[N] 2006 Three-demensional reconstrucyion of the skull of Rapetosaurus krasei
Curry-Rogers, K., Hertel, J. & Groenke, J. (2006) Three-demensional reconstrucyion of the skull of Rapetosaurus krasei (Sauropoda-Titanosauria) JVP 26(3) Abstracts pp.53
Rapetosaurus krausei, a titanosaur from the Late Cretaceous Maevarano Formation of Madagascar is known from a sample of cranial and postcranial material. The holotype adult skull (UA 8698) includes paired and single elements that articulate precisely along sutural margins, and represent the rostrom, mandible, and basicrainum. A referred juvenile skull (FMNH PR 2184-2192, 2194, 2196, 2197, 2209, 2210) preserves elements from the braincase and cranial vault, as well as isolated teeth, which also articulate precisely.
Both skulls preserve pterygoids, basioccipital and paroccipital processes, quadrates, surangulars, and teeth, all of which share autapomorphies that distinguish Rapetosaurus. A 3-D reconstruction of the skull of Rapetosaurus proves challenging given the ontogenetic variation in preserved bones and the lack of most contralateral elements in either skull. Here we utilize 3-D laser scanning and rapid prototype printing to clarify Rapetosaurus cranial morphology through three-dimensional reconstructions of juvenile and adult skulls. Each of the Rapetosaurus elements were rendered with a Minolta Vivid 9i non-contact 3-D digitizer and Polyworks 9.1.6 software, and printed with a ZPrinter 310 rapid prototype printer.
The point cloud manipulation software allowed us to compare the same bones in juveniles and adults in the same three dimensional space, digitally compare articulations, mirror scans to print missing contralateral elements, and digitally scale elements to fit each skull. The percentage of size change observed in overlapping bones (e.g., surangular, quadrate) informed the scaling of printed elements. Juvenile bones were scaled up by ~200% for articulation with preserved adult elements, and adult bones were scaled down by ~50% to articulate with preserved juvenile elements.
In the final reconstructions of the skulls, prints were articulated, and only the articular, quadratojugal, postorbital, and premaxilla were sculpted. The articulated Rapetosaurus skulls indicate that the rostrum is “stepped,” the external nares are more laterally positioned, and the expanded antorbital fenestra is proportionally closer to those of other macronarians.