From Canis mosbachensis to modern wolves: Canid evolutionary insights from the Early and Middle Pleistocene of Atapuerca (Spain)

This study analyses Canis remains recovered from the Sierra de Atapuerca sites over the last 25 years. The sample comprises 108 dentognathic specimens: 106 attributed to C. mosbachensis from Sima del Elefante and Gran Dolina, and 2 to C. lupus from Galería. These remains document a record spanning the Early and Middle Pleistocene, approximately 1.2-0.4 Ma. The results indicate metrical stability in C. mosbachensis, which is consistently smaller than C. lupus. Specimens from the Early Pleistocene (TE9-TE14 and TD3-TD6) and the early Middle Pleistocene (TD8) exhibit more primitive morphological traits, particularly evident in the dentition of the carnassial-molar complex, consistent with mesocarnivory. In contrast, specimens from TD10 (middle Middle Pleistocene) tend to be larger than those from older stratigraphic levels and exhibit morphological features suggesting a gradual transition from C. mosbachensis to C. lupus. The lower carnassial in these individuals shows an elongation of the trigonid, indicating increased cutting efficiency and a shift toward a more carnivorous diet. This pattern likely represents an intermediate stage in this evolutionary transition rather than a fully developed hypercarnivorous condition comparable to that observed in modern wolves. Moreover, the morphological change observed in TD10 Canis coincides with a transition episode from MIS12 to MIS11, associated with a severe climatic shift.