Ichnological aspects related to bone substrate of fossil vertebrates of the upper Miocene Solimões Formation (Acre Basin) are still poorly understood. A recent taphonomic survey of fossils recovered from this unit and housed at the paleontological collection of Museu de Ciências da Terra da Companhia de Pesquisa de Recursos Minerais (MCT/ CPRM) revealed a vertebra of Crocodylia with a biogenic feature. This work describes this trace fossil and provides its ichnotaxonomic characterization, associating it with a possible tracemaker. The ichnoespecies Nihilichnus nihilicus is reported for the first time for the Solimões Formation, corresponding to a trace fossil observed in a posterior dorsal vertebra of a large Crocodylia. Purussaurus is the probable tracemaker, however, it is not possible to discern if the genesis of the ichnofossil is related to either predation or scavenging.