The Phanerozoic history of life is characterized by at least seven protracted, stepwise increases in predation, herbivory, bioturbation, bioerosion, and control of nutrient cycles by organisms. During the Mesozoic era, there are at least two episodes, one concentrated in the Late Triassic to Early Jurassic interval, and the other beginning in the mid-Cretaceous, about 100 Ma. This second Mesozoic revolution witnessed the origin of 19 important innovations related to competition and predation, as well as the enormous expansion of diversity of angiosperms, fungi, and insects on land and of gastropods and fishes in the sea. The great excess of diversity on land, which dates to this revolution, owes its origins to the vast radiations of plants and their associated pests, dispersers, and pollinators. These radiations, as well as the increased emphasis on rapid locomotion and consumption in the sea, were made possible by a three- to four-fold increase in the photosynthetic capacity of phylogenetically derived eudicot angiosperms beginning about 100 Ma. Higher productivity throughout the biosphere made modes of life that require high inputs of energy and power feasible, and brought about renewed enemy-related escalation. The Mesozoic revolution modernized the global biota and set the stage for additional episodes of escalation during the Cenozoic era. The ultimate cause triggering all these episodes is the tectonic and erosion-related introduction of nutrients, together with warm conditions and increasing levels of oxygen in the atmosphere.

The pectinid bivalve genus Neithea is an important indicator for understanding the Cretaceous biogeographic relationships between the Tethyan Realm and peripheral regions. However, its records in the Northeast Pacific have been scarce and Neithea (Neithea) grandicosta Gabb is the only known species from this area, though its stratigraphic range and morphology are poorly known. Recently collected specimens of N. (N.) grandicosta from the Hauterivian and Upper Aptian parts of the Budden Canyon Formation in northern California are described in detail. It is possible that the stratigraphic distribution of Neithea in the Northeast Pacific is also restricted to the Lower Cretaceous as it is in the Northwest Pacific. It can be considered that the demise of the Tethyan biota and following origination of endemic fauna in the post-Aptian Cretaceous occurred not only in the Northwest Pacific, but also in the Northeast Pacific. The stratigraphic distribution of the non-rudist Tethyan bivalves and other Tethyan biota in the Northeast Pacific is an important clue for understanding major mid-Cretaceous biogeographic changes in the entire North Pacific.

The Lamniformes are a shark clade which occupies the highest trophic-level regimes in extant marine ecosystems, and includes the largest fish-eating shark, Carcharodon carcharias. However, the ancestor of this taxon is thought to be a small shark. In order to evaluate the trophic position of the lamniform shark ancestor, I first developed a new method to estimate the mouth size of fossil lamniform sharks from isolated teeth, and then estimated the mouth size of the oldest recorded lamniform shark genus, Protolamna. This method can predict the mouth size of a fossil lamniform shark if the original tooth position within a jaw or the most closely related extant species is unknown. The result suggests that the mouth size of Protolamna was smaller than most extant Lamniformes. This estimate indicates that they likely fed on small prey, considering that mouth size determines the upper limit of prey size. This finding indicates that extant lamniform sharks evolved from lower trophic-level ancestors.

The development of the climate during the Cretaceous greenhouse interval is reviewed based on geological and paleontological records, geochemical proxy records for paleotemperature and atmospheric carbon-dioxide concentration (pCO₂), the production rate of oceanic crust, and the timing and scale of emplacement of large igneous provinces. Geological and paleontological evidence, and paleotemperature records indicate that the Early Cretaceous climate was relatively cool, possibly accompanied by the development of continental ice sheets. Subsequent warming reached a peak in the Turonian, when sea surface temperatures in equatorial and high-latitude regions exceeded 36° C and 20° C, respectively. The possibility of a maximum temperature above 36° C at the equator is inconsistent with the cirrus cloud negative-feedback hypothesis proposed for the modern ocean, which may indicate that the hypothesis is not valid for an ice-free greenhouse system. Although elevated levels of pCO₂ are thought to be responsible for this extreme warming, the timing of the pCO₂ maxima differs from the timing of oceanic volcanic activity, which emitted massive amounts of CO₂ into the atmosphere, by ∼30 m.y.: volcanic activity peaked at ∼120 Ma, whereas pCO₂, temperature, and sea-level peaked at ~90 Ma, indicating that the abiotic Mesozoic marine revolution was not a simple, single event. Moreover, the occurrence of intermittent cooling during the Late Cretaceous, coupled with sea-ice development in the Arctic Ocean, suggests that the mid-Cretaceous greenhouse system was capable of producing not only extreme warmth but also seasonal freezing. Although the Mesozoic marine revolution is assumed to have been triggered by the general warming that occurred during the Cretaceous, a more precise analysis of the timing and magnitude of biotic events is required to understand the paleoecosystem of this greenhouse period.

We have examined the impact of the Mesozoic algal revolution using biogeochemical simulations to analyze the energy flux into the subsurface environment. In particular, the delivery scheme of energy to the subsurface was dramatically altered by the appearance of mineralized exoskeletons, both in algal groups (e.g., coccolithophores) and in zooplanktic taxa. These biominerals, acting as ballast, accentuated the delivery of organic matter to subsurface waters. Thus, the elevated organic carbon flux associated with evolutionary developments in Mesozoic taxa caused an intense but short-lived oceanic euxinia, without an associated mass extinction event, in sharp contrast to the relatively prolonged Paleozoic euxinia that were generally coincident with mass extinctions.

The advent of flowering plants on land has been suggested previously as a potential trigger for Cretaceous innovations in the marine realm by providing a greater energetic base for marine ecosystems through a more nutrient-rich terrestrial runoff. The scope of the angiosperm radiation certainly was unprecedented—flowering plants came to represent the large majority of species in all terrestrial floras in a geologically short span of time—and angiosperms possess much higher photosynthetic and hydraulic capacities than all other plants. Angiosperm evolution could have affected both the organic and inorganic content of terrestrial runoff, but the magnitude of these changes is in question. Angiosperms are more productive than other plants, suggesting an increase in organic matter runoff, but that quantity is small in comparison to native marine photosynthesis even in the modern angiosperm-dominated world. Changing the inorganic nutrient content of terrestrial runoff requires changing weathering rates, but angiosperms and earlier appearing vascular plants appear to be little different in this respect. Thus, the potential for angiosperms to have strongly influenced marine evolution may have been small. The greatest opportunity for angiosperms to have changed weathering rates may come from their impact on terrestrial climate. Their greatly elevated transpiration capacities feed rainfall and this enhancement of the hydrological cycle means that angiosperms may have increased weathering rates in aggregate even if they have little effect individually. The timing of the angiosperm radiation is both crucial and problematic, since their rise to ecological dominance is thought to lag significantly behind their increase in species diversity, thereby diminishing the correspondence with events in the marine realm.

The isotopic composition of fossil animal substances has performed an important role as an indicator of ecological signature for Cenozoic mammals over the last few decades. Recently, isotopic analysis of Cretaceous vertebrates has been used to reconstruct paleoecology, but the effect of diagenesis on such old materials has not been well understood. An evaluation of the effect of diagenesis on enamel from Cretaceous vertebrates is necessary to determine the reliability of isotopic paleoecology. I evaluated the extent of diagenetic effect on enamel from Cretaceous mosasaurs by using Fourier Transform Infrared Spectroscopy (FT-IR). Clear diagenetic alteration was not found in the enamel, showing Cretaceous material may retain pristine isotopic information.