Wednesday 22 August 2012

A fossil Insect from the Late Devonian of Belgium.

The Insects are thought to have first emerged in the Silurian Period, over 416 million years ago, though fossil insects are very rare earlier than the Late Carboniferous, becoming more common after 345 million years ago. Whether this means that insects were rare in this interval, or simply were not preserved is unclear. Traditionally interpretation of the palaeontological record has suggested that the Insects underwent a major bout of diversification during the Late Carboniferous, but recent molecular studies have suggested that several groups of Insects might be older than this.

In a paper published in the journal Nature on 2 August 2012, a team of scientists led by Romain Garrouste of Entomologie at the Muséum national d’Histoire naturelle in Paris, describe the discovery of a complete fossil Insect from the Late Famennian (364.7-360.7 million years old, Late Devonian) Bois des Mouches Formation at Strud in Namur Province, Belgium.

Map showing the location where the new fossil was found. Google Maps.

The new fossil is named Strudiella devonica, the Devonian little fossil from Strud. It is an 8 mm long Arthropod with a body divided into head, thorax and abdomen with three pairs of legs on the thorax (the diagnostic features of an Insect). It also has a pair of long antennae, and mandibles (jaws) which suggest an omnivorous diet. Its bodyplan is more suggestive of a winged Insect than a non-winged Insect, however it lacks wings, suggesting that it might be a nymph of an Insect which underwent incomplete metamorphosis (such as a Dragonfly); in such Insects the larval form (nymph) resembles the adult, but lacks wings and is often aquatic.

Strudiella devonica (Top) Photograph. (Bottom) Interpretive drawing. White arrows
indicate legs visible on part. abd, abdomen; ant, antenna; h, head; md, mandible. Scale bar, 1mm. Garrouste et al. (2012).

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