Isotopic evidence for mammalian diets and environment in Early Pliocene Yepomera, Mexico
Por:
Hannold, Chance, Wang, Yang, Wang, Xiaoming, Carranza-Castaneda, Oscar
Publicada:
15 sep 2021
Resumen:
Concurrent expansion of grassland habitat in the Americas and first
appearances of immigrant taxa to Mexico via the Great American Biotic
Interchange (GABI) during the Late Miocene to Early Pliocene suggest a
possible link between the timing of migrations and changes in the
environmental conditions. However, the causes and environmental context
of GABI migrations are not well understood. This study examined the
stable isotope compositions of tooth enamel samples of the Yepomera
fauna from western Chihuahua, Mexico, to explore environmental
conditions of this region between 4.99 and 5.23 Ma, just after the
arrival of C-4 plants in North and South America and before the first
major migration of GABI. At Yepomera, there was distinct niche
partitioning into C-3 diets, mixed diets, and C-4 diets. Despite
expectations, no niche partitioning between equid species (Dinohippus
mexicanus, Nannippus aztecus, Astrohippus stockii, and Neohipparion
eurystyle) can be determined from carbon isotope ratios. The enamel
carbon and oxygen isotope data suggest a relatively dry, open habitat
dominated by either savanna or grassland, with a substantial C-4
vegetation component and a warmer and somewhat wetter climate than
today. These reconstructions are consistent with a rise in C-4 biomass
before 5.23 Ma and suggest that the conditions needed for growth of C-4
vegetation were prevalent in this region of Mexico. Future work along
the GABI migration route will lead to a more complete understanding of
the ecologic responses to changing climate and faunal interchange
events.
Filiaciones:
Hannold, C (Corresponding Author), Florida State Univ, Dept Earth Ocean & Atmospher Sci, Tallahassee, FL 32306 USA. Hannold, C (Corresponding Author), Natl High Magnet Field Lab, Tallahassee, FL 32306 USA. Hannold, Chance
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