Widespread concern about environmental pollution is putting a new question to the fossil record: How has the biosphere reacted to chemical changes in the past? Monera and Protoctista might be expected to provide valuable clues in this quest since their biomineral remains are generally formed in conditions closely related to the environment. But why do unicells biomineralize at all? It was with such questions in mind that an international symposium of the Systematics Association on “Biomineralization in Lower Plants and Animals” was held at Birmingham on April 15–19, 1985. Monerans, protoctistans, lichens, calcareous algae, and bryozoans were discussed in 36 papers, of which 23 are to be published in a volume by Oxford University Press. This volume, edited by Leadbeater and Riding (1986), will form a natural sequel to the papers in Miller et al. (1984) on mineral phases in biology and in Westbroek and de Jong (1983) on biomineralization and biological metal accumulation.

The evolutionary bootstrap is a new approach to the analysis of patterns of taxonomic diversity. In general, the evolutionary bootstrap works by surveying the diversity history of a taxon, learning its dynamic properties, and then generating randomly large numbers of artificial diversity histories based upon what was learned. The distribution of artificial—or bootstrapped—diversity histories approximates the distribution of diversity histories that were possible for taxa with the dynamic properties of the real taxon, and serves as a paleontological null hypothesis for studying statistically the diversity history of the real taxon.

Two null hypotheses were established, the additive and the multiplicative. The additive null hypothesis assumes that the amount of diversity change that occurs in a higher taxon during an interval of time is independent of the number of member subtaxa present at the beginning of the interval. The multiplicative null hypothesis, in contrast, assumes that the amount of diversity change that occurs is dependent upon the number of member subtaxa present at the start. Thus the two null hypotheses represent end members of a diversity-independent/diversity-dependent continuum of possibilities.

Detailed analyses using the evolutionary bootstrap, in conjunction with the clade statistics of Gould et al. (1977), show that several of the 17 higher taxa studied have diversity histories that are statistically significantly different from the random expectation under one or both null hypotheses. Analyses of multiple taxa in aggregate also reveal several properties of diversity histories that are statistically significantly different from random. Real taxa tend to have higher uniformities and lower maximum diversities than expected under the multiplicative null hypothesis. They have lower uniformities, higher maximum diversities, and longer durations than expected under the additive null hypothesis. And, they have lower centers of gravity than expected under either null hypothesis. Overall, the results provide a possible statistical verification of the process of taxonomic (traditionally, adaptive) radiation and suggest the need to consider deterministic explanations for observed diversity patterns.

Mammalian species often exhibit clinal geographic variation in body size: individuals tend to be larger in areas with lower mean annual temperature. Climatic change involving increasing or decreasing mean annual temperature may cause clines to shift geographically, resulting in a phenotypic shift at all affected locales within a species' range. I assess the potential of shifting geographic clines to produce morphological trends in the fossil record. Five extant North American mammalian species (Didelphis virginiana, Mephitis mephitis, Odocoileus virginianus, Scalopus aquaticus, and Sciurus carolinensis) are examined to quantify size change along latitudinal clines and to estimate the geographic range and temperature difference commonly associated with a given difference in body size. Relative to body size, the observed size range of skeletal characters within each of these five species is comparable to that seen in a much larger sample of North American mammals. Thus patterns of variation documented for the five species may be used to assess the likelihood of dine translocation as an explanation of size change in the mammalian fossil record. As a case study, I examine three lineages from the Early Eocene of the Bighorn Basin, Wyoming. I determine that size change in these chronoclines represents evolutionary change and is not merely the result of shifting geographic clines.

Biometric analyses of the ontogenies of 31 species of fossil echinoids support a hypothesized relationship between regulatory gene changes and environmental stability. In 15 of 17 pairs of related species, the larger species, undergoing slower (neotenic) and/or prolonged (hypermorphic) growth, apparently inhabited the stabler environment. If true, this relationship connects biological processes at a number of levels and explains or agrees with some important macroevolutionary observations, such as onshore evolutionary innovation and Cope's Rule.

Animals evolve by changing their form and by changing the rate at which they develop. Since evolution of development through time may be directly related to the adaptation of their life histories, study of ontogeny in fossils may yield information about the ecology of extinct animals. We need to know how to measure animals' ontogeny and at what taxonomic level structural differences overshadow differences in development. Two closely related species of the Permian ostracode Cavellina were compared to determine how much of the morphological difference between them is due to differences in their ontogenies. Most of the difference is not related to ontogeny. They also differ in a way that could be explained by heterochrony, although this difference is secondary in importance to the structural difference. These findings suggest that ecological adaptation might best be studied by examining the changes in development that occur within species through time and space.

Specific conductance was calculated for secondary xylem in seven Carboniferous stem taxa utilizing an equation derived from the Hagen-Poiseuille relation. Arborescent and lianoid representatives of major pteridophytic (Calamitaceae, Lepidodenraceae, Sphenophyllaceae) and gymnospermous (Cordaitaceae, Medullosaceae) groups were examined. In the calamite Arthropitys communis and the seed plant Cordaites (Cordaixylon sp. and Mesoxylon sp.), conductance corresponded approximately to the low end of the range for both extant conifers and angiosperms. A substantially higher conductance was determined for the wood of Arthropitys deltoides, conforming to the high end of the range for conifers and the low-middle part of the range for angiosperms. The highest conductance values were found in Sphenophyllum plurifoliatum, Medullosa noei, and Paralycopodites brevifolius and corresponded to the middle-high portion of the range for vessel-containing angiosperms. This outcome is particularly significant in light of the fact that tracheary elements in the fossils are imperforate. The results indicate that conductance in secondary xylem of some of the most ancient, woody groups was comparable to that in extant plants and that highly effective conducting tissue developed relatively early in plant evolution. Moreover, it is suggested that the general relationship between wood anatomy, growth habit, and ecology demonstrated for living plants can also be extended back in time to include fossil plants.

Under conditions of normal calcium metabolism, strontium/calcium ratios (Sr/Ca) have been shown to reflect the trophic level of contemporary and recent terrestrial fauna. These ratios therefore offer a potential means of studying fossil ecosystems and the diet of prehistoric humans. In cases in which suitable controls have demonstrated the preservation of biogenic Sr/Ca, it has been possible to investigate the proportionate importance of meat vs. vegetable foods in the diets of prehistoric humans. However, diagenetic change after interment has made it impossible to discern biogenic Sr/Ca in faunal and human skeletons over 15,000 y b.p. A procedure is investigated for the analysis of biogenic and diagenetic apatite in vertebrate fossils, on the basis of solubility differences among carbonate, hydroxy-, and fluorapatites. When applied to the 2 ma b.p. fauna of the Omo Basin (Ethiopia), distinct characterization of the herbivore, omnivore, and carnivore fauna in conformity with trophism was discerned, in spite of anomalous Sr/Ca of one highly specialized carnivore, Homotherium. Possible metabolic and/or taphonomic explanations of this anomaly are discussed, and future basic research into the solubility profile procedure is outlined.

Wolpoff's (1984) recent discussion of evolutionary rates in Homo erectus deserves careful study. Whether Homo erectus or other hominid species exhibit gradual, continuous change in key characters or whether instead there is evidence for morphological stasis in the fossil record is an important question. By allocating all Homo erectus specimens to three groups of early, intermediate, and later geological age and by comparing group means for 13 measurements, Wolpoff attempts to show that gradualism is the rule for this mid-Pleistocene taxon. This method is straightforward, but it is crucial that the samples be composed in a manner which is biologically reasonable. I argue here that Wolpoff has not done this. While there may be legitimate doubt concerning sorting of the fossils, especially where specimens are incomplete, several of the individuals said to be representative of Homo erectus are simply inappropriate for use in this analysis. Wolpoff insists that he has employed a “conservative” definition of the species, but instead he has measured everything in sight. This approach to the record does influence his results.

Focusing on the question of trends in Homo erectus cranial capacity evolution, Rightmire contends to have reanalyzed the data and demonstrated “a pattern of change … quite different from that described by Wolpoff.” Accepting the procedures used in this earlier analysis (Wolpoff 1984), he does this by changing the composition of the Homo erectus sample.