Trackway of a Disabled Seabird

ABSTRACT

An uncommon trackway of a seabird consisting of impressions of the right foot accompanied at the left side at the supposed position of the foot only by holes was produced by a gull having two legs, but only one foot. Foot size and stride are typical of an adult herring gull. The stride is unequal between right-left and left-right impression by ∼15% as the digitigrade producer experienced re-distribution of load due to the missing foot. Tracks of disabled seabirds are underrepresented in reports of both modern settings as well as the fossil record when compared with modern observations. In present time, about 2% of the seabirds have injured feet or legs. Today, however, injuries of seabirds might have increased due to human fishery activities. Actual observations show that fossilisation of such trackways is favoured by microbes preferentially growing in the impressions that are moist for a prolonged period of time.

KEYWORDS:

• Ichnopathology
• Trackway
• Preservation potential
• Microbial mat

Acknowledgments

Achim Reisdorf (Basel) helped with literature search and with preparation of the figures. A.A. Ekdale (Salt Lake City, USA) and T.J. Martin (Atlanta, USA) provided supportive discussions. All these contributions are gratefully acknowledged.