@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Trackway evidence for large bipedal crocodylomorphs from the Cretaceous of Korea

• • Kyung Soo Kim, Martin G. Lockley, Jong Deock Lim, Seul Mi Bae & Anthony Romilio
  • Scientific Reports volume 10, Article number: 8680 (2020)

• Abstract

  

  Photographs of well-preserved in situ Batrachopus grandis ichnosp. nov. track impressions from surface 2. (A,B) Left pes tracks; (C,D) Right pes tracks. A, C = pes of T7 and T9, respectively. B shows skin impression of heel region (see SI Fig. 5). D = holotype IS 2 of Fig. 6. Photos by J-W K, S-M B and M G L, and compiled in Adobe photoshop (version CS6 88) and Canvas X (version, 20 Build 390, http://www.canvasgfx.com/).

(A) Photograph of the surface from which tracings and 3D images of trackways T16 (the holotype) and T17 of Batrachopus grandis and isolated tracks IS 5-6 were obtained; (B–D) 3D images of pair of tracks including right pes track from holotype trackways T 16; (E) map of the surface shown in A, showing holotype trackway T 16 and paratype trackway T 17. Note well-defined digital pad traces especially in holotype. Photographs, line drawings and 3D images made and compiled by K-S K, M G L and A R. in Adobe Photoshop (version CS6 88) and Canvas X (version, 20 Build 390, http://www.canvasgfx.com/). Compare with Figs. 3–5, SI Figs. 3 and 4 and SI Table 1.

Large well-preserved crocodylomorph tracks from the Lower Cretaceous (? Aptian) Jinju Formation of South Korea, represent the well-known crocodylomorph ichnogenus Batrachopus. The Korean sample includes multiple, narrow-gauge, pes-only trackways with footprint lengths (FL) 18–24 cm, indicating trackmaker body lengths up to ~3.0 m. Surprisingly, the consistent absence of manus tracks in trackways, with well-preserved digital pad and skin traces, argues for bipedal trackmakers, here assigned to Batrachopus grandis ichnosp. nov. No definitive evidence, either from pes-on-manus overprinting or poor track preservation, suggests the trackways where made by quadrupeds that only appear bipedal. This interpretation helps solve previous confusion over interpretation of enigmatic tracks of bipeds from younger (? Albian) Haman Formation sites by showing they are not pterosaurian as previously inferred. Rather, they support the strong consensus that pterosaurs were obligate quadrupeds, not bipeds. Lower Jurassic Batrachopus with foot lengths (FL) in the 2–8 cm range, and Cretaceous Crocodylopodus (FL up to ~9.0 cm) known only from Korea and Spain registered narrow gauge trackways indicating semi-terrestrial/terrestrial quadrupedal gaits. Both ichnogenera, from ichnofamily Batrachopodidae, have been attributed to Protosuchus-like semi-terrestrial crocodylomorphs. The occurrence of bipedal B. grandis ichnosp. nov. is evidence of such adaptations in the Korean Cretaceous.

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev