The mules that are not mules - metrics, morphology, archaeogenomics and mtDNA d-loop diversity in equids from Roman Switzerland

Mules (Equus asinus x Equus caballus) represent first-generation hybrids between a female horse (mare) and a male donkey (jack). They are generally considered to have first appeared north of the Alps with Roman influence, a time period in which written and iconographic sources support their key role