In the past fifteen years, the biological interpretation of vertebrate fossils has been markedly advanced by the application of experimental techniques in functional morphology, biomechanical and allometric modelling, more rigorously-derived empirical correlations between form and function in living species, and studies of modern community structure and of the taphonomic processes by which fossil assemblages are formed. Traditional paleontological methods of phylogenetic analysis are under attack by the advocates of cladistics; the resulting debate is leading to increased rigor in paleontological systematics. Paleobiogeographical studies of vertebrates has become an extremely active area of research due to the need to reanalyze past distribution patterns in the light of plate tectonics.

New information has extended the fossil record of vertebrates back to the Late Cambrian, but little more is known about the nature of the earliest vertebrates or of the pre-vertebrate ancestors. Much has been learned of the fishes antecedent to tetrapods but little of the earliest tetrapods. The early reptiles are now well known, but the nature of their amphibian ancestors is uncertain. Restudy of Archaeopteryx has suggested a dinosaurian ancestry for birds. The origin and early evolution of mammals is the subject of extensive research as a result of greatly augmented recent collecting. The most active and innovative research is on the biology of dinosaurs, especially on their physiology. Among Cenozoic mammals, the fossil record of primates has been greatly expanded and knowledge of primate history, from the basal prosimians of the Paleocene to early man, is increasing rapidly.

An equation for the distribution of divergence times between closest relatives is derived to explore the possibility that contemporary data might shed some light on the controversy between supporters of gradual versus punctuated phyletic change. The principal assumptions of the model are uniform rates of speciation and extinction, bifurcating speciation, and uniform patterns of divergence, by whatever measure, among species in a taxon. The structure of the model indicates clear differences between patterns generated by extremes of gradualism and punctuation. But inability to verify critical assumptions considerably weakens the applicability of the model to the gradualism-punctuation problem.

Evolutionary paleontologists seek explanations of form and pattern in a diversity of contexts. A review of this diversity is presented to underscore the difficulty of producing a general model of the factors controlling the morphology of real organisms. A model specific to the marine prosobranch gastropod radula identifies seven factors contributing to form and pattern: (1) phylogenetic, (2) mechanical, (3) ecological, (4) programmatic, (5) maturational, (6) degenerative, and (7) constructional. Aspects of radular morphology attributable to each factor are illustrated in scanning electron micrographs of radulae of marine prosobranch gastropods. Applications of and extrapolations from the radular model are made to promote recognition of a broader range of interacting factors in other systems. Some aspects of form and pattern convey important information about non-evolutionary processes and phenomena and are best examined outside of the evolutionary framework.

Elongate canines evolved independently at least four times among mammalian carnivores, and each time skulls were modified in similar ways. We have compared the cranial morphology of sabertooths to that of their non-sabertoothed relatives, living and extinct, and applied simple biomechanical models to elucidate the functional significance of the morphological differences. Our analysis suggests that (1) sabertooth morphology represents modification for wider gape with retention of a powerful bite force at the carnassial; (2) sabertooths probably used a throat or ventral neck slash to kill prey; and (3) elongate canines and retractile claws may have facilitated the exploitation of relatively larger prey by sabertooths compared to non-sabertooth carnivores.

Ciliary transport of particulate suspensions in water was studied in the mantles of the inarticulate brachiopod Lingula anatina, the articulate brachiopod Coptothyris grayi and in the ciliated epithelium of the scleractinian coral Montipora foliosa. In both brachiopod species a close correlation was found between the water currents induced by the lophophore and by the mantle. Lophophore and mantle are considered here as functionally integrated organs which are active in the transport and capture of food, accumulation and the removal of (pseudo-)faeces, the sorting of particles, the pumping of water and respiration.

The tuberculate surface of Montipora foliosa is lined with ciliated epithelium; the polyps are situated in the depressions of this surface. The particulate suspension within the labyrinth is constantly diluted: particles are funneled through the furrows but end up at the tips of the tubercles. On their way they pick up some mucus. While they concentrate on the tubercles they coalesce to form larger boluses that are easily removed. The tubercular tips thus act as “bolus accumulators” and the unciliated margins of the brachiopod mantles appear to have the same function. In this accumulated form the particles are probably prevented from being recycled through the food-capturing system.

Based on these observations a preliminary functional interpretation is presented of some fossil brachiopods: the Devonian rhynchonellids Uncinulus and Hypothyridina and the Strophomenida, with the genus Marginifera serving as an example of the latter order. The morphology of the inner shell surface, and the inferred configuration of the lining ciliated mantle, was modified in these taxa by a variety of structures such as spines, tubercles, diaphragms and trails. It is suggested that the mantle of the evolved Uncinulidae and of the Strophomenida is particularly suited for the dilution of particulate suspensions before they reach the lophophore and for the accumulation and removal of mucous pseudofaeces. The inhibitory effect of the constrictions on the circulation of water could be counteracted by local ciliary pumping. In the strophomenids the mantle became a specialized and elaborate organ, while the lophophore probably remained relatively simple. In the other articulate stocks the lophophore became the central food-gathering and pumping device and in general the morphology of the mantle was maintained simple.

The bivalves Spisula solidissima, the Atlantic surf clam, and Arctica islandica, the ocean quahog, from the continental shelf off New Jersey, contain repeating structures in their shells. By analyzing the growing shell margins in living specimens at bi-weekly (or sometimes monthly) intervals throughout two consecutive years, it was possible to define an annual cycle of shell growth increment formation in both species. The shell increments in each species are microstructurally distinct units that form over a period of several months at select seasons of the year. Each species has two alternating shell growth increments, GI I and GI II. GI I (the annual growth line of previous studies) is formed annually in the late summer-fall in S. solidissima and in the fall-early winter in A. islandica. These periods correspond to the spawning phase of the reproductive cycle in both species. No winter rings were found. The annual increments were used to determine age and growth rate in both Recent and Pleistocene specimens. They may also be useful in determining season of death. Because shell growth increments are formed in synchrony among living populations in these species, mass mortalities may be distinguished in the fossil record. Accurate age and growth rate determinations in fossils are important in many paleobiologic contexts, such as deciding between increased longevity or growth rate in cases of phyletic size increase.

Based on inspection of gnawing damage done to bones of modern prey animals, sets of typical damage types or patterns are recognized for certain elements. The presence of these damage patterns suggests carnivore activity even when bones exhibit no identifiable tooth marks or other obvious sign of gnawing. Observations are made of these damage types on bones of Pleistocene and Recent North American mammals, including Bison, proboscidean, Alces, Equus, Cervus, and Rangifer. Damage to the following elements is briefly described: antlers, vertebrae, scapulae, humeri, ulnae, radii, femora, tibiae, metapodials, and innominates.

Two types of predation (shell breakage at the lip by calappid crabs and drilling by gastropods) were studied in more than 6000 Recent and 1500 fossil terebrid gastropods. The occurrence of lip-peeling was assessed by the frequency of shell repair, defined as the number of repaired injuries divided by the total number of shells in a sample. This frequency is interpreted as a measure of the demonstrated importance of the shell as a protective device against peeling. In the Recent fauna, frequencies of repair are highest in the tropical Indo-West-Pacific, intermediate in tropical America, and lowest in warm-temperate areas. When comparisons are restricted to particular size classes, these geographical differences become blurred, especially among smaller shells. Slender, many-whorled species have significantly lower frequencies of repair than do terebrids with more compact shells. Samples of Terebra affinis from atolls have fewer repairs than do those from high islands or continental shores. Among fossils, there is no difference in repair between Paleogene and Neogene samples. In the Miocene, warm-temperate terebrids had frequencies of repair similar to those of tropical species. The frequency of repair is loosely correlated with the number of species of shell-peeling calappid crabs. Frequencies of drilling have been at high modern levels since Eocene time. Incomplete drill-holes are common in large Recent species, and suggest that the terebrid shell is well adapted to withstand attacks by naticid gastropods. The results of this study are consistent with those of architectural analyses of soft-bottom gastropod assemblages and with other studies on predation of gastropods.