The complexity of tracking stegosaurs and their gregarious behavior

Area of Science:

• Paleontology
• Ichthyology
• Dinosauria

Background:

• Stegosaur tracks were previously unknown until the discovery of Deltapodus over 20 years ago.
• The Iberian Peninsula, particularly Teruel Province, is a global hotspot for Deltapodus occurrences.
• Distinguishing stegosaur tracks from sauropod tracks is challenging due to morphological similarities.

Purpose of the Study:

• To review and analyze a large global collection of Deltapodus tracks, including the holotype of D. ibericus.
• To describe new occurrences of Deltapodus tracks and address identification issues.
• To investigate variations in track morphology and their potential causes, such as substrate and locomotion dynamics.

Main Methods:

• Analysis of a comprehensive dataset of Deltapodus tracks.
• Morphological and morphometric comparisons, including 3D modeling.
• Comparative analysis with sauropod tracks, focusing on metapodial bone differences.

Main Results:

• Substantial morphological variations were observed within Deltapodus tracks.
• All studied tracks were identified as D. ibericus based on manus morphology and morphometric data.
• Track variations are attributed to substrate differences and/or dynamic foot postures during locomotion.
• 3D modeling confirmed distinct differences between stegosaur and sauropod tracks, particularly in manus and pes proportions.
• Two tracksites provided evidence of gregarious behavior in stegosaurs, a rare finding.

Conclusions:

• Deltapodus ibericus exhibits significant morphological variability, influenced by substrate and locomotion.
• 3D modeling is crucial for differentiating stegosaur tracks from sauropod tracks.
• The identification of gregarious behavior in stegosaurs is supported by new fossil evidence, challenging previous assumptions about their social structure.