Navegando por Assunto "reptiles"

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Artigo
Description of embryonic stages in Melanosuchus niger (Spix, 1825) (Crocodylia: Alligatoridae).
(J. Morphol. Sci, 2011) Vieira, L.G.; Lima, F.C.; Santos, A.L.Q; Mendonça, S.H.S.T.;; Moura, L.R.,; Iasbeck, J.R.; Sebben, A.
The determination of embryonic stages is very useful in comparative and evolutionary anatomy, experimental research and ecological studies. Although tables of development stages already exist for some crocodilian species, no table has yet been published for Melanosuchus niger. Therefore, the aim of this work is to monitor the development of this species of Alligatoridae and characterize its stages based on the main morphological transformations the embryo undergoes during the incubation process. Under natural conditions, two samples were collected daily in the Lake Cuniã Extractive Reserve in Rondônia, Brazil, making a total of 186 eggs. The incubation period was 90 days at an ambient temperature varying from 25.2 to 31.7 °C. We established 24 embryonic stages between the formation of the pharyngeal arch and hatching. Primordia for the sensory organs and somites were observed in the early stages. The buds of the pelvic and thoracic limbs emerged simultaneously, also in the early stages. An analysis of these structures showed evidence of considerable evolutionary modifications when compared with embryos of different species. In stage 12 we observed subtle pigmentation in the region of the head and, in stage 25, the pigmentation and striped pattern were typical of the newly hatched specimen. The eyetooth was visible in stage 18, disappearing within the first few weeks after hatching. The vitellus was completely absorbed in the penultimate stage. Direct comparisons of the table of embryonic stages were made between M. niger and other crocodilian taxa, and the main differences identified were chronological variations.
Artigo
Skeletogenesis of the pelvic girdle and members in embryos of Caiman yacare (Crocodylia: Alligatoridae)
(Scientific Research and Essays, 2013-12) Lima, Fabiano Campos; Santos, André Luiz Quagliatto; Vieira, Lucélia Gonçalves; Mendonça, Sônia Helena Santesso Teixeira de; De Simone, Simone Borges Salgueiro; Martins, Clarissa de Araújo; Coutinho, Marcos Eduardo
Caiman yacare embryos were collected and subjected to the bone cleared and Alizarin staining to analyze the ontogenic patterns of the skeletal ossification of the pelvic girdle and members. Ossification of C. yacare pelvis begins at 36 days of incubation. The femur, tibia and fibula present simultaneous stain retention at 30 days. It has four tarsal bones, the calcaneus, the talus, distal III and distal IV. Their ossification starts with the calcaneus from the 40th day of incubation, followed by the talus. At 54 days, the distal tarsal IV is conspicuous, as is the outline of the distal III. Each foot has five metatarsi (MT) and 13 phalanges (phalangeal formula 2:3:4:4). Ossification of the metatarsi begins at 36 days and follows the sequence MTI=MTII=MTIII=MTIV>MTV. The first phalanges begin the ossification process on the 36th day and continue up to the last day of incubation. The sequence of ossification of the proximal phalanges is PPI=PPII=PPIII>PPIV, while that of the medial phalanges is MPII> MPpIII>MDpIII>MPpIV>MDpIV and that of the distal phalanges is DPI>DPII>DPIII>DPIV, and the ontogenic pattern of the bones of the pelvic girdle and members of C. yacare differs from that of other reptiles, albeit with a few similarities. INTRODUCTION Vertebrates have a unique skeleton that is composed of a set of plastic structures that are able to grow, adapt and repair themselves due to the wide morphological and architectural diversity of the skeletal tissue (White et al., 2003; Hildebrand and Goslow, 2006). This trait is conservative to the point that its general pattern displays in the tetrapods lineages. Its evolutionary pattern also enables this structure to respond to the particular habits of each species (Withers, 1992). In some reptiles, the ossification patterns are well known. Several anatomical studies of the skeletons of reptiles have been conducted, as demonstrated by the.
Artigo
USE OF KNOWN INDIVIDUAL MARKING IN RESEARCH AND MONITORING OF FRESHWATER TURTLE POPULATIONS
(ResearchGate, 2024) Cunha, Fabio; Ândrade, Marcelo
The marking or tagging of turtles is a widely used to facilitate the monitoring of population demography, structure, and conservation of species. Even though they are used in many studies of turtle demography, the available methods are not very efficient, except for microchips (Passive Intergraded Transponder/PIT tags); however, the latter is too expensive to be used on a large scale. Here we present a viable, cost-effective tagging alternative that uses a durable plastic cattle tag and pin. Turtles in the genus Podocnemis were tagged in the Lower-Amazon region, west of the state of Pará, Amazon, Brazil. This method is highly recommended for future work on monitoring and population structure of large species of freshwater turtles. In addition to feasibility, it can be used in the form of citizen science, as the information can be obtained by laypeople and taken to researchers and conservationists. Resumen El marcado o marcaje de tortugas es un método ampliamente utilizado para facilitar el seguimiento de la demografía y estructura de las poblaciones y la conservación de las especies. Aunque se utilizan en muchos estudios de demografía de tortugas, los métodos disponibles no son muy eficaces, excepto los microchips (Passive Intergraded Transponder/PIT tags); sin embargo, estos últimos son demasiado caros para ser utilizados a gran escala. Aquí presentamos una alternativa de marcado viable y rentable que utiliza una marca de plástico duradera para ganado y un alfiler. Se marcaron tortugas del género Podocnemis en la región del Bajo Amazonas, al oeste del estado de Pará, Amazonas, Brasil. Este método es muy recomendable para futuros trabajos de seguimiento y estructura poblacional de grandes especies de tortugas dulceacuícolas. Además de su viabilidad, puede utilizarse en forma de ciencia ciudadana, ya que la información puede ser obtenida por profanos y llevada a investigadores y conservacionistas.