A review of short-term (<3 myr: c. 100 kyr to 2.4 myr) Cretaceous sea-level fluctuations of several tens of metres indicates recent fundamental progress in understanding the underlying mechanisms for eustasy, both in timing and in correlation. Cretaceous third- and fourth-order hothouse sea-level changes, the sequence-stratigraphic framework, are linked to Milankovitch-type climate cycles, especially the longer-period sequence-building bands of 405 kyr and 1.2 myr. In the absence of continental ice sheets during Cretaceous hothouse phases (e.g. Cenomanian–Turonian), growing evidence indicates groundwater-related sea-level cycles: (1) the existence of Milankovitch-type humid-arid climate oscillations, proven via intense humid weathering records during times of regression and sea-level lowstands; (2) missing or inverse relationships of sea-level and the marine δ ¹⁸ O archives, i.e. the lack of a pronounced positive excursion, cooling signal during sea-level lowstands; and (3) the anti-phase relationship of sea and lake levels, attesting to high groundwater levels and charged continental aquifers during sea-level lowstands. This substantiates the aquifer-eustasy hypothesis. Rates of aquifer-eustatic sea-level change remain hard to decipher; however, reconstructions range from a very conservative minimum estimate of 0.04 mm a ⁻¹ (longer time intervals) to 0.7 mm a ⁻¹ (shorter, probably asymmetric cycles). Remarkably, aquifer-eustasy is recognized as a significant component for the Anthropocene sea-level budget.

The Mesozoic era (∼252 to 66 million years ago) was a key interval in Earth's evolution toward its modern state, witnessing the breakup of the supercontinent Pangaea and significant biotic innovations like the early evolution of mammals. Plate tectonic dynamics drove a fundamental climatic transition from the early Mesozoic supercontinent toward the Late Cretaceous fragmented continental configuration. Here, key aspects of Mesozoic long‐term environmental changes are assessed in a climate model ensemble framework. We analyze so far the most extended ensemble of equilibrium climate states simulated for evolving Mesozoic boundary conditions covering the period from 255 to 60 Ma in 5 Myr timesteps. Global mean temperatures are generally found to be elevated above the present and exhibit a baseline warming trend driven by rising sea levels and increasing solar luminosity. Warm (Triassic and mid‐Cretaceous) and cool (Jurassic and end‐Cretaceous) anomalies result from pCO₂ changes indicated by different reconstructions. Seasonal and zonal temperature contrasts as well as continental aridity show an overall decrease from the Late Triassic‐Early Jurassic to the Late Cretaceous. Meridional temperature gradients are reduced at higher global temperatures and less land area in the high latitudes. With systematic sensitivity experiments, the influence of paleogeography, sea level, vegetation patterns, pCO₂, solar luminosity, and orbital configuration on these trends is investigated. For example, long‐term seasonality trends are driven by paleogeography, but orbital cycles could have had similar‐scale effects on shorter timescales. Global mean temperatures, continental humidity, and meridional temperature gradients are, however, also strongly affected by pCO₂.

The mid-Cretaceous Burmese amber (~99 Ma, Myanmar), widely known for exquisite preservation of theropods, also yields microfossils, which can provide important contextual information on paleoenvironment and amber formation. We report the first Cretaceous ostracod in amber—the gigantic (12.9 mm) right valve of an exclusively marine group (Myodocopa: Myodocopida) preserved in Burmese amber. Ostracods are usually small (0.5–2 mm), with well-calcified carapaces that provide an excellent fossil record extending to at least the Ordovician (~485 million years ago), but they are rarely encountered in amber. The new specimen effectively doubles the age of the ostracod amber record, offering the first representative of the Myodocopa, a weakly calcified group with a poor fossil record. Its carapace morphology is atypical and likely plesiomorphic. The preserved valve appears to be either a moulted exuvium or a dead and disarticulated specimen, and subsequent resin flows contain forest floor inclusions with terrestrial arthropods, i.e., fragmentary remains of spiders, and insect frass. These features resolve an enigmatic taphonomic pathway, and support a marginal marine setting for resin production.

Despite the fact that the number of publications on the morphologic terms of ostracod carapace features is impressive, definitions, use and interpretation of many terms remain inconsistent and therefore fraught with problems. A particular problem is the application of certain terms of morphologic features in different ostracod groups without the consideration of their potentially different origin, genesis and nature. This revised and annotated glossary focuses on nonmarine ostracods, families Timiriaseviinae (Cytheroidea, Limnocytheridae) and Cyprideidae (extinct, Cypridoidea), particularly on the extinct genera Theriosynoecum and Cypridea in its selection of terms and given examples, and is strongly connected with the preceding papers of this issue (Sames 2011a, b) which also include the supporting illustrations. It as well comprises detailed discussions on the origin and differentiation of the taxonomic or otherwise significance of selected carapace features, particularly ornamentation. Herein, ornamentation is subdivided into area-wide and local ornamentation elements for that reason. In contrast to their patterns of distribution, the presence of local ornamentation elements as well as their degree of expression are considered of no, or rather low, taxonomic significance. If applicable, local ornamentation elements can be used for paleoenvironmental interpretations or to identify juveniles in some cases (e.g. in Cypridea). Type, occurrence and shape of area-wide ornamentation elements are, by contrast, always taxonomically relevant to a certain degree. As to the Family Cyprideidae, the alveolar ridge is newly introduced and defined, and the terms for the anteroventral (alveolus and its elements) and posteroventral regions (cyathus, cyathus-like protrusion) are redefined and discussed. A morphologic term can never be a matter of common or collective knowledge as long as its appreciation and usage differs between researchers. In fact, the accuracy of its usage can only be identified when we know that we are talking about the same thing. With this glossary it is intended to better communicate the views of the author, to integrate new insights into ostracod paleobiology into the interpretation of carapace features, and to propose a kind of harmonization between different concepts as well as to put these up for discussion and further development.