RAPID, ACCURATE AND LOW COST DIGITAL 3D MODELING OF BEDDING PLANE TRACE FOSSILS: A CASE STUDY USING NEW UNDICHNA FROM THE EDWARD HITCHCOCK COLLECTION

The fish-produced trace fossil Undichna was recently reported for the first time from the Mesozoic of New England as a redescription of the only known specimen (BMNH 36/49) of Hitchcock’s (1858) invalid ichnogenus Cochlea. While other Cochlea specimens were known to be in the Hitchcock Ichnological Cabinet, their location was unknown until 2011 when collections staff at the Beneski Museum of Natural History relocated the two additional specimens reported to contain Cochlea. The rare specimens are additional evidence of the behavior and environmental preferences of fish in Mesozoic rift valley lakes. Critical to their significance is inference of the producer through morphological analysis. The shallow tracks and trails made by animals of low mass, high buoyancy or with appendages of high surface area are often difficult to interpret in hand sample because of the combined effects of surface staining, directional lighting and traditional photographic methods. Moreover, fragile, rare specimens can be degraded through handling and inspection, and with these specimens traditional casting methods are not a good option. Three-dimensional modeling of surficial trace fossils offers the prospect of highly accurate digital reproduction of type specimens with reduced handling and the added benefit of highly flexible perspective, measuring and modeling procedures. An easy, low cost, high-resolution structured light scanning system can be made with a standard digital projector, high quality “webcam”, and a PC running the DAVID Laserscanner software. Three-dimensional models of Hitchcock’s Cochlea specimens were produced, compared and described using this method. The specimen BMNH 36/46 is a sharply incised, shallow Undichna britannica and is likely a hyporelief, although no orientation information is provided with the slab. Specimen BMNH 55/62 remains an enigma, as no evidence of an Undichna-like trail is apparent on the slab although an invertebrate trackway and indeterminate disturbance are present. Analysis of this group of low relief tracks and trails was done safely, without overhandling, and was enhanced by the flexibility provided by accurate digital 3D models. The system, as described, shows promise for other types of trace and body fossil analysis, and could be deployed in the field for in situ data collection.