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Across terrestrial ecosystems, modern ants are ubiquitous. As many as 94 out of every 100 individual arthropods in rainforests are ants, and they constitute up to 15% of animal biomass in the Amazon. Moreover, ants are pervasive agents of natural selection as over 10,000 arthropod species are specialized inquilines or myrmecomorphs living among ants or defending themselves through mimicry. Such impact is traditionally explained by sociality: ants are the first major group of ground-dwelling predatory insects to become eusocial, increasing efficiency of tasks and establishing competitive superiority over solitary species. A wealth of specimens from rich deposits of 99 million-year-old Burmese amber resolves ambiguity regarding sociality and diversity in the earliest ants. The stem-group genus Gerontoformica maintained distinct reproductive castes including morphotypes unknown in solitary aculeate (stinging) wasps, providing insight into early behavior. We present rare aggregations of workers, indicating group recruitment as well as an instance of interspecific combat; such aggression is a social feature of modern ants. Two species and an unusual new genus are described, further expanding the remarkable diversity of early ants. Stem-group ants are recovered as a paraphyletic assemblage at the base of modern lineages varying greatly in size, form, and mouthpart structure, interpreted here as an adaptive radiation. Though Cretaceous stem-group ants were eusocial and adaptively diverse, we hypothesize that their extinction resulted from the rise of competitively superior crown-group taxa that today form massive colonies, consistent with Wilson and Hölldobler's concept of "dynastic succession."

A hallmark of animals that are eusocial, or those with advanced sociality, is reproductive specialization into worker and queen castes. In the most derived societies, these divisions are essentially fixed and in some arthropods, include further specialization--a tripartite system with a soldier caste that defends the colony. Eusociality has originated numerous times among insects but is believed to have appeared first in the termites (Isoptera), in the Early Cretaceous. However, all termites known from the Cretaceous have, until now, only been winged reproductives (alates and dealates); the earliest soldiers and definitive workers were known from just the Miocene (ca. 17-20 million years ago [mya]). Here, we report six termite species preserved in Early Cretaceous (ca. 100 mya) amber from Myanmar, one described as Krishnatermes yoddha gen. et sp. nov., comprising the worker/pseudergate, winged reproductive, and soldier, and a second species, Gigantotermes rex gen. et sp. nov., based on one of the largest soldier termites yet known. Phylogenetic analysis indicates that Krishnatermes are in the basal "Meiatermes-grade" of Cretaceous termites. Workers/pseudergates of another four species are briefly described, but not named. One of these workers/pseudergates reveals that ants--the most serious enemies of modern termites--lived in close proximity to termites in the Burmese paleofauna. These discoveries demonstrate the Mesozoic antiquity of specialized termite caste systems and corroborate that among all social species, termites probably had the original societies.

The amber fossil record of land snails is poorly studied, with few described species relative to other invertebrate groups (e.g., insects and chelicerates). Recently discovered land snail amber fossils from Myanmar present an important opportunity to understand the tropical land snail fauna of the Cretaceous, which was a time when many terrestrial invertebrates were rapidly diversifying. We describe 12 new land snail species in 3 families from mid-Cretaceous Burmese amber: Eotrichophorus kachin gen. et sp. nov., Perissocyclos kyrtostoma gen. et sp. nov., Macropupina electricus gen. et sp. nov., Paleodiplommatina spelomphalos gen. et sp. nov., Xenostoma lophopleura gen. et sp. nov. and Assiminea striatura sp. nov. and six species of uncertain taxonomic affinity. We also discuss the fossil history of the Cyclophoroidea. We report the first mid-Cretaceous land snail species with periostracal hairs and discuss their adaptive significance, as well as the general paleoecology of Burmese mid-Cretaceous tropical land snails.

David Grimaldi introduces amber and the fossils contained therein.

Summary Myrmecophiles—species that depend on ant societies—include some of the most morphologically and behaviorally specialized animals known [1]. Remarkable adaptive characters enable these creatures to bypass fortress-like security, integrate into colony life, and exploit abundant resources and protection inside ant nests [2, 3]. Such innovations must result from intimate coevolution with hosts, but a scarcity of definitive fossil myrmecophiles obscures when and how this lifestyle arose. Here, we report the earliest known morphologically specialized and apparently obligate myrmecophile, in Early Eocene (∼52 million years old) Cambay amber from India. Protoclaviger trichodens gen. et sp. nov. is a stem-group member of Clavigeritae, a speciose supertribe of pselaphine rove beetles (Coleoptera: Staphylinidae) heavily modified for myrmecophily via reduced mouthparts for trophallaxis with worker ants, brush-like trichomes that exude appeasement compounds, and fusions of many body and antennal segments [4, 5]. Protoclaviger captures a transitional stage in the evolutionary development of this novel body plan, most evident in its still-distinct abdominal tergites. The Cambay paleobiota marks one of the first occurrences in the fossil record of a significant presence of modern ants [6]. Protoclaviger reveals that sophisticated social parasites were nest intruders throughout, and probably before, the ascent of ants to ecological dominance, with ancient groups such as Clavigeritae primed to radiate as their hosts became increasingly ubiquitous.

Amber from northern Myanmar has been commercially exploited for millennia, and it also preserves the most diverse palaeobiota among the worlds' seven major deposits of Cretaceous amber. Recent estimated ages vary from Albian to Cenomanian, based on palynology, an ammonoid, and Mesozoic insect taxa preserved within the amber. The burmite-bearing rock is sedimentaryand consists mainly of rounded lithic clasts (0.03w0.15 mm in diameter), with minor fragments of quartz and feldspar. Among the lithic clasts are mostly volcanic rocks. Zircons separated from the amber matrix form two groups: Group-I zircons are overgrown and have variable CL patterns, experienced slight geological disturbances after they formed, and their Ion microprobe 206 Pb/ 238 U ages fall into a very narrow range of w102 Maew108 Ma; Group-II zircons are typical magmatic ones with rhythmically flat zones, inferred to be derived fromvolcanic rock clasts, and yielded a concordia 206 Pb/ 238 U age of 98.79 � 0.62 Ma. The dating on Group-I zircons is only for their interiors, thus hiding what age excursion might come from the overgrowth. Considering the nearshore marine environment and 1-m thickness of the burmite-bearing sediments, and the syn- and post-eruption deposition of volcanic clasts, the age of 98.79 � 0.62 Ma therefore can be used as a maximum limit for the burmite(eitheratorafter),establishinganearliestCenomanianageforthefossilizedinclusions.Theagealso indicates that volcanic eruption occurred at 98.79 � 0.62 Ma in the vicinity of the Hukawng Valley.

Examination of two pieces of amber from the mid-Cretaceous of Myanmar revealed seven inclusions of leafy liverworts that we assign to the extinct Frullania cretacea Hentschel et al. 2009. These inclusions show a suite of characters that were not visible in the type specimen of F. cretacea . The new gametophytes consistently display rectangular to ovate underleaves that have two long-ciliate apical teeth in addition to 0–2 blunt lateral teeth. A narrow stylus is present on at least some leaves. The lobules usually form water sacs that are 1.2–2.3 times longer than wide, and are arranged at some distance from the stem. The observed combination of character states is not present in extant crown group lineages of Frullania . A syninclusion in one of the amber pieces is interpreted as a detached gynoecium of a second Cretaceous Frullania species and is described as F. baerlocheri , sp. nov. The subgynoecial underleaves of the syninclusion are suborbicular in shape, and allow for a separation of this species from F. cretacea . The described amber inclusions are the oldest representatives of an extant genus of leafy liverworts known so far.

Mesozoic bryophyte fossils are rare and often assigned to form genera only. Here, we describe a fragment of a leafy liverwort preserved in Cenomanian amber from northern Alaska, and place it in a new genus, Kaolakia. The extinct species Kaolakia borealis resembles the extant Frullaniaceae in having perianths with a beak, as well as complicate-bilobed incubous leaves with a Frullania-type water sac; however, two water sacs are consistently present on each side of the stem. This character resembles Lepidolaenaceae and Goebeliellaceae, although the extant members of these families have coelocaules or truncate perianths. Thus our fossil likely represents an extinct lineage with affinities to Porellales, the primarily epiphytic clade of the leafy liverworts, and is possibly closely related to Frullaniaceae.

Three genera and species of Scydmaeninae (Staphylinidae) are described as new from mid-Cretaceous Burmese amber: Ektatotricha paradoxa Chatzimanolis, Engel & Newton gen. et sp. nov. and Electroatopos castaneus Chatzimanolis, Engel & Newton gen. et sp. nov. in the emended supertribe Hapsomelitae, and Kachinus antennatus Chatzimanolis, Engel & Newton gen. et sp. nov. in the supertribe Scydmaenitae. The supertribe Hapsomelitae is newly diagnosed and doubt cast on one of its putative apomorphies, with the development of a “patella” considered a misinterpretation by the original authors.

A new amber-rich deposit has been identified in the Upper Cretaceous (Santonian) Eutaw Formation exposed in eastern Alabama, U.S.A. Amber occurs as common parautochthonous clasts and in direct association with conifer plant parts in the lower part of a thin, laterally discontinuous, carbonaceous and pyritiferous clay lens that was deposited in a tidal channel within a transgressive estuarine bayhead-delta system. Organic inclusions are common in amber clasts and include plant and fungal debris and terrestrial arthropod remains. The latter include mites, a spider in association with its web, and scale insects. Amber-plant associations and amber geochemistry indicate that resins were derived from the Cupressaceae, virtually identical to the trees that produced the Turonian-aged amber from central New Jersey, USA.

The verification of DNA sequences obtained from very old tissue sources as indeed ancient is a major point of discussion in the ancient DNA field. Proper controls and the use of the phylogenetic approach are the general methods employed for verification of the ancient DNA. Most studies have reported the recovery of extremely small amounts of nucleic acids which are sheared into rather small fragments. In addition, problems such as 'PCR jumping' can produce spurious sequence information. These observations suggest that random amplification techniques and the development of primers for highly informative but short target regions are essential for the further development of the ancient DNA field.

Attempts to forge amber inclusions have been known from ancient times, when natural materials such as melted amber or copal were used. At the very beginning of the Twentieth Century these natural materials were mostly replaced by Bakelite and similar synthetic polymers. These materials are not transparent and so can readily imitate certain kinds of milky amber but are useless in terms of transparent ambers with inclusions. In the 1940s two new classes of organic materials became available for amber imitation, i.e. polyester resins and epoxy resins. Both are transparent, able to dissolve organic dyes and can achieve an appropriate degree of hardness, depending on the addition of fillers (e.g. fiberglass), the structure of the original monomers, and the degree of crosslinking. With easy commercial availability and sophisticated “artwork” one can prepare convincing imitations of large transparent amber pieces with a wide variety of “inclusion” (ants, bees, lizards, mosquitos, etc.). Py-GC provides a simple test for the unmasking of such fakes, and Py-GC/MS can identify quite precisely the structures of the materials used for these purposes. A growing number of fossil forgeries produced in the Dominican Republic, and sold there and in New York, have been documented. The results reported are based largely on forgeries acquired by D. Grimaldi specifically for this study and kept at the American Museum of Natural History in New York; and from the Conservation Center's collection of forged artifacts and jewelry made available by New York galleries and private collectors.