Vincent Perrichot

Exceptional preservation of marine diatoms in upper Albian amber

Late Albian amber from Charente-Maritime (southwestern France) contains the first known marine diatoms preserved in a fossil resin. Approximately 70 inclusions were assignable to the genera Basilicostephanus, Coscinodiscus, Hemiaulus, Melosira, Paralia, Skeletonema, Stephanopyxis, Trochosira, ?Aulacoseira, and to the order Rhizosoleniales. Some of them are represented by several species. This diatom assemblage is mainly composed of colonial planktonic genera, which are typical for coastal shallow waters. The newly found amber inclusions extend the fossil record of four genera and one order from the Late Cretaceous and support certain molecular phylogenetic assumptions regarding the diversifi cation of marine diatoms in the Early Cretaceous. The unusual introduction of diatom shells from the beach or sea by wind, spray, or high tide onto the resin fl ows was possible because the amber forest grew close to the seashore.

A unique piece of amber and the complexity of ancient forest ecosystems

Studies on amber—fossil resin—have attracted much attention from the scientific community in the last decade. Seven Ph.D. theses with amber as the main material of study recently have been completed (Penney, 1999; Azar, 2000; Schmidt, 2003; Perrichot, 2005; Grund, 2006; Solorzano Kraemer, 2007; Girard, 2008), and two more are currently in progress by Malvina Lak and Jaime Ortega Blanco. From our personal bibliographic databases, we estimate that >1080 papers and books on amber have been published between 1999 and 2008 (as of October 2008). These works have dealt not only with the systematics and phylogeny of arthropods, plant remains, and microorganisms preserved as inclusions in the resin but also with the biogeography, taphonomy, paleoecology, paleoenvironmental reconstructions, chemical and physical properties of amber, its archaeological value, and the development of new methodologies for the analysis of its fossil content.nnA reason for this recent trend, but a consequence of it, too, was the discovery of several new amber deposits during the last 10 years—from the Triassic of Italy (Roghi et al., 2006), the Jurassic of Thailand (Philippe et al., 2005), the Cretaceous of France, South Africa, Spain, and Wyoming in the United States (Alonso et al., 2000; Grimaldi et al., 2000; Gomez et al., 2002; Neraudeau et al., 2002; Guiliano et al., 2006; Pen alver et al., 2007), the Eocene of France, India, and Italy (Nel et al., 1999; Alimohammadian et al., 2005; Trevisani et al., 2005), and the Miocene of Peru (Antoine et al., 2006).nnIn France, Didier Neraudeau, professor of paleontology at the University of Rennes 1, revived studies on Cretaceous amber in 1999 when he discovered the deposit of Archingeay–Les Nouillers, in Charentes, which was soon followed by the discovery of five other deposits …

Testate amoebae from a Cretaceous forest floor microbiocoenosis of France

ABSTRACT. Amber‐preserved shells of testate amoebae often provide as many diagnostic features as the tests of modern taxa. Most of these well‐preserved microfossils are morphologically assignable to modern species indicating either evolutionary stasis or convergent evolution. Here we describe two Lower Cretaceous testate amoebae that are clearly distinguishable from modern species. Centropyxis perforata n. sp. and Leptochlamys galippei n. sp. possessed perforate shells that were previously unknown in these genera. They are preserved in highly fossiliferous amber pieces from the Upper Albian (ca. 100 million years old) of Archingeay/Les Nouillers (Charente‐Maritime, southwestern France). Syninclusions of soil and litter dwelling arthropods and microorganisms indicate a limnetic‐terrestrial microhabitat at the floor of a coastal conifer forest.

Extreme Morphogenesis and Ecological Specialization among Cretaceous Basal Ants

Ants comprise one lineage of the triumvirate of eusocial insects and experienced their early diversification within the Cretaceous [1-9]. Their ecological success is generally attributed to their remarkable social behavior. Not all ants cooperate in social hunting, however, and some of the most effective predatory ants are solitary hunters with powerful trap jaws [10]. Recent evolutionary studies predict that the early branching lineages of extant ants formed small colonies of ground-dwelling, solitary specialist predators [2, 5, 7, 11, 12], while some Cretaceous fossils suggest group recruitment and socially advanced behavior among stem-group ants [9]. We describe a trap-jaw ant from 99 million-year-old Burmese amber with head structures that presumably functioned as a highly specialized trap for large-bodied prey. These are a cephalic horn resulting from an extreme modification of the clypeus hitherto unseen among living and extinct ants and scythe-like mandibles that extend high above the head, both demonstrating the presence of exaggerated morphogenesis early among stem-group ants. The new ant belongs to the Haidomyrmecini, possibly the earliest ant lineage [9], and together these trap-jaw ants suggest that at least some of the earliest Formicidae were solitary specialist predators. With their peculiar adaptations, haidomyrmecines had a refined ecology shortly following the advent of ants.

New Psocoptera in the Early Cretaceous amber of SW France and Lebanon (Insecta: Psocoptera: Trogiomorpha)

Proprionoglaris guyoti gen. nov., sp. nov., Parapsyllipsocus vergereaui gen. nov., sp. nov., and Prospeleketor albianensis gen. nov., sp. nov. are described from the Early Cretaceous amber of Archingeay (SW France). Libanoglaris mouawadi gen. nov., sp. nov. is described from the Early Cretaceous amber of Lebanon. They are all placed into the suborder Trogiomorpha, incertae familiae . The discovery of these new taxa together with a first phylogenetic analysis of the trogiomorphan families demonstrate the necessity of a cladistic redefinition of the currently admitted major subdivisions of this suborder.

The Wagner Parsimony using morphological characters: a new method for palaeosynecological studies

Abstract The limits and difficulties related to the tools currently in use for palaeosynecological comparisons of faunas or floras of different geological periods are discussed. The new method of the Wagner parsimony Applied to Palaeosynecology Using Morphology (WAPUM method), is defined and tested on morphological characters gathered from two insect groups Odonatoptera and Thripida. The difficulties related to the monophyly of the taxonomic groups used in the more traditional approaches are no longer a problem when using the WAPUM method. In the WAPUM a character is ‘presence versus absence of species bearing a morphological structure’. The results obtained from use of the WAPUM minimize the number of changes among character states. Application of the WAPUM could reveal signals to confirm or object the currently available scenarios for the global changes in the evolution of past diversity and disparity of organisms (major changes or global crises of diversity).

A NEW, ENIGMATIC, EVANIOMORPHAN WASP IN THE ALBIAN AMBER OF FRANCE (INSECTA: HYMENOPTERA)

Synopsis Guyotemaimetsha enigmatica, a new genus and species of evaniomorphan wasp, is described from the French Albian amber. Its phylogenetic affinities are discussed. It has strong similarities with the genera Maimetsha and Cretogonalys, which are attributed to the Maimet‐shidae and Trigonalidae, respectively. The exact relationships of these Cretaceous taxa remain enigmatic.

A new fossil mite from French Cretaceous amber (Acari: Heterostigmata: Nasutiacaroidea superfam. nov.), testing evolutionary concepts within the Eleutherengona (Acariformes)

We describe a fossil member of Heterostigmata of Late Cretaceous age that is the first to show an unexpected array of primitive and derived attributes, some of which are perplexing for a member of this specialized group of trombidiform mites. In contrast, previously published records of heterostigmatic mites of similar age have been of fossils readily classified within moderately derivative superfamilies of this clade. With remarkably preserved details visible, our fossil is a male, from amber of Early Santonian to Middle Cenomanian age (c.85–97 Ma), from a deposit in the Department of Vendée in north-western France. A new genus and species, Nasutiacarus perplexus Sidorchuk & Lindquist, representing a new family and superfamily, are described. We discuss the most salient of the perplexing attributes, especially aspects of the gnathosoma, using them to emphasize the significance of parallel and convergent evolution amongst major groups of eleutherengone Trombidiformes. http://zoobank.org/urn:lsid:zoobank.org:pub:F6CF7838-126F-4196-BE38-77791299240E

Production and preservation of resins - past and present.

Amber is fossilised plant resin. It can be used to provide insights into the terrestrial conditions at the time the original resin was exuded. Amber research thus can inform many aspects of palaeontology, from the recovery and description of enclosed fossil organisms (biological inclusions) to attempts at reconstruction of past climates and environments. Here we focus on the resin itself, the conditions under which it may have been exuded, and its potential path to fossilisation, rather than on enclosed fossils. It is noteworthy that not all plants produce resin, and that not all resins can (nor do) become amber. Given the recent upsurge in the number of amber deposits described, it is time to re‐examine ambers from a botanical perspective. Here we summarise the state of knowledge about resin production in modern ecosystems, and review the biological and ecological aspects of resin production in plants. We also present new observations on conifer‐derived resin exudation, with a particular focus on araucarian conifer trees. We suggest that besides disease, insect attacks and traumatic wounding from fires and storms, other factors such as tree architecture and local soil conditions are significant in creating and preserving resin outpourings. We also examine the transformation of resin into amber (maturation), focusing on geological aspects of amber deposit formation and preservation. We present new evidence that expands previous understanding of amber deposit formation. Specific geological conditions such as anoxic burial are essential in the creation of amber from resin deposits. We show that in the past, the production of large amounts of resin could have been linked to global climate changes and environmental disruption. We then highlight where the gaps in our knowledge still remain and potential future research directions.

The first ibis fly in mid-Cretaceous amber of France (Diptera: Athericidae).

A new genus and species of ibis fly is described from an isolated wing in amber from the Late Albian-Early Cenomanian of Charentes, southwestern France. Galloatherix incompletus gen. et sp. n., is the first Athericidae fossilized in Cretaceous amber, and only the eighth Mesozoic species. It adds to the diverse aquatic and semiaquatic paleobiota already identified from Charentese amber.xa0