The role of behavioural flexibility in responding to new or changing environmental challenges is a central theme in cognitive ecology. Studies of behavioural flexibility have focused mostly on mammals and birds because theory predicts that behavioural flexibility is favoured in species or clades that exploit a diversity of habitats or food sources and/or have complex social structure, attributes not associated with ectothermic vertebrates. Here, we present the results of a series of experiments designed to test cognitive abilities across multiple cognitive modules in a tropical arboreal lizard: Anolis evermanni. This lizard shows behavioural flexibility across multiple cognitive tasks, including solving a novel motor task using multiple strategies and reversal learning, as well as rapid associative learning. This flexibility was unexpected because lizards are commonly believed to have limited cognitive abilities and highly stereotyped behaviour. Our findings indicate that the cognitive abilities of A. evermanni are comparable with those of some endothermic species that are recognized to be highly flexible, and strongly suggest a re-thinking of our understanding of the cognitive abilities of ectothermic tetrapods and of the factors favouring the evolution of behavioural flexibility.

There is a 1 in 3 chance of abuse in a case where a child less than 18 months has a skull fracture [1]. The most commonly fractured site on the skull is the parietal bone, however it is currently difficult to establish the causation of injury based on the characteristics of the injury [2]. Thus, injury biomechanics are often utilized in the investigation of suspected child abuse cases [3]. Computer simulations, test dummies, and animal models are all used as aids in the assessment of skull fracture causation. For a given impact situation, a number of variables can control the pattern of skull fracture. A study by Baumer et. al assessed the effects of interface and age using an infant porcine skull model, specifically looking at the location of fracture initiation on the parietal bone [4]. This study showed that in low energy impacts fracture initiation occurs at the bone-suture boundary. Also, a deformable interface caused more fracture than a rigid interface for very young subjects. The current study was conducted to assess the effects of higher energy impacts on the patterns of fracture in this model.

In many forensic cases, the job of forensic pathologists and anthropologists is to determine whether pediatric death is due to an abusive act or an accidental fall. The goal of this study was to compare the cranial fracture patterns generated on the parietal bone of a developing, infant porcine (pig, Sus scrofa) model by a controlled energy head drop onto a plate versus previous data generated by blunt force impact at the same energy onto the head constrained to a plate. The results showed that blunt force impacts on a head constrained to a rigid plate produces more fracture, but the same general pattern, as that for a head dropped onto the plate with the same level of impact energy. The study suggests that head constraint may be an important factor to consider in the evaluation of death causation for blunt force impacts to the pediatric skull.

Across vertebrates, there is a broad correlation between neuroanatomy and the type of habitat preferred by a species. In general, species occupying habitats classified as more structurally complex have relatively larger brains and exaggerated structures related to navigating and exploiting those habitats. We empirically measured the structural habitat complexity of six species of Puerto Rican Anolis lizards, which have traditionally been classified as occupying three distinct habitat types. We also measured the volume of the whole brain as well as six structures putatively related to exploiting complex habitats in these species. We found a significant interspecific variation in structural habitat complexity, including a substantial variation between those belonging to the same ecomorph category. Despite this, we found no evidence to support the hypothesis that interspecific differences in habitat preferences, particularly differences in the relative structural complexity of those habitats, can favor a divergence in neuroanatomy. However, our findings indicate that, at a finer scale, species preferences for structural habitats vary greatly between Anolis species belonging to the same ecomorph category. This variation might contribute to the community structure of anoles by allowing multiple sympatric species of the same ecomorph category to occupy what, at a coarse scale, appears to be the same structural niche. We propose that, in the case of arboreal species, differences in the complexity of arboreal habitats alone may not be sufficient to favor divergent brain evolution.

Patterns of brain evolution have been widely studied across vertebrates, with the bulk of studies using mammals and/or birds as model systems. Within these groups, species occupying different habitats have been shown to have divergent neuroanatomy, particularly with regard to differences in the relative size of different brain structures, correlated with differences in habitat complexity. We examined the pattern of allometric scaling across the telencephalon, dorsal cortex, dorsomedial cortex, medial cortex, dorsal ventricular ridge, medulla and cerebellum in six species of Puerto Rican Anolis lizards, which are grouped in three distinct ecomorphs (i.e. ecological types) according to interspecific differences in preferred habitat type. The differences in habitat preferences are accompanied by morphological and behavioral adaptations for effective use of each habitat type. Our results challenge this trend and demonstrate a lack of convergence in the relative size of different brain structures between species belonging to the same ecomorph type. Overall brain volume explained between 92.5 and 99.8% of the variance in the volume of each of the brain regions measured and 93.8 and 98.5% of the variance in the volume of each component measured within the telencephalon. This pattern of brain allometry is consistent with concerted brain evolution. However, in the case of the cerebellum, interspecific differences in volume exhibit a trend in accordance with mosaic brain evolution. This suggests that both concerted and mosaic brain evolution have shaped the anole brain, with the former playing a dominant role. Concerted brain evolution is the primary mechanism shaping the brain in mammals and cartilaginous fishes, and its presence in Anolis lizards provides additional evidence supporting the hypothesis that concerted brain evolution might result from a conserved pattern of brain development common to all vertebrates. More generally, our findings highlight the necessity of further studies of brain evolution in reptiles as they can provide valuable insights into the mechanisms underlying vertebrate brain evolution.