triassic of Brazil (Riograndia Assemblage Zone, Candelária Sequence), being considered as the sister taxon of Mammaliaformes. Although its phylogenetic position is very important, several aspects of its postcranial anatomy remain unclear or unstudied. Here, we present a detailed description of the postcranial elements referred to Brasilodon, including previously mentioned specimens and new ones, which add relevant information about its postcranial morphology and provide a new insight into the anatomical transition between advanced non-mammaliaform cynodonts and early mammaliaforms. Functional and ecological implications are also investigated, based on the postcranial morphology and muscular reconstructions. The postcranium of Brasilodon differs from most non-mammaliaform cynodonts and presents similarities with tritylodontids, early mammaliaforms and extant therians, such as a ventrally oriented scapular glenoid facet, a distinct and ossified greater humeral tubercle, lack of ectepicondylar foramen, olecranon process, hemispherical humeral and femoral heads and a prominent intertrochanteric crest. The humeral torsion, the length of the deltopectoral crest, the large bicipital groove and the well-developed lesser tubercle, indicate that the forelimb of Brasilodon was hold in a semi-sprawling position, with well-developed adductor muscles to maintain the body off the ground. The short femoral neck and the strong medial projection of the femoral head indicate the femur was held in a more erect posture than in basal non-mammaliaform cynodonts. The anterodorsally projected iliac blade with reduced postacetabular process, reduction of the anterior part of the pubis, medially located lesser trochanter indicate a basically mammalian pattern of pelvic musculature, able to swing the femur in a nearly parasagittal plane.

ANATOMIA ÓSSEA E MUSCULAR DA ESCAPULA E BRAÇO DE Chrysocyon brachyurus (CARNÍVORA, CANIDAE)

Resumo O Lobo-guará Chrysocyon brachyurus - Illiger, 1815, é o maior canídeo da América do Sul, distribuindo-se na região central desse continente, preferencialmente em biomas descampados. Pode atingir entre 20 e 33 kg e até 125 cm de altura. Encontra-se em ameaça de extinção. O conhecimento anatômico é de grande importância para a complementação das informações acerca das espécies silvestres e para implicações clínicas, cirúrgicas e conservacionistas. Objetivou-se descrever os ossos e respectivos acidentes ósseos pertencentes ao cíngulo do membro torácico da região braquial e respectivos músculos do lobo-guará, por meio dos procedimentos de dissecação em animais preservados em solução de formol a 10%. Os animais pertencem ao acervo didático do Laboratório de Ensino e Pesquisa em Animais Silvestres da UFU e são provenientes de atropelamentos. Os ossos são: escápula e úmero. Não foi observada a clavícula. Os músculos são: M. deltoide; M. supraespinhal; M. infraespinhal; M. redondo maior; M. redondo menor; M. tríceps braquial cabeças: lateral, acessória, longa e medial; M. ancôneo; M. bíceps braquial; M. subescapular; M. coracobraquial; M. tensor da fáscia do antebraço; M. braquial. A escápula e o braço têm acidentes específicos, porém são semelhantes aos dos cães domésticos. O úmero é reto. Os músculos apresentam algumas peculiaridades.