Publication: Mortalidad excepcional en los cricétidos (Rodentia) del Mioceno medio de Somosaguas (Pozuelo de Alarcón, Madrid)
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2017-05-10
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Consejo Superior de Investigaciones Científicas (CSIC)
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Abstract
En este estudio se analizó el espectro de desgaste dental de los molares, superiores e inferiores, de individuos de las dos especies de roedores más abundantes registradas en el yacimiento de Somosaguas Sur: Megacricetodon collongensis (Mein, 1958) y Democricetodon larteti (Schaub, 1925). Los resultados muestran gran abundancia de molares poco desgastados en ambas especies, lo que indica la existencia de una mortalidad fuertemente sesgada hacia los individuos juveniles. Este modelo de mortalidad refleja un suceso catastrófico de larga duración y se asocia a periodos de sequía prolongados que produjeron la muerte temprana de los individuos durante generaciones. Esto es coherente con los datos obtenidos para los macromamíferos de Somosaguas donde también existe una mortalidad preferencial de los individuos juveniles asociada a eventos de gran aridez. A pesar de que todos los molares mostraron el mismo patrón de mortalidad preferencial en individuos jóvenes, ambas especies presentaron diferentes niveles de desgaste entre los distintos molares, lo cual sugiere que el proceso de masticación pudo ser distinto entre ambas especies o que el inicio del desgaste de los molares anteriores pudo iniciarse durante la lactancia. Finalmente, el desgaste diferencial observado entre los M1 de M. collongensis y D. larteti podría deberse a la distinta morfología de las cúspides y valles de sus molares, lo que provocaría que el desgaste no se produjese de la misma manera en las dos especies, o a ligeras diferencias dietarias.
In this work we studied the wear degree of the superior and lower molars of the two most abundant rodent species from the South Somosaguas fossil site: Megacricetodon collongensis (Mein, 1958) and Democricetodon larteti (Schaub, 1925). The results show a great abundance of elements with scarce tooth wear in both species, which indicates the existence of a high mortality of young individuals. This mortality model shows an enduring catastrophic event associated to long periods of aridity that produced juvenile mortality along generations. This tendency of mortality fits in the patterns obtained from other works from Somosaguas where the existence of high rates of deaths of young individuals is associated with events of high aridity. D. larteti and M. collongensis have different patterns of wear degree along their dental rows, which could indicate that the mastication process was different in both species or maybe that the tooth wear started earlier. Finally, the differences in wear degree observed in the M1 of M. collongensis and D. larteti can be explained by the different morphology of the peaks and valleys of the molars, which cause a faster wear of the first molar of D. larteti than in those of M. collongensis; or by light dietary differences.
In this work we studied the wear degree of the superior and lower molars of the two most abundant rodent species from the South Somosaguas fossil site: Megacricetodon collongensis (Mein, 1958) and Democricetodon larteti (Schaub, 1925). The results show a great abundance of elements with scarce tooth wear in both species, which indicates the existence of a high mortality of young individuals. This mortality model shows an enduring catastrophic event associated to long periods of aridity that produced juvenile mortality along generations. This tendency of mortality fits in the patterns obtained from other works from Somosaguas where the existence of high rates of deaths of young individuals is associated with events of high aridity. D. larteti and M. collongensis have different patterns of wear degree along their dental rows, which could indicate that the mastication process was different in both species or maybe that the tooth wear started earlier. Finally, the differences in wear degree observed in the M1 of M. collongensis and D. larteti can be explained by the different morphology of the peaks and valleys of the molars, which cause a faster wear of the first molar of D. larteti than in those of M. collongensis; or by light dietary differences.