The ability of adult wild Atlantic spotted dolphins (Stenella frontalis) to synchronize vocalizations and behaviors has been found to be a key factor in overcoming much larger bottlenose dolphins during interspecies aggression (Cusick & Herzing, 2014). Furthermore, an adult baseline of behaviors and vocalizations during aggressive events containing synchrony has been established (Myers, Herzing, & Bjorklund, 2017). The present study examines juvenile aggression that contains bouts of synchrony to look at the development of this valuable skill. Differences of duration between adult and juvenile synchronous bouts, lag sequential analyses, frequencies of behavioral classes depending on the age class of the aggressor-recipient dynamic, differences in the frequencies of behavioral classes depending on the synchronous state and aggressorrecipient dynamic, and differences in behavioral classes exhibited by adults and juveniles during different synchronous states were analyzed. Adults, across group size, were able to maintain physical synchrony for a longer duration. Juveniles were often in loose synchronous groups before forming into a tight synchronous group as seen in adult synchrony. Vocal synchrony during adult aggression in terms of synchronized squawks were longer in duration than vocal synchrony during juvenile aggression. Juveniles used more pursuit behaviors during aggression, which indicates practice of a behavior that was found to be the most frequently used in interspecies aggression (Volker, 2016). Additionally, when adults were present in juvenile aggression, they used fewer aggressive behavioral classes demonstrating self-handicapping based on their opponent. This illustrates that there is a learning period for both vocal and physical synchrony for juvenile dolphins and that juvenile aggression, or play-fighting, is an important aspect of the development of these skills. This study is the first to describe juvenile synchrony in a population of wild Atlantic spotted dolphins. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection