TESTING THE EVOLUTIONARY TRENDS IN BODY SIZE OF MESOZOIC LINGULIDAE BRACHIOPODS

The poor fossil record of Lingulidae brachiopods during Mesozoic times and the lack of taxonomic descriptions hinder accurate assessments of their evolutionary history. A dataset of Lingulidae occurrences and their body size, ranging from Tithonian to Maastrichtian in age, was constructed combining both literature and field surveys. The dataset gathered includes a total of 35 samples and 385 specimens representing almost all geological stages within the time interval under study. Using the shell length as a proxy for overall body size, I apply three different evolutionary modes (i.e., stasis, random walk, and directional trend), to explore the evolution of this group. Results strongly support stasis in body size throughout the Mesozoic history of Lingulidae (Akaike weights GRW: 0.008; URW: 0.084; Stasis 0.908). This result challenges the recently proposed long-term trends in body size of lingulide brachiopods through time.