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Context: Globally, with the continuous increase in human populations, unprecedented changes in land use are taking place. Little is known about how African reptiles respond to this rapid land use change. Objectives: We used sightings to establish if Nile monitors (Varanus niloticus) are persisting in a mosaic of human population densities and land use types in KwaZulu-Natal Province, South Africa. Methods: We collected sighting data throughout KwaZulu-Natal between April 2022 and July 2023, using three main methods, namely urban sightings obtained from reptile relocation groups and collaborations with reptile relocators; sightings obtained from personal encounters and citizen scientist observations using social media,s posters, newspaper articles and interviews; and sightings from iNaturalist observations. Results: We obtained and used 419 sightings and then identified two hotspot areas in the province on which we chose to focus. Site A was dominated by natural habitat, and anthropogenic land use types dominated site B. We found a significant relative selection strength for most tested land covers over anthropogenic cover in site A, whereas most were insignificant in site B. Our results suggest that the use of anthropogenic land use types by Nile monitors in KwaZulu-Natal may be driven by habitat transformation and loss. Nile monitors were found persisting in urban mosaic landscapes and, when compared with available cover, were found in increasingly wooded (natural and urban vegetation) areas with increased human populations. Furthermore, they used small anthropogenic water bodies (e.g., swimming pools and storm drains), making them less reliant on rivers in urban environments. Their population demographics were similar in low and high human population density, but there appeared to be a skew towards smaller and younger individuals in medium human population density areas. Reproduction was occurring successfully in urban environments, but the detection of larger monitors by potential wild and domestic predators and negative human interactions pose risks. Our study outlined the importance of natural and managed (e.g., gardens, parks, golf courses) green spaces in urban mosaic landscapes for wildlife persistence, specifically Nile monitors, and supporting human well-being as well as reptile conservation. There is an overall need for more research on this highly exploited yet understudied reptilian urban adapter. [ABSTRACT FROM AUTHOR]

Fluid therapy is the principal mechanism by which a clinician can stabilize a hemodynamically compromised patient. To ensure the provision of fluids is therapeutic, it is essential to know the osmolality of the administered fluid relative to the plasma of the species being treated. The clinical utility of common isotonic fluids for reptiles was determined through comparisons to the plasma osmolality of 15 Australian reptile species representing 3 genera. All sampled species had an osmolality that was either comparable, or significantly hyperosmolar, to that of the isotonic fluids. Pairwise comparisons revealed a significant difference (P < 0.05) between monitor lizards (Varanus spp.; x ¯ = 329.71 mOsm/kg) and carpet pythons (Morelia spp.; x ¯ = 294.92 mOsm/kg), and at a species-subspecies level, between eastern carpet pythons (Morelia spilota mcdowelli; x ¯ = 318.25 mOsm/kg) and Bredli carpet pythons (Morelia spilota bredli; x ¯ = 306.33 mOsm/kg). In support of previous studies, almost all species demonstrated a wider tolerable range in plasma osmolality than would be expected in mammals. Lizards in the genus Varanus demonstrated the most clinically significant results, with all species means being greater than any commercial isotonic fluid. The facultatively aquatic Mertens water monitor (Varanus mertensi) was the species with the most significant difference ( x ¯ = 344.50 mOsm/kg). A preliminary exploration of taxonomic rank (at the genus and species level) and habitat aridity was also performed to assess their utility as indicators for estimating the plasma osmolality of an unmeasured species. Neither were found to be suitable. [ABSTRACT FROM AUTHOR]

Despite their evolutionary novelty, lizard venoms are much less studied in comparison to the intense research on snake venoms. While the venoms of helodermatid lizards have long been assumed to be for defensive purposes, there is increasing evidence of toxic activities more useful for predation than defence (such as paralytic neurotoxicity). This study aimed to ascertain the effects of Heloderma, Lanthanotus, and Varanus lizard venoms on the coagulation and cardiovascular systems. Anticoagulant toxicity was demonstrated for the Varanus species studied, with the venoms prolonging clotting times in human and bird plasma due to the destructive cleavage of fibrinogen. In contrast, thromboelastographic analyses on human and bird plasmas in this study demonstrated a procoagulant bioactivity for Heloderma venoms. A previous study on Heloderma venom using factor-depleted plasmas as a proxy model suggested a procoagulant factor was present that activated either Factor XI or Factor XII, but could not ascertain the precise target. Our activation studies using purified zymogens confirmed FXII activation. Comparisons of neonate and adult H. exasperatum, revealed the neonates to be more potent in the ability to activate FXII, being more similar to the venom of the smaller species H. suspectum than the adult H. exasperatum. This suggests potent FXII activation a basal trait in the genus, present in the small bodied last common ancestor. This also indicates an ontogenetic difference in prey preferences in the larger Heloderma species paralleing the change in venom biochemistry. In addition, as birds lack Factor XII, the ability to clot avian plasma suggested an additional procoagulant site of action, which was revealed to be the activation of Factor VII, with H. horridum being the most potent. This study also examined the effects upon the cardiovascular system, including the liberation of kinins from kininogen, which contributes to hypotension induction. This form of toxicity was previously described for Heloderma venoms, and was revealed in this study was to also be a pathophysiological effect of Lanthanotus and Varanus venoms. This suggests that this toxic activity was present in the venom of the last common ancestor of the anguimorph lizards, which is consistent with kallikrein enzymes being a shared toxin trait. This study therefore uncovered novel actions of anguimorph lizard venoms, not only contributing to the evolutionary biology body of knowledge but also revealing novel activities to mine for drug design lead compounds. [ABSTRACT FROM AUTHOR]

Amblyomma varanense (Supino) (Ixodida: Ixodidae) is a reptile-associated bont tick native to the Oriental and Australasian zoogeographic regions. This species is primarily ectoparasitic on monitor lizards (Varanidae) and snakes but has been reported to occasionally occur on turtles and mammals. Prior to the research described here, only one collection of A. varanense had been reported from the Philippines. Herein, we present a second Philippines collection of A. varanense as well as updated host records across this tick's geographic range and an overview of associated microbes with zoonotic potential. [ABSTRACT FROM AUTHOR]

Varanus bangonorum, the Bangon Monitor Lizard, is one of eleven Varanidae species endemic to the Philippines; its occurrence is restricted to dwindling habitats on the islands of Mindoro and Semirara. This lizard is still poorly known and is presently classified as "Least Concern" under the IUCN Red List in 2022. Observations recorded during eleven years (2011 to 2022) originate from the north-central Municipality of Abra de Ilog in Occidental Mindoro where this species was never before documented. We emphasise the primary factors that pose threats to the monitor lizard population, including insights gained from the knowledge of local community members. We present information about the lizards' diet, for example, they can consume invasive toxic cane toads without harm. The result of our collective long-term observation records may serve as a baseline for further studies and contribute to evaluating the conservation status of this species. [ABSTRACT FROM AUTHOR]

The group Anguimorpha represents one of the most unified squamate clades in terms of body plan, ecomorphology, ecophysiology and evolution. On the other hand, the anguimorphs vary between different habitats and ecological niches. Therefore, we focused on the group Anguimorpha to test a possible correlation between heart morphology and ecological niche with respect to phylogenetic position in Squamata with Sphenodon, Salvator, and Pogona as the outgroups. The chosen lepidosaurian species were investigated by microCT. Generally, all lepidosaurs had two well‐developed atria with complete interatrial septum and one ventricle divided by ventricular septa to three different areas. The ventricles of all lepidosaurians had a compact layer and abundant trabeculae. The compact layer and trabeculae were developed in accordance with particular ecological niche of the species, the trabeculae in nocturnal animals with low metabolism, such as Sphenodon, Heloderma or Lanthanotus were more massive. On the other hand athletic animals, such as varanids or Salvator, had ventricle compartmentalization divided by three incomplete septa. A difference between varanids and Salvator was found in compact layer thickness: thicker in monitor lizards and possibly linked to their mammalian‐like high blood pressure, and the level of ventricular septation. In summary: heart morphology varied among clades in connection with the ecological niche of particular species and it reflects the phylogenetic position in model clade Anguimorpha. In the absence of fossil evidence, this is the closest approach how to understand heart evolution and septation in clade with different cardiac compartmentalization levels. [ABSTRACT FROM AUTHOR]

Terrestrial animals in global wet-dry tropical ecosystems experience year-round high temperatures but concentrated summer rainfall. This highly seasonal precipitation is expected to have major evolutionary and ecological consequences for animals. We considered how strong seasonal patterns of rainfall might influence the environment and biological attributes of the world's largest predatory lizard, the Komodo dragon (Varanus komodoensis). We predicted that annual variation in rainfall or temperature may influence the seasonal phenology of vegetation, and in turn, the phenology of Komodo dragon reproduction and hatchling emergence. Similarly, seasonal environmental differences may affect Komodo dragon rates of somatic growth, body condition, survival and daily movement. Our results indicated evidence of strong seasonal variation in mean monthly rainfall and leaf area index for open deciduous forest and closed dense forest. These environmental variables were significantly correlated with female Komodo dragon nesting activity and hatchling emergence. Neither Komodo dragon somatic growth rate nor body condition exhibited seasonal differences. There was, however, increased daily movement rates of Komodo dragons during the dry season. This suggests dry season associated life-history activities or thermoregulatory efficiency might explain increased daily movement. Ultimately, the Komodo dragon showed differential sensitivities in its biology to seasonal environmental variation. [ABSTRACT FROM AUTHOR]

Road networks continue to expand globally with predictable effects on ecological systems. Research into the effectiveness of road underpasses and overpasses for wildlife has been concentrated in North America and Europe. In Australia, most studies of underpasses have been of relatively short duration and without reference sites to give context to the measured rates of use. We studied 5–7 road underpasses at two locations in eastern Australia over 2–3 years, comparing camera trap detections of animals in underpasses with those at nearby forest sites. Three species of large macropod (wallabies and kangaroos) were frequently detected in the underpasses, with some underpasses traversed 1–4 times per week, and in many cases exceeded detections in the forest. The lace monitor (Varanus varius) was detected in all underpasses, often once per week during spring and summer, and infrequently in the forest. At each location, a different small macropod species, including one regionally threatened, showed a higher probability of detection in one underpass compared with several of the forest sites. The vulnerable koala (Phascolarctos cinereus) was detected infrequently in underpasses and in the adjoining forest. The short‐beaked echidna (Tachyglossus aculeatus) had a high probability of detection in a single underpass. The "prey‐trap hypothesis" postulates that predators will exhibit increased activity at underpasses as a consequence of prey being funneled. We found the red fox (Vulpes vulpes) had high activity in some underpasses. However, its activity coincided less than expected with the activity of the mammals most at risk to it. Our results provide no consistent support for the "prey‐trap hypothesis." Instead, our study confirms the generic value of underpasses for a range of medium‐large mammals as well as one large reptile. Habitat adjoining underpasses exert a strong influence on their use and require greater consideration to maximize underpass use. [ABSTRACT FROM AUTHOR]

In tropical Australia, conditioned taste aversion (CTA) can buffer vulnerable native predators from the invasion of a toxic prey species (cane toads, Rhinella marina). Thus, we need to develop methods to deploy aversion‐inducing baits in the field, in ways that maximize uptake by vulnerable species (but not other taxa). We constructed and field‐tested baiting devices, in situ with wild animals. Apparatus were set next to waterbodies and baited concurrently at multiple locations (over water, water's edge, and on the bank). Baits were checked and replaced twice daily during the trial; remote cameras recorded visitation by native predators. Bait longevity was compared at sun‐exposed and shaded locations over 12 h. The strength required to remove baits from apparatus was measured in varanids and crocodiles. The device promoted high rates of bait uptake by freshwater crocodiles (47% baits consumed), varanid lizards (19% baits consumed), and non‐target taxa (34% baits consumed). Targeting specific predators can be achieved by manipulating bait location and time of deployment, as well as the force required to dislodge the bait. Crocodiles were best targeted with over‐water baits, whereas varanid lizards preferred baits located at the edges of waterbodies. When testing bait longevity in ambient conditions, during the daytime baits desiccated fully within 12 h, and faster in the sun than in the shade. Based on studies using captive animals, the "pulling force" strength of reptilian predators scaled with body size and was greater in crocodiles than in varanid lizards. We present the first conservation baiting protocol designed specifically for reptiles. Our results demonstrate the feasibility of widespread and taxon‐specific deployment of aversion‐inducing baits to buffer the impacts of invasive cane toads, and our methods are applicable (with modification) to other research and management programs globally. [ABSTRACT FROM AUTHOR]

An important but understudied modality for eavesdropping between predators and prey is olfaction, especially between non-mammalian vertebrate predators and their prey. Here we test three olfactory eavesdropping predictions involving an apex reptilian predator, the sand goanna Varanus gouldii, and several species of its small mammalian prey in arid central Australia: 1) small mammals will recognize and avoid the odour of V. gouldii; 2) V. gouldii will be attracted to the odour of small mammals, especially of species that maximize its energetic returns; and 3) small mammals will be less mobile and will show higher burrow fidelity where V. gouldii is absent compared with where it is present. As expected, we found that small mammals recognized and avoided faecal odour of this goanna, feeding less intensively at food patches where the odour of V. gouldii was present than at patches with no odour or a pungency control odour. Varanus gouldii also was attracted to the odour of small mammals in artificial burrows and dug more frequently at burrows containing the odour of species that were energetically profitable than at those of species likely to yield diminishing returns. Our third prediction received mixed support. Rates of movement of three species of small mammals were no different where V. gouldii was present or absent, but burrow fidelity in two of these species increased as expected where V. gouldii had been removed. We conclude that olfaction plays a key role in the dynamic interaction between V. gouldii and its mammalian prey, with the interactants using olfaction to balance their respective costs of foraging and reducing predation risk. We speculate that the risk of predation from this apex reptilian predator drives the highly unusual burrow-shifting behaviour that characterizes many of Australia's small desert mammals. [ABSTRACT FROM AUTHOR]

How biotic and abiotic factors act together to shape biological diversity is a major question in evolutionary biology. The recent availability of large datasets and development of new methodological approaches provide new tools to evaluate the predicted effects of ecological interactions and geography on lineage diversification and phenotypic evolution. Here, we use a near complete phylogenomic‐scale phylogeny and a comprehensive morphological dataset comprising more than a thousand specimens to assess the role of biotic and abiotic processes in the diversification of monitor lizards (Varanidae). This charismatic group of lizards shows striking variation in species richness among its clades and multiple instances of endemic radiation in Indo‐Australasia (i.e., the Indo‐Australian Archipelago and Australia), one of Earth's most biogeographically complex regions. We found heterogeneity in diversification dynamics across the family. Idiosyncratic biotic and geographic conditions appear to have driven diversification and morphological evolution in three endemic Indo‐Australasian radiations. Furthermore, incumbency effects partially explain patterns in the biotic exchange between Australia and New Guinea. Our results offer insight into the dynamic history of Indo‐Australasia, the evolutionary significance of competition, and the long‐term consequences of incumbency effects. [ABSTRACT FROM AUTHOR]

Squamates present a unique challenge to the homology and evolution of tooth attachment tissues. Their stereotypically pleurodont teeth are fused in place by a single "bone of attachment", with seemingly dubious homology to the three‐part tooth attachment system of mammals and crocodilians. Despite extensive debate over the interpretations of squamate pleurodonty, its phylogenetic significance, and the growing evidence from fossil amniotes for the homology of tooth attachment tissues, few studies have defined pleurodonty on histological grounds. Using a sample of extant squamate teeth that we organize into three broad categories of implantation, we investigate the histological and developmental properties of their dental tissues in multiple planes of section. We use these data to demonstrate the specific soft‐ and hard‐tissue features of squamate teeth that produce their disparate tooth implantation modes. In addition, we describe cementum, periodontal ligaments, and alveolar bone in pleurodont squamates, dental tissues that were historically thought to be restricted to extant mammals and crocodilians. Moreover, we show how the differences between pleurodonty and thecodonty do not relate to the identity of the tooth attachment tissues, but rather the arrangements of homologous tissues around the teeth. [ABSTRACT FROM AUTHOR]

Water monitors (Varanus salvator macromaculatus) are large lizards that inhabit wetlands. However, populations seem to be declining due to habitat fragmentation resulting from urban development. To develop an effective strategic conservation plan, the genetic diversity and population structure of water monitors at Bang Kachao Peninsula, a rich urban ecosystem in Bangkok, were analyzed using mitochondrial (mt) D‐loop II sequences and microsatellite genotyping. Both genetic markers indicated a high degree of population‐level genetic diversity. The consistency of the star‐shaped haplotype network and results of neutrality tests strongly suggest the occurrence of a recent expansion in the population, possibly driven by anthropogenic urbanization. Subpopulations at Bang Kachao Peninsula are unlikely but gene flow between water monitors has occurred, which is suggestive of female‐based dispersal. The large population of water monitors at Bang Kachao Peninsula creates conflict with local residents. Long‐term population management through translocation has been conducted by captive management at Varanus Farm Kamphaeng Saen. The results of genetic monitoring indicate that the captive research population was soundly established. Comparison of allelic profiles between the two populations is necessary before translocation of water monitor groups from Bang Kachao Peninsula to Varanus Farm Kamphaeng Saen to reduce human‐wildlife conflict. This work is the first step toward establishment of long‐term ecological monitoring and an in situ/ex‐situ conservation program, which are part of attempts to promote biodiversity in Thailand, following scientific principles. [ABSTRACT FROM AUTHOR]

Vulnerable native species may survive the impact of a lethally toxic invader by changes in behaviour, physiology and/or morphology. The roles of such mechanisms can be clarified by standardised testing. We recorded behavioural responses of monitor lizards (Varanus panoptes and V. varius) to legs of poisonous cane toads (Rhinella marina) and non-toxic control meals (chicken necks or chicken eggs and sardines) along 1300 and 2500 km transects, encompassing the toad's 85-year invasion trajectory across Australia as well as yet-to-be-invaded sites to the west and south of the currently colonised area. Patterns were identical in the two varanid species. Of monitors that consumed at least one prey type, 96% took control baits whereas toad legs were eaten by 60% of lizards in toad-free sites but 0% from toad-invaded sites. Our survey confirms that the ability to recognise and reject toads as prey enables monitor lizards to coexist with cane toads. As toxic invaders continue to impact ecosystems globally, it is vital to understand the mechanisms that allow some taxa to persist over long time-scales. [ABSTRACT FROM AUTHOR]

There is a functional trade‐off in the design of skeletal muscle. Muscle strength depends on the number of muscle fibers in parallel, while shortening velocity and operational distance depend on fascicle length, leading to a trade‐off between the maximum force a muscle can produce and its ability to change length and contract rapidly. This trade‐off becomes even more pronounced as animals increase in size because muscle strength scales with area (length2) while body mass scales with volume (length3). In order to understand this muscle trade‐off and how animals deal with the biomechanical consequences of size, we investigated muscle properties in the pectoral girdle of varanid lizards. Varanids are an ideal group to study the scaling of muscle properties because they retain similar body proportions and posture across five orders of magnitude in body mass and are highly active, terrestrially adapted reptiles. We measured muscle mass, physiological cross‐sectional area, fascicle length, proximal and distal tendon lengths, and proximal and distal moment arms for 27 pectoral girdle muscles in 13 individuals across 8 species ranging from 64 g to 40 kg. Standard and phylogenetically informed reduced major axis regression was used to investigate how muscle architecture properties scale with body size. Allometric growth was widespread for muscle mass (scaling exponent >1), physiological cross‐sectional area (scaling exponent >0.66), but not tendon length (scaling exponent >0.33). Positive allometry for muscle mass was universal among muscles responsible for translating the trunk forward and flexing the elbow, and nearly universal among humeral protractors and wrist flexors. Positive allometry for PCSA was also common among trunk translators and humeral protractors, though less so than muscle mass. Positive scaling for fascicle length was not widespread, but common among humeral protractors. A higher proportion of pectoral girdle muscles scaled with positive allometry than our previous work showed for the pelvic girdle, suggesting that the center of mass may move cranially with body size in varanids, or that the pectoral girdle may assume a more dominant role in locomotion in larger species. Scaling exponents for physiological cross‐sectional area among muscles primarily associated with propulsion or with a dual role were generally higher than those associated primarily with support against gravity, suggesting that locomotor demands have at least an equal influence on muscle architecture as body support. Overall, these results suggest that larger varanids compensate for the increased biomechanical demands of locomotion and body support at higher body sizes by developing larger pectoral muscles with higher physiological cross‐sectional areas. The isometric scaling rates for fascicle length among locomotion‐oriented pectoral girdle muscles suggest that larger varanids may be forced to use shorter stride lengths, but this problem may be circumvented by increases in limb excursion afforded by the sliding coracosternal joint. [ABSTRACT FROM AUTHOR]

The amphisbaenian and anguimorph fossil lizards from the late Miocene (MN 13) Solnechnodolsk locality (southern European Russia) are described. Amphisbaenians are represented only by isolated vertebrae of which more precise allocation is difficult. The anguine material shows the presence of at least two taxa which are described from this area for the first time: Anguis cf. rarus and Ophisaurus cf. spinari. The A. rarus was previously known only from the early Miocene of Germany. Ophisaurus spinari has a broad stratigraphic range – from the early and middle Miocene of Central Europe, with the last occurrence documented from the late Pliocene of Italy. However, no record was known from the late Miocene, which would show an important part of the story. The parietal of A. cf. rarus forms the first evidence of its survival to the end of the Miocene by its shifting to south areas of Eastern Europe, together with O. spinari. The Solnechnodolsk material is evidence of a broad spatial and/or temporal distribution of both these anguine taxa and the parietal of Anguis unambiguously documents the presence of this taxon in Russia already in the late Miocene. The thermophilic forms in Solnechnodolsk are represented by monitor lizards (Varanus). [ABSTRACT FROM AUTHOR]

The South Pacific subpopulation of the loggerhead turtle Caretta caretta is categorized as Critically Endangered on the IUCN Red List because of significant population declines. Five Queensland beaches support high-density nesting of this subpopulation, but egg and hatchling survival are low at some beaches because of feral and native terrestrial predators. We quantified predation of loggerhead turtle eggs by two species of goanna, Varanus panoptes and Varanus varius, at Wreck Rock beach, one of the turtle's major nesting beaches. In addition, we conducted an experiment to determine the efficacy of a nest protection device. Predation rates at Wreck Rock beach were 15.2% for treatment and 45.8% for non-treatment clutches during the 2013–2014 nesting season. A higher probability of predation (64%) was predicted for the northern beach. Although nests were only partially predated (16.4% of the total number of eggs), nest loss to predators and beach erosion (caused by a cyclone) was 91.7%. If left unmanaged, the cumulative impact of predation and other threats, including those exacerbated by climate change, can cause unsustainable loss of loggerhead turtle nests. This study provides one of the first quantitative data sets on rates of loggerhead turtle clutch predation in the South Pacific. It enhances our understanding of goanna predation impacts and identifies an efficient predator exclusion device for mitigating the effects of terrestrial predators at Wreck Rock beach, and for protecting marine turtle nests across northern Australia and globally. [ABSTRACT FROM AUTHOR]

Minimal annual rainfall in arid environments results in low productivity ecosystems with fluctuating food availability. Large mammalian predators that require frequent consumption of vertebrate prey tend to be less abundant in desert environments; however, such environments often support numerous large‐bodied carnivorous reptiles. Diet is a fundamental component of an animal's ecology, and we explore the diets of three coexisting, sympatric Varanus species occurring in arid Australia: V. tristis, V. gouldii and V. panoptes. We hypothesized that the diet of varanids living in arid environments would primarily consist of relatively abundant invertebrate prey, and that vertebrate prey items would largely be limited to opportunistically consumed mammalian carrion and small reptilian species. All three Varanus species had high dietary overlap and broad, generalist diets. Invertebrate prey, particularly Orthoptera, were key to the diets of all three species. Vertebrate prey was infrequently consumed by all three Varanus species; however, when consumed, tended to comprise small reptilian species and mammalian carrion. Unlike large mammalian predators, varanids can survive on invertebrate prey and infrequent feeds and can aestivate when conditions become unfavourable, contributing to their success in arid environments. [ABSTRACT FROM AUTHOR]

Bites from helodermatid lizards can cause pain, paresthesia, paralysis, and tachycardia, as well as other symptoms consistent with neurotoxicity. Furthermore, in vitro studies have shown that Heloderma horridum venom inhibits ion flux and blocks the electrical stimulation of skeletal muscles. Helodermatids have long been considered the only venomous lizards, but a large body of robust evidence has demonstrated venom to be a basal trait of Anguimorpha. This clade includes varanid lizards, whose bites have been reported to cause anticoagulation, pain, and occasionally paralysis and tachycardia. Despite the evolutionary novelty of these lizard venoms, their neuromuscular targets have yet to be identified, even for the iconic helodermatid lizards. Therefore, to fill this knowledge gap, the venoms of three Heloderma species (H. exasperatum, H. horridum and H. suspectum) and two Varanus species (V. salvadorii and V. varius) were investigated using Gallus gallus chick biventer cervicis nerve–muscle preparations and biolayer interferometry assays for binding to mammalian ion channels. Incubation with Heloderma venoms caused the reduction in nerve-mediated muscle twitches post initial response of avian skeletal muscle tissue preparation assays suggesting voltage-gated sodium (NaV) channel binding. Congruent with the flaccid paralysis inducing blockage of electrical stimulation in the skeletal muscle preparations, the biolayer interferometry tests with Heloderma suspectum venom revealed binding to the S3–S4 loop within voltage-sensing domain IV of the skeletal muscle channel subtype, NaV1.4. Consistent with tachycardia reported in clinical cases, the venom also bound to voltage-sensing domain IV of the cardiac smooth muscle calcium channel, CaV1.2. While Varanus varius venom did not have discernable effects in the avian tissue preparation assay at the concentration tested, in the biointerferometry assay both V. varius and V. salvadorii bound to voltage-sensing domain IV of both NaV1.4 and CaV1.2, similar to H. suspectum venom. The ability of varanid venoms to bind to mammalian ion channels but not to the avian tissue preparation suggests prey-selective actions, as did the differential potency within the Heloderma venoms for avian versus mammalian pathophysiological targets. This study thus presents the detailed characterization of Heloderma venom ion channel neurotoxicity and offers the first evidence of varanid lizard venom neurotoxicity. In addition, the data not only provide information useful to understanding the clinical effects produced by envenomations, but also reveal their utility as physiological probes, and underscore the potential utility of neglected venomous lineages in the drug design and development pipeline.

The Southern Caucasus, with its special geographic position and complex topography, is a well-known biodiversity hotspot. However, the formation of this hotspot remains largely unstudied. To reveal this, a thorough study of the fossil record of the region is necessary. In the present paper, we describe for the first time fossil monitor lizards (Varanus sp.) from two late Miocene localities from the Southern Caucasus (Jradzor, Armenia and Tetri Udabno, Georgia). We suggest that both fossils belong to a small-sized monitor lizard, comparable to the present-day species found in Iran and the Middle East (e.g., Iraq, Saudi Arabian)—the most western part of the extant monitor lizards’ Eurasian distribution range. Our finds show that the genus had a broad distribution in the Eastern Paratethyan region during the late Miocene. In addition, we provide the probable temperature ranges for fossil localities.

The Southern Caucasus, with its special geographic position and complex topography, is a well-known biodiversity hotspot. However, the formation of this hotspot remains largely unstudied. To reveal this, a thorough study of the fossil record of the region is necessary. In the present paper, we describe for the first time fossil monitor lizards (Varanus sp.) from two late Miocene localities from the Southern Caucasus (Jradzor, Armenia and Tetri Udabno, Georgia). We suggest that both fossils belong to a smallsized monitor lizard, comparable to the present-day species found in Iran and the Middle East (e.g., Iraq, Saudi Arabian)-the most western part of the extant monitor lizards' Eurasian distribution range. Our finds show that the genus had a broad distribution in the Eastern Paratethyan region during the late Miocene. In addition, we provide the probable temperature ranges for fossil localities. [ABSTRACT FROM AUTHOR]

Several Late Pleistocene and Holocene South-East Asian subfossil deposits are known to contain important osteological assemblages of Monitor lizards (Varanus sp.) possibly accumulated by past human populations. Indeed, thanks to their large sizes, Monitor lizards are supposed to have been an important source of meat intake for past hunter-gatherer groups. However, the taphonomic and zooarchaeological study of their bones currently suffers from strong limitations related to the lack of appropriate comparative frameworks concerning their osteology and osteometry. These limitations preclude having a good understanding of the biological characteristics of subfossil individuals but also of their accumulation process in the sites and their possible exploitation by past humans. In the present study, we try to solve these issues by producing size and weight estimation equations using bone measurements that are applicable to subfossil Southeast Asian Varanus. These equations are then applied to the study of an archaeological assemblage of Varanus from a Late Pleistocene Thai deposit, the Doi Pha Kan rock shelter. The obtained data help to demonstrate that these lizards were accumulated by Hoabinhian hunter-gatherers, and allow for the description of the hunting strategies of these human groups. We also demonstrate the interest to develop new methodological tools concerning taxa of tropical areas that present a rich biodiversity but remain understudied in zooarchaeology. [ABSTRACT FROM AUTHOR]

Nonconsumptive effects can strongly influence apex predator ecological function. These effects arise because prey often induce costly phenotypic responses to mitigate predation risk. Yet because predator–prey interactions are complex, prey defenses may vary considerably. We investigated if the Komodo dragon (Varanus komodoensis), a reptile apex predator, induced multiscale antipredator responses in key prey, the Rusa deer (Cervus timorensis) and the wild pig (Sus scrofa). To this end, we examin [ABSTRACT FROM AUTHOR]

Monitor lizards (genus Varanus) inhabited Europe at least from the early Miocene to the Pleistocene. Their fossil record is limited to about 40 localities that have provided mostly isolated vertebrae. Due to the poor diagnostic value of these fossils, it was recently claimed that all the European species described prior to the 21st century are not taxonomically valid and a new species, Varanus amnhophilis, was erected on the basis of fragmentary material including cranial elements, from the late Miocene of Samos (Greece). We re-examined the type material of Varanus marathonensis Weithofer, 1888, based on material from the late Miocene of Pikermi (Greece), and concluded that it is a valid, diagnosable species. Previously unpublished Iberian material from the Aragonian (middle Miocene) of Abocador de Can Mata (Vallès-Penedès Basin, Barcelona) and the Vallesian (late Miocene) of Batallones (Madrid Basin) is clearly referable to the same species on a morphological basis, further enabling to provide an emended diagnosis for this species. Varanus amnhophilis appears to be a junior subjective synonym of V. marathonensis. On the basis of the most complete fossil Varanus skeleton ever described, it has been possible to further resolve the internal phylogeny of this genus by cladistically analyzing 80 taxa coded for 495 morphological and 5729 molecular characters. Varanus marathonensis was a large-sized species distributed at relatively low latitudes in both southwestern and southeastern Europe from at least MN7+8 to MN12. Our cladistic analysis nests V. marathonensis into an eastern clade of Varanus instead of the African clade comprising Varanus griseus, to which it had been related in the past. At least two different Varanus lineages were present in Europe during the Neogene, represented by Varanus mokrensis (early Miocene) and V. marathonensis (middle to late Miocene), respectively. [ABSTRACT FROM AUTHOR]

The structures and functions of the vertebrate lung and trunk are linked through the act of ventilation, but the connections between these structures and functions are poorly understood. We used X-ray reconstruction of moving morphology (XROMM) to measure rib kinematics during lung ventilation in three savannah monitor lizards (Varanus exanthematicus). All of the dorsal ribs, including the floating ribs, contributed to ventilation; the magnitude and kinematic pattern showed no detectable cranial-to-caudal gradient. The true ribs acted as two rigid bodies connected by flexible cartilage, with the vertebral rib and ventromedial shaft of each sternal rib remaining rigid and the cartilage between them forming a flexible intracostal joint. Rib rotations can be decomposed into bucket handle rotation around a dorsoventral axis, pump handle rotation around a mediolateral axis and caliper motion around a craniocaudal axis. Dorsal rib motion was dominated by roughly equal contributions of bucket and pump rotation in two individuals and by bucket rotation in the third individual. The recruitment of floating ribs during ventilation in monitor lizards is strikingly different from the situation in iguanas, where only the first few true ribs contribute to breathing. This difference may be related to the design of the pulmonary system and life history traits in these two species. Motion of the floating ribs may maximize ventilation of the caudally and ventrolaterally positioned compliant saccular chambers in the lungs of varanids, while restriction of ventilation to a few true ribs may maximize crypsis in iguanas. [ABSTRACT FROM AUTHOR]

Skeletal remains of a new early Miocene (Ottnangian, MN 4 mammal zone) monitor lizard, Varanus mokrensis sp. nov., are described from two karst fissures in the Mokrá-Western Quarry (1/2001 Turtle Joint; 2/2003 Reptile Joint), Czech Republic, providing the first documented example of a European varanid for which osteological data permit a well-supported assignment to the genus Varanus. The new species is morphologically similar to the Recent Indo-Asiatic varanids of the Varanus bengalensis group. It differs from all other Varanus species on the basis of a single autapomorphy and a combination of 11 characters. As a distinguishing feature of V. mokrensis, the parietal and squamosal processes of the postorbitofrontal form a narrowly acute angle. The teeth show distinct, smooth cutting edges along the mesial and distal margins of the apical portion of their crowns. This feature is not observed in most extant Asiatic Varanus species and may represent a plesiomorphic condition. The results of parsimony phylogenetic analyses, with and without character reweighting, reveal poor resolution within Varanus. A Bayesian analysis shows V. mokrensis to be closely related to extant representatives of the Indo-Asiatic Varanus clade, with close affinities to the V. bengalensis species group. The topology of the Bayesian tree supports the hypothesis that Miocene monitors from Mokrá are representatives of a lineage that is ancestral to the well-defined clade of extant African varanids, including the early Miocene V. rusingensis. In addition, our results support a Eurasian origin for the varanid clade. The extant African Varanus species probably originated in the late Oligocene. The radiation of African varanids probably occurred during the late Oligocene to early Miocene time interval. The occurrence of Varanus in the early Miocene of Mokrá-Western Quarry corresponds to the warm phase of the Miocene Climatic Optimum. Remains of a diverse aquatic and heliophobe amphibian fauna at the 2/2003 Reptile Joint site indicate more humid conditions than those at the 1/2001 Turtle Joint site. [ABSTRACT FROM AUTHOR]

The functional activities of Anguimorpha lizard venoms have received less attention compared to serpent lineages. Bite victims of varanid lizards often report persistent bleeding exceeding that expected for the mechanical damage of the bite. Research to date has identified the blockage of platelet aggregation as one bleeding-inducing activity, and destructive cleavage of fibrinogen as another. However, the ability of the venoms to prevent clot formation has not been directly investigated. Using a thromboelastograph (TEG5000), clot strength was measured after incubating human fibrinogen with Heloderma and Varanus lizard venoms. Clot strengths were found to be highly variable, with the most potent effects produced by incubation with Varanus venoms from the Odatria and Euprepriosaurus clades. The most fibrinogenolytically active venoms belonged to arboreal species and therefore prey escape potential is likely a strong evolutionary selection pressure. The results are also consistent with reports of profusive bleeding from bites from other notably fibrinogenolytic species, such as V. giganteus. Our results provide evidence in favour of the predatory role of venom in varanid lizards, thus shedding light on the evolution of venom in reptiles and revealing potential new sources of bioactive molecules useful as lead compounds in drug design and development.

After a control program for feral foxes was instigated, the monitor lizard Varanus panoptes has become the most common predator of loggerhead turtle nests at the Wreck Rock beach nesting aggregation adjacent to Deepwater National Park in southeastern Queensland. We empirically tested the efficacy of aluminum mesh cages, plastic mesh sheets, red flags, and hot chili powder in protecting loggerhead turtle nests from monitor lizard prédation across 2 nesting seasons (2014-2015 and 2015-2016). Our study indicated that plastic mesh, when applied correctly, is a relatively inexpensive and effective way to prevent monitor lizard nest prédation at sea turtle nestingbeaches. [ABSTRACT FROM AUTHOR]

Monitor lizards are Varanus species widely distributed, endangered reptile in the IUCN red data list. In India, based on the morphological and ecological characteristic, it is divided into four speciesviz.Bengal monitor lizard, Yellow monitor lizard, Desert monitor lizard and Water monitor lizard. These four species listed as Schedule I species in Indian Wildlife (Protection) Act 1972. This paper first attempt to present Forensically Informative Nucleotide Sequencing (FINS) for the Indian Varanus based on three mitochondrial genes. The molecular framework will be useful for the identification of Indian Varanus species and trade products derived from monitors and as such, have important applications for wildlife management and conservation. Here, we used known 14 individual skin pieces of four species of monitor lizards; the partial fragment of three mitochondrial genes (Cyt b, 12S rRNA, and 16S rRNA) were amplified for genetic study. In Cyt b, 12S rRNA and 16s rRNA, we observed, 5, 5 and 4 Haplotypes; 71, 69, and 43 Variables sites; 90, 89, and 50 Parsimony Informative sites within four species of Indian monitor lizards, respectively. Despite it, the nucleotide composition was T 26.4, C 32.8, A 29.2 and G11.6; T 18.8, C 29.7, A 34.0 and G 17.5; T 21.7, C 27.3, A 32.5 and G 18.5 in Cyt b, 12S rRNA and 16S rRNA, respectively. The neighbor joining phylogenetic tree and maximum parsimony tree of three mitochondrial genes, showed similar results and reveal that, there are two major clades are present in Indian monitor lizards. [ABSTRACT FROM PUBLISHER]

Invasive species can trigger trophic cascades in animal communities, but published cases involving their removal of top predators are extremely rare. An exception is the invasive cane toad ( Rhinella marina) in Australia, which has caused severe population declines in monitor lizards, triggering trophic cascades that facilitated dramatic and sometimes unexpected increases in several prey of the predators, including smaller lizards, snakes, turtles, crocodiles, and birds. Persistence of isolated populations of these predators with a decades-long sympatry with toads suggests the possibility of recovery, but alternative explanations are possible. Confirming predator recovery requires longer-term study of populations with both baseline and immediate post-invasion densities. Previously, we quantified short-term impacts of invasive cane toads on animal communities over seven years at two sites in tropical Australia. Herein, we test the hypothesis that predators have begun to recover by repeating the study 12 yr after the initial toad invasion. The three predatory lizards that experienced 71-97% declines in the short-term study showed no sign of recovery, and indeed a worse fate: two of the three species were no longer detectable in 630 km of river surveys, suggesting local extirpation. Two mesopredators that had increased markedly in the short term due to these predator losses showed diverse responses in the medium term; a small lizard species increased by ~500%, while populations of a snake species showed little change. Our results indicate a system still in ecological turmoil, having not yet reached a 'new equilibrium' more than a decade after the initial invasion; predator losses due to this toxic invasive species, and thus downstream effects, were not transient. Given that cane toads have proven too prolific to eradicate or control, we suggest that recovery of impacted predators must occur unassisted by evolutionary means: dispersal into extinction sites from surviving populations with alleles for toxin resistance or toad avoidance. Evolution and subsequent dispersal may be the only solution for a number of species or communities affected by invasive species for which control is either prohibitively expensive, or not possible. [ABSTRACT FROM AUTHOR]

While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated toxins, and related these results to dentition and predatory ecology. Venom composition was shown to be highly variable across the 20 species of Heloderma, Lanthanotus, and Varanus included in our study. While kallikrein enzymes were ubiquitous, they were also a particularly multifunctional toxin type, with differential activities on enzyme substrates and also ability to degrade alpha or beta chains of fibrinogen that reflects structural variability. Examination of other toxin types also revealed similar variability in their presence and activity levels. The high level of venom chemistry variation in varanid lizards compared to that of helodermatid lizards suggests that venom may be subject to different selection pressures in these two families. These results not only contribute to our understanding of venom evolution but also reveal anguimorph lizard venoms to be rich sources of novel bioactive molecules with potential as drug design and development lead compounds. [ABSTRACT FROM AUTHOR]

The new locality of Çeştepe in the Kazan Basin, 45 km NNW of Ankara, yielded the remains of three species of reptiles (cf. Lacerta sp., Anguinae indet. and Varanus sp.) and an ochotonid lagomorph, Ochotona mediterranensis Suata Alpaslan, 2009. The latter species suggests an early Pliocene age (MN14). The fossil layer is included in the Sinap Formation that delivered abundant remains of Mio-Pliocene mammals in the southern part of the basin, but in the northern part of the basin Çeştepe is currently the unique fossil site. The age assigned by the fauna led to revise the stratigraphy of sedimentary formations in the Çeştepe area, previously confusing because of the various lithostratigraphic unit names and ages given in previous work. The taxa described in this note are still poorly known in Turkey. Varanus has been previously reported from Çalta, a locality 16.3 km SW to Çeştepe in the same basin, and O. mediterranensis from Iğdeli in the Sivas Basin. Although represented by a few taxa, the Çeştepe faunule shows Eurasian affinities. [ABSTRACT FROM AUTHOR]

Conditioned taste aversion (CTA) is an adaptive learning mechanism whereby a consumer associates the taste of a certain food with symptoms caused by a toxic substance, and thereafter avoids eating that type of food. Recently, wildlife researchers have employed CTA to discourage native fauna from ingesting toxic cane toads ( Rhinella marina), a species that is invading tropical Australia. In this paper, we compare the results of 2 sets of CTA trials on large varanid lizards ('goannas,' Varanus panoptes). One set of trials (described in this paper) exposed recently-captured lizards to sausages made from cane toad flesh, laced with a nausea-inducing chemical (lithium chloride) to reinforce the aversion response. The other trials (in a recently-published paper, reviewed herein) exposed free-ranging lizards to live juvenile cane toads. The effectiveness of the training was judged by how long a lizard survived in the wild before it was killed (fatally poisoned) by a cane toad. Both stimuli elicited rapid aversion to live toads, but the CTA response did not enhance survival rates of the sausage-trained goannas after they were released into the wild. In contrast, the goannas exposed to live juvenile toads exhibited higher long-term survival rates than did untrained conspecifics. Our results suggest that although it is relatively easy to elicit short-term aversion to toad cues in goannas, a biologically realistic stimulus (live toads, encountered by free-ranging predators) is most effective at buffering these reptiles from the impact of invasive toxic prey. [ABSTRACT FROM AUTHOR]

Geometric morphometrics is a powerful tool for the quantification, visualization and analysis of morphological variation and change. This approach is being applied more frequently in a phylogenetic comparative context to assess the relative influence of size, ecology, function, and developmental constraints on morphological evolution. Geometric morphometric methods rely on homologous landmarks as the source of shape data, and the level of detail and accuracy increases with the amount of information contained in a landmark configuration. It may be possible, however, to capture particular elements of shape variation by concentrating on different observation angles of a complex structure like the vertebrate cranium. Our study examines how observation view (dorsal, ventral and lateral) influences 2D geometric morphometric analysis of interspecific cranial shape variation in monitor lizards. We recover a strong phylogenetic signal in all three views and general concordance in patterns of size-corrected shape diversification within the genus. We also find subtle, but important differences, however, among views in analyses of evolutionary allometry and shape variation, which may reflect both landmark configuration design and adaptive functional trends of the study system. Our study shows that studies restricted to a 2D geometric morphometric analysis of a complex 3D biological structure can combine carefully designed 2D landmark configurations describing alternative planes to maximize shape coverage. [ABSTRACT FROM AUTHOR]

The application of cytochrome oxidase subunit I for genetic divergence and phylogenetic analyses in monitor lizards seems to be limited, despite the practicality and relevance to use the short sequence of this region known as the DNA barcode. Some Indonesian species of monitor lizards are morphologically similar, some of which are legally exported as pet animal commodities and some others being protected by Indonesian national law. Thus, a practical molecular tool that can be useful to help clarify their species identity is essential, especially for closely related species. This study used the DNA barcode to test the application of this mitochondrial DNA region as a molecular tool to identify some species of Indonesian monitor lizards for the first time. Results showed that the Barcodes can facilitate molecular species identification based on their relative amount of genetic divergence and phylogenetic relationships. Closely related species can be distinguished based on the short sequences, as well as a likelihood of species misidentification among samples in this study. Further study should be performed in the future using more species, especially those belong to groups of species complex from the eastern Indonesia and species protected by the Indonesian national law. [ABSTRACT FROM AUTHOR]

Savannah monitor lizards (Varanus exanthematicus) are unusual among ectothermic vertebrates in maintaining arterial pH nearly constant during changes in body temperature in contrast to the typical α-stat regulating strategy of most other ectotherms. Given the importance of pH in the control of ventilation, we examined the CO2/H+ sensitivity of neurons from the locus coeruleus (LC) region of monitor lizard brainstems. Whole-cell patch-clamp electrophysiology was used to recordmembrane voltage in LCneurons in brainstemslices. Artificial cerebral spinal fluid equilibrated with80%O2, 0.0-10.0%CO2, balance N2, was superfused across brainstem slices. Changes in firing rate of LCneuronswere calculated fromaction potential recordings to quantify the chemosensitive response to hypercapnic acidosis. Our results demonstrate that the LC brainstem region contains neurons that can be excited or inhibited by, and/or are not sensitive to CO2 in V. exanthematicus. While few LC neurons were activated by hypercapnic acidosis (15%), a higher proportion of the LC neurons responded by decreasing their firing rate during exposure to high CO2 at 20°C (37%); this chemosensitive response was no longer exhibited when the temperaturewas increased to 30°C. Further, the proportion of chemosensitive LC neurons changed at 35°C with a reduction in CO2-inhibited (11%) neurons and an increase in CO2-activated (35%) neurons. Expressing a high proportion of inhibited neurons at low temperature may provide insights into mechanisms underlying the temperature-dependent pH-stat regulatory strategy of savannah monitor lizards. [ABSTRACT FROM AUTHOR]

The proteocephalidean cestode Kapsulotaenia chisholmae n. sp. (Proteocephalidae: Acanthotaeniinae) is described from the intestine of the monitor lizard Varanus spenceri Lucas & Frost, 1903 (Reptilia: Varanidae) in Australia. Kapsulotaenia chisholmae n. sp. is compared with its five recognized congeners. The new species differs from K. sandgroundi (Carter, 1943), K. varia (Beddard, 1913) and K. tidswelli (Johnston, 1909) by the anterior position of the vagina to the cirrus-sac. It also differs from K. varia, K.frezei Schmidt & Kuntz, 1974 and K. saccifera (Ratz, 1900) by a different egg number in each clusters (8-13 in K. chisholmae versus 12-20, 90-100 and more than 100, respectively), from K. frezei and K. saccifera by a different cluster shape (spherical to oval versus banana-shaped in the latter two species), from K. sandgroundi and K. tidswelli by a greater diameter of the embryophore (37-45 pm versus 25-30 pm and 19-32 pm, respectively); from K. sandgroundi and K. varia (sensu Nybelin, 1917), by the absence of a vaginal sphincter. Finally, K. chisholmae differs from K. varia, K. tidswelli, K.frezei and K. saccifera by a larger size (length of the strobila up to 315 mm versus 30 mm, 27-30 mm, 40 mm, and 10-40 mm, respectively). We consider K. saccifera to be a species inquirenda due to its very poor description (no illustration, nor description of the scolex, number of testes, cirrus-sac ratio, testis field, uterine branches number, etc.). Specimens redescribed by Nybelin (1917) as K. varia (Beddard, 1913) are considered to be another, yet unnamed species of Kapsulotaenia. [ABSTRACT FROM AUTHOR]

We describe a new species of Varanus from Mussau Island, north-east of New Guinea. The new species is a member of the Varanus indicus species group and is distinguished from all other members by both morphological and molecular genetic characters. It is the third species of Varanus reported from the Bismarck Archipelago and the first record of a yellow tongued member of the Varanus indicus species group from a remote oceanic island. The herpetofauna of Mussau Island has not been well studied but the discovery of this new species is in accordance with recent findings indicating that the island may harbor several unknown endemic vertebrates. The distribution of the closely related Varanus finschi is also discussed in the light of recent fieldwork and a review of old records. [ABSTRACT FROM AUTHOR]

Background: The functional design of skeletal muscles is shaped by conflicting selective pressures between support and propulsion, which becomes even more important as animals get larger. If larger animals were geometrically scaled up versions of smaller animals, increases in body size would cause an increase in musculoskeletal stress, a result of the greater scaling of mass in comparison to area. In large animals these stresses would come dangerously close to points of failure. By examining the architecture of 22 hindlimb muscles in 27 individuals from 9 species of varanid lizards ranging from the tiny 7.6 g Varanus brevicauda to the giant 40 kg Varanus komodoensis, we present a comprehensive dataset on the scaling of musculoskeletal architecture in monitor lizards (varanids), providing information about the phylogenetic constraints and adaptations of locomotor muscles in sprawling tetrapods. Results: Scaling results for muscle mass, pennation and physiological cross-sectional area (PCSA), all suggest that larger varanids increase the relative force-generating capacity of femur adductors, knee flexors and ankle plantarflexors, with scaling exponents greater than geometric similarity predicts. Thus varanids mitigate the size-related increases in stress by increasing muscle mass and PCSA rather than adopting a more upright posture with size as is shown in other animals. As well as the scaling effects of muscle properties with body mass, the variation in muscle architecture with changes in hindlimb posture were also prominent. Within varanids, posture varies with habitat preference. Climbing lizards display a sprawling posture while terrestrial lizards display a more upright posture. Sprawling species required larger PCSAs and muscle masses in femur retractors, knee flexors, and ankle plantarflexors in order to support the body. Conclusions: Both size and posture-related muscle changes all suggest an increased role in support over propulsion, leading to a decrease in locomotor performance which has previously been shown with increases in size. These estimates suggest the giant Pleistocene varanid lizard (Varanus megalania priscus) would likely not have been able to outrun early humans with which it co-habitated the Australian landmass with. [ABSTRACT FROM AUTHOR]