The Viperidae is the most speciose family of Brazilian venomous snakes, with 33 known species. Although the family is well defined cladistically, there are few studies concerning the postcranial skeletal morphology, and only a single vertebral synapomorphy has been proposed. The paucity of knowledge on postcranial morphology poses challenges for the study of the Brazilian viper fossil record since most fossils consist of disarticulated and isolated vertebrae. Currently, Bothrops and Crotalus are the only vipers recognized in the Brazilian fossil record. Nonetheless, interspecific differentiation based on vertebral material is hampered due to the lack of comprehensive detailed anatomical data. We compared the trunk vertebrae of extant specimens of Crotalus and Bothrops using two-dimensional geometric morphometrics to obtain discriminant data about their vertebral morphology. We examined the trunk vertebrae of 20 vipers, 10 Crotalus, and 10 Bothrops and performed macroscopic analyses and measurements and landmark-based, two-dimensional geometric morphometric analyses. We sought to identify structural differences between the genera and to assess morphological variation along the spine. Most differences in the trunk vertebrae between Crotalus and Bothrops occurred in the length of the neural spine, the parapophyseal processes, the prezygapophyseal processes, and in the angle on the prezygapophyses. However, when we accounted for intracolumnar variation, differentiation is hampered. We expect our results will serve as a starting point for future studies of viperid vertebrae and aid paleontologists in accurately identifying fossil vipers.

Pre-Pleistocene fossils of Anolis lizards are rare, although 20 Miocene fossils preserved in amber from the island of Hispaniola have been reported on previously. Using light-microscopy and computed-tomography imaging, we studied a new amber fossil Anolis lizard from Hispaniola. The fossil is likely a juvenile and preserves a largely intact left forelimb, including both scales and skeletal elements, as well as some additional skin, skin impressions, and fragmentary skeletal elements from other parts of the body. Using measurements and lamella counts from the forelimb of the fossil and other juvenile anoles, discriminant function analysis and three Euclidean-distance criteria derived from a principal components analysis consistently support classification of the fossil as a member of the trunk ecomorph category, and those results, in combination with two scale characters preserved in the fossil, suggest that it is a member of the Anolis distichus series within the Ctenonotus clade. These results represent only the third case of a well-supported assignment of an Anolis fossil to the trunk ecomorph category and the first to the A. distichus series. They also highlight that such assignments can sometimes be inferred from highly incomplete fossils.

Sexual dimorphism is a fascinating phenomenon that showcases the wide variation of characteristics related to life strategies in organisms. It is driven by two key evolutionary processes: sexual selection and natural selection. Anurans provide an excellent opportunity to study the origin and diversification of sexual dimorphism due to their variation in size and secondary sexual characters, as well as their diverse life histories. Here, we compared the morphology of males and females in six anuran species (Ceratophrys cranwelli, Boana pulchella, Leptodactylus luctator, Odontophrynus americanus, Physalaemus biligonigerus, and Rhinella arenarum) inhabiting the same breeding site. Additionally, we employed an allometric approach to assess changes in magnitude of sexually dimorphic traits relative to body size. No common pattern of sexual size dimorphism emerged, with species exhibiting dissimilar combinations of dimorphic and monomorphic traits. These differences in sexual dimorphism could only be partially attributed to specific behaviors or life histories in certain cases. Discordant patterns of allometry between sexes in most species further contributed to observed diversity. Overall, selective forces shaping morphologies of both sexes appear complex, related not solely to trait function, but also to life history differences between sexes. To fully understand mechanisms driving sexual dimorphism, it is crucial to consider multiple factors such as behavior, reproductive strategies, and environmental conditions. Lack of a common pattern and presence of diverse morphological variations among species underscore the complexity of selection on body size.

Nonnative species mitigation is important to conserve Florida's native wildlife, especially with nonnative reptiles such as Nile Monitors (Varanus niloticus). Nile Monitors are habitat and dietary generalists in their native (Africa) and nonnative (Florida) ranges and were introduced to Florida in the early 1990s through the pet trade. Nile Monitors have since become established in three coastal counties in southern Florida. Confirmed sightings extend beyond established Nile Monitor populations into parts of central and northern Florida, but it is unclear whether spread is likely to these areas or even into surrounding states. Mitigation strategies to locate, remove, and proactively prevent introduction and spread of nonnative species include species distribution models (SDMs). Two Nile Monitor SDMs currently exist but are not at an appropriate scale to inform regional management practices and include various methods that do not meet current model quality standards. Nile Monitor SDMs here represent high-quality, region-scale predictions at a 1 km² resolution fitted with ensembles of algorithms, 14 predictors (including environmental and anthropogenic variables), and occurrence data from both the native and nonnative ranges. Final SDM predictions indicate little habitat suitability and low probability of spread beyond the central region of Florida, contradictory to existing Nile Monitor SDMs. Pathways of suitable habitat exist from established populations into other central and southern parts of Florida along coastlines and suggest possible anthropophilic habitat preferences that will require further telemetric behavioral studies to validate.

As climate change will affect thermal environments and physiological performance of ectotherms, it is critical to understand their thermal ecology. One group of ectotherms with poorly understood thermal ecology is ambystomatid salamanders of central Mexico. We studied water temperature selection in the endangered, endemic salamander species Ambystoma altamirani in the field and in a laboratory thermal gradient. Mean field water temperature was 14.9 °C, with males found at cooler water temperatures than females and juveniles. Mean final selected temperature in the laboratory thermal gradient was 26.3 °C, with males selecting the lowest temperature and females the highest. The difference between laboratory-selected water temperature and field water temperature suggests that A. altamirani may have some capacity to respond to climate change, but more investigations of their thermal physiology are needed.