In recent articles in this journal Hansen (1980) and Jablonski (1980) discussed the planktonic larval stages of fossil benthic invertebrates and the relation of type of larval development to geographic ranges, nearshore-offshore position, speciation, and extinction. The fossil record provides a view of long term consequences of types of larval development, and the emphasis of these, and other, paleobiological studies was on selection among species which are characterized by different developmental adaptations.

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.

The prices of scientific books are much talked about, but data to serve as points of reference on the subject are hard to come by. Table 1 shows the results of some attempts to find such data. The first row of data given is taken from the most frequently cited set of statistics on book prices, the average per-volume prices of hardcover books (U.S. domestic and imported) published annually by the R. R. Bowker Company. The Bowker tabulation attempts to be exhaustive but includes under “science” (i.e., Dewey Decimal 500–599) books intended for general audiences and therefore can be expected to underestimate the prices of books needed by working scientists.

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.

The Field Museum of Natural History, Chicago, held a conference on Macroevolution, October 16–18; it was organized by J. Cracraft, J. Levinton, N. Eldredge and D. M. Raup. The nature of the meeting called to mind the 1946 Princeton conference on Genetics, Paleontology and Evolution (which resulted in the book of the same name1), and indeed 3 members of that conference spoke again, 34 years later, in 1980—Sewall Wright, G. Ledyard Stebbins, and Bobb Schaeffer. However, no book is planned this time.

The presumed geometry of clam and brachiopod clades (brachiopod declines matched closely by clam increases) has long served as primary data for the classic case of gradual replacement by competition in geological time. Agassiz invoked the geometric argument to assert the general superiority of clams, and it remains the standard textbook illustration today. Yet, like so many classic stories, it is not true. The supposed replacement of brachiopods by clams is not gradual and sequential. It is a product of one event: the Permian extinction (which affected brachiopods profoundly and clams relatively little). When Paleozoic and post-Paleozoic times are plotted separately, numbers of clam and brachiopod genera are positively correlated in each phase. Each group pursues its characteristic and different history in each phase—clams increasing, brachiopods holding their own. The Permian extinction simply reset the initial diversities. The two groups seem to track each other in each phase and a plot of brachiopod vs. clam residuals (each from their own within-phase regressions against time) yields significantly positive association. Some of this tracking may be an artifact of available rock volumes; we could, however, detect no effect of stage lengths. Passive extrapolation of microevolutionary theory into the vastness of geological time has often led paleontologists astray. Competitive interaction may rule in local populations, but differential response to mass extinctions (surely not a matter of conventional competition) may set the relative histories of large groups through geological time. Similarly, adaptive superiority in design cannot, in the usual sense of optimal engineering, have much to do with the macroevolutionary success of clams. The interesting question lies one step further back: what in the inherited Bauplan of a clam permits flexibility in design and why are other groups, however successful in their own domain, unable to alter their basic design.

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:

(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.

(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.

(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

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.

In evaluating the biotic effects of transgressions and regression, care must be taken to ensure that observed patterns are not simply an artifact of the location of available stratigraphic sections along an ancient onshore-offshore gradient of adaptive types. Analysis of Recent bivalves suggests that very nearshore benthic assemblages are dominated by species that are geographically more widespread, are more eurytopic, and more often have planktotrophic larvae than species in offshore assemblages (Jackson 1974; Jablonski and Valentine 1980); this pattern may serve as a null hypothesis for paleobiogeographic analysis. Late Cretaceous bivalve and gastropod faunas of the Gulf and Atlantic Coastal Plain exhibit decreasing levels of endemism and increasing mean geographic range over the course of regression and return to high levels of endemism and low mean geographic range with the succeeding transgression. In addition, species with longer durations are more frequent at peak regression, while geologically shorter-lived species are more prevalent at peak transgression. As seen in Recent examples, the molluscan assemblages from nearshore facies have a higher proportion of species with broad environmental tolerances and planktotrophic larvae, and thus more extensive geographic and stratigraphic ranges, than do the more offshore shelf assemblages. Because late regressive phases are represented only by very nearshore facies, these directional changes in biogeographic and evolutionary characteristics are most parsimoniously interpreted as a reflection of the nature of the facies available for sampling rather than biotic effects of transgression and regression.

Previous descriptions and interpretations of the Cycadeoidea pollen organ are followed by a new interpretation based upon its presumed neotenous condition. The sexually mature pollen organ represents a juvenile morphological condition that persisted into the adult stage of the organism and was inherited ultimately from a seed fern ancestor. The neotenous organ is considered to have come into existence abruptly and the altered morphology to have been achieved without an intervening series of intermediates. Abrupt establishment of higher taxa by heterochrony constitutes a mechanism capable of decoupling microevolutionary processes from macrevolutionary differences and poses a distinct challenge to current evolutionary theory.

The statistical significance of differences in evolutionary rate between major taxonomic groups is evaluated using conventional chi-square techniques on stratigraphic range data. Romer's (1966) compilation of stratigraphic ranges of fossil mammals is used to determine whether orders differ significantly from each other in generic origination and extinction rates. The evolutionary histories of 2180 genera (primarily Cenozoic in age) are analyzed. Chi-square testing shows that significantly high or low (P ≥ 0.99) extinction or origination occurs in 15% of the testable cases. Significantly high or low evolutionary turnover in a taxon (orders in this case) we term taxotely. Significantly high turnover rate is equivalent to Simpson's tachytely and significantly low turnover is equivalent to his bradytely.

In the mammal data set, taxotely is largely attributable to the influence of South American endemics. Some of the effect is interpreted as an artifact of biases in the fossil record (or its study) and some is attributed to real biological aspects of mammalian evolution.

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.