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Here be a dragon: exceptional size in a saltwater crocodile (Crocodylus porosus) from the Philippines
... Plants have been promoted as indoor air purifiers for decades, but reports of their effectiveness differ [24]. Some of the top air purifying plants of NAASA and other studies [24,25] has been listed in table 3. Laboratory studies showed that certain plants have the ability to remove specific toxic substances that can be used as best indoor purifier [25,26,27], in houses, hospitals, shops, saloons, buildings and offices etc. Studies indicate that plant induced removal of VOCs is a combination mechanism of direct (e.g. ...
... Plants have been promoted as indoor air purifiers for decades, but reports of their effectiveness differ [24]. Some of the top air purifying plants of NAASA and other studies [24,25] has been listed in table 3. Laboratory studies showed that certain plants have the ability to remove specific toxic substances that can be used as best indoor purifier [25,26,27], in houses, hospitals, shops, saloons, buildings and offices etc. Studies indicate that plant induced removal of VOCs is a combination mechanism of direct (e.g. ...
... absorption) and indirect (e.g. biotransformation by microorganisms) and make interior breathing spaces healthier [27].Certain microorganisms found in the growing media of indoor plants are also involved in the removal of VOCs as illustrated by the fact that when the plant(s) are removed from the media, the VOC concentration continues to decrease [28,24,29] While most leafy plants are practised as indoor air purifier, some of the plants that scientists have found most useful in removing VOCs include Japanese royal ferns, spider plants, Boston ferns, purple waffle plants, English ivy, areca palms, golden pothos, aloe vera, snake plants and peace lilies [25,30,31]. Most of the plants are good purifier of formaldehyde among them the ferns Osmunda japonica, had the highest formaldehyde-removal efficiency [32,30,] . ...
This study is an attempt to investigate the diversity of edible Termitomyses species from Kottayam district. Termitomyses are Termitophilic fungi; monophyletic group of gilled mushrooms belonging to the genus Termitomyces. Termitomyces are cultivated through transport of spores by eusocial insects (termites) belonging to the subfamily Macrotermitinae (Isoptera) using plant material passing through their guts. An extensive exploration carried out during May 2012 to October 2015 at a different geographical location of Kottayam District, Kerala. Traditional knowledge of Termitomyces has been documented based on the experience of local population. Fruiting bodies were sampled and photographed at different stages of their development in the field and samples were examined for macro and microscopic characteristics. Termitomyses were identified based on keys and description of Pegler (1994). Five different species of Termitomyces namely T. microcarpus (large and small form) T. clypatus, T. globulus, T. eurhizus, and T. heimii were identified. The ecological significance of Termites and Termitomyces in Kottayam district of Kerala and its role as a food for local communities have been discussed. Though termitomycetes are largely uncultivable, strategies were recommended for conservation of their habitat and sustainable harvesting of this human nutritional source as an alternative to plant and animal derived food.
... Here we examine a 42-year dataset of attacks by C. porosus, the largest (Britton et al. 2012), most aggressive (Brien et al. 2013) extant crocodilian species in northern Australia where one of the largest C. porosus populations in the world exists (Webb et al. 2010). We hypothesize that the outcome of an attack is affected by certain factors associated with a crocodile, victim, and environment, and identify which of these factors most significantly affects the probability of a victim's survival. ...
... Although the weight of individual crocodiles involved in incidents is unknown, we estimated it from their length, using a length-weight equation. As a previous conversion equation ) erroneously overestimates the body mass of a crocodile, we derived a new equation by fitting an exponential function (Y = aXb where Y and X are the body mass and length of a crocodile, respectively) to morphological data of Saltwater crocodiles in different sizes reported in previous studies (Webb and Messel 1978;Britton et al. 2012). We estimated the weight of victims from their sex and age, using equations obtained by fitting a quadratic function (Y = aX2 + bX + c where Y and X are the body mass and height of a person, respectively) to the average height and weight of people in Australia (males and females, separately) at the age of 20-80 years (Australian Bureau of Statistics 2012). ...
... This stark contrast highlights the particular vulnerability of children to a crocodile attack. Nevertheless, it should be noted that the size of a crocodile has a much greater influence than that of a victim because crocodile body mass increases exponentially with size [eg a 617 cm Saltwater crocodile weighed 1075 kg, (Britton et al. 2012)]. ...
Morelet’s crocodile (Crocodylus moreletii) is distributed from Tamaulipas and the Gulf of Mexico to the northern part of Guatemala and Belize. This species is highly hunted for its skin and meat. In Guatemala, due to unregulated and excessive exploitation of local wild populations, C. moreletii is listed in Appendix I of CITES in order to promote its conservation and protect it from illegal international trade. The main objective of this study was to generate and update basic information on wild C. moreletii populations to inform their conservation, management and sustainable use at local, national and regional levels. To fulfill the main objective, the following specific objectives were established: 1. estimate the relative abundance and age structure of C. moreletii in the priority areas identified in the Morelet’s Crocodile Surveying Manual (Sánchez et al. 2011); 2. identify the direct threats to wild C. moreletii populations; and, 3. contribute to the implementation of the Manual Trinacional de Monitoreo del Cocodrilo de Pantano.
... Here we examine a 42-year dataset of attacks by C. porosus, the largest (Britton et al. 2012), most aggressive (Brien et al. 2013) extant crocodilian species in northern Australia where one of the largest C. porosus populations in the world exists (). We hypothesize that the outcome of an attack is affected by certain factors associated with a crocodile, victim, and environment, and identify which of these factors most significantly affects the probability of a victim's survival. ...
... Although the weight of individual crocodiles involved in incidents is unknown, we estimated it from their length, using a length-weight equation. As a previous conversion equation (Fukuda et al. 2007) erroneously overestimates the body mass of a crocodile, we derived a new equation by fitting an exponential function (Y = aXb where Y and X are the body mass and length of a crocodile, respectively) to morphological data of Saltwater crocodiles in different sizes reported in previous studies (Webb and Messel 1978; Britton et al. 2012). We estimated the weight of victims from their sex and age, using equations obtained by fitting a quadratic function (Y = aX2 + bX + c where Y and X are the body mass and height of a person, respectively) to the average height and weight of people in Australia (males and females, separately) at the age of ). ...
... This stark contrast highlights the particular vulnerability of children to a crocodile attack. Nevertheless, it should be noted that the size of a crocodile has a much greater influence than that of a victim because crocodile body mass increases exponentially with size [eg a 617 cm Saltwater crocodile weighed 1075 kg, (Britton et al. 2012)]. ...
... Here we examine a 42-year dataset of attacks by C. porosus, the largest (Britton et al. 2012), most aggressive (Brien et al. 2013) extant crocodilian species in northern Australia where one of the largest C. porosus populations in the world exists (). We hypothesize that the outcome of an attack is affected by certain factors associated with a crocodile, victim, and environment, and identify which of these factors most significantly affects the probability of a victim's survival. ...
... Although the weight of individual crocodiles involved in incidents is unknown, we estimated it from their length, using a length-weight equation. As a previous conversion equation (Fukuda et al. 2007) erroneously overestimates the body mass of a crocodile, we derived a new equation by fitting an exponential function (Y = aXb where Y and X are the body mass and length of a crocodile, respectively) to morphological data of Saltwater crocodiles in different sizes reported in previous studies (Webb and Messel 1978; Britton et al. 2012). We estimated the weight of victims from their sex and age, using equations obtained by fitting a quadratic function (Y = aX2 + bX + c where Y and X are the body mass and height of a person, respectively) to the average height and weight of people in Australia (males and females, separately) at the age of ). ...
... This stark contrast highlights the particular vulnerability of children to a crocodile attack. Nevertheless, it should be noted that the size of a crocodile has a much greater influence than that of a victim because crocodile body mass increases exponentially with size [eg a 617 cm Saltwater crocodile weighed 1075 kg, (Britton et al. 2012)]. ...
The Species Survival Commission (SSC) is one of six volunteer commissions of IUCN, a union of sovereign states, government agencies and non-government organizations. IUCN has three basic conservation objectives: to secure the conservation of nature, and especially of biological diversity, as an essential foundation for the future; to ensure that where the earth's natural resources are used this is done in a wise, equitable and sustainable way; and to guide the development of human communities towards ways of life that are both of good quality and in enduring harmony with other components of the biosphere. The SSC's mission is to conserve biological diversity by developing and executing programs to save, restore and wisely manage species and their habitats. A volunteer network comprised of nearly 7,000 scientists, field researchers, government officials and conservation leaders from 188 countries, the SSC membership is an unmatched source of information about biological diversity and its conservation. As such, SSC members provide technical and scientific counsel for conservation projects throughout the world and serve as resources to governments, international conventions and conservation organizations. IUCN/SSC also publishes an Action Plan series that assesses the conservation status of species and their habitats, and specifies conservation priorities. The series is one of the world's most authoritative sources of species conservation information available to nature resource managers, conservationists and government officials around the world.
... An adult typically weighs 6 to 7 kg with males growing to an average length of 1.4 meters and females usually not exceeding 1.2 meters [258]. The largest species of crocodylian in the world is the saltwater crocodile Crocodylus porosus (Crocodylidae) from the saltwater habitats and brackish wetlands throughout the tropical regions of Asia and the Pacific [259]. Females rarely surpass 3 meters, but males grow to a length of 4.6 to 5.2 meters and can weigh as much as 1,200 kilograms [259]. ...
... The largest species of crocodylian in the world is the saltwater crocodile Crocodylus porosus (Crocodylidae) from the saltwater habitats and brackish wetlands throughout the tropical regions of Asia and the Pacific [259]. Females rarely surpass 3 meters, but males grow to a length of 4.6 to 5.2 meters and can weigh as much as 1,200 kilograms [259]. ...
Introduction New drug discovery and development programs have historically relied on the identification of novel lead compounds from plant origin. This is understandable when considering that plants have been the main, if not the only sources of therapeutics for managing human diseases for millennia [1]. Only in 1806, a pharmacologically active ingredient (morphine) from a plant (the opium poppy Papaver somniferum (Papaveraceae)) was for the first time isolated from a plant [2]. Currently, morphine is used for, among others, the palliation of severe chronic pain in, for instance, terminal cancer patients [2], and serves as a precursor for a large number of opioid medications such as the antitussive codeine and the antidiarreal agent loperamide [2]. The identification of morphine from P. somniferum was soon followed by many others such as, among others, the central nervous system stimulant caffeine from the beans of the coffee plant Coffea arabica (Rubiaceae) in 1819 [3], the antimalarial quinine from the bark of the cinchona tree Cinchona officinalis (Rubiaceae) in 1820 [4], and the analgesic salicin from the bark of the white willow Salix alba (Salicaceae) in 1828 [5]. Since then, many more breakthrough drugs have been developed from plants, including the antineoplastic agents vincristine and paclitaxel from the periwinkle plant Catharanthus roseus (Apocynaceae) [6] and the Pacific yew Taxus brevifolia (Taxaceae) [7], respectively; the phytoestrogen diosgenin from yam species in the genus Dioscorea (Dioscoreaceae) that serves as precursor for, among others, oral contraceptives and cortisone [8]; and the oral antihyperglycemic biguanide metformin from the French lilac Galega officinalis (Fabaceae) [9]. Other important sources of novel drugs were microorganisms. The fungus Penicillium rubens (Trichocomaceae) and the actinomycete bacterial species Saccharopolyspora erythraea (Pseudonocardiaceae) gave the antibacterial agents penicillin [10] and erythromycin Abstract New drug discovery and development efforts have traditionally relied on ethnopharmacological information and have focused on plants with medicinal properties. In the search for structurally novel and mechanistically unique lead compounds, these progams are increasingly turning to the bioactive molecules provided by the animal biodiversity. This not only involves bioactive constituents from marine and terrestrial invertebrates such as insects and arthropods, but also those from amphibians and other 'higher' vertebrates such as reptiles. The venoms of lizards and snakes are complex mixtures of dozens of pharmacalogically active compounds. So far, these substances have brought us important drugs such as the angiotensin-converting enzyme inhibitors captopril and its derivates for treating hypertension and some types of congestive heart failure, and the glucagon-like peptide-1 receptor agonist exenatide for treating type 2 diabetes mellitus. These drugs have been developed from the venom of the Brazilian pit viper Bothrops jararaca (Viperidae) and that of the Gila monster Heloderma suspectum (Helodermatidae), respectively. Subsequently, dozens of potentially therapeutically applicable compounds from lizards' and snakes' venom have been identified, several of which are now under clinical evaluation. Additionally, components of the immune system from these animals, along with those from turtles and crocodilians, have been found to elicit encouraging activity against various diseases. Like the venoms of lizards and snakes, the immune system of the animals has been refined during millions of years of evolution in order to increase their evolutionary success. This paper addresses some of the bioactive compounds from reptiles, and elaborates on the therapeutic potential of some of them as anticoagulants and antiplatelet drugs, as well as wound healing-promoting, antileishmanial, antiviral, immunomodulating, antimicrobial, and anticancer compounds.
... For example, there is substantial overlap in ontogenetic and evolutionary bodysize trends. Living crocodylians are unique among extant tetrapods for undergoing several-thousand-fold increases in body size during ontogeny (Webb et al. 1983;Britton et al. 2012). A similar size increase is also seen spanning adults of the earliest fossil suchians, like the diminutive Gracilisuchus of the Early Triassic, to the gigantic salt water crocodile of today (C. ...
... A similar size increase is also seen spanning adults of the earliest fossil suchians, like the diminutive Gracilisuchus of the Early Triassic, to the gigantic salt water crocodile of today (C. porosus; Webb et al. 1983;Britton et al. 2012). This ontogenetic-evolutionary overlap extends to shifts in craniofacial robustness, reconstructions of the jaw-closing musculature, tooth form, and diet. ...
There have been a number of attempts to explain how crocodylian bite-force performance covaries with cranial
form and diet. However, the mechanics and morphologies of crocodylian jaws have thus far remained incongruent with data on their performance and evolution. For example, it is largely assumed that the functional anatomy and performance of adults tightly fits the adult niche. At odds with this precept are groups with resource-dependent growth, whose juvenile stages undergo shifts in mass, morphology, and resource usage to overcome strong selection related to issues of small body size, as compared to adults. Crocodylians are an example of such a group. As living suchians, they also have a long and fossil-rich evolutionary history, characterized by analogous increases in body size, diversifications in rostrodental form, and shifts in diet. Here we use biomechanical and evolutionary modeling techniques to study the development and evolution of the suchian feeding apparatus and to formally assess the impact of potential ontogenetic-evolutionary parallels on clade dynamics. We show that patterns of ontogenetic and evolutionary bite-force changes exhibit inverted patterns of heterochrony, indicating that early ontogenetic trends are established as macroevolutionary patterns within Neosuchia, prior to the origin of Eusuchia. Although selection can act on any life-history stage, our findings suggest that selection on neonates and juveniles, in particular, can contribute to functionally important morphologies that aid individual and clade success without being strongly tied to their adult niche.
... The specimen measured 80 cm from snout to pelvis, had a tail length of 122 cm (anterior tail length 62 cm; posterior tail length 60 cm), a dorsal cranial length of 35 cm, snout-eye length 27 cm, maximum cranial width 9 cm, maximum head width 16 cm, and cranial height 11.5 cm ( fig. 1; all measurements taken by the first author following Britton et al. (2012)). High quality photographs and tissues samples were taken. ...
Historical and recent arrivals of crocodilians to the Gulf of Guinean Oceanic Island of São Tomé have intrigued naturalists for several centuries. Here we present the revision of the historical records, and present data regarding the recent arrival of a single specimen in 2021. After being killed by the local authorities, the specimen was preserved and studied both through morphological and molecular methods. Our findings suggest that the specimen was a sub-adult Nile crocodile, Crocodylus niloticus Laurenti, 1768, which most likely drifted from the Congo or Ogooué river mouths in West Africa by the oceanic current acting on the Gulf of Guinea. The story of this individual highlights the dispersion paths that have contributed by the past biological colonization of São Tomé Island.
... Other Early Triassic marine reptiles were clearly smaller, at most 4 m (Scheyer et al. 2014(Scheyer et al. , 2019, as were the marine temnospondyl amphibians (1.5 m; Scheyer et al. 2014), bony fish (1.5 m; Scheyer et al. 2014) and hybodont sharks (1.5 m; Scheyer et al. 2014). For comparison with living aquatic tetrapods, the size estimate for IGPB R660 is similar to some body length measurements noted for very large individuals of modern saltwater crocodiles (Britton et al. 2012) and orcas (Ford 2017). Although the isolated centrum PMO 229.177 described in Engelschiøn et al. (2018) reaches less than 80% of the anteroposterior length of those of IGPB R660 (33 mm vs. 42 mm), it and the associated material described by Engelschiøn et al. (2018) suggest a certain abundance of large-bodied ichthyosaur individuals in the Early Triassic sea covering what now is Svalbard. ...
Ichthyosaurs were a highly successful group of marine reptiles in the Mesozoic. The ichthyosaur radiation is part of the recovery from the Permian-Triassic mass extinction. In the Early Triassic, this group underwent extensive global radiation, filling ecological niches for the first time that were later occupied by various other lineages of marine amniotes. However, the evolution of body size in ichthyosaurs is not fully understood, as most large-bodied taxa originate from the Middle Triassic and later, and are mostly known from only a few specimens. In this study, we describe three articulated posterior dorsal vertebrae (IGPB R660) of the ichthyosaur Cymbospondylus sp. from the latest Olenekian Keyserlingites subrobustus zone of the Vikinghøgda Formation of the Agardhdalen area, eastern Spitsbergen, Svalbard. We numerically estimated the total body length of IGPB R660 from dorsal vertebral centrum length using a comparative dataset of other species of the genus and two different allometric analyses. This approach yields total length estimates of 7.5 m and 9.5 m for the individual, respectively, the highest for any unambiguous Early Triassic ichthyosaur find. Earlier, higher estimates of 11 m were based on taxonomically and stratigraphically inconclusive material but do not appear unreasonable based on evidence provided in this paper. Our study underscores both the rapid ecosystem recovery after a major mass extinction and extremely rapid increases in body size in ichthyosaurs after their adaptation to a secondarily aquatic lifestyle.
... For many crocodylian species, the typical HL:TL allometric relationship is about at 1:7 ratio [48,67], but the exact ratio differs between crocodylian species [48]. Moreover, even within the same species, the allometric ratio can also vary with the size, particularly for very large animals [68][69][70][71]. For example, the ratio of very large C. porosus seems to be closer to 1:8 [49]. ...
Understanding the demographic structure is vital for wildlife research and conservation. For crocodylians, accurately estimating total length and demographic class usually necessitates close observation or capture, often of partially immersed individuals, leading to potential imprecision and risk. Drone technology offers a bias-free, safer alternative for classification. We evaluated the effectiveness of drone photos combined with head length allometric relationships to estimate total length, and propose a standardized method for drone-based crocodylian demographic classification. We evaluated error sources related to drone flight parameters using standardized targets. An allometric framework correlating head to total length for 17 crocodylian species was developed, incorporating confidence intervals to account for imprecision sources (e.g., allometric accuracy, head inclination, observer bias, terrain variability). This method was applied to wild crocodylians through
drone photography. Target measurements from drone imagery, across various resolutions and sizes, were consistent with their actual dimensions. Terrain effects were less impactful than Ground Sample Distance (GSD) errors from photogrammetric software. The allometric framework predicted lengths within ≃11–18% accuracy across species, with natural allometric variation among individuals
explaining much of this range. Compared to traditional methods that can be subjective and risky, our drone-based approach is objective, efficient, fast, cheap, non-invasive, and safe. Nonetheless, further refinements are needed to extend survey times and better include smaller size classes.
... The saltwater crocodile (Crocodylus porosus) is the largest extant species of crocodilian, with individuals capable of obtaining lengths exceeding 6 m and a mass of >1000 kg (Webb et al., 2010;Britton et al., 2012). This species has a broad geographic distribution, with a range extending from southern India to Sri Lanka, throughout southeast Asia, east through the Philippines, and south through Indonesia, Papua New Guinea, the Solomon Islands and the north of Australia (Webb et al., 2010). ...
Diseases affecting wild Australian saltwater crocodiles (Crocodylus porosus) are rarely reported due to the difficulty in capturing animals and obtaining samples. In this investigation, we identified two haemoparasites (Hepatozoon and a filarial nematode) in saltwater crocodiles in Darwin, Australia. Light microscopic examination identified Hepatozoon in 7/7 (100%) wild crocodiles and in 2/20 (10%) of captive ones. When genomic DNAs from these same samples were further investigated using polymerase chain reaction (PCR)-based sequencing, we detected Hepatozoon in all 27 blood samples. Using both microscopy and PCR-based sequencing, we detected a filarial worm (proposed to be Oswaldofilaria) in one of 20 captive crocodiles. The sequence data were compared with sequence data available in public databases, and phylogenetic analyses indicated that the operational taxonomic units of Hepatozoon and Oswaldofilaria discovered here in these crocodiles are likely new species. This study is the first to use molecular tools to explore haemoparasites in Australian saltwater crocodiles and highlights the importance of health investigations in poorly studied vertebrate hosts.
... We classified muggers using cm total length (TL) as juveniles (<100 cm TL) and subadults (<101 to 180> cm TL) or adults (>180 cm TL) based on published literature on growth and sizes of C. palustris (Whitaker and Whitaker, 1984;Mobaraki et al., 2013). We measured the total length dorsally from the snout to tail tip (Britton et al., 2012). We recorded the season in which the collision occurred and defined the seasons as winter (November-February), summer (March-June), and monsoon (July-October), wherein winter and summer months are dry seasons and monsoon months are the wet season. ...
... We classified muggers using cm total length (TL) as juveniles (<100 cm TL) and subadults (<101 to 180> cm TL) or adults (>180 cm TL) based on published literature on growth and sizes of C. palustris (Whitaker and Whitaker, 1984;Mobaraki et al., 2013). We measured the total length dorsally from the snout to tail tip (Britton et al., 2012). We recorded the season in which the collision occurred and defined the seasons as winter (November-February), summer (March-June), and monsoon (July-October), wherein winter and summer months are dry seasons and monsoon months are the wet season. ...
Railway lines, roadways, canals, and electricity cable networks pose serious problems to wildlife, fragmenting habitats worldwide. These infrastructures are well-recognized as linear intrusions. Today they represent a threat to wildlife, including to the mugger or marsh crocodile (Crocodylus palustris Lesson, 1831). The current study documents 15 crocodile-vehicle collisions (CVCs) recorded in 2 years (2021 and 2022); 11 were on roads, and 4 were on railway tracks. Sex was determined for eleven individuals (five males, six females) and four were of undeterminable sex due to crushing. A total of thirteen individuals were found dead at the various sites of collision, and two juvenile individuals were found injured and one of them was treated successfully and returned to the wild. The highest number of CVCs (nine) occurred in Central Gujarat, followed by three CVCs in Saurashtra, two in the Kutch region, and one in North Gujarat. Mitigation measures required for the collision situations in Gujarat are discussed. A literature survey showed that a total of 75 CVCs were recorded within the last 18 years due to the state's road (n= 51, 68%) and railway (n= 24, 32%) networks, with the highest number of CVCs (56) observed in Central Gujarat and the lowest numbers of CVCs noted in North Gujarat (2) and South Gujarat (no CVCs). There was a high number of subadult and juvenile mugger CVC victims. The CVC site location in the different regions of Gujarat state positively corresponds to crocodile populations. However, the mugger crocodile (C. palustris) is nationally protected under the Indian Wildlife Act as a Schedule I species, and the IUCN criteria is 'Vulnerable' and it is an Appendix 1 (CITES) species; therefore, conservation measures are required. CVC incidences were recorded widely in the entire species distribution range, from Iran, India, and Sri Lanka, and can be considered as an emerging threat to mugger crocodiles.
... In this study, we used acoustic telemetry to investigate the presence of alternative movement tactics in a population of male estuarine crocodiles (Crocodylus porosus). Estuarine crocodiles are sexually dimorphic (Webb and Messel 1978), with males growing up to ~ 40% larger than females (max size = ~ 6 m, Britton et al. 2012) and individuals continuing to grow throughout much of their adult lives (Baker et al. 2019). Competition among males for access to reproductive females is believed to be the driving force behind the evolution of this sexual dimorphism (Webb and Smith 1987). ...
In species where conflict is costly, individuals adopt alternative movement tactics to minimise the risk of competitive interactions. Dominant males often maintain defined territories, while less competitive males may be forced to adopt alternative tactics to maximise fitness and reduce conflict. However, the extent to which males switch tactics according to current social or physiological status is poorly understood. Using implanted acoustic tags and a fixed array of tracking receivers, we investigated how the behaviour of 78 male estuarine crocodiles (Crocodylus porosus) shifted over an 11-year period in relation to ontogeny, body condition, and the extent of physical injuries. We discovered that male crocodiles sorted into three common movement classes, with 51% of males maintaining the same movement class across consecutive years (max = 9 years). Males > 4 m in total length maintained confined territories both within and across years and had the greatest extent of injuries and the highest condition score, indicative of territory holders. In contrast, smaller males sorted into high movement roamer or low movement site-philopatric tactics, where the tactic an individual adopted was less stable between years and did not correlate with condition or external injuries. Our study reveals the socio-biological mechanisms by which estuarine crocodiles coexist within a restricted habitat.
Significance statement
Identifying individual-level differences in movement helps us predict which individuals are more likely to be involved in human-wildlife interactions. However, studying long-term shifts in movement is challenging, as large datasets of co-occurring individuals tracked in their natural environment over multiple years are required. We tracked a population of 78 male estuarine crocodiles (1030–4687 mm total length) in a shared environment over 11 years and assessed how eight movement traits were linked to body size and physical condition. At the population level, males sorted into different movement tactics according to ontogeny, with large territorial males having better body condition yet a greater incidence of injury. However, 49% of males showed variability across years, suggesting that tactics were conditional relative to environmental variability and a male’s own status. Our study provides insights into the mechanisms and costs of movement tactics in wild crocodile populations.
... Further, the studies on larger reptiles, the crocodiles, relied on data collected under captive (fully captive or partially restrained) conditions. Capturing and restraining a large reptilian species, for example, the crocodiles, may endanger the organism's life (Britton et al., 2012;Seymourl et al., 1987). Thus, there is a need to develop an automated biometric system for free-ranging populations of crocodilians. ...
... Further, the studies on larger reptiles, the crocodiles, relied on data collected under captive (fully captive or partially restrained) conditions. Capturing and restraining a large reptilian species, for example, the crocodiles, may endanger the organism's life (Britton et al., 2012;Seymourl et al., 1987). Thus, there is a need to develop an automated biometric system for free-ranging populations of crocodilians. ...
Individual identification contributes significantly towards investigating behavioral mechanisms of animals and understanding underlying ecological principles. Most studies employ invasive procedures for individually identifying organisms. In recent times, computer-vision techniques have served as an alternative to invasive methods. However, these studies primarily rely on user input data collected from captivity or from individuals under partially restrained conditions. Challenges in collecting data from free-ranging individuals are higher when compared to captive populations. However, the former is a far more important priority for real-world applications. In this paper, we used UAV to collect data from free-ranging mugger crocodiles, Crocodylus palustris. We applied convolutional neural networks (CNNs) to individually identify muggers based on their dorsal scute patterns. The CNN model was trained on a data set of 88,000 images focusing on the mugger's dorsal body. The data was collected from 143 individuals across 19 different locations along the western part of India. We trained two CNN models, one with an annotated bounding box approach, the YOLO-v5l, and another without annotations, the Inception-v3. We used two parameters, True Positive Rate (TPR) and True Negative Rate (TNR), to validate the efficiency of the trained models. Using YOLO-v5l, TPR (re-identification of trained muggers) and TNR (differentiating untrained muggers as ‘unknown’) values at the 0.84 threshold were 88.8% and 89.6%, respectively. The trained model showed 100% TNR for the non-mugger species, the Gharial, Gavialis gangeticus, and the Saltwater crocodile, Crocodylus porosus. The performance of the CNN model was reliable and accurate while using only 125 images per individual for training purposes. Inception-v3 underperformed for both the parameters, thus, showing that a bounding box approach (YOLO-v5l model) with background elimination is a promising method to individually identify free-ranging mugger crocodiles. Our manuscript demonstrates that UAV imagery appears to be a promising tool for non-invasive collection of data from free-ranging populations. It can be used to train open-source algorithms for individual identification. Further, the identification method is entirely based upon dorsal scute patterns, which can be applied to different crocodilian species, as well.
... Top-down and profile diagrams of entire crocodile (a) and head (b) illustrating measurements taken using Method A (A) and Method B (B). DCL = dorsal cranial length; SEL = snout-eye length; MHW = maximum head width; MCW = maximum cranial width; IOW = inter-orbital width; CH = cranial height; SPL = snoutpelvis length; TaL = tail length; TaL1 = anterior tail length; TaL2 = posterior tail length; SPL + TaL1 = snoutscute junction (SSJ); SPL + TaL1 + TaL2 = total length (TL)[49]. ...
This chapter is a part of the book “Recent advances in biometrics” introduces the importance of biometrics in the aquatic studies in brief view. Biometric measurements (Morphometric, meristics and description) are widely used in various fields’ “taxonomy, species identifications, monitoring of pollution, species abnormalities, comparison, environmental changes, growth variation, feeding behavior, ecological strategies, stock management, and water quality of aquaculture. These data were collected from several articles and books of aquatic animals and presented both applications and required considerations for biometric implementations. It is important also to detect sexual dimorphism, adaptations during evolutionary time and diminishing intraspecific competition by increasing niche portioning. The biometrics could be applied for various aquatic organisms as dolphins, sharks, rays, mollusca, crustaceans, protozoa, … etc. and for specific organs like teeth, otolith and appendages by different techniques and preservations. Scientists are still applying these measurements even with the presence of advanced techniques like PCR as they are low in cost, faster and more applicable. This chapter also presented some recent trends including animal’s biometric recognition systems, followed by challenges and considerations for the biometrics implementations. It is recommended to apply biometrics in wide range together with modern techniques considering the specificity of its quality and preservation status.
... C. porosus is the largest extant crocodilian species, with the largest individuals exceeding a total length of 6 m and weighing over 1,000 kg (Britton et al., 2012). The species is physiologically adapted to both the freshwater and saline environment (Grigg et al., 1980;Grigg, 1981;Taplin and Grigg, 1981) although they require freshwater for breeding (Webb et al., 1977(Webb et al., , 1983. ...
Climate change is predicted to have devastating impacts on apex predators such as eliminating their required habitats. Crocodilians are no exception as most species require freshwater for nesting, and such freshwater habitats are particularly vulnerable to saltwater inundation (SWI) caused by the sea level rise (SLR) from global warming. Here, we examined the impacts of climate change on saltwater crocodiles Crocodylus porosus in terms of the potential loss of nesting habitat in the Northern Territory, Australia; an area that contains the world’s most extensive nesting habitat for the species. Our spatial model, derived from 730 nest locations and selected environmental features, estimated a total of 32,306.91 km² of current suitable habitat across the study region. The most important variable was distance to perennial lakes (71.0% contribution, 87.5% permutation importance), which is negatively correlated with nesting habitat suitability. We found that projected changes in temperature and rainfall by 2100 could impact the area of suitable nesting habitat negatively or positively (0.33% decrease under low future emission climate scenario, and 32.30% increase under high emission scenario). Nevertheless, this can be canceled by the strong negative impact of SLR and concomitant SWI on nesting areas. A portion (16.40%) of the modeled suitable habitat for a subsection of our study area, the Kakadu Region, were already subject to > 0.25 m SWI in 2013. The suitable area for nesting in this region is predicted to be further reduced to 1775.70 km² with 1.1 m SLR predicted for 2100, representing 49.81% loss between 2013 and 2100. Although the estimates of habitat loss do not account for the potential creation of new habitat, nor for the uncertainty in the degree of future SLR, our results suggest that SLR driven by continuing global warming can be the major threat to mound-nest-building crocodilians including C. porosus, rather than direct impacts from changes in temperature and rainfall. The degree of impact on saltwater crocodiles will be determined by the interplay between the loss of nesting habitat, which would appear inevitable under current global warming, and the ability to expand into new areas created by the expansion of the tropics.
... Growth is described as indeterminate, continuing throughout life. The saltwater crocodile (Crocodylus porosus) is usually regarded as the largest, although C. niloticus, C. acutus and Gavialis gangeticus have reputedly reached lengths of 6 m. Britton et al. (2012) described two measured specimens of C. porosus with lengths of 6.17 m and 6.2 m, and there are unsubstantiated or anecdotal reports of larger specimens. However, these 'record lengths' are derived from large sample sizes, compared with the limited number of occurrences of crocodylian tracks and swim traces described herein from the Dunvegan Formation. ...
Delta-plain strata of the Cenomanian Dunvegan Formation, in north-east British Columbia, represent anastomosed rivers that were flanked by vegetated crevasse splays, wetlands and shallow lakes. These rocks preserve a rich record of ankylosaur and ornithopod walking and wading tracks, as well as crocodylian swim traces and tracks. Analysis of depositional, erosional, and trace-making events reveals alternating phases of flooding and emergence that controlled both animal activity (walking, wading, swimming) and mud substrate consistency (firm vs. soupy), and hence fidelity of track preservation. Some tracks resemble those produced by both ankylosaurs and crocodylians, and confident attribution is difficult. The absence of tail drag marks suggests an ankylosaur trackmaker, whereas prominent claw marks might favour a crocodylian origin. Unusually large crocodylian swim traces suggest animals about 9 m, and possibly up to 12 m in length. These large traces may represent a precursor to the giant crocodylian Deinosuchus. Ankylosaur tracks are well-preserved in lake and channel-margin deposits, whereas crocodylian traces are most commonly preserved in firm muddy lake sediments that had experienced previous subaerial exposure and dewatering. Close integration of trace fossils with sedimentary and stratigraphic features makes it possible to reveal a detailed chronology of biotic and sedimentary events on palaeo-surfaces.
... Extant crocodylians do not exhibit major changes in locomotion or head posture during ontogeny. However, they do change their body mass dramatically as they mature (Britton et al., 2012), which impacts ecology, as larger body size allows them to feed on larger prey and venture into new habitats. Hatchlings feed on small prey until their increased body size allows them to secure larger prey items (Gignac & Erickson, 2015). ...
Crocodylians today live in tropical to subtropical environments, occupying mostly shallow waters. Their body size changes drastically during ontogeny, as do their skull dimensions and bite forces, which are associated with changes in prey preferences. Endocranial neurosensory structures have also shown to change ontogenetically, but less is known about the vestibular system of the inner ear. Here we use 30 high-resolution computed tomography (CT) scans and three-dimensional geometric morphometrics to investigate the size and shape changes of crocodylian endosseous labyrinths throughout ontogeny, across four stages (hatchling, juvenile, subadult and adult). We find two major patterns of ontogenetic change. First, the labyrinth increases in size during ontogeny, with negative allometry in relation to skull size. Second, labyrinth shape changes significantly, with hatchlings having shorter semicircular canal radii, with thicker diameters and an overall dorsoventrally shorter labyrinth than those of more mature individuals. We argue that the modification of the labyrinth during crocodylian ontogeny is related to constraints imposed by skull growth, due to fundamental changes in the crocodylian braincase during ontogeny (e.g. verticalisation of the basicranium), rather than changes in locomotion, diet, or other biological functions or behaviours.
... However, exploration activities are still possible by exerting captivity and breeding for commercial purposes with very tight permits and supervision. As reptiles that grow to a maximum length of up to 6-7 m (Whitaker 2008, Webb, Manolis et al. 2010, Britton, Whitaker et al. 2012, these animals become one of the top predators in aquatic ecosystems that maintain ecosystem balance (Thorbjarnarson 2010) and able to change the structure and function of an ecosystem (Hines and Gessner 2012). However, the presence of saltwater crocodiles in the mangrove area of Surabaya has not been studied. ...
A single specimen of saltwater crocodile Crocodylus porosus Schneider, 1801 (1.50 cm in length) was captured and photographed by a local fisherman by gill net at fishpond around mangrove ecosystem of east coast Surabaya on December 2020. The location where the estuarine crocodile caught is an important wetland area in Surabaya with an excellent mangrove cover. Wonorejo mangrove location is about 10 km from the centre of Surabaya, the second-largest city in Indonesia. This finding is considered as a first reported of C. porosus in Surabaya, and at the same time is proof of the importance of the mangrove area on the east coast of Surabaya as a habitat for wildlife that must be conserved appropriately. Routine monitoring of mangrove areas, including their wildlife, is essential so that they are not displaced by the development of the city which changes the land function to become a residential area.
... m) are within the size range of extant Crocodylus. The largest confirmed recorded length for the genus is 6.1 m in C. porosus (Britton et al., 2012), and maximum lengths for C. palustris and C. siamensis are 4-5 m and 3.5 m, respectively (da Silva and Lenin, 2010; Platt et al., 2019). Conversely, estimated lengths of gavialines from Myanmar (7.46 m and 8.63 m) exceed the size limit of extant G. gangeticus (up to 6 m: Stevenson and Whitaker, 2010). ...
... Adult Crocodylia (various species) range from ~10 kg to ~1000 kg (Britton et al., 2012) in body mass. Although a 10 kg crocodile may seem on the larger side of what we can classify as a small animal, crocodiles are an ideal extant species to study the relationship between limb posture (i.e. ...
We developed a three‐dimensional, computational biomechanical model of a juvenile Nile crocodile (Crocodylus niloticus) pelvis and hindlimb, composed of 47 pelvic limb muscles, to investigate muscle function. We tested whether crocodiles, which are known to use a variety of limb postures during movement, use limb orientations (joint angles) that optimise the moment arms (leverages) or moment‐generating capacities of their muscles during different limb postures ranging from a high walk to a sprawling motion. We also describe the three‐dimensional (3D) kinematics of the crocodylian hindlimb during terrestrial locomotion across an instrumented walkway and a treadmill captured via X‐ray Reconstruction of Moving Morphology (biplanar fluoroscopy; ‘XROMM’). We reconstructed the 3D positions and orientations of each of the hindlimb bones and used dissection data for muscle lines of action to reconstruct a focal, subject‐specific 3D musculoskeletal model. Motion data for different styles of walking (a high, crouched, bended and two types of sprawling motion) were fed into the 3D model to identify whether any joints adopted near‐optimal poses for leverage across each of the behaviours. We found that (1) the hip adductors and knee extensors had their largest leverages during sprawling postures and (2) more erect postures typically involved greater peak moment arms about the hip (flexion‐extension), knee (flexion) and metatarsophalangeal (flexion) joints. The results did not fully support the hypothesis that optimal poses are present during different locomotory behaviours because the peak capacities were not always reached around mid‐stance phase. Furthermore, we obtained few clear trends for isometric moment‐generating capacities. Therefore, perhaps peak muscular leverage in Nile crocodiles is instead reached either in early/late stance or possibly during swing phase or other locomotory behaviours that were not studied here, such as non‐terrestrial movement. Alternatively, our findings could reflect a trade‐off between having to execute different postures, meaning that hindlimb muscle leverage is not optimised for any singular posture or behaviour. Our model, however, provides a comprehensive set of 3D estimates of muscle actions in extant crocodiles which can form a basis for investigating muscle function in extinct archosaurs.
... m) are within the size range of extant Crocodylus. The largest confirmed recorded length for the genus is 6.1 m in C. porosus (Britton et al., 2012), and maximum lengths for C. palustris and C. siamensis are 4-5 m and 3.5 m, respectively (da Silva and Lenin, 2010; Platt et al., 2019). Conversely, estimated lengths of gavialines from Myanmar (7.46 m and 8.63 m) exceed the size limit of extant G. gangeticus (up to 6 m: Stevenson and Whitaker, 2010). ...
Although Neogene crocodylians were well documented from Indo-Pakistan, few fossils were known from Southeast Asia, precluding the understanding of their evolutionary and biogeographic history. Here, we describe crocodylians from the Neogene Irrawaddy Formation of central Myanmar and evaluate their taxonomic status. Tebingan, SE of Magway (lower Upper Miocene) yields Gavialis and Crocodylus that differ from the previously known species of each genus, and the Gwebin area, SW of Bagan (Upper Pliocene) produces Crocodylus cf. palaeindicus. Taking into account the materials without provenance data, Neogene crocodylians from Myanmar include at least three gavialids and two Crocodylus that are characterized by different craniomandibular and postcranial features. The body length estimates for the gavialines from Tebingan and an unknown locality in central Myanmar are 7.5 m and 8.6 m, respectively, which exceed the maximum size limit of extant Gavialis gangeticus. Together with the previously reported large taxa, gavialids repeatedly evolved large body sizes in the Neogene of Asia. Gavialis from the Miocene of Myanmar is one of the oldest records of the genus, and its unraised orbital rim suggests that the “telescoped” eyes derived later during the genus evolution. Crocodylus cf. palaeindicus from the Pliocene of Myanmar indicates the species range was extended from western India to Myanmar during the Neogene. The absence of Crocodylus siamensis in the Neogene of India and central Myanmar implies the species originated east of central Myanmar.
... While crocodiles are on record from Tikopia (Burt andBurt 1932, Firth 1970), some 210 km to the east-southeast of the Santa Cruz Islands, they are seemingly absent from Rennell and Bellona, both between 185 km and 210 km west of San Cristobal (Van der Ploeg et al. 2019). North of the Equator, saltwater crocodiles are on record for the Philippines, in particular from Palawan (Ross 1982), north-eastern Luzon (Ross 1982, Tarun et al. 2004, and Mindanao (Britton et al. 2012), but their original distribution would have covered most of the river systems. On Palau, crocodiles have been reported from Babeldoab, Peleliu, Koror, and the Rock Islands (Messel and King 1991, Crombie and Pregill 1999, Brazaitis et al. 2009) as well as the southwest islands of Tobi (Shigetomo Motoda cited in Takashima 1955) and Merir (name for crocodile: rauraig, Eilers 1935). ...
Saltwater crocodiles (Crocodylus porosus) are known to leave their home range and to visit and eventually colonize offshore islands. Being good swimmers, coupled with an ability to go for a prolonged period without food, allows saltwater crocodiles to cover long open water voyages of 2000 km and more. Drawing on modern observations, historic data, and oral traditions, this paper compiles and critically examines all available evidence for vagrant crocodiles in the Pacific Ocean area. The modes of dispersal, as well as potential dispersal success, are discussed.
... The saltwater crocodile (Crocodylus porosus) of South-east Asia and Oceania is considered the largest extant crocodilian species (Britton et al. 2012) and the most wide ranging (Buden and Haglelgam 2010;Grigg and Kirshner 2015). Favouring tidal habitat, where tides and currents greatly assist migration (Campbell et al. 2010), significant populations can also be found in non-tidal freshwater habitat and inland freshwater swamps (Grigg and Kirshner 2015). ...
Saltwater crocodiles (Crocodylus porosus) are extensively distributed throughout South-east Asia, including the Indonesian province of East Nusa Tenggara (ENT), and they account for hundreds of attacks on people annually. Recorded incidents not only tell us where crocodiles are found (useful when survey data are limited), but importantly can improve our understanding of causal factors to better address risk. We compiled public attack records for ENT on humans from 2009 to 2018 using an online database of incidents (CrocBITE), then worked closely with government representatives to visit human–crocodile conflict (HCC) hot spots, where some unreported attack records were collected, and local attitudes towards crocodiles could be assessed. Of the 100 attacks we compiled, 60% were fatal incidents. Most victims were male (84%) and most attacks (75%) occurred during fishing. West Timor had the highest proportion of attacks (70%). Cultural attitudes towards crocodiles were found to be generally positive throughout ENT, similar to neighbouring Timor-Leste, although recent media stories appear to have introduced some negative beliefs and fears. We recommend that resources and training are made available to improve local crocodile knowledge, including habitat surveys in proximity to conflict areas, plus community-based education where the risk of crocodile attack is high.
... In the current example, the dwarf caiman Paleosuchus and dwarf crocodile Osteolaemus both have four premaxillary teeth, as opposed to five in other taxa. The number of vertebrae with postatlantal hypapophyseal keels also seems to be, to some extent, connected to dwarfing, with the small-bodied Chinese alligator Alligator sinensis Fauvel, 1879 along with Paleosuchus and Osteolaemus both showing 12 as opposed to 11 such vertebrae, perhaps due to faster somitgenesis creating more, smaller vertebrae (Müller et al., 2010), although the exception is Crocodylus porosus that also has 12 keeled vertebrae and is the largest extant reptile (Britton et al., 2012). In any case, such characters do seem to be exceptionally labile, probably because of the ease of shifting the mechanisms controlling these characters, e.g. the speed of the 'segmentation clock' regulating somitogenesis and shifting Hox gene expression regions controlling regionalization (Müller et al., 2010), without greatly impeding function or interfering with development of other structures. ...
Phylogenies for fossil taxa must be inferred from morphology, but accuracy of inference is questionable. Here, morphological characters for extant crocodilians are investigated to assess how to improve inference accuracy. The homoplasy of characters is assessed against a DNA-based phylogenetic tree. Cranial characters are significantly less homoplastic, but this result is perhaps confounded by research effort. Meristic characters are significantly more homoplastic and should be used with caution. Characters were reassessed first hand and documented. Those characters passing tests of robust construction are significantly less homoplastic. Suggestions are made for means to improve coding of discrete characters. Phylogenies inferred using only robust characters and a reassessed matrix, including corrected scorings, were not overall closer to the DNA tree, but did often place the gharial (Gavialis) in a position agreeing with or closer to it. The effects of the choice of analytical method were modest, but Bayesian analysis of the reassessed matrix placed Gavialis and Mecistops (slender-snouted crocodile) in DNA-concordant positions. Use of extant rather than extinct outgroups, even with the original matrix, placed Gavialis in a more DNA-concordant position, as did factoring out 3D skull shape. The morphological case for placement of Gavialis outside other extant crocodilians is arguably overstated, with many characters linked to skull shape.
... Estuarine crocodiles can grow up to 6 m in length (Britton et al. 2012). This species has been responsible for >1,000 human attacks in the past decade, of which 53% were fatal (CrocBite 2020). ...
Negative human-wildlife interactions can be better managed by early detection of the wildlife species involved. However, many animals that pose a threat to humans are highly cryptic, and detecting their presence before the interaction occurs can be challenging. We describe a method whereby the presence of the estuarine crocodile (Crocodylus porosus), a cryptic and potentially dangerous predator of humans, was detected using traces of DNA shed into the water, known as environmental DNA (eDNA). The estuarine crocodile is present in waterways throughout southeast Asia and Oceania and has been responsible for >1,000 attacks upon humans in the past decade. A critical factor in the crocodile's capability to attack humans is their ability to remain hidden in turbid waters for extended periods, ambushing humans that enter the water or undertake activities around the waterline. In northern Australia, we sampled water from ponds where crocodiles were present or absent, and we were able to discriminate the presence of estuarine crocodile from the freshwater crocodile (C. johnstoni), a closely related sympatric species that does not pose a threat to humans. Further, we could detect the presence of estuarine crocodiles within an hour of its entry and up to 72 hours after the crocodiles were removed from the ponds. We conclude that eDNA could be a valuable tool for reducing human-wildlife conflict through early detection of the species.
... m (their Table 5). Compared to the more massive and robust appearance of P. brasiliensis, the more 'gracile' P. mirandai specimen AMU-CURS-541 could have had the tail alone weighing up to 472-738 kg (based on Willey et al., 2004; values that exceed most average masses of extant crocodylians (Grigg and Kirschner, 2015); the exceptionally large 'Lolong', an old Crocodylus porosus 6.17 m long, was reported to be 1075 kg: Britton et al., 2012). ...
The number of precaudal vertebrae in all extant crocodylians is remarkably conservative, with nine cervicals, 15 dorsals and two sacrals, a pattern present also in their closest extinct relatives. The consistent vertebral count indicates a tight control of axial patterning by Hox genes during development. Here we report on a deviation from this pattern based on an associated skeleton of the giant caimanine Purussaurus, a member of crown Crocodylia, and several other specimens from the Neogene of the northern neotropics. P. mirandai is the first crown-crocodylian to have three sacrals, two true sacral vertebrae and one non-pathological and functional dorsosacral, to articulate with the ilium (pelvis). The giant body size of this caiman relates to locomotory and postural changes. The iliosacral configuration, a more vertically oriented pectoral girdle, and low torsion of the femoral head relative to the condyles are hypothesized specializations for more upright limb orientation or weight support.
... Using a 1:8 ratio would result in a minimum TBL estimate for A. bugtiensis of 6.4 m for UM-DB-LCJ1-02 and of 7.3 m for NHMUK R.5266. A TL/HL of 1:8.8 was established for the longest C. porosus ever measured, which possesses a skull length of 70 cm (Britton et al., 2012), which is significantly smaller than the skull length estimated above for A. bugtiensis. Here, applying this ratio gives a TBL of 7 m for UM-DB-LCJ1-02 and of 8 m for NHMUK R.5266. ...
Cenozoic continental deposits of the Bugti Hills crop out South of the Sulaiman Range in Balochistan, Pakistan, and they have been renowned since Vickary (1846) for their exceptionally rich vertebrate-bearing Miocene localities. This led G.E. Pilgrim (Geological Survey of India) then C. Foster-Cooper (University of Cambridge) to conduct expeditions in the beginning of the 20th century. More recent expeditions in the late 1990s have reported the occurrence of successive fossiliferous horizons spanning the Eocene–Pleistocene interval (Welcomme et al., 1997, 2001; Welcomme and Ginsburg, 1997). Fossil-yielding series around Dera Bugti document marine, coastal, then fluvio-lacustrine depositional environments during the Eocene, the earliest Oligocene, and the late Oligocene–Pleistocene intervals, respectively (Welcomme et al., 2001; Métais et al., 2009; Roddaz et al., 2011; Antoine et al., 2013). The most species-rich intervals, at least for mammals, are Oligocene and Miocene in age (Marivaux et al., 1999, 2001, 2002a, 2002b, 2005; Antoine and Welcomme, 2000; Antoine et al., 2003, 2004, 2010, 2013; Métais et al., 2003, 2006, 2009, 2017; Marivaux and Welcomme, 2003; Orliac et al., 2009, 2010). As for crocodylians, fossil remains were initially described from the Bugti Hills by Pilgrim (1908, 1912), but their precise stratigraphic provenance has not been recorded. Most of those fossils are quite fragmentary and they consist of large tomistomine skull fragments (Martin, 2018) formerly referred to species of Gavialis (Pilgrim, 1908, 1912). Together with these remains, Crocodilus bugtiensis Pilgrim, 1908 was erected from a left maxilla and associated skull fragments of remarkable size found at Pishi Nala. Since its formal description four years later (Pilgrim, 1912), the taxon has been briefly mentioned from several levels in the Bugti Hills (Welcomme et al., 1997) but no detailed account has been given ever since. Here, we describe partial, yet diagnostic, mandibular elements of a large crocodyloid recovered from upper Oligocene deposits of the Bugti Hills, which are morphologically compatible with the skull elements described by Pilgrim (1912). This material was collected from a well-identified Oligocene horizon within the framework of the field campaigns that took place in Baluchistan between 1995 and 2000. We also report a partial mandible collected in the 1920s from Baluchistan but with no provenance data. Finally, we mention the presence of toothmarks on associated megaherbivore remains.
... The human population of East Nusa Tenggara is 4,683,827 (as of the 2010 census) with nearly equal ratios of male and female citizens and 80.66% of which were living in rural areas (UN OCHA). The Saltwater crocodile (Crocodylus porosus) is considered the world's largest crocodilian species, with some individuals on rare occasions reaching over 6 m in length (Britton et al. 2012). Saltwater crocodile populations have been drastically reduced throughout much of their range, with extirpation from most of mainland Southeast Asia. ...
East Nusa Tenggara is a province in Indonesian consisting of much of the eastern Lesser Sunda Islands (including Flores, Sumba and the western half of the island of Timor). Historically the Saltwater crocodile, Crocodylus porosus, was present within suitable habitat throughout virtually all portions of East Nusa Tenggara, but hide-hunting during the mid-20th Century combined with widespread habitat destruction resulted in the disappearance of the species from many areas. In recent years a sharp increase in reports of crocodile attacks on humans suggests that the species may be on the rebound within the province. Most of the reported attacks came from West Timor, but a small number of attacks were also reported from Flores, Lembata, Rote, and Sumba. Recent human-crocodile conflict surveys of the Kupang and Malaka regencies of West Timor and the West Manggarai regency of Flores have included short visits to crocodile habitat which revealed resident populations of crocodiles existing in these areas. In addition, information and photos from wildlife officials in Sumba have shown the species to present within eastern portions of the island, even far upriver in some areas.
... Saltwater crocodiles are the largest (Britton, Whitaker, & Whitaker, 2012) and most aggressive (Brien, Webb, Lang, McGuinness, & Christian, 2013) of all crocodilians in the world. They occupy all coastal wetlands and have sea-going capabilities (Webb & Manolis, 1989). ...
Cultural beliefs based on Timor-Leste´s creation myth "Lafaek Diak-The Good Crocodile" are anchored in the East Timorese traditional belief system lulik and involve worship of the widely distributed, but dangerous , saltwater crocodile (Crocodylus porosus). The wild saltwater crocodile population and rate of fatal attacks on people are both increasing due to conservation action. More innovative management is needed to reduce the frequency of attacks, but reverence for crocodiles constrains the management options available. We used semi-structured interviews with Timorese stakeholders (25 local authorities, 10 national experts, 15 citizens) to understand the cultural beliefs and traditional ecological knowledge underlying human-crocodile interactions, and conflict (HCC) in Timor-Leste. Interviewees knew this species was a risk (respect, fear) and its population was expanding, and had culturally determined beliefs (ceremonies, rituals) that included differentiating between local "ancestor" crocodiles and invasive "troublemakers." Cost-effective management could integrate stakeholder groups, especially traditional elders and local knowledge holders.
... Crocodylians are extreme among living vertebrates for traversing several-thousandfold changes in body mass during their lifetimes (15,000-fold increases in the largest species; C. porosus; Webb et al. 1983;Britton et al. 2012). How vertebrates manage such body-size transitions is a major unresolved issue among biologists (Cole 1944;Singer 1957;Schwenk 2000). ...
Living crocodylians are exceptional ambush predators in near-shore environments. Utilizing a combination of large body size, stealth, and remarkable prey-capture abilities, these apex predators have dominated regions within and around ponds, lakes, rivers, and oceans since the age of the dinosaurs. Cleuren and de Vree (2000), in their contribution to the previous edition of this text (Feeding: Form, Function and Evolution in Tetrapod Vertebrates; Schwenk 2000), provided detailed overviews about the anatomical configurations and functions of hyolingual anatomy, jaw kinematics, muscle activation patterns, cranial osteology, and hunting behaviors in the context of crocodylian feeding success. In the period since Feeding, there has been mounting interest in the extreme performance of crocodylian jaws and teeth for seizing and subduing prey, as well as the interaction between biomechanical factors, development, and diversification. These efforts have leveraged new technologies, analytical techniques, and phylogenetic comparative frameworks to study living and fossil taxa to address longstanding questions about crocodylian head anatomy from the reciprocal perspectives of ontogeny and evolution. Here, we focus on synthesizing these efforts in order to provide context for interpreting how the development and evolution of performance are thought to have shaped the vertebrate head—as informed by the deep evolutionary history of living crocodylians and their fossil precursors.
... Using Timor-Leste as a case study, here we demonstrate how potential habitats of Saltwater Crocodiles (Crocodylus porosus) can be mapped using cost-free tools and data from the World Wide Web, and local knowledge. One of the least developed countries in the World, Timor-Leste struggles to manage HCC with C. porosus, the largest and one of the most aggressive crocodilian species (Britton et al. 2012;Brien et al. 2013), the population of which has increased significantly in Timor-Leste since its independence from Indonesian occupation in 2002. Since 1996 at least 130 people have been attacked by crocodiles in Timor-Leste, yet the information available is insufficient to identify priority areas for a conservation scheme on a national scale (NBWG 2015;Sideleau et al. 2016;Brackhane et al. 2018). ...
... Large saltwater crocodiles can exceed 6 m in length and weigh >907 kg (Britton et al. 2012). ...
In northern Australia and nearby Timor‐Leste, saltwater crocodile (Crocodylus porosus) populations were seriously depleted historically but recovered rapidly after protection: 1969–1974 in northern Australia, and 2000–2005 in Timor‐Leste. In both places, recovery caused increased rates of human‐crocodile conflict (HCC). Within northern Australia, the crocodile recovery and HCC have been documented over time. In contrast, this has not been the situation in Timor‐Leste, where we investigated HCC based on 130 attack records (1996–2014; 52% fatal). In 1996–2006, 0.55 attacks/year were reported in Timor‐Leste. By 2007–2014, 9 years later, a 23‐fold increase had occurred (13 attacks/year). Traditional subsistence fishing (82.5% of all attack records) is the highest risk activity, followed by bathing (7.5%) and water collecting (4.2%). Although the human population was correlated with crocodile attacks in Timor‐Leste, it likely does not explain the dramatic increase in crocodile attacks. Alternatively, crocodile numbers may have increased, either in the remnant resident crocodile population, or via migrants from elsewhere. Permanent crocodile habitat is limited, and limited breeding does not explain the high number of large crocodiles, and consequent increase in attacks in such a short time. A plausible explanation, consistent with traditional knowledge in Timor‐Leste, is that the influx of large crocodiles attacking people are migrants from Australia. We examined this possibility from available sources. Within Australia crocodiles have recovered since protection and they regularly invade adjacent habitats, such as Darwin harbor, where they are removed to prevent attacks on people. Saltwater crocodiles have been sighted at oil rigs, in the open ocean, moving between northern Australia and the south coast of Timor‐Leste. The likelihood of crocodiles migrating from Australia to Timor‐Leste raises obvious conservation, moral, and ethical dilemmas when conserving a large dangerous predator in one country to increase abundance results in dispersal to another country, where the predator attacks and kills people.
... Despite high levels of deforestation, Sabah retains many large animal species, including the estuarine crocodile (Crocodylus porosus), the world's largest reptile, reaching in excess of seven meters [6]. They are apex predators found throughout South and East Asia and into Australasia [7]. ...
Riparian ecosystems are amongst the most biodiverse tropical habitats. They are important, and essential, ecological corridors, linking remnant forest fragments. In this study, we hypothesised that crocodile’s actively select nocturnal resting locations based on increased macaque predation potential. We examined the importance of riparian vegetation structure in the maintenance of crocodile hunting behaviours. Using airborne Light Detection and Ranging (LiDAR) and GPS telemetry on animal movement, we identified the repeated use of nocturnal resting sites by adult estuarine crocodiles (Crocodylus porosus) throughout the fragmented Lower Kinabatangan Wildlife Sanctuary in Sabah, Malaysia. Crocodile resting locations were found to resemble, in terms of habitat characteristics, the sleeping sites of long-tailed macaque; positioned in an attempt to avoid predation by terrestrial predators. We found individual crocodiles were actively selecting overhanging vegetation and that the protrusion of trees from the tree line was key to site selection by crocodiles, as well as influencing both the presence and group size of sleeping macaques. Although these findings are correlational, they have broad management implications, with the suggestion that riparian corridor maintenance and quality can have implications beyond that of terrestrial fauna. We further place our findings in the context of the wider ecosystem and the maintenance of trophic interactions, and discuss how future habitat management has the potential to mitigate human-wildlife conflict.
... The result is a potential demographic bias in the literature towards the study of young individuals that could yield a relatively myopic view of ontogenetic changes in physiological function that may accompany the extreme a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 growth and large body sizes achieved by crocodilians. For example, the largest of the extant crocodilians, the saltwater crocodile (Crocodylus porosus), changes in body mass by more than four orders of magnitude across a lifetime from a~60 g hatchling [5] to just over 1,000 kg in the very largest of adults [6]. ...
Due in part to their large size, aggressive temperament, and difficulty in handling, there are few physiological studies of adult crocodilians in the literature. As a result, studies comparing individuals across an ontogenetic series and comparisons among species are also lacking. We addressed this gap in knowledge by measuring standard metabolic rates (SMR) of three species of crocodilians (Crocodylus porosus, C. johnsoni, and Alligator mississippiensis), and included individuals that ranged from 0.22 to 114 kg. Allometric scaling of SMR with body mass was similar among the species, but C. porosus had significantly higher SMR than did C. johnsoni or A. mississippiensis. Differences in SMR among species are potentially related to behavioural differences in levels of aggression; C. porosus are the most aggressive of the crocodilians measured, and have rates of standard metabolism that are approximately 36% higher at the grand mean body size than those measured for C. johnsoni or A. mississippiensis, which are among the least aggressive crocodilians.
... The presence of an alytid frog implies wet habitats, which is the common environment for the extant members of the group (Vitt and Caldwell, 2014). All extant crocodilians are known to be water dwellers, inhabiting river systems, lakes, and even venture into the open sea (Steel, 1973;Britton et al., 2012). The fragmentary nature of the Cretan crocodilian does not allow us to make a proper specific or generic identification, but as the teeth from Plakias bear strong resemblance with certain Neogene finds from the Mediterranean that are assigned to Crocodyloidea or Alligatoroidea, we can infer a similar lifestyle. ...
Fossil amphibians and reptiles from the earliest late Miocene (early Tortonian, MN 9) of Plakias (Crete, Greece) are described in this paper. Most of the material is fragmentary, precluding precise taxonomic assignment. Nevertheless, the herpetofauna of Plakias is here shown to be diverse, comprising at least six different taxa: an alytid anuran, a crocodilian, two turtles (a pan-trionychid and a geoemydid) and two squamates (an amphisbaenian and a colubroid snake). The crocodilian material represents the first such fossils described from Greece and furthermore, one of the latest occurrences of this group in Europe. The pan-trionychid and the geoemydid represent the oldest occurrences of these groups in Greece and further add to their scarce Miocene record from this country. The first description of a fossil amphisbaenian from Greece is also provided. The new specimens from Plakias add to our knowledge of the Miocene herpetofaunas of southeastern Europe.
... In Timor-Leste, the largest predator is the saltwater crocodile (Crocodylus porosus). This is also the largest living crocodilian, with rare individuals confirmed at lengths of over 6 m (20 ft) (Britton et al. 2012). The species will prey on humans if given the opportunity (Webb et al. 2010), and it is estimated that between 200 and 300 people a year are attacked (approximately half of attacks proving fatal) by C. porosus across its entire range annually (CrocBITE Worldwide Crocodilian Attack Database, see http://www. ...
Saltwater crocodiles (Crocodylus porosus) are potentially dangerous to humans, yet they have major cultural value to many people in Timor-Leste. Recent increases in attack risk are influencing traditional attitudes, threatening culls of remaining wild crocodile populations. To understand patterns that may assist mitigation, we compiled attack records for the period of April 2007 to April 2014, using the CrocBITE online database. Recorded attacks (n = 45) showed a high fatality rate (82.2%), the majority (77.8%) being recorded since 2010. The highest proportion of attacks (46.7%) occurred in southern coastal wetlands suited to crocodiles, areas representing major sources of food, livelihoods and ecosystem services (i.e. fisheries, timber, coastal protection) for locals. Subsistence fishing posed the highest attack risk, particularly from September to February when food security is low. Attacks matched gender roles (most victims were males, the primary fishers) and demographic patterns (teenagers, the fastest growth group, comprised the highest proportion). Predicted increases in food insecurity, fishing activities, coastal impacts and rising human and crocodile populations pose worrying implications for human–crocodile conflict. We recommend essential baseline surveys enabling meaningful management decisions, and suggest that tailored management and educational awareness based on proven existing models could substantially mitigate attack risk while remaining compatible with traditional Timorese attitudes towards crocodiles.
A management program prepared under the Territory Parks and Wildlife Conservation Act 1976. An Act to make provision for and in relation to the establishment of Territory Parks and other Parks and Reserves and the study, protection, conservation and sustainable utilisation of wildlife
Interactions between people and the saltwater crocodile Crocodylus porosus frequently occur on islands and in coastal regions. Saltwater crocodiles impact people's lives and livelihoods by attacking them, resulting in minor or serious injuries, and by interfering in people's foraging activities. Retaliation may include killing the crocodiles involved. To reduce such human–crocodile interactions, data about the occurrence of incidents are required. We present data on encounters with crocodiles and attacks on people in the Roviana Lagoon, Solomon Islands. Data includes time of incident, gender, age and activity of the victim, water conditions and what happened to the crocodile after the incident. We used a questionnaire to capture the details of incidents that occurred during 2000–2020 in the villages of Dunde, Baraulu, Nusa Hope and Kozou. Most incidents were in the evening, mostly involving women, and most victims were aged 20–39 years or ≥ 60 years. In all cases people were attacked while gleaning for shellfish in the mangroves. Attacks occurred irrespective of whether the water was clear or murky, and in all cases the crocodiles were not killed. Such site-specific data will facilitate the formulation of strategies for reducing negative interactions between people and crocodiles in this particular location. Although the saltwater crocodile is categorized as Least Concern on the IUCN Red List, research such as this provides data that can be used for promoting coexistence with and conservation of this species.
A new Mystriosuchinae phytosaur, Colossosuchus techniensis, is described from the Upper Triassic Tiki Formation of India. Colossosuchus is diagnosed by multiple apomorphies, including a strongly downturned terminal rosette (c. 70°), closely spaced mediolateral band‐like ornamentation on dorsal surface of the nasal, dorsolaterally oriented supratemporal fenestra, ventrolaterally inclined postorbital–squamosal bars depressed below the skull table, dorsally convex parietal–squamosal bar that descends ventrolaterally below the skull roof, dome‐shaped skull in lateral view, prominent neural arch laminae and fossae, three sacral vertebrae, robust proximal end of the tibia, and fibula with high anteroposterior flaring of the distal end. The total body length of the largest individual recovered from the bonebed is estimated to be more than 8 m, suggesting that Colossosuchus is one of the largest phytosaurs known. Phylogenetic analysis nests Colossosuchus and other undescribed specimens from India within Mystriosuchinae. These form a distinct clade and represent the earliest record of endemism among Gondwanan phytosaurs. This clade is recovered as sister taxa to ((Volcanosuchus + Rutiodon) + Leptosuchomorpha), where the depressed supratemporal fenestra first appeared in the phytosaur lineage, a feature previously used to diagnose the derived leptosuchomorphs. Early‐diverging phytosaur diversification may have coincided with the final stages of the Carnian Pluvial Event with their possible migratory routes along the circum‐Tethyan coastline. The lineage continued to evolve mostly through endemic radiations and experienced an extinction event during early Norian, which marked the disappearance of most of the non‐leptosuchomorph taxa. This is attributed to post‐CPE aridification, although more study is required.
Body size is fundamental to the physiology and ecology of organisms. Crocodyliforms are no exception, and several methods have been developed to estimate their absolute body sizes from bone measurements. However, species-specific sizes, such as sexually mature sizes and the maximum sizes were not taken into account due to the challenging maturity assessment of osteological specimens. Here, we provide a vertebrae-based method to estimate absolute and species-specific body lengths in crocodylians. Lengths of cervical to anterior caudal centra were measured and relations between the body lengths (snout–vent and total lengths [TLs]) and lengths of either a single centrum or a series of centra were modeled for extant species. Additionally, states of neurocentral (NC) suture closure were recorded for the maturity assessment. Comparisons of TLs and timings of NC suture closure showed that most extant crocodylians reach sexual maturity before closure of precaudal NC sutures. Centrum lengths (CLs) of the smallest individuals with closed precaudal NC sutures within species were correlated with the species maximum TLs in extant taxa; therefore, the upper or lower limit of the species maximum sizes can be determined from CLs and states of NC suture closure. The application of the current method to noncrocodylian crocodyliforms requires similar numbers of precaudal vertebrae, body proportions, and timings of NC suture closure as compared to extant crocodylians.
The information on the population size and habitat condition of the Saltwater crocodile (Crocodylus porosus) in East Nusa Tenggara is unavailable. The present paper discusses preliminary data on population and habitat characteristics of the Saltwater crocodile in three conservation areas in Timor island, namely Teluk Kupang Marine Nature Tourism Park, Menipo Nature Tourism Park, and Maubesi Mangrove Forest Nature Reserve. Spotlight surveys and vegetation analyses were carried out in each location. The crocodile encounter rate was calculated as individuals detected per km surveyed. The encounter rates in Teluk Kupang, Menipo, and Maubesi were 0.3 crocodiles/km, 0.4 crocodiles/km, and 0.6 crocodiles/km, respectively. Hatchlings, juveniles, and adult saltwater crocodiles were found in Maubesi, and only hatchlings were found in Menipo. Hatchlings were found in paddy fields, and adults were found in mangroves, estuaries, and rivers. Mangrove densities in Teluk Kupang, Menipo, and Maubesi were 127 trees/ha, 124 trees/ha, and 186 trees/ha, respectively. These are the first systematic surveys in the areas studied, and additional work is needed to characterize the population and habitat of the saltwater crocodile in East Nusa Tenggara.
Saltwater crocodiles Crocodylus porosus are listed as critically endangered in Myanmar because they are limited to Meinmahlakyun Wildlife Sanctuary (MKWS) in the Ayeyarwady delta region. Little contemporary data exists on their distribution and population size which hinders effective conservation and management. We conducted standardized spotlight surveys and camera trap surveys along the rivers inside MKWS, and two nearby reserved forests. We used Hierarchical N-mixture models, Spatial Count models, and the relative abundance index to estimate site use by and population sizes of saltwater crocodiles in the Ayeyarwady delta. To address biases in detectability, we used maximum-likelihood and Bayesian approaches (1) to assess occupancy (site use) and population parameters of saltwater crocodiles, and (2) to assay abiotic and anthropogenic factors affecting it. Saltwater crocodiles were more likely to be abundant and occupy in the waterways inside MKWS than the reserved forests, and in the narrow and low salinity waterways than the wide and high salinity ones. Abundance of saltwater crocodiles was lower in areas with the human settlements than in areas with no settlement. Creeks within MKWS had moderate salinity and no human settlement and therefore it can be regared as the last remaining optimal saltwater crocodile habitat of the Ayeyarwady Delta. We estimated the saltwater crocodile population sizes in MKWS were 75 ± 9.92 individuals as absolute spotlight index, 58 ± 8.02 individuals as the maximum likelihood estimate of the N-mixture models and 68 ± 10.00 individuals as the Bayesian estimate of the spatial count models. Current population estimates of saltwater crocodiles are lower than the previously reported population size in 1999, and the declining population is now restricted to MKWS. We suggest developing buffer zones in the reserved forests around the wildlife sanctuary to increase habitat areas for saltwater crocodiles and to improve the outlook for long-term saltwater crocodile survival in Myanmar.
We report on a large crocodile skull recovered from a river bank in August 2010 near Đầu Sấu Bridge, in An Binh, Ninh Kieu District, Cần Thơ Province, in southern Vietnam. As the skull from Cần Thơ, named “Đầu Sấu“ herein, is now deposited in the Vietnam National Museum of Nature, Hanoi, we reinvestigated the circumstances surrounding its discovery and provide exact measurements. Skull length (dorsal mid-point) is 70.7 cm. The morphological features confirm it is from a Saltwater crocodile (Crocodylus porosus), and not a Siamese crocodile (C. siamensis), which historically also occurred throughout the Mekong Delta of Vietnam. Skull measurements are compared with those of other large C. porosus skulls for which reliable estimates of total length are available. We also provide measurements of the prepared skull of “Lolong” (69.8 cm), a 6.17 m long C. porosus captured in the Philippines in 2011. On the basis of known skull length:total length ratios the crocodile from Cần Thơ is estimated to be 6.3-6.8 m long. The skull of Đầu Sấu is likely to have been buried for at least 100 years. We discuss the origin of the local name Đầu Sấu, which has traditional and cultural significance, and provide historical reports of crocodiles in the area. Đầu Sấu is smaller than the largest known C. porosus skull (76 cm), but is the largest ever reported from Vietnam, and one of the largest C. porosus known.
We report on a large crocodile skull recovered from a river bank in August 2010 near Đầu Sấu Bridge, in An Binh, Ninh Kieu District, Cần Thơ Province, in southern Vietnam. As the skull from Cần Thơ, named “Đầu Sấu“ herein, is now deposited in the Vietnam National Museum of Nature, Hanoi, we reinvestigated the circumstances surrounding its discovery and provide exact measurements. Skull length (dorsal mid-point) is 70.7 cm. The morphological features confirm it is from a Saltwater crocodile (Crocodylus porosus), and not a Siamese crocodile (C. siamensis), which historically also occurred throughout the Mekong Delta of Vietnam. Skull measurements are compared with those of other large C. porosus skulls for which reliable estimates of total length are available. We also provide measurements of the prepared skull of “Lolong” (69.8 cm), a 6.17 m long C. porosus captured in the Philippines in 2011. On the basis of known skull length:total length ratios the crocodile from Cần Thơ is estimated to be 6.3-6.8 m long. The skull of Đầu Sấu is likely to have been buried for at least 100 years. We discuss the origin of the local name Đầu Sấu, which has traditional and cultural significance, and provide historical reports of crocodiles in the area. Đầu Sấu is smaller than the largest known C. porosus skull (76 cm), but is the largest ever reported from Vietnam, and one of the largest C. porosus known.
The Solomon Islands National Biodiversity Strategic Action Plan 2016–2020 identifies the need to develop a management plan for saltwater crocodiles. However, there is a lack of reliable information on the population status of saltwater crocodiles and the extent of human-crocodile conflict in the country. This report summarizes the results of a nationwide survey that aimed to fill these knowledge gaps
We critically evaluated a published historic account purported to be a new size record for A. mississippiensis (American Alligator). According to a newspaper article published in 1885, this large alligator was killed in Natchitoches, LA, and reportedly measured 823 cm (27 ft) in length and weighed 355.3 kg (783.5 lbs). We compared the reported values for total length (TL) and body mass (BM) with those predicted by a growth model describing the allometric relationship between these 2 variables. According to this model, an American Alligator with a TL of 823 cm would have a BM of 2534 kg; alternatively, an American Alligator weighing 355.3 kg would measure only 432 cm in length. Given these morphometric discrepancies, we are unable to accept this record. The largest credible size record for an American Alligator remains an individual measuring 450 cm in length and weighing 458 kg, harvested in Wilcox County, AL, in 2014.
Incubation temperature determines sex in crocodilians and influences other features of hatchlings. We investigated the effects of incubation temperature, clutch, and sex on the dimensions, mass, and energy reserves of hatchling Alligator mississippiensis. Eggs from three clutches were incubated to pipping at constant temperatures of 29°, 31°, 32°, and 33° C; females were produced at 29° and 31° C, mixed sex ratios at 32° C, and males at 33° C Incubation temperature affects hatchling size and yolk utilization in a consistent, but complex, pattern. Maximum yolk-free hatchling mass occurred at 32° C, and minimum mass at 31° C. Similarly, dimensions were maximized at 32° C and minimized at 29° C Residual yolk mass was inversely related to yolk-free hatchling mass. Higher yolk mass occurred at 31° and 33° C; at 29° and 32° C, values were lower. However, fat mass remained constant in all clutches. Strong clutch effects were present in nearly all traits. At 32° C, males were heavier and had less yolk than females. These differential effects of incubation temperature, and consequently sex, affect important hatchling characteristics and may influence hatchling survival and fitness, in accord with recent theory.
In C. porosus < 80 cm SVL (snout-vent length), growth rate decreases as body size increases; males grow faster than females, and both sexes grow faster in the wet season than in the dry season. If the exponential growth curve for specimens < 80cm SVL is extrapolated, it underestimates the maximum size of C. porosus. A second growth curve for specimens > 80cm SVL has been derived separately, and the two curves intersect in the vicinity of 70 cm SVL. The size at which C. porosus cease growing seems quite variable and some data indicate a range of 3.9-6.0 m total length for males. The twocurve growth model is thought to reflect an energetic advantage in feeding on large rather than small prey.
Recent phylogenetic analyses of fossil and living crocodylians allow us to compare the taxonomic, geographic, and temporal distributions of morphological features, such as snout shapes. A few basic snout morphotypes—generalized, blunt, slender, deep, and excessively broad (“duck-faced”)—occur multiple times in distantly-related lineages. Some clades—especially those found in the Northern Hemisphere or with minimum origination dates in the Cretaceous or lower Tertiary—are morphologically uniform, but geographically widespread; crocodylian faunas of the early Tertiary tend to be composite, with sympatric taxa being distantly related, and similar-looking taxa on different continents being close relatives. In contrast, crocodylian faunas of the later Tertiary tend to be more endemic, with local adaptive radiations occurring in Africa and Australia containing members of most basic snout shapes. Endemic radiations in Africa and Australia have largely been replaced by Crocodylus, which can be divided into subclades that may individually represent endemic adaptive radiations.
Regression analysis between body and head measurements of Chinese alligators (Alligator sinensis) in the captive population Análisis de regresión entre las mediciones del cuerpo y la cabeza del aligator chino (Alligator sinensis) en las poblaciones en cautividad.- Se tomaron medidas de cuatro dimensiones del cuerpo y catorce de la cabeza de cada uno de los aligatores chinos (Alligator sinensis) según las mediciones de Verdade adaptadas. Se presentaron ecuaciones de regresión entre las variables del tamaño del cuerpo y de la cabeza, para predecir el tamaño corporal a partir de las dimensiones cefálicas. Puede considerarse que los coeficientes de determinación de los animales cautivos, concernientes a las variables del tamaño del cuerpo y la cabeza son muy altos, lo que significa que la mayoría de las variables del tamaño cefálico estudiadas pueden ser útiles para predecir la longitud del cuerpo. Los resultados del análisis alométrico multivariante indicaron que la cabeza se alarga como en la mayoría de especies de cocodrilos. Los coeficientes alométricos de la longitud del hocico (SL) y del ramus inferior (LM) fueron mayores que otras variables de la cabeza, estando correlacionados, posiblemente, con las luchas y la captura de presas. Por el contrario, los coeficientes alométricos para las variables de las óribitas (OW, OL) y del techo craneano postorbital (LCR) son relativamente menores que para otras variables.
In the present study, regression equations between body and head length measurements for the broad-snouted caiman (Caiman latirostris) are presented. Age and sex are discussed as sources of variation for allometric models. Four body-length, fourteen head-length, and ten ratio variables were taken from wild and captive animals. With the exception of body mass, log-transformation did not improve the regression equations. Besides helping to estimate body-size from head dimensions, the regression equations stressed skull shape changes during the ontogenetic process. All age-dependent variables are also size-dependent (and consequently dependent on growth rate), which is possibly related to the difficulty in predicting age of crocodilians based on single variable growth curves. Sexual dimorphism was detected in the allometric growth of cranium but not in the mandible, which may be evolutionarily related to the visual recognition of gender when individuals exhibit only the top of their heads above the surface of the water, a usual crocodilian behavior.
Few papers concerning seagrasses of the eastern Pacific have been published. This paper presents the first ecological data on the seagrass, Ruppia maritima, from a non-lagoonal setting in the eastern Pacific. A 5000 m2 patch formed by R. maritima, at Playa Iguanita, Bahía Culebra, Pacific coast of Costa Rica was studied. Plant density and leaf length of R. maritima were determined along two transects on different dates. Above and below ground biomass were calculated along one transect. Plant density ranged from 1590 to 8630 individuals m(-2) along the two transects, with means of 5990 +/- 1636 and 6100 +/- 1876 plants m(-2) for transect 1 and 2, respectively. Longest leaf length per plant varied between 0.5 and 23.0 cm. Leaf biomass (LB) ranged from 10 to 97 gm(-2), and root-rhizome biomass (RB) from 31 to 411 gm(-2), resulting in RB:LB ratios of 3.07 to 15.27. Total biomass at Bahía Culebra was lower than at tropical lagoons on the Pacific coast of Mexico, but higher than in the Gulf of Mexico. The below ground: above ground biomass ratio was much higher at Bahía Culebra than at other sites on the Pacific coast of Mexico and the Gulf of Mexico. Another seagrass present at Bahía Culebra was Halophila baillonii, with low densities on the deepest section of the patch. At least 44 invertebrate species associated with the seagrass bed have also been identified. The patch at Playa Iguanita and other sites within Bahía Culebra, as well as their associated organisms, disappeared after a severe storm in June 1996. No seagrasses have been found in the area or in any other location on the Pacific coast of Costa Rica since then.
The cranial morphometry of New Guinea crocodiles (Crocodylus novaeguineae) was investigated to quantify ontogenetic variation in relative growth of the skull to provide possible demographic insights into commercially harvested populations. Growth attributes were, in general, linear, and univariate statistics provided estimates of size from untransformed values. Curvilinear size (total length) to age transformations were attempted through applications of three growth models: a reparameterized Richards curve, the von Bertalannfy model, and a Brody curve. Satisfactory performance was attained only through the Brody model, with reliable age estimates restricted to smaller (≤2 m) individuals. The utility of relative growth ratios to correctly predict the sex of known gender animals was assessed by both parametric (multivariate discriminant analysis--DISCRIM) and nonparametric (binary tree classification analysis--CART) methods. Crossvalidation data sets were created to reduce model biases and to evaluate the correctness of classification rates. CART models consistently showed greater congruence of apparent error rates with true error rates than did DISCRIM models, while the 'best fit' models of each method closely paralleled one another in providing conservative overall ability to correctly discriminate gender from measured attributes. Skull growth occurs in three distinctive stages that mimic a saltatory ontogenetic response and are hypothesized to be related to functional foraging responses.
The longest male and female alligators (Alligator mississippiensis) measured in Florida during 1977-1993 were 426.9 cm and 309.9 cm total length. The heaviest male and female alligators weighed 473.1 and 129.3 kg. A predictive model for calculating total length from head length is presented. Estimated total lengths for three large alligators described in the literature were substantially shorter than reported lengths. The longest alligator for which a total length can be corroborated from skull measurements was 454 cm. We discuss the plausibility of past reports of exceptionally large alligators with respect to verified lengths of specimens, harvest pressure, growth patterns, and longevity.
Utilizing measurements from 1354 C. porosus, we have derived formulae for predicting snout-vent length from 17 other attributes. The specific problem of predicting body size from an isolated head or skull is treated separately and some data are presented on proportional tissue loss in skull preparation. Sexual dimorphism was examined, and is demonstrated in interocular width, the width at the midpoint of the cranial platform, and the length of the tail. Discriminant analysis has been used to distinguish males from females on the basis of external measurements of both the whole animal and the isolated head. Hatchling C. porosus from Arnhem Bay and the Blyth River have longer heads than those from the Liverpool River. C. porosus from Sarawak have longer tails and are heavier than those from northern Australia. Predicting the maximum size of C. porosus from large skulls in museums is difficult because of variations in basic skull shape. The body size at which mandibular teeth protrude through the premaxilla is quantified.
Green turtles Chelonia mydas of immature and adult size (n = 19, curved carapace length 49 to 118 cm) were equipped with time-depth recorders for short periods (≤ 7 d) to investigate diel and seasonal variation in diving behaviour. Research sessions were distributed over 2 years to cover seasonal variation in sea temperature from 14 °C to 30 °C. Diurnal dives were shallower and shorter than nocturnal dives, with diel patterns also evident in dawn and dusk peaks in occupation of depths within 1 m of the surface, elevated diurnal occupation of depths 1 to 2 m below the surface and elevated nocturnal occupation of depths > 2 m. Dive duration increased as sea temperature decreased, showing strong negative correlation by day and by night. Study turtles made resting dives that were 3 to 4 times longer in median duration, and six times longer in maximum duration, at cool temperatures than they were at warm temperatures, but there was no evidence of winter diapause or location shift to avoid cold water. The large majority of turtles spent 89 to 100% of their time at depths ≤ 5 m below the surface, three individuals did not exceed 3 m and the maximum depth recorded by any turtle was 7.9 m, although deeper water was available. Furthermore, the dive data indicated that study turtles collectively spent more than 80% of their time at charted (low tide) depths of 3 m or less, indicating that they consistently used the shallow margins of the bay where human activities tend to be concentrated, thereby potentially increasing their exposure to anthropogenic threats.
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