An illustrated record book of theropod facts and figures-from the biggest to the fastest to the smartest
The theropod dinosaurs ruled the planet for millions of years, with species ranging from the ...mightyTyrannosaurus rex to feathered raptors no bigger than turkeys. Dinosaur Facts and Figures is a stunningly illustrated book of records for these marvelous creatures-such as the biggest, the smallest, and the fastest theropods, as well as the ones with the most powerful bite.
This one-of-a-kind compendium features more than 3,000 records, covers some 750 theropod species, and includes a wealth of illustrations ranging from diagrams and technical drawings to full-color reconstructions of specimens. The book is divided into sections that put numerous amazing theropod facts at your fingertips. "Comparing Species" is organized by taxonomic group and gives comparisons of the size of species, how long ago they lived, and when they were discovered. "Mesozoic Calendar" includes spreads showing the positions of the continents at different geological time periods and reconstructions of creatures from each period. "Prehistoric Puzzle" compares bones, teeth, and feathers while "Theropod Life" uses vivid, user-friendly graphics to answer questions such as which dinosaur was the smartest and which had the most powerful bite. Other sections chart theropod distribution on the contemporary world map, provide comprehensive illustrated listings of footprints, compile the physical specifications of all known theropods and Mesozoic birds, and much more.
The essential illustrated record book for anyone interested in dinosaurs
Features thousands of records on everything from the smartest and fastest theropods to the largest theropod eggs
Includes more than 2,000 diagrams and drawings and more than 300 digital reconstructions
Covers more than 750 theropod species, including Mesozoic birds and other dinosauromorphs
Provides detailed listings of footprints, biometric specifications, and scholarly and popular references
Exotic species pose a threat to most ecosystems because of their potential to establish negative interactions with native biota. However, exotic species can also offer resources to native species, ...especially within highly modified environments such as urban ecosystems. We studied 17 exotic-native pairs of species with the potential to compete with one another, or in which one of the species could offer resources to the other, in an urban ecological reserve located within Mexico City. We used two-species occupancy models to analyze the potential association between the presence of the exotic species and the spatial distribution of the native species, as well as to assess if these species tend to avoid each other (negative spatial interaction) or to co-occur more often than expected under the hypothesis of independent occurrences (positive spatial interaction). Our results revealed few cases in which the exotic species influenced occupancy of the native species, and these spatial interactions were mainly positive, indicated by the fact that the occupancy of the native species was usually higher when the exotic species was also present. Seven of the eight observed non-independent patterns of co-occurrence were evident during the dry months of the year, when resources become scarce for most species. Our results also demonstrate that the observed patterns of species co-occurrence depend on the distance to the nearest urban structure and the amount of herb, shrub, and tree cover, indicating that these habitat features influence whether native species avoid or co-occur with exotic species. Our study represents an important contribution to the understanding of temporal dynamics in the co-occurrence between exotic and native species within urban ecological reserves.
Invasive species hinder the conservation objectives of natural protected areas, particularly of those found within or nearby urban settlements. Identifying the habitat and landscape traits that ...determine the establishment and persistence of populations is essential for implementing effective management plans to control invasive species. We employed multi-season occupancy models to identify the habitat and landscape traits that determined the local colonization and extinction probabilities of an invasive bird (House Sparrow—
Passer domesticus
), in order to provide recommendations for controlling its population within a natural protected area immersed in Mexico City. We selected traits that exhibited management potential to provide feasible recommendations for controlling the species. We observed that increasing values of shrub cover, tree cover, and distance to developed areas discouraged the sparrow from invading new sites of the reserve. Simultaneously, greater distances to developed areas promoted the extinction of the species across invaded sites. These effects might be related to resource availability, foraging preferences of the species, predatory exposure, and competition. Preserving tree and shrub cover as a natural barrier for dissuading species arrival represents a key management objective for its control in the reserve. Greater management efforts must be focused at those sites of the reserve that are closer to developed areas, given that the latter may function as source habitats for the House Sparrow. Our approach for identifying management actions that impact the population dynamics of an invasive species might provide crucial results to control this type of populations. Such a strategy could be replicated for other species and natural protected areas to enhance the conservation value of reserves and provide alternatives when dealing with invasive species.
Despite being highly modified environments, cities are important reservoirs of biodiversity. The ecological reserve situated within southern Mexico City houses several species of mammals, including ...the ringtail
Bassariscus astutus
. However, the urban areas surrounding the reserve are subject to various types of uses that could affect the presence of wild species inside and out of the reserve areas. Here, I tested the hypothesis that recreational activities, especially the walking of domestic dogs, can cause the ringtails, smaller sized carnivores, to avoid certain areas. To achieve this, I carried out a survey throughout the reserve and urban landscape, and registered the presence of domestic dogs and ringtails by direct observation or via the detection of feces and latrines during two sampling seasons. I used single species occupancy models to determine the environmental covariates associated with the presence of these carnivores within the reserve and the urban areas around it. In addition, I used two-species occupancy models to estimate the species interaction factor between these species to assess if the presence of domestic dogs has a negative effect over the presence of ringtails. My results reveal that shrub cover in the area affects the occurrence of these species, and that there is no clear evidence that domestic dogs negatively affect the occupancy of ringtails during the studied seasons. These results highlight the capacity of the ringtails to adapt to rapid urbanization, but do not guarantee that recreational activities, especially those involving dogs, have no negative effects on the local distribution of other smaller mammals within this urban reserve.
Long‐distance migration allows many bird species to overcome the severe climatic changes that occur in seasonal environments. Migration is highly demanding, and given its cyclical nature, we ...currently know that it has substantial effects on the population parameters of migratory birds during both breeding and wintering seasons. However, the potential effects of the presence of migratory birds in their wintering grounds on populations of resident birds have remain largely unexplored. Here, we propose the hypothesis that migratory birds negatively affect the habitat occupancy and population abundance of resident birds because of the arrival of numerous individuals during the most limiting months of the year. Here, we studied different species of migratory and resident birds that coexist during winter in an urban ecological reserve located within Mexico City. We used single‐species multiseason occupancy models, two‐species occupancy models, and distance sampling techniques to evaluate changes in occupancy and population density of resident bird species during three consecutive winters. We found an aggregation pattern between two resident species (Psaltriparus minimus and Thryomanes bewickii) with three migratory warblers (Cardellina pusilla, Setophaga coronata and Setophaga townsendi). Thus, our results provide evidence of the formation of mixed‐species flocks in our study area. We also conclude that resident birds experience different demographic and behavioral processes during winter that not necessarily result from interspecific interactions with migratory birds.
We used occupancy models and distance sampling techniques to evaluate changes in occupancy and population density of resident bird species in response to the presence of migratory birds within an urban ecological reserve. We found an aggregation pattern between two resident species with three migratory warblers. Our results provide evidence of the formation of mixed‐species flocks in our study area, and suggest that some of the observed demographic changes were not necessarily derived from interspecific interactions.
Abstract Urban ecological reserves are large green areas immersed within cities where native and exotic species of plants and animals coexist. Here, we examined the environmental features that ...facilitate the occurrence of nine species of native birds in an urban ecological reserve located within one of the largest cities in the world, Mexico City. We also searched for changes in occupancy rates among the three distinct climatic seasons that occur in central Mexico: warm-dry, rainy, and cold-dry. Using data collected during four years and multi-season occupancy models, we found that most of our study species prefer the urbanized sites that surround the reserve over the core conservation areas. This urban affinity can be explained by the diverse vegetation that prevails in such urban sites, which offers a high habitat heterogeneity that facilitates the presence of bird species with distinct ecological needs. In contrast, the reserve consists of a relatively homogeneous xerophytic scrubland where a few species of shrubs and small trees are dominant. We also detected seasonal changes in five species, with highest occupancy during the warm-dry season of each year, which coincides with both their breeding season and the driest period of the year. This finding indicates that these birds find in the reserve and surrounding urban areas enough food and water during this limiting season as well as safe nesting sites. Our study provides evidence that some native birds can become urban exploiters and that the benefits that they obtain from urban settings are greatest during their breeding season.
•Harris’s hawks occupy between 16% and 32% of the green areas in Mexico City.•There are between 81 and 181 individuals of this species in central Mexico City.•Population density ranges between 0.28 ...and 0.62 individuals per square kilometer.•Both population abundance and occupancy increased during the rainy season.•Harris’s hawks contribute to controlling populations of invasive species.
Urban green spaces have the potential to harbor a rich biodiversity, including top predators, which maintain the structure and regulate the dynamic processes of these urban ecosystems. Conservation of top predators in cities requires quantitative knowledge of their populations. In this study, we provide critical information about population abundance and site occupancy rates of Harris’s hawks (Parabuteo unicinctus) inhabiting urban green spaces in one of the largest cities in the world, Mexico City. We asked if this population permanently resides in the city or, alternatively, if individuals move into the city only during particular periods of the year. In addition, we tested the hypothesis that prey abundance in urban green spaces is the most important environmental trait that promotes the presence of this raptor in this megacity. We found that both population abundance and site occupancy rates differed between the dry and rainy seasons, increasing during the latter season. This seasonal change indicated that some individuals immigrated to the city and/or the presence of juveniles that were born just before the rainy season. Interestingly, their habitat preferences differed between seasons. During the dry season, when hawks are apparently nesting, they occupy parks surrounded by tall buildings and located relatively far from other green areas. In contrast, during the rainy season, hawks prefer parks with high abundance of large prey (doves and pigeons). Based on our findings, we propose specific management actions aimed at facilitating the presence of nesting individuals in the urban landscape.
The evolution of matrotrophy (post-fertilization maternal provisioning to developing embryos) has been explained through several hypotheses. Trexler and DeAngelis proposed in 2003 a theoretical model ...that defines the ecological conditions under which matrotrophy would be favored over lecithotrophy (pre-fertilization maternal provisioning). According to this model, matrotrophy offers a selective advantage in environments with abundant and constantly available food, whereas environments with limited and fluctuating food resources should instead promote a lecithotrophic mode of maternal provisioning. This model also proposes that matrotrophy entails the consequence of leaner reproductive females and in turn shorter lifespans. In this study, we examined the Trexler-DeAngelis model using data from 45 populations of five viviparous species from the fish genus
Poeciliopsis
(family Poeciliidae). We used the matrotrophy index (MI) as a measure of post-fertilization maternal provisioning, and the index of stomach fullness and individual body condition (BC) as proxies for food availability. We also estimated the magnitude of fluctuations in food availability by calculating the temporal variances of these two proxies. Neither abundant nor constantly available food were associated with greater degrees of matrotrophy, which fails to support the predictions of the Trexler-DeAngelis model with respect to the ecological drivers of increased post-fertilization provisioning to embryos. Nonetheless, in all five species we observed that females with greater degrees of matrotrophy had poorer BC compared to females that provided less nutrients to embryos after fertilization. This finding is consistent with one of the expected consequences of advanced matrotrophy according to the Trexler-DeAngelis model, namely, a detriment to the nutritional status of females. Our study provides compelling evidence that gestating females experience a trade-off between post-fertilization provisioning to embryos and self-maintenance, revealing in turn that matrotrophy is a costly reproductive strategy.
Exotic species are fairly common within cities. However, urban areas also contain isolated fragments of original ecosystems, which may act as small ecological reserves. Unfortunately, these natural ...areas that are completely surrounded by urban structures are more vulnerable to human-induced disturbance and to the presence of nonnative species. Given the importance of these remnants of original ecosystems embedded within cities, efforts must be made to know if, once a nonnative species enters an urban reserve, it occupies the majority of the area or becomes restricted to some specific patches. This knowledge is important to determine the invasiveness and success of nonnative species, as well as the level of threat to the native biota. Additionally, it is important to understand which microhabitat conditions promote the presence and establishment of such nonnative species. Here, we used occupancy models to estimate the proportion of the total area that is occupied by exotic species of plants and animals within a natural reserve completely surrounded by urban areas. We also examined which environmental factors are associated with the presence of these exotic plants and animals. Our results revealed that occupancy of nonnative species is relatively high (>40%) within this urban reserve. However, we found an overall preference of nonnatives for specific patches of the reserve where human-made structures are present and where gardening activities take place. Some of the species that we studied deserve special attention because of their potential negative effects on native species.
In North American glyptodonts, the identification of the genus Glyptotherium revolves primarily around characters of the carapace. However, previous studies suggest the possibility of a wide range of ...intraspecific variation. We report two glyptodont specimens from the Mexican states of Tamaulipas and Tlaxcala. We offer a description of their skeletal and carapace elements as well as a brief review of glyptodont distribution in Mexico. Our initial analysis led us to conclude that the glyptodont from Tamaulipas bears similarities to Glyptotherium cylindricum whereas the Tlaxcala specimen resembles Glyptotherium floridanum. However, further study of previously unreported skeletal elements, in association with characters of the carapace, suggested similarity between the two species. Hence we assigned the two glyptodonts to the species G. cylindricum, which has nomenclatural priority. The addition of new morphological characteristics helped to discern synonymy of these two glyptodont species.
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