Benthic ecologists have successfully applied rarefaction techniques to the problem of compensating for the effect of sample size on apparent species diversity (= species richness). The same method can be used in studies of diversity at higher taxonomic levels (families and orders) in the fossil record where samples represent world-wide distributions of species or genera over long periods of geologic time.

Application of rarefaction to several large samples of post-Paleozoic echinoids (totaling 7,911 species) confirms the utility of the method. Rarefaction shows that the observed increase in the number of echinoid families since the Paleozoic is real in the sense that it cannot be explained solely by the increase in numbers of preserved species. There has been no statistically significant increase in the number of families since mid-Cretaceous, however. At the order level, echinoid diversity may have been nearly constant since late Triassic or early Jurassic.

Taxonomic survivorship curves may reflect stratigraphic as well as biologic factors. The approximately lognormal distribution of lengths of Phanerozoic time intervals produces an error in the estimation of taxonomic durations that is also lognormally distributed. As demonstrated by several simulated examples, this error may cause concave taxonomic survivorship curves to appear linear, especially if the maximum durations involved are relatively short. The error of estimation also makes highly concave taxonomic survivorship curves virtually unrecognizable. Incomplete sampling of the fossil record, on the other hand, may not be a serious problem in survivorship analysis. Simulated paleontological sampling employing a simple model suggests that survivorship curves tend to retain their original shapes even when as few as 20% of the taxa have been discovered. However, concave taxonomic survivorship curves tend to lose their concavity as efficiency of sampling declines.

The linear survivorship curve of Van Valen's Law can be generated from stochastic loss of lineages, given a decreasing sample size within an adaptive zone. No special biological explanation is required or called for in order to explain “linearity” in taxonomic survivorship curves.

While the importance of allopatric speciation in the fossil record has long been underestimated, phyletic change within single unbranching lineages also occurs. The 50% increase in thoracic width observed in the radiolarian species Pseudocubus vema from an Antarctic deep-sea core is a clear example of a long-term phyletic trend in a continuous fossil sequence. Phyletic change in P. vema occurred at varying rates, but changes in the morphologic rate of evolution do not correspond to any obvious breaks in the fossil record such as would be indicated by missing segments of the core's magnetic stratigraphy. Variation in thoracic width, as measured by the coefficient of variation, does not depend on the morphologic rate of evolution, proportional rate of evolution, nor the amount of time required for the width to change by one standard deviation, so much as it depends on whether change was accomplished by addition or removal of extreme phenotypes to or from the population.

Open-ended tubes were found extending inward from the inner surfaces of brachial valves of three different species of Emsian spiriferid brachiopods. It is believed that these tubes were formed by the outer epithelium of the brachiopods, precipitating shell material around a small commensal filter feeding organism living in the outer mantle cavity. The position of the open ends of these tubes, the business end of the filter feeding organism, in every case discovered is between the bases of the two spiralia. This lends support to the suggestion of Ager (1961) and Wallace and Ager (1966) that spiriferid brachiopods had median inhalant and lateral exhalant feeding currents. These structures are named Burrinjuckia spiriferidophilia n.gen. n.sp. They are trace fossils of indeterminate taxonomic position.

Magadina cumingi (Davidson) lives in an environment of high current energy and mobile sediments using the pedicle as an elevating device. This previously undescribed substrate relationship is reflected in pedicle form, the muscular system, distribution of secondary thickening and characters of the beak. The cardinalia provide the evidence of key differences in the muscular system from an attached species Magellania australis (Quoy and Gaimard) and a free lying species with atrophied pedicle Neothyris lenticularis (Deshayes). The possession of an open foramen in articulate brachiopods is not synonymous with permanent attachment.

It has been claimed that articulate brachiopods are excluded from turbulent environments by the weakness of their pedicle attachment. The evidence does not support this conclusion. Experiments on the force required to remove brachiopods from their substrate show that removal force often equals that of bivalve mussels from turbulent environments having the same valve area. Intertidal brachiopods probably occupy cryptic habitats to avoid desiccation, not to avoid waves. Subtidal brachiopods are abundant in tidal currents of 4 knots (2 m/sec) where they are usually attached in exposed positions.

Although paleoecologists often assume that the size of the pedicle foramen is directly proportional to attachment strength, the relationship is not precise. Experimental detachment of brachiopods resulted from failure of the substrate, pedicle-substrate attachment, pedicle, or pedicle adjustor muscles, in approximately equal frequencies. At the same attachment strength, the foramen in Terebratalia is four times the size of the foramen in Hemithiris.

Although subapical foramina are supposedly unable to enlarge as the brachiopod grows, the subapical foramen of Hemithiris appears to do so.