The way in which living reptiles are related to prehistoric reptiles is constantly being revised, as more and earlier fossils are unearthed and dating becomes more sophisticated. The earliest reptiles, descendents of ancient amphibian-like creatures, appeared about 300 million years ago (mya). These ancestral reptiles were able to invade land by developing a waterproof skin and laying shelled eggs in which their young could develop on land. Together with the dinosaurs and the pterosaurs (the first flying reptiles, often known as pterodactyls), crocodilians (modern crocodiles and alligators) and birds have evolved from an ancestral group known as the Archosauria or Ruling Reptiles. <...>

This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the National Research Council’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. <...>

As the need grows for conceptualization, formalization, and abstraction in biology,so too does math- ematics’relevance to the field (Fagerström et al. 1996).Math- ematics is particularly important for analyzing and characterizing random variation of, for example,size and weight of individuals in populations,their sensitivity to chemicals, and time-to-event cases, such as the amount of time an individ- ual needs to recover from illness.The frequency distribution of such data is a major factor determining the type of statistical analysis that can be validly carried out on any data set. Many widely used statistical methods,such as ANOVA (analysis of variance) and regression analysis,require that the data be normally distributed, but only rarely is the frequency distribution of data tested when these techniques are used. <...>

The concept of longwall mining in the United States dates back to the late 19th century when wide faces were used for coal extraction in the Pittsburgh seam. But modern, fully mechanized longwall mining employing plows and frame supports was first introduced from West Germany in the early 1950s in southern West Virginia. It was used mainly for thin seam mining. During the 1950s and 1960s, the practice did not expand. In fact, due to its poor performance, only a few mines in southern West Virginia employed this technique.