2. Materials and methods
Teeth of 350 specimens representing 10 species of dolphins were analysed (Table 1). Specimens were accessed in five scientific collections from southern Brazil: Instituto de Pesquisas Cananéia (acronym IPeC); Museu de Ciências Naturais UFPR (MCN); Departamento de Ecologia e Zoologia UFSC (UFSC); Fundação Oceanográfica de Rio Grande (FURG) and Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul (GEMARS). Osteological material deposited in these collections came from stranded or accidentally entangled animals, normally processed by water maceration or buried in sand.
Table 1
Species, number of individuals, body length range and number of teeth analysed.
Species Number of individuals Body length range (cm) Number of teeth analysed
Delphinus capensis (long-beaked common dolphin) 18 178–222 1690
Lagenodelphis hosei (Fraser's dolphin) 9 216–258 1032
Orcinus orca (killer whale) 3 378–397 68
Pseudorca crassidens (false killer whale) 4 370–523 104
Sotalia guianensis (Guiana dolphin) 205 83–203 17,867
Stenella coeruleoalba (striped dolphin) 8 212–243 869
Stenella clymene (Clymene dolphin) 2 198–200 188
Stenella frontalis (Atlantic spotted dolphin) 23 157–204 2033
Steno bredanensis (rough-toothed dolphin) 17 200–277 1055
Tursiops truncatus (bottlenose dolphin) 61 150–358 3071
Total 350 – 27,977
Teeth were visually inspected under a stereoscopic microscope in order to highlight the wear facets. According to Thewissen et al.22 and Butler,27 these facets are seen as smooth and flat surfaces evidenced by light reflection. Wear facets were categorized according to their location, anatomical extent and intensity, using dental anatomical terminology.28