ECOLOGICAL FUNCTION AND MACROEVOLUTIONARY PATTERNS IN PROBOSCIDEANS

ALBERDI M. T.; SANISIDRO, O.; PRADO, J. L.; BLANCO F.; CANTALAPIEDRA, J. L.; ZHANG H.; SAARINEN J.

Brisbane

Congreso; 79th Annual Meeting of the Society of Vertebrate Paleontology; 2019

Society of Vertebrate Paleontology

With only three living species, today?s proboscideans represent but a tiny fraction of their Cenozoicdiversity. During their 60 myr of evolution, proboscideans dispersed over Africa, Eurasia and America,they evolved into remarkable diversity of body sizes and dental adaptations, and have been part of manymammalian communities. Which factors drove the rise and fall of this iconic lineage? Despite theircosmopolitanism and relevant ecologic role (most of the largest Cenozoic terrestrial mammals wereproboscideans), we lack comprehensive quantitative approaches that assess the large-scale processes thatshaped their diversity trends: speciation, extinction and the potential role of ecological adaptation inspecies selection. We present preliminary results based on an up-to-date paleobiological database ofproboscideans that includes 2300 occurrences for 196 species, and 12 ecomorphological traits. The earlyproboscideans fossil record (57 to 40 Ma) is scarce, and yet we recover the signal of a sustained highturnover during this interval (high speciation and extinction). From 40 to 2.5 Ma the clade shows a steadyincrease in diversity rendered by an overall-constant, moderate net diversification (0.1 species Myr-1). Inthe earliest Miocene we recover a sudden increase in ecological disparity, which has plateaued out sincethen. Even though diversity and ecological designs increase through the Neogene, these designs do notrepresent large innovations, being added to already-opened regions of the ecological space. The diversitytrend peaks in the early Pleistocene, when we estimate a global species richness of around 30 species.Speciation through the Neogene was mainly clustered in the ecological space, whereas extinction hasshifted in its ecological scope, being generally clustered within ecological niches until Pleistocenetimes. Since 15 to 6 Ma, the increase in functional diversity, which may have fueled the steady netdiversification rates, was maintained at the expense of increasing functional vulnerability (higherfrequency of unique designs). The Pleistocene, specially the last 1.5 myr, brought about a very severeextinction pulse that hit a wide array of ecological niches, wiping off two thirds of the species by the endof this period and a significant part of the functional disparity too.