No abstract

Paleogene arthropod biotas have proved important for tracing the faunal turnover and intercontinental faunal interchange driven by climatic warming and geodynamic events [1-5]. Despite the large number of Paleogene fossil arthropods in Europe and North America [5-8], little is known about the typical Asian (Laurasia-originated) arthropod biota. Here, we report a unique amber biota (50-53 million years ago) from the Lower Eocene of Fushun in northeastern China, which fills a large biogeographic gap in Eurasia. Fushun amber is derived from cupressaceous trees, as determined by gas chromatography-mass spectrometry, infrared spectroscopy, and paleobotanical observations. Twenty-two orders and more than 80 families of arthropods have been reported so far, making it among the most diverse amber biotas. Our results reveal that an apparent radiation of ecological keystone insects, including eusocial, phytophagous, and parasitoid lineages, occurred at least during the Early Eocene Climatic Optimum. Some insect taxa have close phylogenetic affinities to those from coeval European ambers, showing a biotic interchange between the eastern and western margins of the Eurasian landmass during the Early Paleogene.

Insect faunas are extremely rare near the latest Cretaceous with a 24-million-year gap spanning from the early Campanian to the early Eocene. Here, we report a unique amber biota from the Upper Cretaceous (uppermost Campanian ~72.1 Ma) of Tilin, central Myanmar. The chemical composition of Tilin amber suggests a tree source among conifers, indicating that gymnosperms were still abundant in the latest Campanian equatorial forests. Eight orders and 12 families of insects have been found in Tilin amber so far, making it the latest known diverse insect assemblage in the Mesozoic. The presence of ants of the extant subfamilies Dolichoderinae and Ponerinae supports that tropical forests were the cradle for the diversification of crown-group ants, and suggests that the turnover from stem groups to crown groups had already begun at ~72.1 Ma. Tilin amber biota fills a critical insect faunal gap and provides a rare insight into the latest Campanian forest ecosystem.

The end-Permian mass extinction (EPME; ca. 252 Ma) led to profound changes in lacustrine ecosystems. However, whether or not post-extinction recovery of lacustrine ecosystems was delayed has remained uncertain, due to the apparent rarity of Early and Middle Triassic deep perennial lakes. Here we report on mid–Middle Triassic lacustrine organic-rich shales with abundant fossils and tuff interlayers in the Ordos Basin of China, dated to ca. 242 Ma (around the Anisian-Ladinian boundary of the Middle Triassic). The organic-rich sediments record the earliest known appearance, after the mass extinction, of a deep perennial lake that developed at least 5 m.y. earlier than the globally distributed lacustrine shales and mudstones dated as Late Triassic. The fossil assemblage in the organic-rich sediments is diverse and includes plants, notostracans, ostracods, insects, fishes, and fish coprolites, and thus documents a Mesozoic-type, trophically multileveled lacustrine ecosystem. The results reveal the earliest known complex lacustrine ecosystem after the EPME and suggest that Triassic lacustrine ecosystems took at most 10 m.y. to recover fully, which is consistent with the termination of the “coal gap” that signifies substantial restoration of peat-forming forests.

A comprehensive, but simple-to-use software package for executing a range of standard numerical analysis and operations used in quantitative paleontology has been developed. The program, called PAST (PAleontological STatistics), runs on standard Windows computers and is available free of charge. PAST integrates spreadsheet-type data entry with univariate and multivariate statistics, curve fitting, timeseries analysis, data plotting, and simple phylogenetic analysis. Many of the functions are specific to paleontology and ecology, and these functions are not found in standard, more extensive, statistical packages. PAST also includes fourteen case studies (data files and exercises) illustrating use of the program for paleontological problems, making it a complete educational package for courses in quantitative methods.

Chinese fossils reveal a Triassic insect radiation.

No abstract

Being implied in flight, mimetism, communication, and protection, the insect wings were crucial organs for the mega diversification of this clade. Despite several attempts, the problem of wing evolution remains unresolved because the basal parts of the veins essential for vein identification are hidden in the basivenal sclerites. The homologies between wing characters thus cannot be accurately verified, while they are of primary importance to solve long-standing problems, such as the monophyly of the Palaeoptera, viz. Odonatoptera, Panephemeroptera, and Palaeozoic Palaeodictyopterida mainly known by their wings. Hitherto the tools to homologize venation were suffering several cases of exceptions, rendering them unreliable. Here we reconstruct the odonatopteran venation using fossils and a new 3D imaging tool, resulting congruent with the concept of Riek and Kukalová-Peck, with important novelties, viz. median anterior vein fused to radius and radius posterior nearly as convex as radius anterior (putative synapomorphies of Odonatoptera); subcostal anterior (ScA) fused to costal vein and most basal primary antenodal crossvein being a modified posterior branch of ScA (putative synapomorphies of Palaeoptera). These findings may reveal critical for future analyses of the relationships between fossil and extant Palaeoptera, helping to solve the evolutionary history of the insects as a whole.