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This chapter presents some of the basic physical and chemical relationships that are relevant to an understanding of the behavior of CO2 in the Earth's surface environment. It would be an understatement to say that the literature on this subject is extensive—it is prodigious! In Chapter 2 we dealt with the Earth's atmosphere in the past and present that is based mostly on the model of an ideal gas. However, CO2 on the Earth's surface interacts with other gases, it dissolves in water, and reacts with water, other dissolved species, and minerals. Many of the chemical reactions involving CO2 are either directly or indirectly mediated by biological processes, as is briefly discussed in Chapter 1 and further addressed in Chapters 6 and 9. [ABSTRACT FROM AUTHOR]

Stable and radioactive isotopes are extensively used as tracers of numerous processes in the planetary and terrestrial environment. The relative abundances of isotopic species measured by their ratios provide indications of the origin of various materials and differences in the abundance ratios that develop in different processes make it possible to identify the mechanisms behind a variety of phenomena in extraterrestrial space, within the solid Earth, on its surface, and in the biosphere. The improvements in the sensitivity and precision of mass spectrometers used for the determination of isotope abundances are continually expanding the number of isotopes that can be identified in natural materials aswell as the understanding of the mechanisms that drivemany parts of the Earth's system. The involvement of carbon dioxide in many geochemical inorganic as well as biogeochemical processes focused long ago attention on the behavior of the different isotopic species of CO2 and made possible many new interpretations of processes in the atmosphere, on land, in the oceanic and continental waters, and within the biosphere. The goal of this Chapter is to review the essentials of the isotope geochemistry of carbon dioxide and the mechanisms of its isotopic fractionation, and to discuss the broader aspects of the global carbon cycle that are based on the carbonisotope geochemistry. [ABSTRACT FROM AUTHOR]

Among the carbon-containing minerals, the carbonates are by far the most abundant in the outer shell of the Earth. Elemental carbon, in the mineral forms of diamond and graphite, forms at higher temperatures and pressures. Occurrences of mineral carbides, such as silicon carbide moissanite (SiC), in terrestrial rocks are rare, but several metal carbides have been found in meteorites (Bernatowicz et al., 1996; Di Pierro et al., 2003). There are salts of organic acids classified as minerals, either containing metal cations or without them, that occur as alteration products in organic-matter-rich sediments or on other minerals that were probably subject to bacterial alteration. [ABSTRACT FROM AUTHOR]

In Chapter 2 we discussed some aspects of the beginnings of the carbon cycle and Precambrian atmospheric CO2 concentrations. The major conclusions, among others, were that (1) atmospheric CO2 levels were relatively high at that time and they provided a necessary greenhouse warming in the period of the faint young Sun, in addition to the possible presence of higher concentrations of other potential greenhouse gases and aerosols (e.g., CH4 and organic volatiles) in the Hadean and early Precambrian atmosphere; (2) because of the high atmospheric CO2 levels, the early oceans were rich in dissolved inorganic carbon and total alkalinity, had a relatively low pH, and might have been depleted in dissolved Ca2+; and (3) as Precambrian time progressed, carbon was removed from the atmosphere and stored mainly in the large geochemical reservoirs of inorganic and organic carbon. [ABSTRACT FROM AUTHOR]

This last chapter of the book examines the global carbon cycle and its links to those of nitrogen and phosphorus in the Earth's outer shell that has been continuously perturbed by human activities for some time. The carbon cycle is linked to other cycles, particularly nutrientNand P, mainly by the biological formation of organic matter that requires N, P, and other elements for the functioning of living cells. The human industrial perturbation started about 200 years ago, the beginnings of the agricultural perturbation are much older, and both may be expected to intensify in the future. Understandably, questions of the future can be answered only from reasonable projections of the past and present, and such answers should be viewed as indications of the trends rather than accurate estimates of where the global environment would be in the next centuries. [ABSTRACT FROM AUTHOR]

In this chapter we review the evolution of the long-term behavior of the global carbon cycle through geologic time and some events of biological evolution and climatic change relevant to that behavior. A discussion of glacial-interglacial changes in the carbon cycle follows to provide background of carbon system behavior prior to major human interference in the carbon cycle. We utilize and emphasize portions of the previous chapters to present a coherent story of trends in the carbon cycle and events that took place and led to major reorganizations of the cycle. This material provides background for discussion in Chapter 11 of the modern carbon cycle and its drivers of nutrient N and P since major human interference in the cycle, a period of time that has become known as the Anthropocene. [ABSTRACT FROM AUTHOR]

In this chapter we address the behavior of inorganic and organic carbon in the shallow coastal ocean where a large part of the biological production and sediment accumulation occur. At present, the coastal zone is more or less synonymous with the continental shelf that is covered by ocean water as a result of ice melting and sea level rise of 120 meters since the end of the Last Glacial Maximum about 18,000 years ago. In some intervals of the geologic past, shallow epicontinental seas were much more widespread during the periods of marine transgressions when the land was covered by seawater due to a rising sea level, caused by such factors as change in the relative elevation of land and(or) displacement of the ocean-water volume by the growth of spreading ridges on the ocean floor. In fact, a large part of marine sediments preserved on the continents was formed in shallow seas of the past that covered parts of the cratons of what are now different continents. The importance of the coastal ocean in the regulation of the global carbon cycle is primarily related to its position at the junction of the land, atmosphere, and open ocean, with all of which it interacts differently and modifies the transport fluxes of carbon. We emphasize in this chapter the inorganic and organic carbon cycles in the coastal ocean at the time scale of the Industrial Era, the last approximately 300 years, and up to three centuries into the future that are the time of increasing perturbations of the global carbon cycle by human activities. [ABSTRACT FROM AUTHOR]

Carbon dioxide dissolved in rain and soil and ground waters is the main acid that reacts with minerals in the sedimentary and crystalline crust, releasing the ionic constituents of river water and producing the bicarbonate ion, HCO-3, in the process. The consumption of CO2 in mineral weathering reactions is a major transfer path of CO2 from the atmosphere to the land in the carbon cycle. On land, CO2 is bound in organic matter by plant photosynthesis, and released into the soil pore space by the remineralization of organic matter. [ABSTRACT FROM AUTHOR]

It is well known that the temperature of the Earth's surface without the atmosphere would have been much colder and probably not suitable for life in the form as we know it. As the conditions on the surface of the two nearest neighboring planets, Venus and Mars, are very different from those on Earth and no life has yet been detected outside our planet, it is difficult to dispute the view that life on Earth is tied to the presence of liquid water and a gaseous atmosphere within the range of temperatures and pressures that characterize the terrestrial near-surface environment. [ABSTRACT FROM AUTHOR]

In this chapterwe discuss Earth's early prebiotic history and the conditions underwhich life emerged. The chapter focuses in particular on the sources and fate of the volatiles that degassed from the Earth's interior and formed its atmosphere, hydrosphere, and sedimentary rocks, giving rise to the global carbon cycle. The chapter also discusses the cooling history and compositional changes of the primordial atmosphere and the early oceans up to the time when life appears. The environmental conditions and the material and energy sources of the early organismal groups are primarily inferred from those of the chemosynthesizing and photosynthesizing organisms of the present. [ABSTRACT FROM AUTHOR]

In the minds of the broad public, carbon dioxide is associated primarily, if not exclusively, with considerations of global warming. This topic has been the focus of undoubtedly great attention in the last decades of the 20th and in the early 21st century owing to the coverage of the subject of global warming and climate change by the news media drawing their information from the results of scientific studies. The role of carbon dioxide as one of the gases that warm the Earth's atmosphere by absorption of infrared or longwave, outgoing Earth radiation has been known since the work of the French scientist Jean-Baptiste-Joseph Fourier in the early nineteenth century and that of the Irish polymath John Tyndall in the middle part of that century. [ABSTRACT FROM AUTHOR]

The Tlayúa Quarry in Tepexi de Rodríguez, Puebla, Mexico, is one of the most important localities in the New World because of its uniquely rich biota. For the last twenty years, its exceptionally well-preserved fossil content and its taphonomical and paleoecological implications have caught the attention of many geologists and paleontologists since this Lagerstätte represents an important new asset in Mexican Paleontology. In this paper, we review all the recent investigations related to a development of the paleoecological models to explain the extraordinary conservation of the rich and diverse fossil assemblage of Tlayúa. [ABSTRACT FROM AUTHOR]

Although the earliest report of a fossil mammal from Mexico dates from 1799, our knowledge of the group is still poor. The Mexican mammalian fossil record is biased towards the large-sized taxa and younger ages. The mammalian record in Mexico ranges from the Jurassic to the Quaternary. Most of the Cenozoic epochs, except for the Paleocene, have mammal bearing deposits. There are exists gaps, such as late Eocene early Oligocene, early Miocene, and early-late Miocene, where no fossils have been found. The Mesozoic mammalian record is poorly represented by three localities in the northern part of Mexico. The early Tertiary is also represented by only a few localities widespread throughout Mexico. The late Tertiary (late Miocene-early Pliocene) is represented from well documented exposures in the central part of Mexico. Although the Quaternary record is very abundant and is present in all the states of Mexico, there are problems with detailed dating of these localities and little is known about small size mammals. Due to its geological history and geographic position, Mexico bears a great diversity of environmental conditions, which is reflected in its high extant mammal biodiversity. Mexico played an important role in the evolution of several mammal groups during the Cenozoic. During the late Mesozoic and early Cenozoic, Mexico was the southernmost landmass of North America, where several mammal groups evolved, adapting to more tropical conditions. Later, during the Great American Faunal Interchange, Mexico was the path for the South American mammal immigrants to northern lands and it was the region where some immigrants remained. The role that Mexico played during the Ice Ages, whether if it was a refuge for northern forms or not has been questioned. Additional work is needed in order to have a more comprehensive understanding of Mexican paleomammals. [ABSTRACT FROM AUTHOR]

Several dinosaur localities have been reported from Mexico. In 1926 Werner Janensch reported the first dinosaur bone remains as Monoclonius from La Soledad, western Coahuila. Since 1926, more dinosaur remains have been reported from the northern Mexican states of Baja California, Sonora, Chihuahua, Coahuila and Tamaulipas. Several dinosaur footprint localities have also been reported from the northern portion of Mexico. From the central and southern Mexican states of Michoacán, Puebla and Chiapas dinosaur remains have also been reported. Recently, fragments of Heterodontosaurus and Syntarsus were found in Tamaulipas. Re-evaluation of dinosaur remains from Puebla indicate that they belong to a tetrapod. In Baja California there are recent findings of Aublysodon teeth. In Chihuahua fragments of a member of Titanosauridae have been found. In Michoacán hadrosaur bones have been reported. The ichnological record has increased in recent years with the discovery of new localities in Coahuila and Puebla, where two localities include tracks of tetrapods, sauropods and ornitopods. Ichnites from one ornitopod family and from several tetrapod families have been reported from Michoacán. Since the discovery of dinosaur remains about 80 years ago, dinosaur discoveries in Mexico have been significant however the field is still in its infancy with much still to be learned. [ABSTRACT FROM AUTHOR]

The amphibian and reptile fossil record in Mexico is scarce. There have been reported 255 unique taxon/locality/age records from 85 localities. Most fossils are fragmentary and their taxonomic status is difficult to assess; however, some are beautifully preserved, permitting even good cladistic and biogeographical analysis. Among amphibians there are records of caudates and anuras, restricted to the Neogene and Quaternary. Reptiles include turtles (which are the most abundant), crocodiles, ichthyosaurs, sauropterygians, a basal lepidosauromorph, sphenodontians, a basal squamate, true squamate lizards, and snakes, from the Late Triassic to the Holocene. Localities are distributed in 21 Mexican states from which Sonora bears most records. Nineteen species based on Mexican fossils have been erected. Three have been considered invalid, one has changed taxonomic status, and at least two more are questioned. Most of the type specimens designated are housed in Mexican institutions. There have been 99 main non-redundant published documents that mention, list, or describe fossil amphibians and reptiles, including scientific papers, books and book chapters of international and national circulation, meeting abstracts, guidebooks and newsletters. Of all papers published, only 51 are formal publications in either national or international press and 40 were published in international journals or editorials. Mexicans have published only 10 international papers. However, Mexican paleoherpetology has significantly increased in the last two decades, although most information is hidden in gray literature of difficult access to the international community. It is imperative that Mexican workers document their discoveries in formal publications. [ABSTRACT FROM AUTHOR]

This paper provides an updated review of the Mesozoic fossil Osteichthyan record of Mexico. This catalogue includes multiple entries of papers, theses, and diverse scientific meeting reports regarding Cretaceous Osteichthyan fishes of Mexico that reflect the present state of knowledge. In addition, it provides a review of the Mexican paleoichthyology history, including the most recent fossil Osteichthyan discoveries. Within this framework some systematic and paleobiogeographical implications generated from the enrichment of the Mexican Mesozoic Osteichthyan record are briefly discussed providing future perspectives to this young field of Mexican science. [ABSTRACT FROM AUTHOR]

Upper Paleozoic fossil invertebrates of Mexico represent communities of marine environments associated with continental margins. A high percentage of very diverse brachiopods and mollusks, accompanied by other lesser diverse groups such as echinoderms, arthropods, bryozoans and corals occur throughout the Upper Paleozoic sequence of Mexico. Outcrops of Carboniferous and Permian rocks are especially abundant and Mexican fossil faunas from those systems exhibit an affinity to similar age fossil faunas from the rest of North America; this is especially true in the youngest faunas. This similarity may be explained by the configuration and geographic position of the Late Paleozoic crustal portions that form modern day Mexico. During the Late Paleozoic Pangea was forming and the ocean that existed between Gondwana and the northern continents was narrowing: during the entire Carboniferous and Early-Middle Permian, that ocean covered large regions of North America and extended over the majority of what constitutes present-day Mexico. [ABSTRACT FROM AUTHOR]

This chapter offers an up to date list of Upper Cretaceous Mexican fossil echinoids. There are 149 known Cretaceous echinoids from 16 states of Mexico including: Baja California Sur, Chiapas, Chihuahua, Coahuila, Guerrero, Hidalgo, Jalisco, Michoacán, Nuevo León, Oaxaca, Puebla, San Luis Potosí, Sonora, Tamaulipas, Tlaxcala and Colima. Up until the first half of the XIX century reports on the fossil echinoids of Mexico were only vaguely mentioned within geological papers. After the XIX century date specific paleontological work on echinoids began to frequently appear. Recently, diverse paleontological studies are in progress, in the State of Chiapas which has generated a local list of nine species registered for the fist time in Mexico belonging to the following genera: Orthopsis sp., Salenia sp., Goniopigus sp., Neotlingaster sp., Gompechinus sp., Lanieria sp., Petalobrissus sp., Gitolampas, sp., and Heteraster sp. These species show great affinities with Caribbean, European and Asiatic faunas. In Mexico there are two principal problems referring to the study of fossil echinoids: one is the lack of investigations focused on biogeographic, evolution and paleobiological aspects; and the second is the lack of a taxonomic revision of echinoid species reported in the literature. [ABSTRACT FROM AUTHOR]

In recent years, the number of described species of fossil crustaceans from Mexico has increased noticeably. Numerous new occurrences and new taxa were described from lithostratigraphic units that range in age from Early Cretaceous to Miocene. These reports included not only the systematic description of the specimens, but also information on paleoenvironment, paleoecology and evolution. The present work is a review of the fossil record of fossil crustaceans from Mexico, including comments on new localities and fauna that are under study. Based on the ongoing research in this field, it is possible that the number of fossil species of brachyurans will reach twice as much as the ones reported nowadays in a few years. [ABSTRACT FROM AUTHOR]

The majority of the Mesozoic scleractinian corals reported from Mexico, 117 species or about 80 percent, are from Cretaceous strata. Comparatively little is known of the earlier Mesozoic corals. The Jurassic corals, a total of 17 species, have been described from five localities in Mexico, all in Upper Jurassic rocks. The 10 Triassic coral species described from Mexico are from the Upper Triassic Antimonio Formation of northwestern Sonora. The majority of the Jurassic and Triassic coral species reported from Mexico have been described previously from occurrences in Europe. [ABSTRACT FROM AUTHOR]

Here we present an up to date study on fossil ophiuroids from Mexico. The specimens come from the following States within the Mexican Republic: Baja California Sur, Chiapas, Chihuahua, Coahuila, Oaxaca and Puebla. The total number of specimens is 20 and one ophiuroid bed that bears many specimens. The ophiuroids have been collected in rocks from upper Paleozoic age (Pennsylvanian) to Pliocene. Almost all specimens are well preserved and with the aid of several techniques such as X rays and detailed images taken from SEM, they are being described. We have recognized two families and four genera all belonging to the order Ophiurida. A new species will soon be published in a research paper. [ABSTRACT FROM AUTHOR]

Mexico, as a country, is remarkable for its abundant Cretaceous fossil invertebrate fauna. During the Cretaceous, what now is Mexico, was almost entirely covered by large shallow seas, which record a number of rudist deposits. The distribution of land masses, seas, climate and low ocean water depth were very suitable for rudist growth. As time passed, the geography changed and rudist abundance, distribution and faunal associations declined. This chapter reviews the close relationship between rudist assemblages and Mexican paleogeography. The data offered herein, concerning the number of genera and species of rudists, is based on what is recorded in the literature. This is not a systematic review because we never take into account synonyms or particular opinions about the validity of one or another genera or species of rudists. Finally we will examine some selected areas with interesting fossil rudist faunas. [ABSTRACT FROM AUTHOR]

The joint discussion of biotic and abiotic factors allows proposal of a hypothesis in which the dynamic nature of the geological processes and of the organisms facilitate the understanding of the biodiversity of Mexico. In this respect, we highlight that since the Cretaceous, Mexico had a configuration similar to that of a peninsula that increased in size through time, but that with the establishment of the Isthmus of Panama approximately 3.5 my ago, it no longer had such a configuration. During this peninsular configuration, the main mountain belts of Mexico formed in different episodes of time attaining variable sizes through dynamic and fluctuant processes until they reached their extant physiognomy. At the same time the retreat of the seas was significant in exposing positive zones of the continent, where life was established. Finally, after occupying their current positions, the Baja California Peninsula and the Yucatan Peninsula started providing cover to the central continental mass of Mexico. The fossil record suggests that while all of this occurred, the newly generated environments were occupied by plants that were formerly part of higher latitude communities of North America. That through the land bridges that connected North America with Europe and Asia, plants with different geographical affinities arrived in Mexico. Also with the establishment of the Chords Block as the northern part of Central America, at least part of the plants already growing on the Chortis Block arrived into the rest of Central America eventually expanding their distribution into South America. The interaction of the biological processes, as suggested by the fossil record with the environment, coupled with the geological setting, promoted the development and establishment of a distinctive biota among which, the endemic plants that characterize today the vegetation of Mexico stand out. Some of the extant Mexican plants were already present in the Oligocene and possibly since the Eocene. Finally, the current landscape and the elements that conform it began their “modernization” some 3.5 million years ago, but they may have a longer history that started in the Cretaceous. [ABSTRACT FROM AUTHOR]

The present work includes a palynofloristic synthesis of Tertiary research carried out at marine and continental basins with particular emphasis on stratigraphy of the Balsas Group sensu Fries (1960). Also it includes palynostratigraphic information related with San Gregorio Formation (Baja California Sur State) and Cuayuca Formation (Puebla State) assemblages. Taxa of chronostratigraphic and ecologic importance are emphasized at every paleobasin. The numerical and cladistic correlation showed that palynological assemblages of units belonging to the Balsas Group are closely related to San Gregorio flora. The results indicate that since the Paleocene, under a tropical regime, an evergreen forest was present together with warm temperate elements. Later, in the Eocene epoch, the tropical floras remained as the principal components of the vegetation. In the Late Eocene - Early Oligocene, the assemblages are a mixture of temperate and desert taxa prevailing over tropical elements at the Sierra Madre Occidental Province. But the subtropical and tropical floras continued as the main components in the Gulf Coast Province where the tropical vegetation stayed up to the Holocene. In contrast, in the western basin localities (Sierra Madre Occidental Province) it was detected a desertification since the Oligocene where savannas and grasses became established. Afterwards, in the Miocene, at the same region, the xerophitic flora dominates the assemblages, proving the existence of a desert at that time. It is evident that the coniferous forest and oak communities inhabit the mountain ranges since the Eocene becoming more abundant in the Oligocene, but they became the dominant taxa in the pollen assemblages from the Neogene to Quaternary. According with the Tertiary flora analyzed in this survey the actual vegetation present in Mexico is a response to climatic changes and active volcanism throughout the Tertiary. Finally, different types of vegetation began to be recognizable in the fossil assemblages since the Oligocene. The historical development of Mexico (tectonic, rifting, volcanism) explains the richness and endemism of Mexican flora. [ABSTRACT FROM AUTHOR]