论文标题：Trackway evidence for large bipedal crocodylomorphs from the Cretaceous of Korea

期刊：Scientific Reports

作者：Kyung Soo Kim, Martin G. Lockley et al.

发表时间：2020/06/11

DOI：10.1038/s41598-020-66008-7

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根据《科学报告》本周发表的一篇论文Trackway evidence for large bipedal crocodylomorphs from the cretaceous of Korea，韩国下白垩统晋州组（Jinju Formation）发现了保存良好的较大足迹，这些足迹来自现代鳄鱼的祖先。研究指出，之前发现的曾被认为是双足行走的巨型翼龙的足迹，实际上可能是古代鳄鱼近亲留下的。

韩国晋州教育大学的Kyung Soo Kim、美国科罗拉多大学丹佛分校的Martin G. Lockley和同事在韩国泗川市附近的泗川自惠里遗址发掘过程中发现了多组足迹。作者将这些足迹取名为Batrachopus grandis，它们来自一个鳄形类新种，是现代鳄鱼、食鱼鳄鱼和短吻鳄的祖先。这些足迹的大小是此前发现的batrachopodid足迹的两倍多，一些足迹长18–24厘米，显示其体长可能达到三米。较窄的行迹完全是后足留下的，有些区域保存了从脚跟到脚趾的清晰印痕和皮肤印痕。并未发现有后足足迹覆盖前足足迹或是保存较差的决定性足迹证据表明行迹是由四足鳄形类留下的，说明B. grandis代表一种双足行走的动物。这种步态此前在这一科的行迹样本中未有发现。

保存完好的Batrachopus grandis足迹 | 图片来自晋州教育大学Kyung Soo Kim

之前在年代更早遗址发现的足迹曾被认为是巨型翼龙为保护翅膀而在陆地上双足行走时留下的，但这次的研究结果表明，这些足迹可能来自鳄形类。这支持了足迹化石研究人员达成的共识，即翼龙行走时四肢共用；有必要重新检视历史上同一时期的其他形态类似的样本。

摘要：

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. grandisichnosp. nov. is evidence of such adaptations in the Korean Cretaceous.

（来源：科学网）