Meeting Abstract

P1-286  Friday, Jan. 4 15:30 – 17:30  Changes in relative molar size in the small-bodied mammal Macrocranion across the Paleocene-Eocene Thermal Maximum follow predictions of nutritional deficit VITEK, NS*; MORSE, PE; STRAIT, SG; BOYER, DM; BLOCH, JI; University of Florida, Gainesville, FL nvitek@ufl.edu; Duke University, Durham, NC; Marshall University, Huntington, WV; Duke University, Durham, NC; Florida Museum of Natural History, Gainesville FL nvitek@ufl.edu

Variation in relative molar crown area (RCA) is a promising phenotype in which to measure mammalian response to climate change because of its links to diet and nutritional deficit in modern species. A relevant interval in which to study these responses is the Paleocene-Eocene Thermal Maximum (PETM) ~56 Ma. It is associated with a shift towards warmer mean annual temperatures (MAT) by ~5-8 °C for ~175 ky, followed by a recovery to pre-PETM MAT. Changes in RCA in response to these climatic shifts should follow predictions of the inhibitory cascade model (ICM). However, much of the PETM mammalian fossil record consists of isolated teeth instead of the complete molar rows for which the ICM was intended. To test the possibility of environmentally-linked change in RCA, we first asked if we could reconstruct RCA from averages of isolated molars. Using simulations from modern populations, we demonstrate that this approach accurately reflects molar-row RCA. Next, we asked whether RCA changed through the PETM, and, if it did, whether changes in RCA through the PETM follow expectations of the ICM. We measured RCA from isolated M_1-3 of the small-bodied (~24 g), insectivorous Macrocranion junnei. RCA changes across the PETM in proportions consistent with the ICM. Macrocranion has smaller M_2-3 during the late and post-PETM at most. The timing and direction of change is consistent with nutritional deficit associated with turnover in the surrounding flora and associated insect fauna at the end of the PETM.