Variación del patrón de escutelación nucal del cocodrilo americano (Crocodylus acutus cuvier 1807) en la Ventanilla, Oaxaca, México

Abstract

Mexicana (n. s.), 25(2): 375-382. RESUMEN. Se analizó el patrón de escutelación post-occipital y nucal de 111 cocodrilos (Crocodylus acutus) en La Ventanilla, Oaxaca. Se obtuvieron 33 patrones de escutelación diferentes. El patrón más frecuente observado (31.5%) fue la presencia de 4 escudos post-occipitales, la ausencia de 2 escudos nucales anteriores externos y la presencia de 2 escudos nucales posteriores (4-2EE-2) y en menor proporción (6.31%) se registró el arreglo considerado típico para la especie. Se observó una diferencia significativa entre las frecuencias de patrones más comunes encontrados en este trabajo y de la misma manera se realizó la comparación del patrón de escutelación más frecuente registrado en este estudio con respecto a otros reportes para C. acutus. Palabras clave: Crocodylus acutus, patrón de escutelación, morfología, osteodermos. from La Ventanilla, Oaxaca were analyzed. Thirty three different scutellation patterns were found. The most frequently observed pattern (31.5%) was 4 post-occipital scales present 2 external previous nucal scales absent, and 2 posterior nucal scales present (4-2EE-2). The pattern considered typical for this species was observed only in 6.31% of individuals. There were differences between the frequency distribution of common patterns when compared to other studies on C. acutus. García-Grajales

Variation in crocodilian dorsal scute organization and geometry with a discussion of possible functional implications

“…Scute dimensions are more variable in Crocodylus acutus and Paleosuchus trigonatus than in Alligator mississippiensis , Caiman yacare , and Crocodylus porosus . However, only Crocodylus acutus exhibits significantly greater fluctuating asymmetry relative to other species, corroborating previous qualitative observations for this species (Brazaitis, ; Garcia‐Grajales et al, ; Ross & Mayer, ; Thorbjarnarson, ) and suggesting that Crocodylus acutus may have experienced relaxed selection on dorsal osteoderm morphology. As one of the larger species of living crocodilians (maximum length 6–7ft), Crocodylus acutus may experience reduced competition with other crocodilian species and predation on mature individuals (Somaweera, Brien, & Shine, ; Thorbjarnarson, ).…”

“…Rather, the majority of information about crocodilian physiology and behavior are generalizations stemming from a few well-studied taxa (e.g., Smith, 1979, Somaweera et al, 2013. Qualitative observation of other species not analyzed in this study suggests that Crocodylus moreletii, Crocodylus acutus, and Paleosuchus trigonatus are the only extant crocodilians to exhibit the morphologies described here (Brazaitis, 1973;Garcia-Grajales et al, 2009;Medem, 1958;Ross & Mayer, 1983;Thorbjarnarson, 2010;personal observation). Hopefully future studies of rare and cryptic taxa will reveal whether these three species are unique in other respects as well.…”

“…In the majority of extant species, the dorsal carapace is formed of a rectangular tessellation of osteoderms with their overlying scutes (Figure a). Different species vary in the number of average scutes per row and although some intraspecific variation in the number and dimensions of scutes is present in all species, it was previously noted that Crocodylus acutus and to a lesser extent Crocodylus moreletii have highly irregular scute patterns and sizes (Brazaitis, ; Garcia‐Grajales, Buenrostro Silva, & Téllez‐Rodriguez, ; Ross & Mayer, ; Thorbjarnarson, ). Paleosuchus trigonatus also was identified as having highly irregular lateral position of scute centroids, resulting in keels that are not aligned with each other cranio‐caudally as they are in other species (Figure c) (Brazaitis, ; Medem, ; Ross & Mayer, ).…”

Discovery of a suburban wetland refuge for a depleted American crocodile (Crocodylus acutus) population in northwestern Mexico, using a commercial Unmanned Aerial Vehicle

“…The American crocodile usually nests during the annual dry season and eggs hatch at the beginning of the annual rainy season (Thorbjarnarson, 2010), which would correspond to the months of November to June, and late June, respectively, in the UCL (Jara-Marini et al, 2008). According to this information and existing models for estimating the age of American crocodiles based on individual growth rates (García-Grajales et al, 2012), the collected yearling crocodiles were probably born in early June 2022. However, the models depend on TL at birth and individual growth rates, which depend on local environmental characteristics of the habitat (Charruau et al, 2010;Charruau, 2011;Seijas, 2017).…”

Un refugio para el cocodrilo (Crocodylus acutus) en Banco Chinchorro, arrecife coralino del Caribe Mexicano

“…Esto permitió obtener un modelo de estimación de la edad de los cocodrilos de Banco Chinchorro con base en su longitud corporal (Charruau 2011). Los cocodrilos de Banco Chinchorro tienen tasas de crecimiento más bajas y alcanzan tallas más pequeñas a edades específicas en comparación con otras poblaciones (Charruau et al 2010b, Charruau 2011, García-Grajales et al 2012. Además, las hembras parecen alcanzar la madurez sexual con tallas más pequeñas (<2.1 m) que las reportadas (2.1-3.0 m; Charruau et al 2010a).…”