Leverhulmia

Introduction

Morphology

Palaeoecology

Introduction

Known only from one specimen, Leverhulmia mariae is a recent addition to the Rhynie fauna and has been described by Anderson and Trewin (2003). The lack of diagnostic features in this specimen means its affinity beyond being a myriapod remains unknown. What makes this animal particularly worthy of mention here is the fact that this one specimen appears to preserve the contents of the gut. This and the overall morphology of the animal are outlined below.

 

Morphology

Longitudinal cross section of Leverhulmia showing gut contents

Above: Longitudinal section of Leverhulmia mariae (anterior towards the left of photograph) showing trunk with gut contents (g) and uniramous appendages (l) comprising at least five pairs (1 - 5) (scale bar = 2mm).

Leverhulmia was at least 11mm in length with at least 5 pairs of walking legs (see inset above), each leg possessed densely crowded hairs or setae on the posterior of the last (tarsal) segment (see inset below right). At present, it is not certain whether the animal was diplopodous (having two leg pairs per body segment, as seen in millipedes). The morphology of the head and posterior segments of Leverhulmia are not known, both of which would be expected to exhibit diagnostic features which would help to assign this animal to a higher myriapod group.

 
As mentioned above, the most important feature of this particular specimen is the presence of visible gut contents lying within the body cavity as defined by the dorsal and ventral surfaces of cuticle. The contents comprise primarily fungal and spore debris together with fragments of macerated plant tissue (see inset above). They are believed to be true gut contents rather than post-mortal transported material since the surrounding chert matrix is remarkably free of similar debris. The preservation of the gut contents indicates that this specimen is an actual body-fossil of the organism rather than its moulted cuticle. As such this specimen represents the earliest example of preserved gut contents in a terrestrial arthropod described to date, and is the earliest example of detritivory in the fossil record of terrestrial organisms.

 

Close up on the gut contents of Leverhulmia

Above: Close-up on gut contents in Leverhulmia showing spores (s) and macerated plant tissue (o). This view also shows the hairs on the tarsal segments of the legs (h) (scale bar = 500Ám).

 

 

Palaeoecology

The gut contents of macerated plant tissue and spores imply that this animal was a detritivore, feeding within plant litter. The one specimen found to date occurs in chert displaying a clotted or 'mulm-like' texture, together with coprolites and fragments of the crustacean Lepidocaris, implying an aquatic setting. This suggests that the animal was probably washed into a small pond where it was preserved. Maybe it was caught in a hot water eruption and instantly killed so preserving the contents of the gut.