Society of Vertebrate Paleontology (SVP) 73st Annual Meeting

Karme, A. (Puhuja: esitelmän pitäjä)

Aktiviteetti: Tapahtumaan osallistumisen ja tapahtuman järjestämisen tyypitKonferensseihin, kursseille ja seminaareihin osallistuminen ja näiden järjestäminen

Kuvaus

1. A NEW ANGLE ON MESOWEAR - ANGULAR CRITERIA FOR FAST AND CONSISTENT RECORDING OF MESOWEAR DATA; 2. NEW APPROACH TO MAMMALIAN PALEOECOLOGY - OCCLUSAL WEAR ANGLES OF MOLAR TEETH AS A MEASURE OF DIET ABRASIVENESS IN ELEPHANTS AND THEIR FOSSIL RELATIVES (MAMMALIA, PROBOSCIDEA)

1. Karme, A. & Saarinen, J., 2013. A New Angle on Mesowear - Angular Criteria for Fast and Consistent Recording of Mesowear Data. Society of Vertebrate Paleontology 2013 Program and Abstracts. 2. Saarinen, J., Karme, A., Uno, K., Säilä, L., 2013. New Approach to Mammalian Paleoecology - Occlusal Wear Angles of Molar Teeth as a Measure of Diet Abrasiveness in Elephants and Their Fossil Relatives (Mammalia, Proboscidea). Society of Vertebrate Paleontology 2013 Program and Abstracts. 1. A NEW ANGLE ON MESOWEAR - ANGULAR CRITERIA FOR FAST AND CONSISTENT RECORDING OF MESOWEAR DATA Mesowear (the relief and sharpness) of worn ungulate molars has been widely used for paleodiet reconstructions. It has been shown that the method is a robust proxy for the abrasiveness of herbivore diets. A major challenge of mesowear has been achieving consistency of the subjective scoring procedure and the awkwardness of the objective criteria, especially for scoring relief. We introduce a new method replacing linear measurements with angles and provide simple tools for easy scoring. We used the threshold values that separate high and low relief, defined originally as the ratio of cusp height and molar length, for calculating corresponding mesowear angles by using trigonometry. These mesowear angles have been tested for all the groups for which mesowear was originally designed (selenodonts and plagiolophodont horses, rhinoceroses and hyracoids). The new method and tools were found to be readily applicable by comparing them to traditional measuring of cusp height ratio in mesowear scoring. This was done for approximately 1000 samples, which were correctly classified with no exceptions. The tools include a reference plate, which is a simple sheet of translucent plastic, and a 3D printable tool, both with angles for the different animal groups. Mesowear angles can be used for analyzing complete ungulate communities, also from paleoanthropological and archaeological localities, to gain information about feeding ecology and local environmental conditions. It is an easy and reliable tool for researchers without earlier experience in mesowear scoring and for experienced mesowear users a quick one for measuring cases close to the high/low boundary. Compared to mesowear scoring by visual inspection, the mesowear tools allow more objective, more accurate and faster data collection. 2. NEW APPROACH TO MAMMALIAN PALEOECOLOGY - OCCLUSAL WEAR ANGLES OF MOLAR TEETH AS A MEASURE OF DIET ABRASIVENESS IN ELEPHANTS AND THEIR FOSSIL RELATIVES (MAMMALIA, PROBOSCIDEA) The analysis of the secondary, wear induced shape of the occlusal surface of herbivorous mammal teeth, known as mesowear analysis, has proven out to be a rapid and robust method for assessing the proportion of abrasive plant material (mainly grass) in the diet of herbivorous mammals. This method has important applications for paleoecological reconstruction, because it reflects the actual diet in populations of herbivorous mammals and it gives valuable information about feeding ecology in fossil mammal communities, and ultimately it reflects environmental conditions. The traditional mesowear method can only be applied for herbivorous mammals with selenodont, ectolophodont or plagiolophodont molar morphology, because a buccal enamel crest is needed to show facets from which relief and shape of the buccal cusps can be readily observed. However, the principle can be extended to other kinds of tooth morphology. Elephants have specialised lamellar tooth morphology, and their propalineal chewing causes a wear pattern that cannot be analysed with the traditional mesowear method, because the enamel ridges of the lamellae are rubbed against each other in oblique direction and facets do not develop. However, the relief of the occlusal surface of elephant molars should follow similar principles as those of other herbivorous mammals so that increasingly abrasive food causes a lower relief. Here we introduce a new approach similar in principle to the mesowear method based on angle measurements taken from dentine valleys between the enamel lamellae on the occlusal surface of an elephant molar. We show that these tooth wear angles correlate significantly with stable carbon isotope values measured from tooth enamel of fossil and recent populations of elephants in tropical Eastern Africa and Asia. Because the carbon isotope values reflect the proportion of C4-photosynthetising grasses in the diet of tropical elephant populations, we conclude that the wear angle measurements reflect the proportion of abrasive material, mainly C4 grass, in elephant diet. We applied the wear angle method for assessing the diet of the Late Pleistocene Columbian mammoth (Mammuthus columbi) population from Rancho la Brea, California, and found it to be highly abrasion dominated, as expected.
Aikajakso27 lokakuuta 2013 - 3 marraskuuta 2013
Tapahtuman tyyppiMuu
SijaintiLos Angeles, CA, Yhdysvallat (USA)
Tunnustuksen arvoKansainvälinen