Stages Of Tooth Wear Research Articles

EARLY PLEISTOCENE SEROTINE BAT <i>EPTESICUS PRAEGLACIALIS</i> (VESPERTILIONIDAE, CHIROPTERA) FROM THE TAURIDA CAVE IN CRIMEA

The cranial and mandibular remains of a large serotine bat Eptesicus praeglacialis Kormos, 1930 are described from the Lower Pleistocene deposits of the Taurida cave in the central Crimea. This is the first finding of the skull material of E. praeglacialis and the first record of the species in Crimea. Judging by the tooth wear stages, the remains of both young and adult specimens are present in the taphocenosis. The small mammal tooth marks on the bones (caused by eating the remnants of soft tissues) in the absence of signs of digestion, characterizing materials from the predatory bird pellets, indicate that the taphocenosis includes the remains of E. praeglacialis individuals that used the cave as a shelter and died there. This corresponds to the idea of appearance of hibernation in caves as a climatically determined ecological adaptation in some European forest-dwelling bats (including Eptesicus) at the Pliocene–Pleistocene transition.

Determining Age and Season of Death by Use of Incremental Lines in Norwegian Reindeer Tooth Cementum

ABSTRACTUsing incremental patterns in tooth cementum is a powerful tool for age assessment. Recent developments have shown that the method has a large potential as an indicator of the season of death of the individual in question. In this paper, the results of a study comparing thin sections of teeth of the modern Hardangervidda reindeer population to those of Iron Age, eleventh, and thirteenth century reindeer hunting stations from the same area are presented. The tooth wear stages were compared to the actual age of the individual (based on the number of incremental lines and the age at eruption). It was established that in the studied reindeer populations wear stages sometimes result in too low an age estimate. Having identified the start of the period of deposition for rest lines in the modern reindeer population as early autumn and winter, analysis of the outermost layer in the tooth cementum at the archaeological sites points to a prolonged hunting season in the thirteenth century, while in the earlier phases hunters were probably present on fewer and shorter visits.

Evaluation of methods to age Scottish red deer: the balance between accuracy and practicality

AbstractKnowing the age of individuals is crucial for almost any analysis of population dynamics, evolution, palaeontology, management and conservation. The aim of this study was to provide the practitioner with a practical and cost‐effective method to estimate the age of large numbers of red deer samples. Using 694 mandibles ofScottish red deer of known age, we compared the bias and precision of five of the most widely used methods for estimating the age of red deer based on tooth characters. Two methods based on reference collections of photographs representing different stages of tooth wear, two methods describing the traits that characterise different classes of the tooth wear and age, and one method based on counting the cementum layers of the radicular pad of the first permanent molar, were used. We also described 13 age classes up to 38 months of age based on different stages of eruption of lower molar teeth. We applied a sequential stepwise‐like selection procedure in conjunction with cross‐validated predictions using the prediction error sum of squares statistic, with the aim of reducing the large number of traits that the two methods based on tooth wear trait descriptions require to estimate age. We were able to reduce the number of traits by 70% and still gain precision and reduce bias in the predictions, which indicated that the equations provided by these two methods overfitted the age of our reference samples. The cementum layers method was the most precise and least biased of all the methods, followed byDudley's method. We provide the practitioner with recommendations to allow estimation of the ages ofScottish red deer, together with comprehensive graphic material to facilitate the use of the different methods.

A new index to measure tooth wear--methodolgy and practical advice.

A new tooth wear index, designed to measure stages of tooth wear in enamel and dentine is presented. The index measures the lateral spread of wear in enamel and the depth of tooth wear in dentine. The index scores enamel loss at 5 levels and 6 levels in dentine and provides a more sensitive index for monitoring the progression of wear than older indices. The protocols and methods of the index are described and incorporate refinements based on the combined experiences of two independent studies conducted on adults and children. The findings of both studies are summarised and recommendations are made for future studies which investigate the prevalence of tooth wear in adults or children.

Fossil middle triassic “sea cows” – placodont reptiles as macroalgae feeders along the north-western Tethys coastline with Pangaea and in the Germanic basin

The descriptions of fossil Triassic marine pla- codonts as durophagous reptiles are revised through comparisons with the sirenia and basal proboscidean mammal and palaeoenvironment analyses. The jaws of placodonts are conver- gent with those of Halitherium/Dugong or Mo- eritherium in their general function. Whereas Halitherium possessed a horny oral pad and counterpart and a special rasp-like tongue to grind seagrass, as does the modern Dugong, placodonts had large teeth that covered their jaws to form a similar grinding pad. The sirenia also lost their anterior teeth during many Millions of years and built a horny pad instead and specialized tongue to fed mainly on seagrass, whereas placodonts had only macroalgae availa- ble. Indirect evidence for Triassic macroalgae is provided by benthic palaeocommunities from different layers and extended European regions in the Germanic Basin. Studies of tooth wear stages for Placodus indicate that anterior teeth may have been used in a similar manner to the procumbent front teeth of modern Dugong. Paraplacodus and Placodus seem to have used these teeth as spatulas to dig out seaplants. Cyamodus and other placodonts such as Placochelys had smaller or reduced anterior teeth. The scarcity of highly worn palatine or maxillary and lower jaw dentary Placodus or Cyamodus teeth (less then 0.5%) suggests that they had a relatively soft diet. The seaplants would only have been squeezed in a similar feeding strategy to that of modern Dugong feeding on seagrass without jaw rotation and grinding. The phylogenetic trend in tooth reduction within the placodonts Paraplacodus, Placodus, especially in Cyamodus but also Placochelys, and Henodus within 11 My appears to have been a result of this plant-feeding adaptation and may even explain the origin or at least close relationship of the earliest Upper Triassic turtles as toothless algae and jellyfish feeders, in terms of the long-term convergent development with the sirens.

Connecting morphology, function and tooth wear in microchiropterans

A key objective in understanding the dentition of mammals is the ability to predict the function of teeth from their shape. Very few studies have used dental measurements that allow the prediction of comparative tooth effectiveness, particularly when modification in shape due to tooth wear is considered. Here, dental parameters are used in which a change in the parameter is readily interpretable in terms of change in factors such as increased force or energy required for cusps or crests to break down food. The functional parameters were measured for 3-D digital tooth reconstructions of the upper molars of the microchiropteran Chalinolobus gouldii at various stages of tooth wear. The changes in the majority of the parameters, such as decreased tip, edge and cusp sharpnesses, cusp occlusion relief, rake angle and fragment clearance, predict a deterioration in efficacy with increased wear. This conclusion has not been possible with alternative approaches; for instance, there was no significant change in crest length with wear, and so no change in function would be predicted from that measure. Some of the parameters did not change significantly with heavy wear, such as capture area of a crest, pointing to geometrical and design characteristics for the maintenance of shape with wear in the dilambdodont tooth form. Attrition and abrasion can be considered as wear on the relief and rake surfaces of tribosphenic-like crests, respectively. The differences in function of these two surfaces account for the differences in wear patterns. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85, 81–96.

Systematics and paleobiology of the anthropoid primate Pondaungia from the late Middle Eocene of Myanmar

Several newly recovered specimens documenting the Eocene Myanmar (South East Asia) anthropoid taxa Pondaungia and Amphipithecus modify the classical understanding of the taxonomy of these two primates, which have in fact no substantial morphological differences. Using tooth wear stages and the elevation of the horizontal branch of the mandible below the foramen mentale, we show a continuous variation, here attributed to individual aging. In addition, a strong size dimorphism is demonstrated, which is attributed to sexual dimorphism. In this context, Amphipithecus mogaungensis holotype is interpreted as a male of Pondaungia cotteri, which is recognized as the only large-bodied anthropoid of the Pondaung Formation. Growth arrest lines (LAGs) have been observed in several sections of lower jaws attributed to that species. These LAGs are here interpreted as regular increments, which formed in response to seasonal variability in the environment. They likely correspond to annual cycles, and the minimum longevity of the individuals can thus be roughly estimated. Several features indicate that P. cotteri may have been adapted to hard food diet and to survive in a strong seasonal climate with annual food shortage periods. To cite this article: J.-J. Jaeger et al., C. R. Palevol 3 (2004).