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Scientists have discovered Labrujasuchus expectatus, a bizarre crocodile relative that looked more like an ostrich-like dinosaur than anything resembling a modern crocodile。 It walked on two legs, had tiny arms, and sported a toothless beak—an unexpected combination for a member of the crocodile lineage

Scientists have solved the mystery of the Seychelles’ vanished crocodiles using DNA from historic museum specimens。 The reptiles were not a unique species after all, but an isolated population of saltwater crocodiles that likely drifted thousands of kilometers across the Indian Ocean

The population biology of the American crocodile (Crocodylus acutus) was studied in southern Florida during 1977-1982. Crocodiles occur primarily in inland mangrove swamps protected from wave action. Females use the open waters of Florida Bay only for access to nesting sites. Individuals have large (86-262 ha), overlapping activity areas. Nesting occurs in spring and summer, avoiding the cold and the wet seasons, either of which can affect incubation. Clutches averaging 38 eggs were laid both in mounds and in holes in the ground, either singly or communally. Available data cannot support the view that the number of nests has decreased in recent years. Hatching failure occurred as a result of infertility, predation, and embryonic mortality from desiccation and flooding. Hole and creek nests were most susceptible to embryonic mortality. Seventy-eight percent of nests hatched some young. We found no evidence of adults defending nests or young, but nest opening by adults was essential for hatching. Disturbance at nest sites caused females to abandon the site. All expected age classes occurred in the population. Size at maturity was 2.25 m TL for females. Documented mortality of adults and subadults of approximately 2 crocodiles per year was predominantly human-caused. At least 45 crocodiles have been released into southern Florida in 17 years. We estimate the southern Florida population to be about 220 ? 78 adults and subadults. The northernmost population of the American crocodile (Crocodylus acutus) occurs on the extreme southern tip of the Florida peninsula, USA. The range of this tropical species has always been limited, probably by temperature constraints (Kushlan and Mazzotti, 1989). Early reports of crocodiles in Florida are notices and discussions of its occurrence (Wyman, 1870; Hornaday, 1891; Smith, 1896; Barbour, 1923); Moore (1953) provided the first detailed account of its status. Ogden (1978) documented aspects of its nesting biology. More recently, Gaby et al. (1985) reported on the population biology of a small number of crocodiles living in a power plant cooling system. 3 Present Address: Department of Wildlife and Range Sciences, University of Florida, 3245 College Avenue, Davie, Florida 33314, USA. st population of the Ameriil ( ocodylus acutus) oc urs on the e tip of the Florida peninsula, e of this tropical species has alli ite , probably by temperature ( s la and az ot i, 1989). Early iles in Florida are notices and its occurrence ( yman, 1870; ; S ith, 1896; Barbour, 1923); ) ided the first detailed ac ount . e (1978) documented aspects i iolog . ore recently, Gaby et te on the population biology er of crocodiles living in a powli s ste . ess: epart ent of Wildlife and s, iversity of Florida, 3245 College Many crocodilian populations are endang red because their effective population sizes h ve been reduced by human-related factors such as as hunting and habitat loss. Small poplations, particularly when isolated, risk extirpation because of the action of natural or artificial forces that erode their numbers. The Florida population of the American crocodile is thought to be of limited size (Ogden, 1978), and therefore susceptible to chance and human inerference. As a result it has long been considred to be endangered (Barbour, 1923; Hines et al., 1984). Unfortunately, limited information has inhibited understanding of its population biology, and therefore of its true status or appropriate conservation needs. In this paper we discuss the population biology of the the American crocodile based on a five-year study of the population in the core of its northernmost range, northeastern Florida crocodilian populations are endanbecause their e fective opulation sizes een reduced by human-related factors as as hunting and habi at loss. Small popi s, particularly when isolated, risk extiri because of the action of natural o arti7 This content downloaded from 157.55.39.162 on Thu, 11 Aug 2016 05:12:47 UTC All use subject to http://about.jstor.org/terms J. A. KUSHLAN AND F. J. MAZZOTTI Bay. Where appropriate, we compare information from studies conducted simultaneously and cooperatively with our own on other segments of the population (Gaby et al., 1975; P. Moler, pers. comm.). Other aspects of our overall study program are discussed elsewhere (Behler, 1978; Hall et al., 1979; Dunson, 1982; Lutz and Dunbar-Cooper, 1984; Stoneburner and Kushlan, 1984; Kushlan, 1988; Mazzotti et al., 1988; Kushlan and Mazzotti, 1989).

The Nile crocodile (Crocodylus niloticus) is an ancient icon of both cultural and scientific interest. The species is emblematic of the great civilizations of the Nile River valley and serves as a model for international wildlife conservation. Despite its familiarity, a centuries-long dispute over the taxonomic status of the Nile crocodile remains unresolved. This dispute not only confounds our understanding of the origins and biogeography of the 'true crocodiles' of the crown genus Crocodylus, but also complicates conservation and management of this commercially valuable species. We have taken a total evidence approach involving phylogenetic analysis of mitochondrial and nuclear markers, as well as karyotype analysis of chromosome number and structure, to assess the monophyletic status of the Nile crocodile. Samples were collected from throughout Africa, covering all major bioregions. We also utilized specimens from museum collections, including mummified crocodiles from the ancient Egyptian temples at Thebes and the Grottes de Samoun, to reconstruct the genetic profiles of extirpated populations. Our analyses reveal a cryptic evolutionary lineage within the Nile crocodile that elucidates the biogeographic history of the genus and clarifies long-standing arguments over the species' taxonomic identity and conservation status. An examination of crocodile mummy haplotypes indicates that the cryptic lineage corresponds to an earlier description of C. suchus and suggests that both African Crocodylus lineages historically inhabited the Nile River. Recent survey efforts indicate that C. suchus is declining or extirpated throughout much of its distribution. Without proper recognition of this cryptic species, current sustainable use-based management policies for the Nile crocodile may do more harm than good.

Captivity is an important measure for conservation of an endangered species and it is becoming a hot topic in conservation biology, which integrates gut microbiota and endangered species management in captivity. As an ancient reptile, the crocodile lizard (Shinisaurus crocodilurus) is facing extreme danger of extinction, resulting in great significance to species conservation in the reserve. Thus, it is critical to understand the differences in gut microbiota composition between captive and wild populations, as it could provide fundamental information for conservative management of crocodile lizards. Here, faecal samples of crocodile lizards were collected from two wild and one captive populations with different ages (i.e. juveniles and adults), and were analyzed for microbiota composition by 16S rRNA gene amplicon sequencing. This study showed that the lizard gut microbiota was mainly composed of Firmicutes and Proteobacteria. The gut microbiota composition of crocodile lizard did not differ between juveniles and adults, as well as between two wild populations. Interestingly, captivity increased community richness and influenced community structures of gut microbiota in crocodile lizards, compared with wild congeners. This was indicated by higher abundances of the genera Epulopiscium and Glutamicibacter. These increases might be induced by complex integration of simple food resources or human contact in captivity. The gut microbiota functions of crocodile lizards are primarily enriched in metabolism, environmental information processing, genetic information processing, and cellular processes based on the KEGG database. This study provides fundamental information about the gut microbiota of crocodile lizards in wild and captive populations. In the future, exploring the relationship among diet, gut microbiota, and host health is necessary for providing animal conservation strategies.

Empirical field data describing daily and seasonal cycles in body temperature (Tb) of free-ranging Crocodylus porosus (32-1010 kg) can be predicted by a mathematical analysis. The analysis provides a mechanistic explanation for the decreased amplitude of daily cycles in Tb and the increase in 'average' Tb with increasing mass. Assessments of 'average' daily Tb were made by dividing the integral of the difference between measured values of Tb and minimum operative temperature by the period of integration, to yield a thermal index expressing relative 'warmth' of crocodiles. The average daily Tb of a 1010 kg crocodile was 3.7 degreesC warmer than that of a 42 kg individual in summer and 1.9 degreesC warmer than that of a 32 kg individual in winter. The success of this mathematical approach confirms that crocodiles are simple ectotherms and that there is unlikely to be a significant contribution to their thermal biology from physiological mechanisms. Behaviour, however, is very important even in large individuals. Crocodiles in the field typically move daily between land and water in cycles that vary seasonally. We predicted Tb for the reverse of these behavioural cycles, which more than doubled seasonal fluctuations in Tb compared with the observed fluctuations. We were also able to predict the Tb of very large, dinosaur-sized crocodiles in a similar climate to that at our study site. A 10 000 kg 'crocodile', for example, would be expected to have a Tb of 31 degreesC in winter, varying by less than 0.1 degreesC during a day when operative temperatures varied by nearly 20 degreesC, from 20 to 38 degreesC. The study confirms that, in low latitudes at least, large dinosaurs must have had an essentially high and stable value of Tb, without any need for endothermy. Also, access to shade or water must have been crucial for the survival of large dinosaurs at low latitudes. Furthermore, the finding of increasing 'average' Tb as ectotherms grow larger may have implications for the metabolic rates of very large reptiles, because the Q10 effect could counteract the downscaling of metabolic rate with mass, an effect that seems not to have been recognised previously.

The crocodile lizard is a critically endangered reptile, and serious diseases have been found in this species in recent years, especially in captive lizards. Whether these diseases are caused by changes in the gut microbiota and the effect of captivity on disease remain to be determined. Here, we examined the relationship between the gut microbiota and diet and disease by comparing the fecal microbiota of wild lizards with those of sick and healthy lizards in captivity. The gut microbiota in wild crocodile lizards was consistently dominated by Proteobacteria (~56.4%) and Bacteroidetes (~19.1%). However, the abundance of Firmicutes (~2.6%) in the intestine of the wild crocodile lizards was distinctly lower than that in other vertebrates. In addition, the wild samples from Guangdong Luokeng Shinisaurus crocodilurus National Nature Reserve also had a high abundance of Deinococcus-Thermus while the wild samples from Guangxi Daguishan Crocodile Lizard National Nature Reserve had a high abundance of Tenericutes. The gut microbial community in loach-fed crocodile lizards was significant different from the gut microbial community in the earthworm-fed and wild lizards. In addition, significant differences in specific bacteria were detected among groups. Notably, in the gut microbiota, the captive lizards fed earthworms resulted in enrichment of Fusobacterium, and the captive lizards fed loaches had higher abundances of Elizabethkingia, Halomonas, Morganella and Salmonella, all of which are pathogens or opportunistic pathogens in human or other animals. However, there is no sufficient evidence that the gut microbiota contributes to either disease A or disease B. These results provide a reference for the conservation of endangered crocodile lizards and the first insight into the relationship between disease and the gut microbiota in lizards.

Summary 1. Lake Rudolf, nothern Kenya, has one of the largest undisturbed populations of the Nile Crocodile. In 1965 the Kenya Game Department initiated the Lake Rudolf Crocodile Research Project. Central Island, where the crocodiles live under undisturbed conditions, was chosen for studying breeding behaviour and ecology of the reptile. Eight months were spent on the island. 2. On the island most of the crocodile population was confined to a crater lake, Lake C, which supported up to 500 animate at the height of the 1965‐66 breeding season. 3. The 1200 m shoreline of Lake C was shared out between about a dozen large males each guarding his territory by patrolling up and down the shore. The territorial shore lengths ranged from 60 to 230 m. The territories extended about 50 m into the water. 4. The crocodiles were first seen courting on 10.10.65 in Lake C. The territorial males exhibited a “courtship splash display”. Copulation ranged from 30 to 100 seconds; eleven copulations averaged 58 seconds. 5. The factors important in site selection for nesting are shade, suitable soil, proximity to water and the degree of slope of the shore. Because the shores of a second crater lake, Lake A, satisfied these conditions they had the largest number of nests. The fully exposed sites on Lake C, and the Lake Rudolf shores, had very few nests. 6. The females dig the nests with their forelimbs, using them in turn. The hind limbs and the belly are used to push away the soil collecting at the mouth of the burrow. The female guards the nest constantly throughout the incubation period of three months against monitor luzards. Laying began in the third week of November, 1965 reaching its peak during the second week of December. The crocodile egg is oblong, measuring 55.5 to 89.0 mm in length and 43.0 to 54.0 mm in width. Mean weights of the eggs from 15 clutches ranged from 83.7 to 126.6 g. Clutch sizes on Central Island varied from 14 to 46 eggs, giving a mean of 33 eggs per clutch. When the young are about to hatch, the mother releases them by digging up the nest. The young when they hatch are about 31.0 cm long and weigh about 76.8 g. They are guarded by the mother for at least six weeks. Infant mortality is probably very considerable.

The genomes of warm-blooded vertebrates are characterized by a strong heterogeneity in base composition, with GC-rich and GC-poor isochores. The GC content of sequences, especially in third codon positions, is highly correlated with that of the isochore they are embedded in. In amphibian and fish genomes, GC-rich isochores are nearly absent. Thus, it has been proposed that the GC increase in a part of mammalian and avian genomes represents an adaptation to homeothermy. To test this selective hypothesis, we sequenced marker protein genes in two cold-blooded vertebrates, the Nile crocodile Crocodylus niloticus (10 genes) and the red-eared slider Trachemys scripta elegans (6 genes). The analysis of base composition in third codon position of this original data set shows that the Nile crocodile and the turtle also exhibit GC-rich isochores, which rules out the homeothermy hypothesis. Instead, we propose that the GC increase results from a mutational bias that took place earlier than the adaptation to homeothermy in birds and before the turtle/crocodile divergence. Surprisingly, the isochore structure appears very similar between the red-eared slider and the Nile crocodile than between the chicken and the Nile crocodile. This point questions the phylogenetic position of turtles as a basal lineage of extant reptiles. We also observed a regular molecular clock in the Archosauria, which enables us, by using a more extended data set, to confirm Kumar and Hedges's dating of the bird-crocodile split.

<title>Abstract</title> This book was written for veterinarians, scientists, wildlife officials, students and crocodile farmers. The gathered data was based on years of work with farmed Nile crocodiles, some with wild and wild-caught African dwarf crocodiles in the Congo Republic, as well as on information from available literature. This book is a comprehensive reference on the biology, management and health of crocodiles, alligators and gharials. Emphasis is on diagnosis, treatment, and prevention of diseases as these occur on crocodile farms; clinical aspects of disease are also discussed. Photographs depicting various cases and conditions have been compiled. Anatomy, physiology, biochemistry, behaviour, nutrition, rearing, breeding, slaughter and welfare are also covered.

The threat of coronavirus disease 2019 to health systems in sub-Saharan Africa (SSA) can be compared metaphorically to a lake in Africa infested with a bask of crocodiles and the saying "the eye of the crocodile." In the lake, only the eyes of the crocodile appear on the surface while the rest of the body is submerged in water. In this Viewpoint, the eyes and the body of the crocodile represent the public health preparedness and health systems, respectively, in SSA. SSA has had multiple epidemics, including, in the last 3 decades, HIV and Ebola virus. Interestingly, HIV, Ebola virus, and SARS-CoV-2 are all of zoonotic origin. HIV resulted from cross-species transfer of simian immunodeficiency virus from chimpanzees, found in eastern and central Africa, to humans (1). Ebola virus was discovered in humans during concurrent outbreaks in the Democratic Republic of Congo and the Sudan in 1976 (2, 3). It is believed that bats are the natural hosts of Ebola virus. SARS-CoV-2 also originated from bats found in caves in China. Although HIV and Ebola originated in Africa, SARS-CoV-2 was imported from China. This Viewpoint discusses the potential impact of the COVID-19 epidemic on already-fragile health systems in SSA and forecasts lessons likely to be learned from COVID-19 in SSA.