The imaging of subsurface crocodile remains in a limestone slab using holographic radar

RASCAN holographic radar has been used to observe a rostrum of an Upper Jurassic–Lower Cretaceous fossil crocodylomorph under the upper surface 21 mm thick limestone slab (Maiolica Formation). The specimen, recovered in the Altopiano di Asiago (Vicenza Province, Italy), is at present housed in the paleontological collections of the Rovereto Civic Museum (Trento Province, Italy). The holographic radar response correlates well with the actual fossil shape revealed on the reverse side of the slab. This study has been made using the RASCAN-4/7000 holographic radar which can penetrate through several centimeters of the limestone. It works by comparing the phase of a sinusoid electromagnetic wave reflected from the subsurface of the fossil with the internal reference of the transmitting antennae. The radar has receiving antennas with both cross and parallel polarizations relative to the transmitter. On a processed radar plan-view image, objects can often be identified directly by their shape and texture as was first demonstrated in a similar research field for dinosaurs’ tracks investigation [1, 2]. This is a great simplification compared with the processing needed using impulse radar [3]. The RASCAN method is suitable for portable and on-site applications due to its small size, light weight and low power consumption. The images generated can be used for diagnostic purposes similar to X-ray methods, but without the complications that the use of ionizing radiation entails. Another advantage is the possibility to make measurements from just one side of the object under investigation. Comparison of microwave holographic radar and the X-Ray images are used here to evaluate the proposed method.