Find research datasets worth reusing

opencc-by-4.0Aug 2007View details →

Figure 5. Internal choana, ventral view. A, AMNH 3101, Voay robustus. B, TMM m-1786, Crocodylus niloticus. C, AMNH 10083 in Morphology, relationships, and biogeographical significance of an extinct horned crocodile (Crocodylia, Crocodylidae) from the Quaternary of Madagascar

Figure 5. Internal choana, ventral view. A, AMNH 3101, Voay robustus. B, TMM m-1786, Crocodylus niloticus. C, AMNH 10083, Osteolaemus osborni (holotype). Scale = 1 cm.

opencc-by-4.0Aug 2007View details →

Figure 9 in Morphology, relationships, and biogeographical significance of an extinct horned crocodile (Crocodylia, Crocodylidae) from the Quaternary of Madagascar

Figure 9. Right suborbital fenestra, lateral oblique view, showing condition of the anterior ramus of the ectopterygoid (ear). A, BMNH uncategorized, Voay robustus. B, TMM m-1786, Crocodylus niloticus. Scale = 1 cm.

opencc-by-4.0Aug 2007View details →

Figure 17 in Morphology, relationships, and biogeographical significance of an extinct horned crocodile (Crocodylia, Crocodylidae) from the Quaternary of Madagascar

Figure 17. Strict consensus of 344 972 equally optimal trees (consistency index = 0.408, retention index = 0.794, length = 472); maximum parsimony analysis, 66 ingroup taxa, 166 morphological characters (see the Appendix).

opencc-zeroNov 2022View details →

Identification of free-ranging mugger crocodiles by applying deep learning methods on UAV imagery

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 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.

Fig. 4. Predicted suitable habitats for S in Discovery of a new crocodile lizard population in Vietnam: Population trends, future prognoses and identification of key habitats for conservation

Fig. 4. Predicted suitable habitats for S. crocodilurus in the period between 2020 to 2080, based on bioclimatic data and elevation. Habitat suitability increases from yellow to dark brown.

Fig. 5 in Discovery of a new crocodile lizard population in Vietnam: Population trends, future prognoses and identification of key habitats for conservation

Fig. 5. Predicted suitable habitats throughout the distribution range of S. crocodilurus in northern Vietnam, using combined vegetation, bioclimatic and elevation data. Red squares indicate recommended priority areas for habitat conservation (bottom left: proposed corridor to link two existing reserves; top right: proposed reserve to be established in the future).

Fig. 3 in Discovery of a new crocodile lizard population in Vietnam: Population trends, future prognoses and identification of key habitats for conservation

Fig. 3. Observed population structure of Vietnamese S. crocodilurus from 2010 to 2015. Photos M. van Schingen.

Fig. 2 in Discovery of a new crocodile lizard population in Vietnam: Population trends, future prognoses and identification of key habitats for conservation

Fig. 2. Population trends of S. crocodilurus in Vietnam from 2010 to 2015. (A) Estimated total population sizes in Vietnam. (B) Observed total subpopulation sizes. (C) Observed effective subpopulation sizes. Arrows indicate trend lines.

opencc-zeroMar 2023View details →

Discovery of facultative parthenogenesis in a New World crocodile

Over the past two decades, there has been an astounding growth in the documentation of vertebrate facultative parthenogenesis (FP). This unusual reproductive mode has been documented in birds, non-avian reptiles—specifically lizards and snakes—, and elasmobranch fishes. Part of this growth among vertebrate taxa is attributable to awareness of the phenomenon itself and advances in molecular genetics/genomics and bioinformatics, and as such our understanding has developed considerably. Nonetheless, questions remain as to its occurrence outside of these vertebrate lineages, most notably in Chelonia (turtles) and Crocodylia (crocodiles, alligators, and gharials). The latter group is particularly interesting because unlike all previously documented cases of FP in vertebrates, crocodilians lack sex chromosomes and sex determination is controlled by temperature. Here, using whole-genome sequencing data, we provide the first evidence of FP in a crocodilian, the American Crocodile, Crocodylus acutus. The data support terminal fusion automixis as the reproductive mechanism; a finding which suggests a common evolutionary origin of FP across reptiles, crocodilians, and birds. With FP now documented in the two main branches of extant archosaurs, this discovery offers tantalizing insights into the possible reproductive capabilities of the extinct archosaurian relatives of crocodilians and birds, notably members of Pterosauria and Dinosauria.

opencc-zeroSep 2023View details →

Data from: The biogeographic history of neosuchian crocodiles and the impact of saltwater tolerance variability

Extant neosuchian crocodiles are represented by only 24 taxa that are confined to the tropics and subtropics. However, at other intervals during their 200 million-year evolutionary history, the clade reached considerably higher levels of species-richness, matched by more widespread distributions. Neosuchians have occupied numerous habitats and niches, ranging from dwarf riverine forms to large marine predators. Despite numerous previous studies, several unsolved questions remain with respect to their biogeographic history, including the geographic origins of major groups, e.g., Eusuchia and Neosuchia itself. We carried out the most comprehensive biogeographic analysis of Neosuchia to date, based on a multivariate K-means clustering approach followed by the application of two ancestral area estimation methods (BioGeoBEARS and Bayesian Ancestral Location Estimation) applied to two recently published phylogenies. Our results placed the origin of Neosuchia in north-western Pangaea, with subsequent radiations into Gondwana. Eusuchia probably emerged in the European archipelago during the Late Jurassic/Early Cretaceous, followed by dispersal to the North American and Asian landmasses. We show that putative transoceanic dispersal events are statistically significantly less likely to happen in alligatoroids. This finding is consistent with the saltwater intolerant physiology of extant alligatoroids, bolstering inferences of such intolerance in their ancestral lineages.