Different trackway patterns in titanosaur sauropods: Analysis of new Titanopodus tracks from the Upper Cretaceous of Mendoza, Neuquén Basin, Argentina

The discovery of new Titanopodus trackways (Loncoche Formation, Argentina) shed light on the locomotion of titanosaur sauropods. Two patterns related with different size of trackmakers are identified based on ichnological and anatomical evidences. AC-1 and AC-4 trackways (pattern 1) are characterized by alternated manus and pes tracks. This is congruent with an asynchronous gait produced by large individuals that walked at 4.7-4.8 km/h. AC-3 trackway (pattern 2) shows some elongated and distorted tracks interpreted as overlapped manus and pes prints. This interpretation is supported by the presence of clear juxtaposed or partially overlapped manus and pes prints in some parts of the trackway. Pattern 2 is preliminary assigned to an amble gait produced by a smaller individual that walked at 3.7 km/h. These two patterns can be analyzed as different gaits in titanosaurs that walked together.