First Record of Twin Fetuses of South American Sea Lion on the Southern Brazilian Coast

Abstract

We report the first known occurrence of South American sea lion (Otaria flavescens) twins on the South American coast. In January 2021 a female pregnant with dizygotic male and female fetuses was found dead in southern Brazil. The timing of the stranding event suggests that the pregnancy was near-term. However, the total body length and weight of fetuses suggested poor development and growth, which could be due to the advanced age of the mother and/or poor nutrition of the individual during pregnancy. The female fetus was larger and heavier than the male and could have been implanted and developed earlier.