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The new aeshnopteran family Enigmaeshnidae is proposed for Enigmaeshna deprei gen. et …


Biology Articles » Paleobiology » Paleozoology » A new dragonfly family from the Upper Cretaceous of France » Introduction

Introduction
- A new dragonfly family from the Upper Cretaceous of France

Although Aeshnoptera are rather frequent in the Jurassic and Cre− taceous fossil record, they almost all belong to the most inclusive clades of this group (Nel et al. 1994; Bechly et al. 2001).Mesozoic representatives of the Recent clade Neoaeshnida Bechly, 1996 are almost exclusively represented by the Gomphaeschnidae Tillyard and Fraser, 1940, sister group of the Aeshnodea Bechly, 1996. The few Mesozoic fossils of the latter clade belong to the family Allopetaliidae Cockerell, 1913 (genus Baissaeshna Pritykina, 1977). Little is known on the aeshnopteran history during the Late Creta− ceous because of the lack of significant fossils. Thus, the present discovery of an Aeshnodea in the lowermost Cenomanian of France is of great interest in the knowledge of its diversity and morphological disparity during this crucial period of its evolution. The new fossil is characterized by several unique characters, allowing us to include it within a new family.

The fossil dragonfly comes from the Puy−Puy quarry, at Tonnay−Charente (Charente−Maritime, SW France), about 20 km from the Charente river estuary (Fig. 1). In this quarry, the uppermost Albian−lowermost Cenomanian deposits are trans− gressive and erosive on the Kimmeridgian substratum. These deposits are mainly composed of fluvial and paralic sand, but contain several clay intercalations with local concentrations of plant compressions or lignite and amber (Néraudeau et al. 2005). Stratigraphically (Fig. 2), the clay level containing fossil arthropod imprints is located about seven metres under the first facies clearly dated as Early Cenomanian, a marine shelly sand (lithological sub−unit B1) containing dense accumulation of the large benthic foraminifera Orbitolina conica (Vullo et al. 2003). The clay level bearing the fossil Aeshnodea corresponds to the base of the sand and clay alternations (lithological sub−unit A2), underlying the shelly sand. Just a few decimeters underneath the fossiliferous clay there is 2–3 m thick fluvial azoic sand ar− ranged in large cross beddings (top of the sub−unit A1). The clay bearing arthropods and plants is devoid of sporomorphs and cannot be palaeontologically dated in this quarry (Peyrot et al. 2005). However, stratigraphical correlations with well−dated sections of other quarries from the same region (Néraudeau et al. 2002, in press), suggest an earliest Cenomanian age for the lithological sub−unit A2 from Puy−Puy.

The clay containing the fossil Aeshnodea corresponds to the basal part of the two main levels rich in plant compressions (P1, P2), as previously described by Gomez et al. (2004) and Nérau− deau et al. (2005). Apart from numerous fossil ferns, conifers and angiosperms, the level P1 delivered a few imprints of undeter− mined Blattodea and decapod crustaceans. The Aeshnodea im− print was fossilized at a clay surface at a few centimeters of an 80−cm−l3ong Dammarophyllum leaf (Coniferale: Araucariaceae or Podocarpaceae).


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