An eye for an eye, a tooth for a tooth: Archosaurian teeth from the Açu Formation (Albian–Cenomanian), Potiguar Basin, Northeast Brazil

Several studies have used isolated crocodyliform and theropod teeth as an important tool for taxonomic identification, as they can often be the only record of some taxa. The objective of this paper is the description and identification of the isolated crocodyliform and theropod teeth in order to clarify which taxa inhabited the western portion of the Potiguar Basin during mid-Cretaceous. The material consists of six tooth crowns from Acu Formation (Albian–Cenomanian), Potiguar Basin, northeastern Brazil. The crowns were identified by a set of qualitative (morphological comparisons and cladistics) and quantitative analyses. UFRJ-DG 659Rd was identified through morphological comparison as a peirosaurid crocodyliform due to its true ziphodont condition, enamel with an irregular texture, and faint lingual fluting. Five of the tooth crowns were identified as abelisaurid theropods based on the results of the cladistic analysis and morphological comparison, with the quantitative analysis supporting this result only for two of the five teeth. This result represents the first report of peirosaurids and abelisaurids in Potiguar Basin, and possibly one of the oldest abelisaurid records in Brazil.